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authorGraham Christensen <graham@grahamc.com>2018-10-02 14:13:12 -0400
committerGraham Christensen <graham@grahamc.com>2018-10-02 14:13:12 -0400
commit8bf342ffb86eedf8a9749420b4019ab1e4c21629 (patch)
treecdaaffd4e3102b0c6be500d8f78a91691a19b463 /doc/functions.xml
parent0856d5c4add0abe92c1a8d15f95003ce5a2b828d (diff)
nixpkgs docs: move dockertool to its own file
Diffstat (limited to 'doc/functions.xml')
-rw-r--r--doc/functions.xml564
1 files changed, 1 insertions, 563 deletions
diff --git a/doc/functions.xml b/doc/functions.xml
index ac75c4fc10e4..4fc387f0fbd6 100644
--- a/doc/functions.xml
+++ b/doc/functions.xml
@@ -13,567 +13,5 @@
<xi:include href="functions/debug.xml" />
<xi:include href="functions/fhs-environments.xml" />
<xi:include href="shell.section.xml" />
- <section xml:id="sec-pkgs-dockerTools">
- <title>pkgs.dockerTools</title>
-
- <para>
- <varname>pkgs.dockerTools</varname> is a set of functions for creating and
- manipulating Docker images according to the
- <link xlink:href="https://github.com/moby/moby/blob/master/image/spec/v1.2.md#docker-image-specification-v120">
- Docker Image Specification v1.2.0 </link>. Docker itself is not used to
- perform any of the operations done by these functions.
- </para>
-
- <warning>
- <para>
- The <varname>dockerTools</varname> API is unstable and may be subject to
- backwards-incompatible changes in the future.
- </para>
- </warning>
-
- <section xml:id="ssec-pkgs-dockerTools-buildImage">
- <title>buildImage</title>
-
- <para>
- This function is analogous to the <command>docker build</command> command,
- in that can used to build a Docker-compatible repository tarball containing
- a single image with one or multiple layers. As such, the result is suitable
- for being loaded in Docker with <command>docker load</command>.
- </para>
-
- <para>
- The parameters of <varname>buildImage</varname> with relative example
- values are described below:
- </para>
-
- <example xml:id='ex-dockerTools-buildImage'>
- <title>Docker build</title>
-<programlisting>
-buildImage {
- name = "redis"; <co xml:id='ex-dockerTools-buildImage-1' />
- tag = "latest"; <co xml:id='ex-dockerTools-buildImage-2' />
-
- fromImage = someBaseImage; <co xml:id='ex-dockerTools-buildImage-3' />
- fromImageName = null; <co xml:id='ex-dockerTools-buildImage-4' />
- fromImageTag = "latest"; <co xml:id='ex-dockerTools-buildImage-5' />
-
- contents = pkgs.redis; <co xml:id='ex-dockerTools-buildImage-6' />
- runAsRoot = '' <co xml:id='ex-dockerTools-buildImage-runAsRoot' />
- #!${stdenv.shell}
- mkdir -p /data
- '';
-
- config = { <co xml:id='ex-dockerTools-buildImage-8' />
- Cmd = [ "/bin/redis-server" ];
- WorkingDir = "/data";
- Volumes = {
- "/data" = {};
- };
- };
-}
-</programlisting>
- </example>
-
- <para>
- The above example will build a Docker image <literal>redis/latest</literal>
- from the given base image. Loading and running this image in Docker results
- in <literal>redis-server</literal> being started automatically.
- </para>
-
- <calloutlist>
- <callout arearefs='ex-dockerTools-buildImage-1'>
- <para>
- <varname>name</varname> specifies the name of the resulting image. This
- is the only required argument for <varname>buildImage</varname>.
- </para>
- </callout>
- <callout arearefs='ex-dockerTools-buildImage-2'>
- <para>
- <varname>tag</varname> specifies the tag of the resulting image. By
- default it's <literal>null</literal>, which indicates that the nix output
- hash will be used as tag.
- </para>
- </callout>
- <callout arearefs='ex-dockerTools-buildImage-3'>
- <para>
- <varname>fromImage</varname> is the repository tarball containing the
- base image. It must be a valid Docker image, such as exported by
- <command>docker save</command>. By default it's <literal>null</literal>,
- which can be seen as equivalent to <literal>FROM scratch</literal> of a
- <filename>Dockerfile</filename>.
- </para>
- </callout>
- <callout arearefs='ex-dockerTools-buildImage-4'>
- <para>
- <varname>fromImageName</varname> can be used to further specify the base
- image within the repository, in case it contains multiple images. By
- default it's <literal>null</literal>, in which case
- <varname>buildImage</varname> will peek the first image available in the
- repository.
- </para>
- </callout>
- <callout arearefs='ex-dockerTools-buildImage-5'>
- <para>
- <varname>fromImageTag</varname> can be used to further specify the tag of
- the base image within the repository, in case an image contains multiple
- tags. By default it's <literal>null</literal>, in which case
- <varname>buildImage</varname> will peek the first tag available for the
- base image.
- </para>
- </callout>
- <callout arearefs='ex-dockerTools-buildImage-6'>
- <para>
- <varname>contents</varname> is a derivation that will be copied in the
- new layer of the resulting image. This can be similarly seen as
- <command>ADD contents/ /</command> in a <filename>Dockerfile</filename>.
- By default it's <literal>null</literal>.
- </para>
- </callout>
- <callout arearefs='ex-dockerTools-buildImage-runAsRoot'>
- <para>
- <varname>runAsRoot</varname> is a bash script that will run as root in an
- environment that overlays the existing layers of the base image with the
- new resulting layer, including the previously copied
- <varname>contents</varname> derivation. This can be similarly seen as
- <command>RUN ...</command> in a <filename>Dockerfile</filename>.
- <note>
- <para>
- Using this parameter requires the <literal>kvm</literal> device to be
- available.
- </para>
- </note>
- </para>
- </callout>
- <callout arearefs='ex-dockerTools-buildImage-8'>
- <para>
- <varname>config</varname> is used to specify the configuration of the
- containers that will be started off the built image in Docker. The
- available options are listed in the
- <link xlink:href="https://github.com/moby/moby/blob/master/image/spec/v1.2.md#image-json-field-descriptions">
- Docker Image Specification v1.2.0 </link>.
- </para>
- </callout>
- </calloutlist>
-
- <para>
- After the new layer has been created, its closure (to which
- <varname>contents</varname>, <varname>config</varname> and
- <varname>runAsRoot</varname> contribute) will be copied in the layer
- itself. Only new dependencies that are not already in the existing layers
- will be copied.
- </para>
-
- <para>
- At the end of the process, only one new single layer will be produced and
- added to the resulting image.
- </para>
-
- <para>
- The resulting repository will only list the single image
- <varname>image/tag</varname>. In the case of
- <xref linkend='ex-dockerTools-buildImage'/> it would be
- <varname>redis/latest</varname>.
- </para>
-
- <para>
- It is possible to inspect the arguments with which an image was built using
- its <varname>buildArgs</varname> attribute.
- </para>
-
- <note>
- <para>
- If you see errors similar to <literal>getProtocolByName: does not exist
- (no such protocol name: tcp)</literal> you may need to add
- <literal>pkgs.iana-etc</literal> to <varname>contents</varname>.
- </para>
- </note>
-
- <note>
- <para>
- If you see errors similar to <literal>Error_Protocol ("certificate has
- unknown CA",True,UnknownCa)</literal> you may need to add
- <literal>pkgs.cacert</literal> to <varname>contents</varname>.
- </para>
- </note>
-
- <example xml:id="example-pkgs-dockerTools-buildImage-creation-date">
- <title>Impurely Defining a Docker Layer's Creation Date</title>
- <para>
- By default <function>buildImage</function> will use a static
- date of one second past the UNIX Epoch. This allows
- <function>buildImage</function> to produce binary reproducible
- images. When listing images with <command>docker list
- images</command>, the newly created images will be listed like
- this:
- </para>
- <screen><![CDATA[
-$ docker image list
-REPOSITORY TAG IMAGE ID CREATED SIZE
-hello latest 08c791c7846e 48 years ago 25.2MB
-]]></screen>
- <para>
- You can break binary reproducibility but have a sorted,
- meaningful <literal>CREATED</literal> column by setting
- <literal>created</literal> to <literal>now</literal>.
- </para>
- <programlisting><![CDATA[
-pkgs.dockerTools.buildImage {
- name = "hello";
- tag = "latest";
- created = "now";
- contents = pkgs.hello;
-
- config.Cmd = [ "/bin/hello" ];
-}
-]]></programlisting>
- <para>
- and now the Docker CLI will display a reasonable date and
- sort the images as expected:
- <screen><![CDATA[
-$ docker image list
-REPOSITORY TAG IMAGE ID CREATED SIZE
-hello latest de2bf4786de6 About a minute ago 25.2MB
-]]></screen>
- however, the produced images will not be binary reproducible.
- </para>
- </example>
- </section>
-
- <section xml:id="ssec-pkgs-dockerTools-buildLayeredImage">
- <title>buildLayeredImage</title>
-
- <para>
- Create a Docker image with many of the store paths being on their own layer
- to improve sharing between images.
- </para>
-
- <variablelist>
- <varlistentry>
- <term>
- <varname>name</varname>
- </term>
- <listitem>
- <para>
- The name of the resulting image.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>
- <varname>tag</varname> <emphasis>optional</emphasis>
- </term>
- <listitem>
- <para>
- Tag of the generated image.
- </para>
- <para>
- <emphasis>Default:</emphasis> the output path's hash
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>
- <varname>contents</varname> <emphasis>optional</emphasis>
- </term>
- <listitem>
- <para>
- Top level paths in the container. Either a single derivation, or a list
- of derivations.
- </para>
- <para>
- <emphasis>Default:</emphasis> <literal>[]</literal>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>
- <varname>config</varname> <emphasis>optional</emphasis>
- </term>
- <listitem>
- <para>
- Run-time configuration of the container. A full list of the options are
- available at in the
- <link xlink:href="https://github.com/moby/moby/blob/master/image/spec/v1.2.md#image-json-field-descriptions">
- Docker Image Specification v1.2.0 </link>.
- </para>
- <para>
- <emphasis>Default:</emphasis> <literal>{}</literal>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>
- <varname>created</varname> <emphasis>optional</emphasis>
- </term>
- <listitem>
- <para>
- Date and time the layers were created. Follows the same
- <literal>now</literal> exception supported by
- <literal>buildImage</literal>.
- </para>
- <para>
- <emphasis>Default:</emphasis> <literal>1970-01-01T00:00:01Z</literal>
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>
- <varname>maxLayers</varname> <emphasis>optional</emphasis>
- </term>
- <listitem>
- <para>
- Maximum number of layers to create.
- </para>
- <para>
- <emphasis>Default:</emphasis> <literal>24</literal>
- </para>
- </listitem>
- </varlistentry>
- </variablelist>
-
- <section xml:id="dockerTools-buildLayeredImage-arg-contents">
- <title>Behavior of <varname>contents</varname> in the final image</title>
-
- <para>
- Each path directly listed in <varname>contents</varname> will have a
- symlink in the root of the image.
- </para>
-
- <para>
- For example:
-<programlisting><![CDATA[
-pkgs.dockerTools.buildLayeredImage {
- name = "hello";
- contents = [ pkgs.hello ];
-}
-]]></programlisting>
- will create symlinks for all the paths in the <literal>hello</literal>
- package:
-<screen><![CDATA[
-/bin/hello -> /nix/store/h1zb1padqbbb7jicsvkmrym3r6snphxg-hello-2.10/bin/hello
-/share/info/hello.info -> /nix/store/h1zb1padqbbb7jicsvkmrym3r6snphxg-hello-2.10/share/info/hello.info
-/share/locale/bg/LC_MESSAGES/hello.mo -> /nix/store/h1zb1padqbbb7jicsvkmrym3r6snphxg-hello-2.10/share/locale/bg/LC_MESSAGES/hello.mo
-]]></screen>
- </para>
- </section>
-
- <section xml:id="dockerTools-buildLayeredImage-arg-config">
- <title>Automatic inclusion of <varname>config</varname> references</title>
-
- <para>
- The closure of <varname>config</varname> is automatically included in the
- closure of the final image.
- </para>
-
- <para>
- This allows you to make very simple Docker images with very little code.
- This container will start up and run <command>hello</command>:
-<programlisting><![CDATA[
-pkgs.dockerTools.buildLayeredImage {
- name = "hello";
- config.Cmd = [ "${pkgs.hello}/bin/hello" ];
-}
-]]></programlisting>
- </para>
- </section>
-
- <section xml:id="dockerTools-buildLayeredImage-arg-maxLayers">
- <title>Adjusting <varname>maxLayers</varname></title>
-
- <para>
- Increasing the <varname>maxLayers</varname> increases the number of layers
- which have a chance to be shared between different images.
- </para>
-
- <para>
- Modern Docker installations support up to 128 layers, however older
- versions support as few as 42.
- </para>
-
- <para>
- If the produced image will not be extended by other Docker builds, it is
- safe to set <varname>maxLayers</varname> to <literal>128</literal>.
- However it will be impossible to extend the image further.
- </para>
-
- <para>
- The first (<literal>maxLayers-2</literal>) most "popular" paths will have
- their own individual layers, then layer #<literal>maxLayers-1</literal>
- will contain all the remaining "unpopular" paths, and finally layer
- #<literal>maxLayers</literal> will contain the Image configuration.
- </para>
-
- <para>
- Docker's Layers are not inherently ordered, they are content-addressable
- and are not explicitly layered until they are composed in to an Image.
- </para>
- </section>
- </section>
-
- <section xml:id="ssec-pkgs-dockerTools-fetchFromRegistry">
- <title>pullImage</title>
-
- <para>
- This function is analogous to the <command>docker pull</command> command,
- in that can be used to pull a Docker image from a Docker registry. By
- default <link xlink:href="https://hub.docker.com/">Docker Hub</link> is
- used to pull images.
- </para>
-
- <para>
- Its parameters are described in the example below:
- </para>
-
- <example xml:id='ex-dockerTools-pullImage'>
- <title>Docker pull</title>
-<programlisting>
-pullImage {
- imageName = "nixos/nix"; <co xml:id='ex-dockerTools-pullImage-1' />
- imageDigest = "sha256:20d9485b25ecfd89204e843a962c1bd70e9cc6858d65d7f5fadc340246e2116b"; <co xml:id='ex-dockerTools-pullImage-2' />
- finalImageTag = "1.11"; <co xml:id='ex-dockerTools-pullImage-3' />
- sha256 = "0mqjy3zq2v6rrhizgb9nvhczl87lcfphq9601wcprdika2jz7qh8"; <co xml:id='ex-dockerTools-pullImage-4' />
- os = "linux"; <co xml:id='ex-dockerTools-pullImage-5' />
- arch = "x86_64"; <co xml:id='ex-dockerTools-pullImage-6' />
-}
-</programlisting>
- </example>
-
- <calloutlist>
- <callout arearefs='ex-dockerTools-pullImage-1'>
- <para>
- <varname>imageName</varname> specifies the name of the image to be
- downloaded, which can also include the registry namespace (e.g.
- <literal>nixos</literal>). This argument is required.
- </para>
- </callout>
- <callout arearefs='ex-dockerTools-pullImage-2'>
- <para>
- <varname>imageDigest</varname> specifies the digest of the image to be
- downloaded. Skopeo can be used to get the digest of an image, with its
- <varname>inspect</varname> subcommand. Since a given
- <varname>imageName</varname> may transparently refer to a manifest list
- of images which support multiple architectures and/or operating systems,
- supply the `--override-os` and `--override-arch` arguments to specify
- exactly which image you want. By default it will match the OS and
- architecture of the host the command is run on.
-<programlisting>
-$ nix-shell --packages skopeo jq --command "skopeo --override-os linux --override-arch x86_64 inspect docker://docker.io/nixos/nix:1.11 | jq -r '.Digest'"
-sha256:20d9485b25ecfd89204e843a962c1bd70e9cc6858d65d7f5fadc340246e2116b
-</programlisting>
- This argument is required.
- </para>
- </callout>
- <callout arearefs='ex-dockerTools-pullImage-3'>
- <para>
- <varname>finalImageTag</varname>, if specified, this is the tag of the
- image to be created. Note it is never used to fetch the image since we
- prefer to rely on the immutable digest ID. By default it's
- <literal>latest</literal>.
- </para>
- </callout>
- <callout arearefs='ex-dockerTools-pullImage-4'>
- <para>
- <varname>sha256</varname> is the checksum of the whole fetched image.
- This argument is required.
- </para>
- </callout>
- <callout arearefs='ex-dockerTools-pullImage-5'>
- <para>
- <varname>os</varname>, if specified, is the operating system of the
- fetched image. By default it's <literal>linux</literal>.
- </para>
- </callout>
- <callout arearefs='ex-dockerTools-pullImage-6'>
- <para>
- <varname>arch</varname>, if specified, is the cpu architecture of the
- fetched image. By default it's <literal>x86_64</literal>.
- </para>
- </callout>
- </calloutlist>
- </section>
-
- <section xml:id="ssec-pkgs-dockerTools-exportImage">
- <title>exportImage</title>
-
- <para>
- This function is analogous to the <command>docker export</command> command,
- in that can used to flatten a Docker image that contains multiple layers.
- It is in fact the result of the merge of all the layers of the image. As
- such, the result is suitable for being imported in Docker with
- <command>docker import</command>.
- </para>
-
- <note>
- <para>
- Using this function requires the <literal>kvm</literal> device to be
- available.
- </para>
- </note>
-
- <para>
- The parameters of <varname>exportImage</varname> are the following:
- </para>
-
- <example xml:id='ex-dockerTools-exportImage'>
- <title>Docker export</title>
-<programlisting>
-exportImage {
- fromImage = someLayeredImage;
- fromImageName = null;
- fromImageTag = null;
-
- name = someLayeredImage.name;
-}
- </programlisting>
- </example>
-
- <para>
- The parameters relative to the base image have the same synopsis as
- described in <xref linkend='ssec-pkgs-dockerTools-buildImage'/>, except
- that <varname>fromImage</varname> is the only required argument in this
- case.
- </para>
-
- <para>
- The <varname>name</varname> argument is the name of the derivation output,
- which defaults to <varname>fromImage.name</varname>.
- </para>
- </section>
-
- <section xml:id="ssec-pkgs-dockerTools-shadowSetup">
- <title>shadowSetup</title>
-
- <para>
- This constant string is a helper for setting up the base files for managing
- users and groups, only if such files don't exist already. It is suitable
- for being used in a <varname>runAsRoot</varname>
- <xref linkend='ex-dockerTools-buildImage-runAsRoot'/> script for cases like
- in the example below:
- </para>
-
- <example xml:id='ex-dockerTools-shadowSetup'>
- <title>Shadow base files</title>
-<programlisting>
-buildImage {
- name = "shadow-basic";
-
- runAsRoot = ''
- #!${stdenv.shell}
- ${shadowSetup}
- groupadd -r redis
- useradd -r -g redis redis
- mkdir /data
- chown redis:redis /data
- '';
-}
-</programlisting>
- </example>
-
- <para>
- Creating base files like <literal>/etc/passwd</literal> or
- <literal>/etc/login.defs</literal> are necessary for shadow-utils to
- manipulate users and groups.
- </para>
- </section>
- </section>
+ <xi:include href="functions/dockertools.xml" />
</chapter>