Add (guix ci).

* guix/ci.scm: New file.
* Makefile.am (MODULES): Add it.

Makefile.am

@@ -115,6 +115,7 @@ MODULES =					\
   guix/build-system/trivial.scm			\
   guix/ftp-client.scm				\
   guix/http-client.scm				\
+  guix/ci.scm					\
   guix/gnupg.scm				\
   guix/elf.scm					\
   guix/profiling.scm				\

guix/ci.scm

@@ -0,0 +1,78 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 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/>.
+
+(define-module (guix ci)
+  #:use-module (guix http-client)
+  #:autoload   (json parser) (json->scm)
+  #:use-module (srfi srfi-9)
+  #:export (build?
+            build-id
+            build-derivation
+            build-system
+            build-status
+            build-timestamp
+
+            %query-limit
+            queued-builds
+            latest-builds))
+
+;;; Commentary:
+;;;
+;;; This module provides a client to the HTTP interface of the Hydra and
+;;; Cuirass continuous integration (CI) tools.
+;;;
+;;; Code:
+
+(define-record-type <build>
+  (make-build id derivation system status timestamp)
+  build?
+  (id          build-id)                          ;integer
+  (derivation  build-derivation)                  ;string | #f
+  (system      build-system)                      ;string
+  (status      build-status)                      ;integer
+  (timestamp   build-timestamp))                  ;integer
+
+(define %query-limit
+  ;; Max number of builds requested in queries.
+  1000)
+
+(define (json-fetch url)
+  (let* ((port (http-fetch url))
+         (json (json->scm port)))
+    (close-port port)
+    json))
+
+(define (json->build json)
+  (make-build (hash-ref json "id")
+              (hash-ref json "derivation")
+              (hash-ref json "system")
+              (hash-ref json "buildstatus")
+              (hash-ref json "timestamp")))
+
+(define* (queued-builds url #:optional (limit %query-limit))
+  "Return the list of queued derivations on URL."
+  (let ((queue (json-fetch (string-append url "/api/queue?nr="
+                                          (number->string limit)))))
+    (map json->build queue)))
+
+(define* (latest-builds url #:optional (limit %query-limit))
+  (let ((latest (json-fetch (string-append url "/api/latestbuilds?nr="
+                                           (number->string limit)))))
+    ;; Note: Hydra does not provide a "derivation" field for entries in
+    ;; 'latestbuilds', but Cuirass does.
+    (map json->build latest)))