Support handling /nar requests

If the nar is known about, X-Accel-Redirect is used to pass the
request back to the webserver which should then respond with the nar.
If the nar isn't known about, then a 404 response is returned.

In either case, there's a metric incremented to record the request.

1 files changed, 33 insertions, 0 deletions

diff --git a/nar-herder/server.scm b/nar-herder/server.scm
index c977956..ea0c0a8 100644
--- a/nar-herder/server.scm
+++ b/nar-herder/server.scm
@@ -17,6 +17,7 @@
 ;;; <http://www.gnu.org/licenses/>.
 
 (define-module (nar-herder server)
+  #:use-module (srfi srfi-1)
   #:use-module (ice-9 match)
   #:use-module (web uri)
   #:use-module (web response)
@@ -145,6 +146,38 @@
                             (string-take narinfo 32)))))
              (values (build-response #:code 404)
                      "404"))))
+      (('GET "nar" compression filename)
+       (let* ((hash (string-take filename 32))
+              (narinfo-files
+               (database-select-narinfo-files
+                database
+                hash))
+              (narinfo-file-for-compression
+               (find (lambda (file)
+                       (string=? (assq-ref file 'compression)
+                                 compression))
+                     narinfo-files)))
+
+         (when (or narinfo-file-for-compression
+                   ;; Check for a common compression to avoid lots of
+                   ;; metrics being generated if compression is random
+                   (member compression '("gzip" "lzip" "zstd")))
+           (increment-request-metric
+            (string-append "nar/"
+                           compression)
+            (if narinfo-file-for-compression "200" "404")))
+
+         (if narinfo-file-for-compression
+             (values (build-response
+                      #:code 200
+                      #:headers `((X-Accel-Redirect
+                                   . ,(string-append
+                                       "/internal/nar/"
+                                       compression "/"
+                                       filename))))
+                     #f)
+             (values (build-response #:code 404)
+                     "404"))))
       (('GET "recent-changes")
        (let ((query-parameters
               (or (and=> (uri-query (request-uri request))