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1 | ;;; GNU Guix --- Functional package management for GNU |
2 | ;;; Copyright © 2017 Ricardo Wurmus <rekado@elephly.net> | |
b1edfbc3 | 3 | ;;; Copyright © 2017 Ludovic Courtès <ludo@gnu.org> |
03476a23 RW |
4 | ;;; |
5 | ;;; This file is part of GNU Guix. | |
6 | ;;; | |
7 | ;;; GNU Guix is free software; you can redistribute it and/or modify it | |
8 | ;;; under the terms of the GNU General Public License as published by | |
9 | ;;; the Free Software Foundation; either version 3 of the License, or (at | |
10 | ;;; your option) any later version. | |
11 | ;;; | |
12 | ;;; GNU Guix is distributed in the hope that it will be useful, but | |
13 | ;;; WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | ;;; GNU General Public License for more details. | |
16 | ;;; | |
17 | ;;; You should have received a copy of the GNU General Public License | |
18 | ;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>. | |
19 | ||
20 | (define-module (guix docker) | |
21 | #:use-module (guix hash) | |
4c0c4db0 | 22 | #:use-module (guix base16) |
03476a23 | 23 | #:use-module ((guix build utils) |
9e84ea36 LC |
24 | #:select (mkdir-p |
25 | delete-file-recursively | |
03476a23 | 26 | with-directory-excursion)) |
b1edfbc3 | 27 | #:use-module (guix build store-copy) |
84dda5a9 | 28 | #:use-module (srfi srfi-19) |
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29 | #:use-module (rnrs bytevectors) |
30 | #:use-module (ice-9 match) | |
31 | #:export (build-docker-image)) | |
32 | ||
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33 | ;; Load Guile-JSON at run time to simplify the job of 'imported-modules' & co. |
34 | (module-use! (current-module) (resolve-interface '(json))) | |
35 | ||
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36 | ;; Generate a 256-bit identifier in hexadecimal encoding for the Docker image |
37 | ;; containing the closure at PATH. | |
38 | (define docker-id | |
39 | (compose bytevector->base16-string sha256 string->utf8)) | |
40 | ||
41 | (define (layer-diff-id layer) | |
42 | "Generate a layer DiffID for the given LAYER archive." | |
43 | (string-append "sha256:" (bytevector->base16-string (file-sha256 layer)))) | |
44 | ||
45 | ;; This is the semantic version of the JSON metadata schema according to | |
46 | ;; https://github.com/docker/docker/blob/master/image/spec/v1.2.md | |
47 | ;; It is NOT the version of the image specification. | |
48 | (define schema-version "1.0") | |
49 | ||
50 | (define (image-description id time) | |
51 | "Generate a simple image description." | |
52 | `((id . ,id) | |
53 | (created . ,time) | |
54 | (container_config . #nil))) | |
55 | ||
56 | (define (generate-tag path) | |
57 | "Generate an image tag for the given PATH." | |
58 | (match (string-split (basename path) #\-) | |
59 | ((hash name . rest) (string-append name ":" hash)))) | |
60 | ||
61 | (define (manifest path id) | |
62 | "Generate a simple image manifest." | |
63 | `(((Config . "config.json") | |
64 | (RepoTags . (,(generate-tag path))) | |
65 | (Layers . (,(string-append id "/layer.tar")))))) | |
66 | ||
67 | ;; According to the specifications this is required for backwards | |
68 | ;; compatibility. It duplicates information provided by the manifest. | |
69 | (define (repositories path id) | |
70 | "Generate a repositories file referencing PATH and the image ID." | |
71 | `((,(generate-tag path) . ((latest . ,id))))) | |
72 | ||
73 | ;; See https://github.com/opencontainers/image-spec/blob/master/config.md | |
74 | (define (config layer time arch) | |
75 | "Generate a minimal image configuration for the given LAYER file." | |
76 | ;; "architecture" must be values matching "platform.arch" in the | |
77 | ;; runtime-spec at | |
78 | ;; https://github.com/opencontainers/runtime-spec/blob/v1.0.0-rc2/config.md#platform | |
79 | `((architecture . ,arch) | |
80 | (comment . "Generated by GNU Guix") | |
81 | (created . ,time) | |
82 | (config . #nil) | |
83 | (container_config . #nil) | |
84 | (os . "linux") | |
85 | (rootfs . ((type . "layers") | |
86 | (diff_ids . (,(layer-diff-id layer))))))) | |
87 | ||
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88 | (define %tar-determinism-options |
89 | ;; GNU tar options to produce archives deterministically. | |
90 | '("--sort=name" "--mtime=@1" | |
91 | "--owner=root:0" "--group=root:0")) | |
92 | ||
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93 | (define symlink-source |
94 | (match-lambda | |
95 | ((source '-> target) | |
96 | (string-trim source #\/)))) | |
97 | ||
98 | (define (topmost-component file) | |
99 | "Return the topmost component of FILE. For instance, if FILE is \"/a/b/c\", | |
100 | return \"a\"." | |
101 | (match (string-tokenize file (char-set-complement (char-set #\/))) | |
102 | ((first rest ...) | |
103 | first))) | |
104 | ||
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105 | (define* (build-docker-image image path |
106 | #:key closure compressor | |
9e84ea36 | 107 | (symlinks '()) |
5461115e | 108 | (system (utsname:machine (uname))) |
84dda5a9 | 109 | (creation-time (current-time time-utc))) |
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110 | "Write to IMAGE a Docker image archive from the given store PATH. The image |
111 | contains the closure of PATH, as specified in CLOSURE (a file produced by | |
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112 | #:references-graphs). SYMLINKS must be a list of (SOURCE -> TARGET) tuples |
113 | describing symlinks to be created in the image, where each TARGET is relative | |
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114 | to PATH. SYSTEM is a GNU triplet (or prefix thereof) of the system the |
115 | binaries at PATH are for; it is used to produce metadata in the image. | |
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116 | |
117 | Use COMPRESSOR, a command such as '(\"gzip\" \"-9n\"), to compress IMAGE. Use | |
118 | CREATION-TIME, a SRFI-19 time-utc object, as the creation time in metadata." | |
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119 | (let ((directory "/tmp/docker-image") ;temporary working directory |
120 | (closure (canonicalize-path closure)) | |
121 | (id (docker-id path)) | |
84dda5a9 | 122 | (time (date->string (time-utc->date creation-time) "~4")) |
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123 | (arch (let-syntax ((cond* (syntax-rules () |
124 | ((_ (pattern clause) ...) | |
125 | (cond ((string-prefix? pattern system) | |
126 | clause) | |
127 | ... | |
128 | (else | |
129 | (error "unsupported system" | |
130 | system))))))) | |
131 | (cond* ("x86_64" "amd64") | |
132 | ("i686" "386") | |
133 | ("arm" "arm") | |
134 | ("mips64" "mips64le"))))) | |
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135 | ;; Make sure we start with a fresh, empty working directory. |
136 | (mkdir directory) | |
137 | ||
138 | (and (with-directory-excursion directory | |
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139 | (mkdir id) |
140 | (with-directory-excursion id | |
141 | (with-output-to-file "VERSION" | |
142 | (lambda () (display schema-version))) | |
143 | (with-output-to-file "json" | |
144 | (lambda () (scm->json (image-description id time)))) | |
145 | ||
9e84ea36 | 146 | ;; Wrap it up. |
b1edfbc3 LC |
147 | (let ((items (call-with-input-file closure |
148 | read-reference-graph))) | |
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149 | ;; Create SYMLINKS. |
150 | (for-each (match-lambda | |
151 | ((source '-> target) | |
152 | (let ((source (string-trim source #\/))) | |
153 | (mkdir-p (dirname source)) | |
154 | (symlink (string-append path "/" target) | |
155 | source)))) | |
156 | symlinks) | |
157 | ||
b1edfbc3 | 158 | (and (zero? (apply system* "tar" "-cf" "layer.tar" |
54241dc8 | 159 | (append %tar-determinism-options |
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160 | items |
161 | (map symlink-source symlinks)))) | |
162 | (for-each delete-file-recursively | |
163 | (map (compose topmost-component symlink-source) | |
164 | symlinks))))) | |
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165 | |
166 | (with-output-to-file "config.json" | |
167 | (lambda () | |
168 | (scm->json (config (string-append id "/layer.tar") | |
169 | time arch)))) | |
170 | (with-output-to-file "manifest.json" | |
171 | (lambda () | |
172 | (scm->json (manifest path id)))) | |
173 | (with-output-to-file "repositories" | |
174 | (lambda () | |
175 | (scm->json (repositories path id))))) | |
176 | ||
177 | (and (zero? (apply system* "tar" "-C" directory "-cf" image | |
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178 | `(,@%tar-determinism-options |
179 | ,@(if compressor | |
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180 | (list "-I" (string-join compressor)) |
181 | '()) | |
182 | "."))) | |
183 | (begin (delete-file-recursively directory) #t))))) |