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;;; Nar Herder
;;;
;;; Copyright © 2021 Christopher Baines <mail@cbaines.net>
;;;
;;; This program is free software: you can redistribute it and/or
;;; modify it under the terms of the GNU Affero General Public License
;;; as published by the Free Software Foundation, either version 3 of
;;; the License, or (at your option) any later version.
;;;
;;; This program 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
;;; Affero General Public License for more details.
;;;
;;; You should have received a copy of the GNU Affero General Public
;;; License along with this program. If not, see
;;; <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)
#:use-module (web request)
#:use-module (logging logger)
#:use-module (prometheus)
#:use-module (json)
#:use-module (nar-herder database)
#:use-module (nar-herder storage)
#:export (make-request-handler))
(define* (render-json json #:key (extra-headers '())
(code 200))
(values (build-response
#:code code
#:headers (append extra-headers
'((content-type . (application/json))
(vary . (accept)))))
(lambda (port)
(scm->json json port))))
(define (parse-query-string query)
(let lp ((lst (map uri-decode (string-split query (char-set #\& #\=)))))
(match lst
((key value . rest)
(cons (cons key value) (lp rest)))
(("") '())
(() '()))))
(define (get-gc-metrics-updater registry)
(define metrics
`((gc-time-taken
. ,(make-gauge-metric registry "guile_gc_time_taken"))
(heap-size
. ,(make-gauge-metric registry "guile_heap_size"))
(heap-free-size
. ,(make-gauge-metric registry "guile_heap_free_size"))
(heap-total-allocated
. ,(make-gauge-metric registry "guile_heap_total_allocated"))
(heap-allocated-since-gc
. ,(make-gauge-metric registry "guile_allocated_since_gc"))
(protected-objects
. ,(make-gauge-metric registry "guile_gc_protected_objects"))
(gc-times
. ,(make-gauge-metric registry "guile_gc_times"))))
(lambda ()
(let ((stats (gc-stats)))
(for-each
(match-lambda
((name . metric)
(let ((value (assq-ref stats name)))
(metric-set metric value))))
metrics))))
(define* (make-request-handler database storage-root
#:key ttl negative-ttl logger
metrics-registry)
(define (narinfo? str)
(and
(= (string-length str) 40)
(string-suffix? ".narinfo" str)))
(define gc-metrics-updater
(get-gc-metrics-updater metrics-registry))
(define requests-total-metric
(make-counter-metric metrics-registry
"server_requests_total"))
(define (increment-request-metric category response-code)
(metric-increment
requests-total-metric
#:label-values `((category . ,category)
(response_code . ,response-code))))
(lambda (request body)
(log-msg logger
'DEBUG
(request-method request)
" "
(uri-path (request-uri request)))
(match (cons (request-method request)
(split-and-decode-uri-path
(uri-path (request-uri request))))
(('GET (? narinfo? narinfo))
(let ((narinfo-contents
(database-select-narinfo-contents-by-hash
database
(string-take narinfo 32))))
(increment-request-metric "narinfo"
(if narinfo-contents
"200"
"404"))
(if narinfo-contents
(values `((content-type . (text/plain))
,@(if ttl
`((cache-control (max-age . ,ttl)))
'()))
narinfo-contents)
(values (build-response #:code 404
#:headers (if negative-ttl
`((cache-control
(max-age . ,negative-ttl)))
'()))
"404"))))
(('GET (? narinfo? narinfo) "info")
(let ((narinfo-contents
(database-select-narinfo-contents-by-hash
database
(string-take narinfo 32))))
(increment-request-metric "narinfo/info"
(if narinfo-contents
"200"
"404"))
(if narinfo-contents
(render-json
`((stored . ,(store-item-in-local-storage?
database
storage-root
(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 "/"
(uri-encode filename)))))
#f)
(values (build-response #:code 404)
"404"))))
(('GET "recent-changes")
(let ((query-parameters
(or (and=> (uri-query (request-uri request))
parse-query-string)
'())))
(increment-request-metric "recent-changes" "200")
(render-json
`((recent_changes . ,(list->vector
(database-select-recent-changes
database
(or
(assoc-ref query-parameters "since")
"1970-01-01 00:00:01"))))))))
(('GET "latest-database-dump")
(increment-request-metric "latest-database-dump" "200")
(values (build-response
#:code 200
#:headers '((X-Accel-Redirect . "/internal/database/nar_herder_dump.db")))
#f))
(('GET "metrics")
(gc-metrics-updater)
(increment-request-metric "metrics" "200")
(values (build-response
#:code 200
#:headers '((content-type . (text/plain))
(vary . (accept))))
(lambda (port)
(write-metrics metrics-registry
port))))
(_
(increment-request-metric "unhandled" "404")
(values (build-response #:code 404)
"404")))))
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