ci: Remove hydra support.

This removes hydra support to use Cuirass as the only continuous integration
system.

* build-aux/hydra/gnu-system.scm: Remove it.
* build-aux/hydra/guix-modular.scm: Ditto.
* build-aux/hydra/guix.scm: Ditto.
* build-aux/cuirass/hydra-to-cuirass.scm: Ditto.
* Makefile.am (EXTRA_DIST): Update it.
(hydra-jobs.scm): Remove it.
(cuirass-jobs.scm): Update it.
* build-aux/hydra/evaluate.scm: Move it to ...
* build-aux/cuirass/evaluate.scm: ... here.
* build-aux/cuirass/guix-modular.scm: Remove it.
* build-aux/cuirass/gnu-system.scm: Ditto.
* guix/packages.scm (%hydra-supported-systems): Rename it to ...
(%cuirass-supported-systems): ... this variable.
* build-aux/check-final-inputs-self-contained: Adapt it.
* etc/release-manifest.scm: Ditto.
* gnu/ci.scm (package->alist): Remove it.
(derivation->job): New procedure.
(package-job, package-cross-job, cross-jobs, image-jobs, system-test-jobs,
tarball-jobs): Use it.
(guix-jobs): New procedure.
(hydra-jobs): Rename it to ...
(cuirass-jobs): ... this procedure.

13 files changed, 320 insertions, 769 deletions

diff --git a/Makefile.am b/Makefile.am
index bb27297096..0f87c958f7 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -608,14 +608,7 @@ EXTRA_DIST +=						\
   etc/historical-authorizations				\
   build-aux/build-self.scm				\
   build-aux/compile-all.scm				\
-  build-aux/hydra/evaluate.scm				\
-  build-aux/hydra/gnu-system.scm			\
-  build-aux/hydra/guix.scm				\
-  build-aux/hydra/guix-modular.scm			\
-  build-aux/cuirass/gnu-system.scm			\
-  build-aux/cuirass/guix-modular.scm			\
   build-aux/cuirass/hurd-manifest.scm			\
-  build-aux/cuirass/hydra-to-cuirass.scm		\
   build-aux/check-final-inputs-self-contained.scm	\
   build-aux/check-channel-news.scm			\
   build-aux/compile-as-derivation.scm			\
@@ -955,28 +948,18 @@ check-channel-news: $(GOBJECTS)
 	$(AM_V_at)$(top_builddir)/pre-inst-env "$(GUILE)"	\
 	  "$(top_srcdir)/build-aux/check-channel-news.scm"
 
-# Compute the Hydra jobs and write them in the target file.
-hydra-jobs.scm: $(GOBJECTS)
-	$(AM_V_at)$(MKDIR_P) "`dirname "$@"`"
+# Compute the Cuirass jobs.
+cuirass-jobs: $(GOBJECTS)
+	rm -rf "$@"
+	$(AM_V_at)$(MKDIR_P) "$@"
 	$(AM_V_GEN)$(top_builddir)/pre-inst-env "$(GUILE)"		\
-	  "$(top_srcdir)/build-aux/hydra/evaluate.scm"			\
-	  "$(top_srcdir)/build-aux/hydra/gnu-system.scm" > "$@.tmp"
-	$(AM_V_at)mv "$@.tmp" "$@"
-
-# Compute the Cuirass jobs and write them in the target file.
-cuirass-jobs.scm: $(GOBJECTS)
-	$(AM_V_at)$(MKDIR_P) "`dirname "$@"`"
-	$(AM_V_GEN)$(top_builddir)/pre-inst-env "$(GUILE)"		\
-	  "$(top_srcdir)/build-aux/hydra/evaluate.scm"			\
-	  "$(top_srcdir)/build-aux/cuirass/gnu-system.scm" 		\
-	  cuirass > "$@.tmp"
-	$(AM_V_at)mv "$@.tmp" "$@"
+	  "$(top_srcdir)/build-aux/cuirass/evaluate.scm" "$@"
 
 .PHONY: gen-ChangeLog gen-AUTHORS gen-tarball-version
 .PHONY: assert-no-store-file-names assert-binaries-available
 .PHONY: assert-final-inputs-self-contained check-channel-news
 .PHONY: clean-go make-go as-derivation authenticate
-.PHONY: update-guix-package update-NEWS release
+.PHONY: update-guix-package update-NEWS cuirass-jobs release
 
 # Downloading up-to-date PO files.
 
diff --git a/build-aux/check-final-inputs-self-contained.scm b/build-aux/check-final-inputs-self-contained.scm
index c819086508..a6148d12e3 100644
--- a/build-aux/check-final-inputs-self-contained.scm
+++ b/build-aux/check-final-inputs-self-contained.scm
@@ -83,5 +83,4 @@ refer to the bootstrap tools."
     (set-build-options store #:use-substitutes? #t)
 
     (for-each (cut test-final-inputs store <>)
-              %hydra-supported-systems)))
-
+              %cuirass-supported-systems)))
diff --git a/build-aux/cuirass/evaluate.scm b/build-aux/cuirass/evaluate.scm
new file mode 100644
index 0000000000..fc0744ad2a
--- /dev/null
+++ b/build-aux/cuirass/evaluate.scm
@@ -0,0 +1,105 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2016, 2017, 2018, 2020 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2017 Jan Nieuwenhuizen <janneke@gnu.org>
+;;; Copyright © 2021 Mathieu Othacehe <othacehe@gnu.org>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; This program replicates the behavior of Cuirass's 'evaluate' process.
+;;; It displays the evaluated jobs on the standard output.
+
+(use-modules (guix channels)
+             (guix derivations)
+             (guix git-download)
+             (guix inferior)
+             (guix packages)
+             (guix store)
+             (guix ui)
+             ((guix ui) #:select (build-notifier))
+             (ice-9 match)
+             (ice-9 threads))
+
+(define %top-srcdir
+  (and=> (assq-ref (current-source-location) 'filename)
+         (lambda (file)
+           (canonicalize-path
+            (string-append (dirname file) "/../..")))))
+
+(match (command-line)
+  ((command directory)
+   (let ((real-build-things build-things))
+     (with-store store
+       ;; Make sure we don't resort to substitutes.
+       (set-build-options store
+                          #:use-substitutes? #f
+                          #:substitute-urls '())
+
+       ;; The evaluation of Guix itself requires building a "trampoline"
+       ;; program, and possibly everything it depends on.  Thus, allow builds
+       ;; but print a notification.
+       (with-build-handler (build-notifier #:use-substitutes? #f)
+
+         ;; Add %TOP-SRCDIR to the store with a proper Git predicate so we
+         ;; work from a clean checkout.
+         (let ((source (add-to-store store "guix-source" #t
+                                     "sha256" %top-srcdir
+                                     #:select? (git-predicate %top-srcdir))))
+           (define instances
+             (list (checkout->channel-instance source)))
+
+           (define channels
+             (map channel-instance-channel instances))
+
+           (define derivation
+             ;; Compute the derivation of Guix for COMMIT.
+             (run-with-store store
+               (channel-instances->derivation instances)))
+
+           ;; TODO: Remove 'show-what-to-build' call when Cuirass' 'evaluate'
+           ;; scripts uses 'with-build-handler'.
+           (show-what-to-build store (list derivation))
+           (build-derivations store (list derivation))
+
+
+           ;; Evaluate jobs on a per-system basis for two reasons.  It speeds
+           ;; up the evaluation speed as the evaluations can be performed
+           ;; concurrently.  It also decreases the amount of memory needed per
+           ;; evaluation process.
+           (n-par-for-each
+            (/ (current-processor-count) 2)
+            (lambda (system)
+              (with-store store
+                (let ((inferior
+                       (open-inferior (derivation->output-path derivation)))
+                      (channels (map channel-instance->sexp instances)))
+                  (inferior-eval '(use-modules (gnu ci)) inferior)
+                  (let ((jobs
+                         (inferior-eval-with-store
+                          inferior store
+                          `(lambda (store)
+                             (cuirass-jobs store
+                                           '((subset . all)
+                                             (systems . ,(list system))
+                                             (channels . ,channels))))))
+                        (file
+                         (string-append directory "/jobs-" system ".scm")))
+                    (call-with-output-file file
+                      (lambda (port)
+                        (write jobs port)))))))
+            %cuirass-supported-systems))))))
+  (x
+   (format (current-error-port) "Wrong command: ~a~%." x)
+   (exit 1)))
diff --git a/build-aux/cuirass/gnu-system.scm b/build-aux/cuirass/gnu-system.scm
deleted file mode 100644
index 0eb834cfba..0000000000
--- a/build-aux/cuirass/gnu-system.scm
+++ /dev/null
@@ -1,25 +0,0 @@
-;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2017 Jan Nieuwenhuizen <janneke@gnu.org>
-;;;
-;;; This file is part of GNU Guix.
-;;;
-;;; GNU Guix is free software; you can redistribute it and/or modify it
-;;; under the terms of the GNU General Public License as published by
-;;; the Free Software Foundation; either version 3 of the License, or (at
-;;; your option) any later version.
-;;;
-;;; GNU Guix is distributed in the hope that it will be useful, but
-;;; WITHOUT ANY WARRANTY; without even the implied warranty of
-;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-;;; GNU General Public License for more details.
-;;;
-;;; You should have received a copy of the GNU General Public License
-;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
-
-;;;
-;;; This file defines build jobs for the Cuirass continuation integration
-;;; tool.
-;;;
-
-(include "../hydra/gnu-system.scm")
-(include "hydra-to-cuirass.scm")
diff --git a/build-aux/cuirass/guix-modular.scm b/build-aux/cuirass/guix-modular.scm
deleted file mode 100644
index cbbdbf1133..0000000000
--- a/build-aux/cuirass/guix-modular.scm
+++ /dev/null
@@ -1,6 +0,0 @@
-;;;
-;;; This file defines Cuirass build jobs to build Guix itself.
-;;;
-
-(include "../hydra/guix-modular.scm")
-(include "hydra-to-cuirass.scm")
diff --git a/build-aux/cuirass/hydra-to-cuirass.scm b/build-aux/cuirass/hydra-to-cuirass.scm
deleted file mode 100644
index 75c77ea35a..0000000000
--- a/build-aux/cuirass/hydra-to-cuirass.scm
+++ /dev/null
@@ -1,47 +0,0 @@
-;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2017 Jan Nieuwenhuizen <janneke@gnu.org>
-;;;
-;;; This file is part of GNU Guix.
-;;;
-;;; GNU Guix is free software; you can redistribute it and/or modify it
-;;; under the terms of the GNU General Public License as published by
-;;; the Free Software Foundation; either version 3 of the License, or (at
-;;; your option) any later version.
-;;;
-;;; GNU Guix is distributed in the hope that it will be useful, but
-;;; WITHOUT ANY WARRANTY; without even the implied warranty of
-;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-;;; GNU General Public License for more details.
-;;;
-;;; You should have received a copy of the GNU General Public License
-;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
-
-;;;
-;;; This file defines the conversion of Hydra build jobs to Cuirass build
-;;; jobs.  It is meant to be included in other files.
-;;;
-
-(use-modules ((guix licenses)
-              #:select (license? license-name license-uri license-comment)))
-
-(define (cuirass-jobs store arguments)
-  "Return Cuirass jobs."
-  (map hydra-job->cuirass-job (hydra-jobs store arguments)))
-
-(define (hydra-job->cuirass-job hydra-job)
-  (let ((name (car hydra-job))
-        (job ((cdr hydra-job))))
-    (lambda _ (acons #:job-name (symbol->string name)
-                     (map symbol-alist-entry->keyword-alist-entry job)))))
-
-(define (symbol-alist-entry->keyword-alist-entry entry)
-  (cons (symbol->keyword (car entry)) (entry->sexp-entry (cdr entry))))
-
-(define (entry->sexp-entry o)
-  (match o
-    ((? license?) `((name . (license-name o))
-                    (uri . ,(license-uri o))
-                    (comment . ,(license-comment o))))
-    ((lst ...)
-     (map entry->sexp-entry lst))
-    (_ o)))
diff --git a/build-aux/hydra/evaluate.scm b/build-aux/hydra/evaluate.scm
deleted file mode 100644
index c74fcdb763..0000000000
--- a/build-aux/hydra/evaluate.scm
+++ /dev/null
@@ -1,131 +0,0 @@
-;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2016, 2017, 2018, 2020 Ludovic Courtès <ludo@gnu.org>
-;;; Copyright © 2017 Jan Nieuwenhuizen <janneke@gnu.org>
-;;;
-;;; This file is part of GNU Guix.
-;;;
-;;; GNU Guix is free software; you can redistribute it and/or modify it
-;;; under the terms of the GNU General Public License as published by
-;;; the Free Software Foundation; either version 3 of the License, or (at
-;;; your option) any later version.
-;;;
-;;; GNU Guix is distributed in the hope that it will be useful, but
-;;; WITHOUT ANY WARRANTY; without even the implied warranty of
-;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-;;; GNU General Public License for more details.
-;;;
-;;; You should have received a copy of the GNU General Public License
-;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
-
-;;; This program replicates the behavior of Hydra's 'hydra-eval-guile-job'.
-;;; It evaluates the Hydra job defined by the program passed as its first
-;;; arguments and outputs an sexp of the jobs on standard output.
-
-(use-modules (guix store)
-             (guix git-download)
-             ((guix build utils) #:select (with-directory-excursion))
-             ((guix ui) #:select (build-notifier))
-             (srfi srfi-19)
-             (ice-9 match)
-             (ice-9 pretty-print)
-             (ice-9 format))
-
-(define %top-srcdir
-  (and=> (assq-ref (current-source-location) 'filename)
-         (lambda (file)
-           (canonicalize-path
-            (string-append (dirname file) "/../..")))))
-
-(define %user-module
-  ;; Hydra user module.
-  (let ((m (make-module)))
-    (beautify-user-module! m)
-    m))
-
-(define (call-with-time thunk kont)
-  "Call THUNK and pass KONT the elapsed time followed by THUNK's return
-values."
-  (let* ((start  (current-time time-monotonic))
-         (result (call-with-values thunk list))
-         (end    (current-time time-monotonic)))
-    (apply kont (time-difference end start) result)))
-
-(define (call-with-time-display thunk)
-  "Call THUNK and write to the current output port its duration."
-  (call-with-time thunk
-    (lambda (time . results)
-      (format #t "~,3f seconds~%"
-              (+ (time-second time)
-                 (/ (time-nanosecond time) 1e9)))
-      (apply values results))))
-
-(define (assert-valid-job job thing)
-  "Raise an error if THING is not an alist with a valid 'derivation' entry.
-Otherwise return THING."
-  (unless (and (list? thing)
-               (and=> (assoc-ref thing 'derivation)
-                      (lambda (value)
-                        (and (string? value)
-                             (string-suffix? ".drv" value)))))
-    (error "job did not produce a valid alist" job thing))
-  thing)
-
-
-;; Without further ado...
-(match (command-line)
-  ((command file cuirass? ...)
-   ;; Load FILE, a Scheme file that defines Hydra jobs.
-   (let ((port (current-output-port))
-         (real-build-things build-things))
-     (with-store store
-       ;; Make sure we don't resort to substitutes.
-       (set-build-options store
-                          #:use-substitutes? #f
-                          #:substitute-urls '())
-
-       ;; The evaluation of Guix itself requires building a "trampoline"
-       ;; program, and possibly everything it depends on.  Thus, allow builds
-       ;; but print a notification.
-       (with-build-handler (build-notifier #:use-substitutes? #f)
-
-         ;; Add %TOP-SRCDIR to the store with a proper Git predicate so we work
-         ;; from a clean checkout
-         (let ((source (add-to-store store "guix-source" #t
-                                     "sha256" %top-srcdir
-                                     #:select? (git-predicate %top-srcdir))))
-           (with-directory-excursion source
-             (save-module-excursion
-              (lambda ()
-                (set-current-module %user-module)
-                (format (current-error-port)
-                        "loading '~a' relative to '~a'...~%"
-                        file source)
-                (primitive-load file))))
-
-           ;; Call the entry point of FILE and print the resulting job sexp.
-           (pretty-print
-            (match ((module-ref %user-module
-                                (if (equal? cuirass? "cuirass")
-                                    'cuirass-jobs
-                                    'hydra-jobs))
-                    store `((guix
-                             . ((file-name . ,source)))))
-              (((names . thunks) ...)
-               (map (lambda (job thunk)
-                      (format (current-error-port) "evaluating '~a'... " job)
-                      (force-output (current-error-port))
-                      (cons job
-                            (assert-valid-job job
-                                              (call-with-time-display thunk))))
-                    names thunks)))
-            port))))))
-  ((command _ ...)
-   (format (current-error-port) "Usage: ~a FILE [cuirass]
-Evaluate the Hydra or Cuirass jobs defined in FILE.~%"
-           command)
-   (exit 1)))
-
-;;; Local Variables:
-;;; eval: (put 'call-with-time 'scheme-indent-function 1)
-;;; End:
-
diff --git a/build-aux/hydra/gnu-system.scm b/build-aux/hydra/gnu-system.scm
deleted file mode 100644
index a03324daeb..0000000000
--- a/build-aux/hydra/gnu-system.scm
+++ /dev/null
@@ -1,88 +0,0 @@
-;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2020 Ludovic Courtès <ludo@gnu.org>
-;;; Copyright © 2017 Jan Nieuwenhuizen <janneke@gnu.org>
-;;; Copyright © 2018, 2019 Clément Lassieur <clement@lassieur.org>
-;;;
-;;; This file is part of GNU Guix.
-;;;
-;;; GNU Guix is free software; you can redistribute it and/or modify it
-;;; under the terms of the GNU General Public License as published by
-;;; the Free Software Foundation; either version 3 of the License, or (at
-;;; your option) any later version.
-;;;
-;;; GNU Guix is distributed in the hope that it will be useful, but
-;;; WITHOUT ANY WARRANTY; without even the implied warranty of
-;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-;;; GNU General Public License for more details.
-;;;
-;;; You should have received a copy of the GNU General Public License
-;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
-
-;;;
-;;; This file defines build jobs for the Hydra continuation integration
-;;; tool.
-;;;
-
-(use-modules (guix inferior) (guix channels)
-             (guix)
-             (guix ui)
-             (srfi srfi-1)
-             (ice-9 match))
-
-;; XXX: Debugging hack: since `hydra-eval-guile-jobs' redirects the output
-;; port to the bit bucket, let us write to the error port instead.
-(setvbuf (current-error-port) 'line)
-(set-current-output-port (current-error-port))
-
-(define (find-current-checkout arguments)
-  "Find the first checkout of ARGUMENTS that provided the current file.
-Return #f if no such checkout is found."
-  (let ((current-root
-         (canonicalize-path
-          (string-append (dirname (current-filename)) "/../.."))))
-    (find (lambda (argument)
-            (and=> (assq-ref argument 'file-name)
-                   (lambda (name)
-                     (string=? name current-root)))) arguments)))
-
-(define (hydra-jobs store arguments)
-  "Return a list of jobs where each job is a NAME/THUNK pair."
-
-  (define checkout
-    (find-current-checkout arguments))
-
-  (define commit
-    (assq-ref checkout 'revision))
-
-  (define source
-    (assq-ref checkout 'file-name))
-
-  (define instance
-    (checkout->channel-instance source #:commit commit))
-
-  (define derivation
-    ;; Compute the derivation of Guix for COMMIT.
-    (run-with-store store
-      (channel-instances->derivation (list instance))))
-
-  ;; TODO: Remove 'show-what-to-build' call when Cuirass' 'evaluate' scripts
-  ;; uses 'with-build-handler'.
-  (show-what-to-build store (list derivation))
-  (build-derivations store (list derivation))
-
-  ;; Open an inferior for the just-built Guix.
-  (let ((inferior (open-inferior (derivation->output-path derivation))))
-    (inferior-eval '(use-modules (gnu ci) (ice-9 match)) inferior)
-
-    (map (match-lambda
-           ((name . fields)
-            ;; Hydra expects a thunk, so here it is.
-            (cons name (lambda () fields))))
-         (inferior-eval-with-store
-          inferior store
-          `(lambda (store)
-             (map (match-lambda
-                    ((name . thunk)
-                     (cons name (thunk))))
-                  (hydra-jobs store '((superior-guix-checkout . ,checkout)
-                                      ,@arguments))))))))
diff --git a/build-aux/hydra/guix-modular.scm b/build-aux/hydra/guix-modular.scm
deleted file mode 100644
index 060b84b8ef..0000000000
--- a/build-aux/hydra/guix-modular.scm
+++ /dev/null
@@ -1,91 +0,0 @@
-;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2017, 2018, 2020 Ludovic Courtès <ludo@gnu.org>
-;;;
-;;; This file is part of GNU Guix.
-;;;
-;;; GNU Guix is free software; you can redistribute it and/or modify it
-;;; under the terms of the GNU General Public License as published by
-;;; the Free Software Foundation; either version 3 of the License, or (at
-;;; your option) any later version.
-;;;
-;;; GNU Guix is distributed in the hope that it will be useful, but
-;;; WITHOUT ANY WARRANTY; without even the implied warranty of
-;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-;;; GNU General Public License for more details.
-;;;
-;;; You should have received a copy of the GNU General Public License
-;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
-
-;;;
-;;; This file defines a continuous integration job to build the same modular
-;;; Guix as 'guix pull', which is defined in (guix self).
-;;;
-
-(use-modules (guix store)
-             (guix config)
-             (guix utils)
-             ((guix packages) #:select (%hydra-supported-systems))
-             (guix derivations)
-             (guix monads)
-             ((guix licenses) #:prefix license:)
-             (srfi srfi-1)
-             (ice-9 match))
-
-;; XXX: Debugging hack: since `hydra-eval-guile-jobs' redirects the output
-;; port to the bit bucket, let us write to the error port instead.
-(setvbuf (current-error-port) 'line)
-(set-current-output-port (current-error-port))
-
-(define* (build-job store source version system)
-  "Return a Hydra job a list building the modular Guix derivation from SOURCE
-for SYSTEM.  Use VERSION as the version identifier."
-  (lambda ()
-    (define build
-      (primitive-load (string-append source "/build-aux/build-self.scm")))
-
-    (let ((drv (run-with-store store
-                 (build source #:version version #:system system
-                        #:pull-version 1
-                        #:guile-version "2.2"))))
-      `((derivation . ,(derivation-file-name drv)) ;the latest 2.2.x
-        (log . ,(log-file store (derivation-file-name drv)))
-        (outputs . ,(filter-map (lambda (res)
-                                  (match res
-                                    ((name . path)
-                                     `(,name . ,path))))
-                                (derivation->output-paths drv)))
-        (nix-name . ,(derivation-name drv))
-        (system . ,(derivation-system drv))
-        (description . "Modular Guix")
-        (long-description
-         . "This is the modular Guix package as produced by 'guix pull'.")
-        (license . ,license:gpl3+)
-        (home-page . ,%guix-home-page-url)
-        (maintainers . (,%guix-bug-report-address))))))
-
-(define (hydra-jobs store arguments)
-  "Return Hydra jobs."
-  (define systems
-    (match (assoc-ref arguments 'systems)
-      (#f              %hydra-supported-systems)
-      ((lst ...)       lst)
-      ((? string? str) (call-with-input-string str read))))
-
-  (define guix-checkout
-    (or (assq-ref arguments 'guix)                ;Hydra on hydra
-        (assq-ref arguments 'guix-modular)))      ;Cuirass on berlin
-
-  (define version
-    (or (assq-ref guix-checkout 'revision)
-        "0.unknown"))
-
-  (let ((file (assq-ref guix-checkout 'file-name)))
-    (format (current-error-port) "using checkout ~s (~s; arguments: ~s)~%"
-            guix-checkout file arguments)
-
-    (map (lambda (system)
-           (let ((name (string->symbol
-                        (string-append "guix." system))))
-             `(,name
-               . ,(build-job store file version system))))
-         systems)))
diff --git a/build-aux/hydra/guix.scm b/build-aux/hydra/guix.scm
deleted file mode 100644
index 08193ec82e..0000000000
--- a/build-aux/hydra/guix.scm
+++ /dev/null
@@ -1,106 +0,0 @@
-;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2013, 2014, 2015, 2016, 2017, 2018 Ludovic Courtès <ludo@gnu.org>
-;;;
-;;; This file is part of GNU Guix.
-;;;
-;;; GNU Guix is free software; you can redistribute it and/or modify it
-;;; under the terms of the GNU General Public License as published by
-;;; the Free Software Foundation; either version 3 of the License, or (at
-;;; your option) any later version.
-;;;
-;;; GNU Guix is distributed in the hope that it will be useful, but
-;;; WITHOUT ANY WARRANTY; without even the implied warranty of
-;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-;;; GNU General Public License for more details.
-;;;
-;;; You should have received a copy of the GNU General Public License
-;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
-
-;;;
-;;; This file defines build jobs of Guix itself for the Hydra continuation
-;;; integration tool.
-;;;
-
-;; Attempt to use our very own Guix modules.
-(eval-when (expand load eval)
-
-  ;; Ignore any available .go, and force recompilation.  This is because our
-  ;; checkout in the store has mtime set to the epoch, and thus .go files look
-  ;; newer, even though they may not correspond.
-  (set! %fresh-auto-compile #t)
-
-  ;; Display which files are loaded.
-  (set! %load-verbosely #t)
-
-  (and=> (assoc-ref (current-source-location) 'filename)
-         (lambda (file)
-           (let ((dir (string-append (dirname file) "/../..")))
-             (format (current-error-port) "prepending ~s to the load path~%"
-                     dir)
-             (set! %load-path (cons dir %load-path))))))
-
-
-(use-modules (guix store)
-             (guix packages)
-             (guix utils)
-             (guix grafts)
-             (guix derivations)
-             (guix build-system gnu)
-             (gnu packages package-management)
-             (srfi srfi-1)
-             (srfi srfi-26)
-             (ice-9 match))
-
-;; XXX: Debugging hack: since `hydra-eval-guile-jobs' redirects the output
-;; port to the bit bucket, let us write to the error port instead.
-(setvbuf (current-error-port) _IOLBF)
-(set-current-output-port (current-error-port))
-
-(define* (package->alist store package system
-                         #:optional (package-derivation package-derivation))
-  "Convert PACKAGE to an alist suitable for Hydra."
-  `((derivation . ,(derivation-file-name
-                    (parameterize ((%graft? #f))
-                      (package-derivation store package system
-                                          #:graft? #f))))
-    (description . ,(package-synopsis package))
-    (long-description . ,(package-description package))
-    (license . ,(package-license package))
-    (home-page . ,(package-home-page package))
-    (maintainers . ("bug-guix@gnu.org"))))
-
-(define (hydra-jobs store arguments)
-  "Return Hydra jobs."
-  (define systems
-    (match (filter-map (match-lambda
-                        (('system . value)
-                         value)
-                        (_ #f))
-                       arguments)
-      ((lst ..1)
-       lst)
-      (_
-       (list (%current-system)))))
-
-  (define guix-checkout
-    (assq-ref arguments 'guix))
-
-  (let ((file (assq-ref guix-checkout 'file-name)))
-    (format (current-error-port) "using checkout ~s (~s)~%"
-            guix-checkout file)
-
-    `((tarball . ,(cute package->alist store
-                        (dist-package guix file)
-                        (%current-system)))
-
-      ,@(map (lambda (system)
-               (let ((name (string->symbol
-                            (string-append "guix." system))))
-                 `(,name
-                   . ,(cute package->alist store
-                            (package
-                              (inherit guix)
-                              (version "latest")
-                              (source file))
-                            system))))
-             %hydra-supported-systems))))
diff --git a/etc/release-manifest.scm b/etc/release-manifest.scm
index da98d6e00b..a1f731a945 100644
--- a/etc/release-manifest.scm
+++ b/etc/release-manifest.scm
@@ -103,7 +103,7 @@ TARGET."
                       (if (string=? system "i586-gnu")
                           %base-packages/hurd
                           %base-packages)))
-               %hydra-supported-systems)))
+               %cuirass-supported-systems)))
 
 (define %system-manifest
   (manifest
diff --git a/gnu/ci.scm b/gnu/ci.scm
index 96bff64875..6edcdd0e19 100644
--- a/gnu/ci.scm
+++ b/gnu/ci.scm
@@ -3,7 +3,7 @@
 ;;; Copyright © 2017, 2020 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
 ;;; Copyright © 2018, 2019 Clément Lassieur <clement@lassieur.org>
 ;;; Copyright © 2020 Julien Lepiller <julien@lepiller.eu>
-;;; Copyright © 2020 Mathieu Othacehe <othacehe@gnu.org>
+;;; Copyright © 2020, 2021 Mathieu Othacehe <othacehe@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -21,6 +21,7 @@
 ;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
 
 (define-module (gnu ci)
+  #:use-module (guix channels)
   #:use-module (guix config)
   #:use-module (guix store)
   #:use-module (guix grafts)
@@ -64,67 +65,69 @@
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-26)
   #:use-module (ice-9 match)
-  #:export (%cross-targets
+  #:export (%core-packages
+            %cross-targets
             channel-source->package
-            hydra-jobs))
+            cuirass-jobs))
 
 ;;; Commentary:
 ;;;
-;;; This file defines build jobs for the Hydra and Cuirass continuation
-;;; integration tools.
+;;; This file defines build jobs for Cuirass.
 ;;;
 ;;; Code:
 
-(define* (package->alist store package system
-                         #:optional (package-derivation package-derivation))
-  "Convert PACKAGE to an alist suitable for Hydra."
-  (parameterize ((%graft? #f))
-    (let ((drv (package-derivation store package system
-                                   #:graft? #f)))
-      `((derivation . ,(derivation-file-name drv))
-        (log . ,(log-file store (derivation-file-name drv)))
-        (outputs . ,(filter-map (lambda (res)
-                                  (match res
-                                    ((name . path)
-                                     `(,name . ,path))))
-                                (derivation->output-paths drv)))
-        (nix-name . ,(derivation-name drv))
-        (system . ,(derivation-system drv))
-        (description . ,(package-synopsis package))
-        (long-description . ,(package-description package))
-
-        ;; XXX: Hydra ignores licenses that are not a <license> structure or a
-        ;; list thereof.
-        (license . ,(let loop ((license (package-license package)))
-                      (match license
-                        ((? license?)
-                         (license-name license))
-                        ((lst ...)
-                         (map loop license)))))
-
-        (home-page . ,(package-home-page package))
-        (maintainers . ("bug-guix@gnu.org"))
-        (max-silent-time . ,(or (assoc-ref (package-properties package)
-                                           'max-silent-time)
-                                3600))              ;1 hour by default
-        (timeout . ,(or (assoc-ref (package-properties package) 'timeout)
-                        72000))))))                  ;20 hours by default
-
-(define (package-job store job-name package system)
+(define* (derivation->job name drv
+                          #:key
+                          period
+                          (max-silent-time 3600)
+                          (timeout 3600))
+  "Return a Cuirass job called NAME and describing DRV.  PERIOD is the minimal
+duration that must separate two evaluations of the same job. If PERIOD is
+false, then the job will be evaluated as soon as possible.
+
+MAX-SILENT-TIME and TIMEOUT are build options passed to the daemon when
+building the derivation."
+  `((#:job-name . ,name)
+    (#:derivation . ,(derivation-file-name drv))
+    (#:outputs . ,(filter-map
+                   (lambda (res)
+                     (match res
+                       ((name . path)
+                        `(,name . ,path))))
+                   (derivation->output-paths drv)))
+    (#:nix-name . ,(derivation-name drv))
+    (#:system . ,(derivation-system drv))
+    (#:period . ,period)
+    (#:max-silent-time . ,max-silent-time)
+    (#:timeout . ,timeout)))
+
+(define* (package-job store job-name package system
+                      #:key cross? target)
   "Return a job called JOB-NAME that builds PACKAGE on SYSTEM."
-  (let ((job-name (symbol-append job-name (string->symbol ".")
-                                 (string->symbol system))))
-    `(,job-name . ,(cut package->alist store package system))))
+  (let ((job-name (string-append job-name "." system)))
+    (parameterize ((%graft? #f))
+      (let* ((drv (if cross?
+                      (package-cross-derivation store package target system
+                                                #:graft? #f)
+                      (package-derivation store package system
+                                          #:graft? #f)))
+             (max-silent-time (or (assoc-ref (package-properties package)
+                                             'max-silent-time)
+                                  3600))
+             (timeout (or (assoc-ref (package-properties package)
+                                     'timeout)
+                          72000)))
+        (derivation->job job-name drv
+                         #:max-silent-time max-silent-time
+                         #:timeout timeout)))))
 
 (define (package-cross-job store job-name package target system)
   "Return a job called TARGET.JOB-NAME that cross-builds PACKAGE for TARGET on
 SYSTEM."
-  `(,(symbol-append (string->symbol target) (string->symbol ".") job-name
-                    (string->symbol ".") (string->symbol system)) .
-    ,(cute package->alist store package system
-           (lambda* (store package system #:key graft?)
-             (package-cross-derivation store package target system
-                                       #:graft? graft?)))))
+  (let ((name (string-append target "." job-name "." system)))
+    (package-job store name package system
+                 #:cross? #t
+                 #:target target)))
 
 (define %core-packages
   ;; Note: Don't put the '-final' package variants because (1) that's
@@ -200,6 +203,22 @@ SYSTEM."
               (remove (either from-32-to-64? same? pointless?)
                       %cross-targets)))
 
+(define* (guix-jobs store systems #:key source commit)
+  "Return a list of jobs for Guix itself."
+  (define build
+    (primitive-load (string-append source "/build-aux/build-self.scm")))
+
+  (map
+   (lambda (system)
+     (let ((name (string->symbol
+                  (string-append "guix." system)))
+           (drv (run-with-store store
+                  (build source #:version commit #:system system
+                         #:pull-version 1
+                         #:guile-version "2.2"))))
+       (derivation->job name drv)))
+   systems))
+
 ;; Architectures that are able to build or cross-build Guix System images.
 ;; This does not mean that other architectures are not supported, only that
 ;; they are often not fast enough to support Guix System images building.
@@ -219,32 +238,11 @@ SYSTEM."
   "Return a list of jobs that build images for SYSTEM.  Those jobs are
 expensive in storage and I/O operations, hence their periodicity is limited by
 passing the PERIOD argument."
-  (define (->alist drv)
-    `((derivation . ,(derivation-file-name drv))
-      (log . ,(log-file store (derivation-file-name drv)))
-      (outputs . ,(filter-map (lambda (res)
-                                (match res
-                                  ((name . path)
-                                   `(,name . ,path))))
-                              (derivation->output-paths drv)))
-      (nix-name . ,(derivation-name drv))
-      (system . ,(derivation-system drv))
-      (description . "Stand-alone image of the GNU system")
-      (long-description . "This is a demo stand-alone image of the GNU
-system.")
-      (license . ,(license-name gpl3+))
-      (period . ,(hours 48))
-      (max-silent-time . 3600)
-      (timeout . 3600)
-      (home-page . ,%guix-home-page-url)
-      (maintainers . ("bug-guix@gnu.org"))))
-
   (define (->job name drv)
-    (let ((name (symbol-append name (string->symbol ".")
-                               (string->symbol system))))
-      `(,name . ,(lambda ()
-                   (parameterize ((%graft? #f))
-                     (->alist drv))))))
+    (let ((name (string-append name "." system)))
+      (parameterize ((%graft? #f))
+        (derivation->job name drv
+                         #:period (hours 48)))))
 
   (define (build-image image)
     (run-with-store store
@@ -256,25 +254,26 @@ system.")
     (expt 2 20))
 
   (if (member system %guix-system-supported-systems)
-      `(,(->job 'usb-image
+      `(,(->job "usb-image"
                 (build-image
                  (image
                   (inherit efi-disk-image)
                   (operating-system installation-os))))
-        ,(->job 'iso9660-image
+        ,(->job "iso9660-image"
                 (build-image
                  (image
                   (inherit (image-with-label
-                             iso9660-image
-                             (string-append "GUIX_" system "_"
-                                            (if (> (string-length %guix-version) 7)
-                                                (substring %guix-version 0 7)
-                                                %guix-version))))
+                            iso9660-image
+                            (string-append "GUIX_" system "_"
+                                           (if (> (string-length %guix-version) 7)
+                                               (substring %guix-version 0 7)
+                                               %guix-version))))
                   (operating-system installation-os))))
         ;; Only cross-compile Guix System images from x86_64-linux for now.
         ,@(if (string=? system "x86_64-linux")
               (map (lambda (image)
-                     (->job (image-name image) (build-image image)))
+                     (->job (symbol->string (image-name image))
+                            (build-image image)))
                    %guix-system-images)
               '()))
       '()))
@@ -322,112 +321,72 @@ system.")
 (define* (system-test-jobs store system
                            #:key source commit)
   "Return a list of jobs for the system tests."
-  (define (test->thunk test)
-    (lambda ()
-      (define drv
-        (run-with-store store
-          (mbegin %store-monad
-            (set-current-system system)
-            (set-grafting #f)
-            (set-guile-for-build (default-guile))
-            (system-test-value test))))
-
-      ;; Those tests are extremely expensive in I/O operations and storage
-      ;; size, use the "period" attribute to run them with a period of at
-      ;; least 48 hours.
-      `((derivation . ,(derivation-file-name drv))
-        (log . ,(log-file store (derivation-file-name drv)))
-        (outputs . ,(filter-map (lambda (res)
-                                  (match res
-                                    ((name . path)
-                                     `(,name . ,path))))
-                                (derivation->output-paths drv)))
-        (nix-name . ,(derivation-name drv))
-        (system . ,(derivation-system drv))
-        (description . ,(format #f "Guix '~a' system test"
-                                (system-test-name test)))
-        (long-description . ,(system-test-description test))
-        (license . ,(license-name gpl3+))
-        (period . ,(hours 48))
-        (max-silent-time . 3600)
-        (timeout . 3600)
-        (home-page . ,%guix-home-page-url)
-        (maintainers . ("bug-guix@gnu.org")))))
-
   (define (->job test)
-    (let ((name (string->symbol
-                 (string-append "test." (system-test-name test)
-                                "." system))))
-      (cons name (test->thunk test))))
+    (parameterize ((current-guix-package
+                    (channel-source->package source #:commit commit)))
+      (let ((name (string-append "test." (system-test-name test)
+                                 "." system))
+            (drv (run-with-store store
+                   (mbegin %store-monad
+                     (set-current-system system)
+                     (set-grafting #f)
+                     (set-guile-for-build (default-guile))
+                     (system-test-value test)))))
+
+        ;; Those tests are extremely expensive in I/O operations and storage
+        ;; size, use the "period" attribute to run them with a period of at
+        ;; least 48 hours.
+        (derivation->job name drv
+                         #:period (hours 24)))))
 
   (if (member system %guix-system-supported-systems)
       ;; Override the value of 'current-guix' used by system tests.  Using a
       ;; channel instance makes tests that rely on 'current-guix' less
       ;; expensive.  It also makes sure we get a valid Guix package when this
       ;; code is not running from a checkout.
-      (parameterize ((current-guix-package
-                      (channel-source->package source #:commit commit)))
-        (map ->job (all-system-tests)))
+      (map ->job (all-system-tests))
       '()))
 
 (define (tarball-jobs store system)
-  "Return Hydra jobs to build the self-contained Guix binary tarball."
-  (define (->alist drv)
-    `((derivation . ,(derivation-file-name drv))
-      (log . ,(log-file store (derivation-file-name drv)))
-      (outputs . ,(filter-map (lambda (res)
-                                (match res
-                                  ((name . path)
-                                   `(,name . ,path))))
-                              (derivation->output-paths drv)))
-      (nix-name . ,(derivation-name drv))
-      (system . ,(derivation-system drv))
-      (description . "Stand-alone binary Guix tarball")
-      (long-description . "This is a tarball containing binaries of Guix and
-all its dependencies, and ready to be installed on \"foreign\" distributions.")
-      (license . ,(license-name gpl3+))
-      (home-page . ,%guix-home-page-url)
-      (maintainers . ("bug-guix@gnu.org"))
-      (period . ,(hours 24))))
-
+  "Return jobs to build the self-contained Guix binary tarball."
   (define (->job name drv)
-    (let ((name (symbol-append name (string->symbol ".")
-                               (string->symbol system))))
-      `(,name . ,(lambda ()
-                   (parameterize ((%graft? #f))
-                     (->alist drv))))))
+    (let ((name (string-append name "." system)))
+      (parameterize ((%graft? #f))
+        (derivation->job name drv
+                         #:period (hours 24)))))
 
   ;; XXX: Add a job for the stable Guix?
-  (list (->job 'binary-tarball
-               (run-with-store store
-                 (mbegin %store-monad
-                   (set-guile-for-build (default-guile))
-                   (>>= (profile-derivation (packages->manifest (list guix)))
-                        (lambda (profile)
-                          (self-contained-tarball "guix-binary" profile
-                                                  #:localstatedir? #t
-                                                  #:compressor
-                                                  (lookup-compressor "xz")))))
-                 #:system system))))
+  (list
+   (->job "binary-tarball"
+          (run-with-store store
+            (mbegin %store-monad
+              (set-guile-for-build (default-guile))
+              (>>= (profile-derivation (packages->manifest (list guix)))
+                   (lambda (profile)
+                     (self-contained-tarball "guix-binary" profile
+                                             #:localstatedir? #t
+                                             #:compressor
+                                             (lookup-compressor "xz")))))
+            #:system system))))
 
 (define job-name
   ;; Return the name of a package's job.
-  (compose string->symbol package-name))
+  package-name)
 
 (define package->job
   (let ((base-packages
          (delete-duplicates
           (append-map (match-lambda
-                       ((_ package _ ...)
-                        (match (package-transitive-inputs package)
-                          (((_ inputs _ ...) ...)
-                           inputs))))
+                        ((_ package _ ...)
+                         (match (package-transitive-inputs package)
+                           (((_ inputs _ ...) ...)
+                            inputs))))
                       (%final-inputs)))))
     (lambda (store package system)
       "Return a job for PACKAGE on SYSTEM, or #f if this combination is not
 valid."
       (cond ((member package base-packages)
-             (package-job store (symbol-append 'base. (job-name package))
+             (package-job store (string-append "base." (job-name package))
                           package system))
             ((supported-package? package system)
              (let ((drv (package-derivation store package system
@@ -461,14 +420,19 @@ valid."
                           packages)))
                  #:select? (const #t)))           ;include hidden packages
 
-(define (arguments->manifests arguments)
+(define (arguments->manifests arguments channels)
   "Return the list of manifests extracted from ARGUMENTS."
+  (define (channel-name->checkout name)
+    (let ((channel (find (lambda (channel)
+                           (eq? (channel-name channel) name))
+                         channels)))
+      (channel-url channel)))
+
   (map (match-lambda
-         ((input-name . relative-path)
-          (let* ((checkout (assq-ref arguments (string->symbol input-name)))
-                 (base (assq-ref checkout 'file-name)))
-            (in-vicinity base relative-path))))
-       (assq-ref arguments 'manifests)))
+         ((name . path)
+          (let ((checkout (channel-name->checkout name)))
+            (in-vicinity checkout path))))
+       arguments))
 
 (define (manifests->packages store manifests)
   "Return the list of packages found in MANIFESTS."
@@ -484,100 +448,94 @@ valid."
                              load-manifest)
                     manifests))))
 
-(define (find-current-checkout arguments)
-  "Find the first checkout of ARGUMENTS that provided the current file.
-Return #f if no such checkout is found."
-  (let ((current-root
-         (canonicalize-path
-          (string-append (dirname (current-filename)) "/.."))))
-    (find (lambda (argument)
-            (and=> (assq-ref argument 'file-name)
-                   (lambda (name)
-                     (string=? name current-root)))) arguments)))
-
 
 ;;;
-;;; Hydra entry point.
+;;; Cuirass entry point.
 ;;;
 
-(define (hydra-jobs store arguments)
-  "Return Hydra jobs."
+(define (cuirass-jobs store arguments)
+  "Register Cuirass jobs."
   (define subset
-    (match (assoc-ref arguments 'subset)
-      ("core" 'core)                              ; only build core packages
-      ("hello" 'hello)                            ; only build hello
-      (((? string?) (? string?) ...) 'list)       ; only build selected list of packages
-      ("manifests" 'manifests)                    ; only build packages in the list of manifests
-      (_ 'all)))                                  ; build everything
+    (assoc-ref arguments 'subset))
 
   (define systems
     (match (assoc-ref arguments 'systems)
-      (#f              %hydra-supported-systems)
+      (#f              %cuirass-supported-systems)
       ((lst ...)       lst)
       ((? string? str) (call-with-input-string str read))))
 
-  (define checkout
-    (or (find-current-checkout arguments)
-        (assq-ref arguments 'superior-guix-checkout)))
+  (define channels
+    (let ((channels (assq-ref arguments 'channels)))
+      (map sexp->channel channels)))
+
+  (define guix
+    (find guix-channel? channels))
 
   (define commit
-    (assq-ref checkout 'revision))
+    (channel-commit guix))
 
   (define source
-    (assq-ref checkout 'file-name))
+    (channel-url guix))
 
   ;; Turn off grafts.  Grafting is meant to happen on the user's machines.
   (parameterize ((%graft? #f))
     ;; Return one job for each package, except bootstrap packages.
-    (append-map (lambda (system)
-                  (format (current-error-port)
-                          "evaluating for '~a' (heap size: ~a MiB)...~%"
-                          system
-                          (round
-                           (/ (assoc-ref (gc-stats) 'heap-size)
-                              (expt 2. 20))))
-                  (invalidate-derivation-caches!)
-                  (case subset
-                    ((all)
-                     ;; Build everything, including replacements.
-                     (let ((all (all-packages))
-                           (job (lambda (package)
-                                  (package->job store package
-                                                system))))
-                       (append (filter-map job all)
-                               (image-jobs store system)
-                               (system-test-jobs store system
-                                                 #:source source
-                                                 #:commit commit)
-                               (tarball-jobs store system)
-                               (cross-jobs store system))))
-                    ((core)
-                     ;; Build core packages only.
-                     (append (map (lambda (package)
-                                    (package-job store (job-name package)
-                                                 package system))
-                                  %core-packages)
-                             (cross-jobs store system)))
-                    ((hello)
-                     ;; Build hello package only.
-                     (let ((hello (specification->package "hello")))
-                       (list (package-job store (job-name hello) hello system))))
-                    ((list)
-                     ;; Build selected list of packages only.
-                     (let* ((names (assoc-ref arguments 'subset))
-                            (packages (map specification->package names)))
-                       (map (lambda (package)
-                              (package-job store (job-name package)
-                                           package system))
-                            packages)))
-                    ((manifests)
-                     ;; Build packages in the list of manifests.
-                     (let* ((manifests (arguments->manifests arguments))
-                            (packages (manifests->packages store manifests)))
-                       (map (lambda (package)
-                              (package-job store (job-name package)
-                                           package system))
-                            packages)))
-                    (else
-                     (error "unknown subset" subset))))
-                systems)))
+    (append-map
+     (lambda (system)
+       (format (current-error-port)
+               "evaluating for '~a' (heap size: ~a MiB)...~%"
+               system
+               (round
+                (/ (assoc-ref (gc-stats) 'heap-size)
+                   (expt 2. 20))))
+       (invalidate-derivation-caches!)
+       (match subset
+         ('all
+          ;; Build everything, including replacements.
+          (let ((all (all-packages))
+                (job (lambda (package)
+                       (package->job store package system))))
+            (append
+             (filter-map job all)
+             (image-jobs store system)
+             (system-test-jobs store system
+                               #:source source
+                               #:commit commit)
+             (tarball-jobs store system)
+             (cross-jobs store system))))
+         ('core
+          ;; Build core packages only.
+          (append
+           (map (lambda (package)
+                  (package-job store (job-name package)
+                               package system))
+                %core-packages)
+           (cross-jobs store system)))
+         ('guix
+          ;; Build Guix modules only.
+          (guix-jobs store systems
+                     #:source source
+                     #:commit commit))
+         ('hello
+          ;; Build hello package only.
+          (let ((hello (specification->package "hello")))
+            (list (package-job store (job-name hello)
+                               hello system))))
+         (('packages . rest)
+          ;; Build selected list of packages only.
+          (let ((packages (map specification->package rest)))
+            (map (lambda (package)
+                   (package-job store (job-name package)
+                                package system))
+                 packages)))
+         (('manifests . rest)
+          ;; Build packages in the list of manifests.
+          (let* ((manifests (arguments->manifests rest channels))
+                 (packages (manifests->packages store manifests)))
+            (map (lambda (package)
+                   (package-job store (job-name package)
+                                package system))
+                 packages)))
+         (else
+          (error "unknown subset" subset))))
+     systems)))
diff --git a/guix/packages.scm b/guix/packages.scm
index eae8fcbb6e..a057a88c63 100644
--- a/guix/packages.scm
+++ b/guix/packages.scm
@@ -131,7 +131,7 @@
 
             %supported-systems
             %hurd-systems
-            %hydra-supported-systems
+            %cuirass-supported-systems
             supported-package?
 
             &package-error
@@ -351,7 +351,7 @@ name of its URI."
   ;; The GNU/Hurd systems for which support is being developed.
   '("i586-gnu" "i686-gnu"))
 
-(define %hydra-supported-systems
+(define %cuirass-supported-systems
   ;; This is the list of system types for which build machines are available.
   ;;
   ;; XXX: MIPS is unavailable in CI: