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1 | ;;; GNU Guix --- Functional package management for GNU |
2 | ;;; Copyright © 2017 Ricardo Wurmus <rekado@elephly.net> | |
3 | ;;; | |
4 | ;;; This file is part of GNU Guix. | |
5 | ;;; | |
6 | ;;; GNU Guix is free software; you can redistribute it and/or modify it | |
7 | ;;; under the terms of the GNU General Public License as published by | |
8 | ;;; the Free Software Foundation; either version 3 of the License, or (at | |
9 | ;;; your option) any later version. | |
10 | ;;; | |
11 | ;;; GNU Guix is distributed in the hope that it will be useful, but | |
12 | ;;; WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | ;;; GNU General Public License for more details. | |
15 | ;;; | |
16 | ;;; You should have received a copy of the GNU General Public License | |
17 | ;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>. | |
18 | ||
19 | (define-module (guix docker) | |
20 | #:use-module (guix hash) | |
21 | #:use-module (guix store) | |
4c0c4db0 | 22 | #:use-module (guix base16) |
03476a23 RW |
23 | #:use-module (guix utils) |
24 | #:use-module ((guix build utils) | |
25 | #:select (delete-file-recursively | |
26 | with-directory-excursion)) | |
27 | #:use-module (json) | |
28 | #:use-module (rnrs bytevectors) | |
29 | #:use-module (ice-9 match) | |
30 | #:export (build-docker-image)) | |
31 | ||
32 | ;; Generate a 256-bit identifier in hexadecimal encoding for the Docker image | |
33 | ;; containing the closure at PATH. | |
34 | (define docker-id | |
35 | (compose bytevector->base16-string sha256 string->utf8)) | |
36 | ||
37 | (define (layer-diff-id layer) | |
38 | "Generate a layer DiffID for the given LAYER archive." | |
39 | (string-append "sha256:" (bytevector->base16-string (file-sha256 layer)))) | |
40 | ||
41 | ;; This is the semantic version of the JSON metadata schema according to | |
42 | ;; https://github.com/docker/docker/blob/master/image/spec/v1.2.md | |
43 | ;; It is NOT the version of the image specification. | |
44 | (define schema-version "1.0") | |
45 | ||
46 | (define (image-description id time) | |
47 | "Generate a simple image description." | |
48 | `((id . ,id) | |
49 | (created . ,time) | |
50 | (container_config . #nil))) | |
51 | ||
52 | (define (generate-tag path) | |
53 | "Generate an image tag for the given PATH." | |
54 | (match (string-split (basename path) #\-) | |
55 | ((hash name . rest) (string-append name ":" hash)))) | |
56 | ||
57 | (define (manifest path id) | |
58 | "Generate a simple image manifest." | |
59 | `(((Config . "config.json") | |
60 | (RepoTags . (,(generate-tag path))) | |
61 | (Layers . (,(string-append id "/layer.tar")))))) | |
62 | ||
63 | ;; According to the specifications this is required for backwards | |
64 | ;; compatibility. It duplicates information provided by the manifest. | |
65 | (define (repositories path id) | |
66 | "Generate a repositories file referencing PATH and the image ID." | |
67 | `((,(generate-tag path) . ((latest . ,id))))) | |
68 | ||
69 | ;; See https://github.com/opencontainers/image-spec/blob/master/config.md | |
70 | (define (config layer time arch) | |
71 | "Generate a minimal image configuration for the given LAYER file." | |
72 | ;; "architecture" must be values matching "platform.arch" in the | |
73 | ;; runtime-spec at | |
74 | ;; https://github.com/opencontainers/runtime-spec/blob/v1.0.0-rc2/config.md#platform | |
75 | `((architecture . ,arch) | |
76 | (comment . "Generated by GNU Guix") | |
77 | (created . ,time) | |
78 | (config . #nil) | |
79 | (container_config . #nil) | |
80 | (os . "linux") | |
81 | (rootfs . ((type . "layers") | |
82 | (diff_ids . (,(layer-diff-id layer))))))) | |
83 | ||
84 | (define* (build-docker-image path #:key system) | |
85 | "Generate a Docker image archive from the given store PATH. The image | |
86 | contains the closure of the given store item." | |
87 | (let ((id (docker-id path)) | |
88 | (time (strftime "%FT%TZ" (localtime (current-time)))) | |
89 | (name (string-append (getcwd) | |
90 | "/docker-image-" (basename path) ".tar")) | |
91 | (arch (match system | |
92 | ("x86_64-linux" "amd64") | |
93 | ("i686-linux" "386") | |
94 | ("armhf-linux" "arm") | |
95 | ("mips64el-linux" "mips64le")))) | |
96 | (and (call-with-temporary-directory | |
97 | (lambda (directory) | |
98 | (with-directory-excursion directory | |
99 | ;; Add symlink from /bin to /gnu/store/.../bin | |
100 | (symlink (string-append path "/bin") "bin") | |
101 | ||
102 | (mkdir id) | |
103 | (with-directory-excursion id | |
104 | (with-output-to-file "VERSION" | |
105 | (lambda () (display schema-version))) | |
106 | (with-output-to-file "json" | |
107 | (lambda () (scm->json (image-description id time)))) | |
108 | ||
109 | ;; Wrap it up | |
110 | (let ((items (with-store store | |
111 | (requisites store (list path))))) | |
112 | (and (zero? (apply system* "tar" "-cf" "layer.tar" | |
113 | (cons "../bin" items))) | |
114 | (delete-file "../bin")))) | |
115 | ||
116 | (with-output-to-file "config.json" | |
117 | (lambda () | |
118 | (scm->json (config (string-append id "/layer.tar") | |
119 | time arch)))) | |
120 | (with-output-to-file "manifest.json" | |
121 | (lambda () | |
122 | (scm->json (manifest path id)))) | |
123 | (with-output-to-file "repositories" | |
124 | (lambda () | |
125 | (scm->json (repositories path id))))) | |
126 | (and (zero? (system* "tar" "-C" directory "-cf" name ".")) | |
127 | (begin (delete-file-recursively directory) #t)))) | |
128 | name))) |