mirror of
https://github.com/NixOS/nixpkgs.git
synced 2024-11-27 16:11:58 +00:00
607 lines
20 KiB
XML
607 lines
20 KiB
XML
<section xmlns="http://docbook.org/ns/docbook"
|
|
xmlns:xlink="http://www.w3.org/1999/xlink"
|
|
xmlns:xi="http://www.w3.org/2001/XInclude"
|
|
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 it can be 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' />
|
|
#!${pkgs.runtimeShell}
|
|
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 images</command>, the newly created images will be listed
|
|
like this:
|
|
</para>
|
|
<screen><![CDATA[
|
|
$ docker images
|
|
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 images
|
|
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>100</literal>
|
|
</para>
|
|
<para>
|
|
<emphasis>Maximum:</emphasis> <literal>125</literal>
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>
|
|
<varname>extraCommands</varname> <emphasis>optional</emphasis>
|
|
</term>
|
|
<listitem>
|
|
<para>
|
|
Shell commands to run while building the final layer, without access
|
|
to most of the layer contents. Changes to this layer are "on top"
|
|
of all the other layers, so can create additional directories
|
|
and files.
|
|
</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 it 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' />
|
|
finalImageName = "nix"; <co xml:id='ex-dockerTools-pullImage-3' />
|
|
finalImageTag = "1.11"; <co xml:id='ex-dockerTools-pullImage-4' />
|
|
sha256 = "0mqjy3zq2v6rrhizgb9nvhczl87lcfphq9601wcprdika2jz7qh8"; <co xml:id='ex-dockerTools-pullImage-5' />
|
|
os = "linux"; <co xml:id='ex-dockerTools-pullImage-6' />
|
|
arch = "x86_64"; <co xml:id='ex-dockerTools-pullImage-7' />
|
|
}
|
|
</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. This argument is required.
|
|
</para>
|
|
</callout>
|
|
<callout arearefs='ex-dockerTools-pullImage-3'>
|
|
<para>
|
|
<varname>finalImageName</varname>, if specified, this is the name 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 equal to
|
|
<varname>imageName</varname>.
|
|
</para>
|
|
</callout>
|
|
<callout arearefs='ex-dockerTools-pullImage-4'>
|
|
<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-5'>
|
|
<para>
|
|
<varname>sha256</varname> is the checksum of the whole fetched image. This
|
|
argument is required.
|
|
</para>
|
|
</callout>
|
|
<callout arearefs='ex-dockerTools-pullImage-6'>
|
|
<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-7'>
|
|
<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>
|
|
|
|
<para>
|
|
<literal>nix-prefetch-docker</literal> command can be used to get required
|
|
image parameters:
|
|
|
|
<screen>
|
|
<prompt>$ </prompt>nix run nixpkgs.nix-prefetch-docker -c nix-prefetch-docker --image-name mysql --image-tag 5
|
|
</screen>
|
|
|
|
Since a given <varname>imageName</varname> may transparently refer to a
|
|
manifest list of images which support multiple architectures and/or
|
|
operating systems, you can supply the <option>--os</option> and
|
|
<option>--arch</option> 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.
|
|
|
|
<screen>
|
|
<prompt>$ </prompt>nix-prefetch-docker --image-name mysql --image-tag 5 --arch x86_64 --os linux
|
|
</screen>
|
|
|
|
Desired image name and tag can be set using
|
|
<option>--final-image-name</option> and <option>--final-image-tag</option>
|
|
arguments:
|
|
|
|
<screen>
|
|
<prompt>$ </prompt>nix-prefetch-docker --image-name mysql --image-tag 5 --final-image-name eu.gcr.io/my-project/mysql --final-image-tag prod
|
|
</screen>
|
|
</para>
|
|
</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 it can be 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 = ''
|
|
#!${pkgs.runtimeShell}
|
|
${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> is necessary for shadow-utils to
|
|
manipulate users and groups.
|
|
</para>
|
|
</section>
|
|
</section>
|