diff options
Diffstat (limited to 'doc/functions.xml')
| -rw-r--r-- | doc/functions.xml | 1110 |
1 files changed, 558 insertions, 552 deletions
diff --git a/doc/functions.xml b/doc/functions.xml index b2e450972947..155ea2bd0043 100644 --- a/doc/functions.xml +++ b/doc/functions.xml @@ -1,144 +1,139 @@ <chapter xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xml:id="chap-functions"> - -<title>Functions reference</title> - -<para> - The nixpkgs repository has several utility functions to manipulate Nix expressions. -</para> - -<section xml:id="sec-overrides"> + <title>Functions reference</title> + <para> + The nixpkgs repository has several utility functions to manipulate Nix + expressions. + </para> + <section xml:id="sec-overrides"> <title>Overriding</title> <para> - Sometimes one wants to override parts of - <literal>nixpkgs</literal>, e.g. derivation attributes, the results of - derivations or even the whole package set. + Sometimes one wants to override parts of <literal>nixpkgs</literal>, e.g. + derivation attributes, the results of derivations or even the whole package + set. </para> <section xml:id="sec-pkg-override"> - <title><pkg>.override</title> + <title><pkg>.override</title> - <para> - The function <varname>override</varname> is usually available for all the - derivations in the nixpkgs expression (<varname>pkgs</varname>). - </para> - <para> - It is used to override the arguments passed to a function. - </para> - <para> - Example usages: + <para> + The function <varname>override</varname> is usually available for all the + derivations in the nixpkgs expression (<varname>pkgs</varname>). + </para> + + <para> + It is used to override the arguments passed to a function. + </para> - <programlisting>pkgs.foo.override { arg1 = val1; arg2 = val2; ... }</programlisting> - <programlisting>import pkgs.path { overlays = [ (self: super: { + <para> + Example usages: +<programlisting>pkgs.foo.override { arg1 = val1; arg2 = val2; ... }</programlisting> +<programlisting>import pkgs.path { overlays = [ (self: super: { foo = super.foo.override { barSupport = true ; }; })]};</programlisting> - <programlisting>mypkg = pkgs.callPackage ./mypkg.nix { +<programlisting>mypkg = pkgs.callPackage ./mypkg.nix { mydep = pkgs.mydep.override { ... }; }</programlisting> - </para> - - <para> - In the first example, <varname>pkgs.foo</varname> is the result of a function call - with some default arguments, usually a derivation. - Using <varname>pkgs.foo.override</varname> will call the same function with - the given new arguments. - </para> - + </para> + + <para> + In the first example, <varname>pkgs.foo</varname> is the result of a + function call with some default arguments, usually a derivation. Using + <varname>pkgs.foo.override</varname> will call the same function with the + given new arguments. + </para> </section> <section xml:id="sec-pkg-overrideAttrs"> - <title><pkg>.overrideAttrs</title> - - <para> - The function <varname>overrideAttrs</varname> allows overriding the - attribute set passed to a <varname>stdenv.mkDerivation</varname> call, - producing a new derivation based on the original one. - This function is available on all derivations produced by the - <varname>stdenv.mkDerivation</varname> function, which is most packages - in the nixpkgs expression <varname>pkgs</varname>. - </para> - - <para> - Example usage: - - <programlisting>helloWithDebug = pkgs.hello.overrideAttrs (oldAttrs: rec { + <title><pkg>.overrideAttrs</title> + + <para> + The function <varname>overrideAttrs</varname> allows overriding the + attribute set passed to a <varname>stdenv.mkDerivation</varname> call, + producing a new derivation based on the original one. This function is + available on all derivations produced by the + <varname>stdenv.mkDerivation</varname> function, which is most packages in + the nixpkgs expression <varname>pkgs</varname>. + </para> + + <para> + Example usage: +<programlisting>helloWithDebug = pkgs.hello.overrideAttrs (oldAttrs: rec { separateDebugInfo = true; });</programlisting> - </para> + </para> - <para> - In the above example, the <varname>separateDebugInfo</varname> attribute is - overridden to be true, thus building debug info for - <varname>helloWithDebug</varname>, while all other attributes will be - retained from the original <varname>hello</varname> package. - </para> + <para> + In the above example, the <varname>separateDebugInfo</varname> attribute is + overridden to be true, thus building debug info for + <varname>helloWithDebug</varname>, while all other attributes will be + retained from the original <varname>hello</varname> package. + </para> + + <para> + The argument <varname>oldAttrs</varname> is conventionally used to refer to + the attr set originally passed to <varname>stdenv.mkDerivation</varname>. + </para> + <note> <para> - The argument <varname>oldAttrs</varname> is conventionally used to refer to - the attr set originally passed to <varname>stdenv.mkDerivation</varname>. + Note that <varname>separateDebugInfo</varname> is processed only by the + <varname>stdenv.mkDerivation</varname> function, not the generated, raw + Nix derivation. Thus, using <varname>overrideDerivation</varname> will not + work in this case, as it overrides only the attributes of the final + derivation. It is for this reason that <varname>overrideAttrs</varname> + should be preferred in (almost) all cases to + <varname>overrideDerivation</varname>, i.e. to allow using + <varname>sdenv.mkDerivation</varname> to process input arguments, as well + as the fact that it is easier to use (you can use the same attribute names + you see in your Nix code, instead of the ones generated (e.g. + <varname>buildInputs</varname> vs <varname>nativeBuildInputs</varname>, + and involves less typing. </para> - - <note> - <para> - Note that <varname>separateDebugInfo</varname> is processed only by the - <varname>stdenv.mkDerivation</varname> function, not the generated, raw - Nix derivation. Thus, using <varname>overrideDerivation</varname> will - not work in this case, as it overrides only the attributes of the final - derivation. It is for this reason that <varname>overrideAttrs</varname> - should be preferred in (almost) all cases to - <varname>overrideDerivation</varname>, i.e. to allow using - <varname>sdenv.mkDerivation</varname> to process input arguments, as well - as the fact that it is easier to use (you can use the same attribute - names you see in your Nix code, instead of the ones generated (e.g. - <varname>buildInputs</varname> vs <varname>nativeBuildInputs</varname>, - and involves less typing. - </para> - </note> - + </note> </section> - <section xml:id="sec-pkg-overrideDerivation"> - <title><pkg>.overrideDerivation</title> - - <warning> - <para>You should prefer <varname>overrideAttrs</varname> in almost all - cases, see its documentation for the reasons why. - <varname>overrideDerivation</varname> is not deprecated and will continue - to work, but is less nice to use and does not have as many abilities as - <varname>overrideAttrs</varname>. - </para> - </warning> - - <warning> - <para>Do not use this function in Nixpkgs as it evaluates a Derivation - before modifying it, which breaks package abstraction and removes - error-checking of function arguments. In addition, this - evaluation-per-function application incurs a performance penalty, - which can become a problem if many overrides are used. - It is only intended for ad-hoc customisation, such as in - <filename>~/.config/nixpkgs/config.nix</filename>. - </para> - </warning> + <title><pkg>.overrideDerivation</title> + <warning> <para> - The function <varname>overrideDerivation</varname> creates a new derivation - based on an existing one by overriding the original's attributes with - the attribute set produced by the specified function. - This function is available on all - derivations defined using the <varname>makeOverridable</varname> function. - Most standard derivation-producing functions, such as - <varname>stdenv.mkDerivation</varname>, are defined using this - function, which means most packages in the nixpkgs expression, - <varname>pkgs</varname>, have this function. + You should prefer <varname>overrideAttrs</varname> in almost all cases, + see its documentation for the reasons why. + <varname>overrideDerivation</varname> is not deprecated and will continue + to work, but is less nice to use and does not have as many abilities as + <varname>overrideAttrs</varname>. </para> + </warning> + <warning> <para> - Example usage: - - <programlisting>mySed = pkgs.gnused.overrideDerivation (oldAttrs: { + Do not use this function in Nixpkgs as it evaluates a Derivation before + modifying it, which breaks package abstraction and removes error-checking + of function arguments. In addition, this evaluation-per-function + application incurs a performance penalty, which can become a problem if + many overrides are used. It is only intended for ad-hoc customisation, + such as in <filename>~/.config/nixpkgs/config.nix</filename>. + </para> + </warning> + + <para> + The function <varname>overrideDerivation</varname> creates a new derivation + based on an existing one by overriding the original's attributes with the + attribute set produced by the specified function. This function is + available on all derivations defined using the + <varname>makeOverridable</varname> function. Most standard + derivation-producing functions, such as + <varname>stdenv.mkDerivation</varname>, are defined using this function, + which means most packages in the nixpkgs expression, + <varname>pkgs</varname>, have this function. + </para> + + <para> + Example usage: +<programlisting>mySed = pkgs.gnused.overrideDerivation (oldAttrs: { name = "sed-4.2.2-pre"; src = fetchurl { url = ftp://alpha.gnu.org/gnu/sed/sed-4.2.2-pre.tar.bz2; @@ -146,98 +141,90 @@ }; patches = []; });</programlisting> - </para> + </para> - <para> - In the above example, the <varname>name</varname>, <varname>src</varname>, - and <varname>patches</varname> of the derivation will be overridden, while - all other attributes will be retained from the original derivation. - </para> + <para> + In the above example, the <varname>name</varname>, <varname>src</varname>, + and <varname>patches</varname> of the derivation will be overridden, while + all other attributes will be retained from the original derivation. + </para> + + <para> + The argument <varname>oldAttrs</varname> is used to refer to the attribute + set of the original derivation. + </para> + <note> <para> - The argument <varname>oldAttrs</varname> is used to refer to the attribute set of - the original derivation. + A package's attributes are evaluated *before* being modified by the + <varname>overrideDerivation</varname> function. For example, the + <varname>name</varname> attribute reference in <varname>url = + "mirror://gnu/hello/${name}.tar.gz";</varname> is filled-in *before* the + <varname>overrideDerivation</varname> function modifies the attribute set. + This means that overriding the <varname>name</varname> attribute, in this + example, *will not* change the value of the <varname>url</varname> + attribute. Instead, we need to override both the <varname>name</varname> + *and* <varname>url</varname> attributes. </para> - - <note> - <para> - A package's attributes are evaluated *before* being modified by - the <varname>overrideDerivation</varname> function. - For example, the <varname>name</varname> attribute reference - in <varname>url = "mirror://gnu/hello/${name}.tar.gz";</varname> - is filled-in *before* the <varname>overrideDerivation</varname> function - modifies the attribute set. This means that overriding the - <varname>name</varname> attribute, in this example, *will not* change the - value of the <varname>url</varname> attribute. Instead, we need to override - both the <varname>name</varname> *and* <varname>url</varname> attributes. - </para> - </note> - + </note> </section> <section xml:id="sec-lib-makeOverridable"> - <title>lib.makeOverridable</title> - - <para> - The function <varname>lib.makeOverridable</varname> is used to make the result - of a function easily customizable. This utility only makes sense for functions - that accept an argument set and return an attribute set. - </para> + <title>lib.makeOverridable</title> - <para> - Example usage: + <para> + The function <varname>lib.makeOverridable</varname> is used to make the + result of a function easily customizable. This utility only makes sense for + functions that accept an argument set and return an attribute set. + </para> - <programlisting>f = { a, b }: { result = a+b; } + <para> + Example usage: +<programlisting>f = { a, b }: { result = a+b; } c = lib.makeOverridable f { a = 1; b = 2; }</programlisting> - - </para> - - <para> - The variable <varname>c</varname> is the value of the <varname>f</varname> function - applied with some default arguments. Hence the value of <varname>c.result</varname> - is <literal>3</literal>, in this example. - </para> - - <para> - The variable <varname>c</varname> however also has some additional functions, like - <link linkend="sec-pkg-override">c.override</link> which can be used to - override the default arguments. In this example the value of - <varname>(c.override { a = 4; }).result</varname> is 6. - </para> - + </para> + + <para> + The variable <varname>c</varname> is the value of the <varname>f</varname> + function applied with some default arguments. Hence the value of + <varname>c.result</varname> is <literal>3</literal>, in this example. + </para> + + <para> + The variable <varname>c</varname> however also has some additional + functions, like <link linkend="sec-pkg-override">c.override</link> which + can be used to override the default arguments. In this example the value of + <varname>(c.override { a = 4; }).result</varname> is 6. + </para> </section> - -</section> - -<section xml:id="sec-generators"> + </section> + <section xml:id="sec-generators"> <title>Generators</title> <para> - Generators are functions that create file formats from nix - data structures, e. g. for configuration files. - There are generators available for: <literal>INI</literal>, - <literal>JSON</literal> and <literal>YAML</literal> + Generators are functions that create file formats from nix data structures, + e. g. for configuration files. There are generators available for: + <literal>INI</literal>, <literal>JSON</literal> and <literal>YAML</literal> </para> <para> - All generators follow a similar call interface: <code>generatorName - configFunctions data</code>, where <literal>configFunctions</literal> is - an attrset of user-defined functions that format nested parts of the - content. - They each have common defaults, so often they do not need to be set - manually. An example is <code>mkSectionName ? (name: libStr.escape [ "[" "]" - ] name)</code> from the <literal>INI</literal> generator. It receives the - name of a section and sanitizes it. The default - <literal>mkSectionName</literal> escapes <literal>[</literal> and - <literal>]</literal> with a backslash. + All generators follow a similar call interface: <code>generatorName + configFunctions data</code>, where <literal>configFunctions</literal> is an + attrset of user-defined functions that format nested parts of the content. + They each have common defaults, so often they do not need to be set + manually. An example is <code>mkSectionName ? (name: libStr.escape [ "[" "]" + ] name)</code> from the <literal>INI</literal> generator. It receives the + name of a section and sanitizes it. The default + <literal>mkSectionName</literal> escapes <literal>[</literal> and + <literal>]</literal> with a backslash. </para> <para> - Generators can be fine-tuned to produce exactly the file format required - by your application/service. One example is an INI-file format which uses - <literal>: </literal> as separator, the strings - <literal>"yes"</literal>/<literal>"no"</literal> as boolean values - and requires all string values to be quoted: + Generators can be fine-tuned to produce exactly the file format required by + your application/service. One example is an INI-file format which uses + <literal>: </literal> as separator, the strings + <literal>"yes"</literal>/<literal>"no"</literal> as boolean values and + requires all string values to be quoted: </para> <programlisting> @@ -270,7 +257,9 @@ in customToINI { } </programlisting> - <para>This will produce the following INI file as nix string:</para> + <para> + This will produce the following INI file as nix string: + </para> <programlisting> [main] @@ -284,111 +273,138 @@ str\:ange:"very::strange" merge:"diff3" </programlisting> - <note><para>Nix store paths can be converted to strings by enclosing a - derivation attribute like so: <code>"${drv}"</code>.</para></note> + <note> + <para> + Nix store paths can be converted to strings by enclosing a derivation + attribute like so: <code>"${drv}"</code>. + </para> + </note> <para> - Detailed documentation for each generator can be found in - <literal>lib/generators.nix</literal>. + Detailed documentation for each generator can be found in + <literal>lib/generators.nix</literal>. </para> - -</section> - -<section xml:id="sec-debug"> + </section> + <section xml:id="sec-debug"> <title>Debugging Nix Expressions</title> - <para>Nix is a unityped, dynamic language, this means every value can - potentially appear anywhere. Since it is also non-strict, evaluation order - and what ultimately is evaluated might surprise you. Therefore it is important - to be able to debug nix expressions.</para> - - - <para>In the <literal>lib/debug.nix</literal> file you will find a number of - functions that help (pretty-)printing values while evaluation is runnnig. You - can even specify how deep these values should be printed recursively, and - transform them on the fly. Please consult the docstrings in - <literal>lib/debug.nix</literal> for usage information.</para> -</section> - + <para> + Nix is a unityped, dynamic language, this means every value can potentially + appear anywhere. Since it is also non-strict, evaluation order and what + ultimately is evaluated might surprise you. Therefore it is important to be + able to debug nix expressions. + </para> -<section xml:id="sec-fhs-environments"> + <para> + In the <literal>lib/debug.nix</literal> file you will find a number of + functions that help (pretty-)printing values while evaluation is runnnig. + You can even specify how deep these values should be printed recursively, + and transform them on the fly. Please consult the docstrings in + <literal>lib/debug.nix</literal> for usage information. + </para> + </section> + <section xml:id="sec-fhs-environments"> <title>buildFHSUserEnv</title> <para> - <function>buildFHSUserEnv</function> provides a way to build and run - FHS-compatible lightweight sandboxes. It creates an isolated root with - bound <filename>/nix/store</filename>, so its footprint in terms of disk - space needed is quite small. This allows one to run software which is hard or - unfeasible to patch for NixOS -- 3rd-party source trees with FHS assumptions, - games distributed as tarballs, software with integrity checking and/or external - self-updated binaries. It uses Linux namespaces feature to create - temporary lightweight environments which are destroyed after all child - processes exit, without root user rights requirement. Accepted arguments are: + <function>buildFHSUserEnv</function> provides a way to build and run + FHS-compatible lightweight sandboxes. It creates an isolated root with bound + <filename>/nix/store</filename>, so its footprint in terms of disk space + needed is quite small. This allows one to run software which is hard or + unfeasible to patch for NixOS -- 3rd-party source trees with FHS + assumptions, games distributed as tarballs, software with integrity checking + and/or external self-updated binaries. It uses Linux namespaces feature to + create temporary lightweight environments which are destroyed after all + child processes exit, without root user rights requirement. Accepted + arguments are: </para> <variablelist> - <varlistentry> - <term><literal>name</literal></term> - - <listitem><para>Environment name.</para></listitem> - </varlistentry> - - <varlistentry> - <term><literal>targetPkgs</literal></term> - - <listitem><para>Packages to be installed for the main host's architecture - (i.e. x86_64 on x86_64 installations). Along with libraries binaries are also - installed.</para></listitem> - </varlistentry> - - <varlistentry> - <term><literal>multiPkgs</literal></term> - - <listitem><para>Packages to be installed for all architectures supported by - a host (i.e. i686 and x86_64 on x86_64 installations). Only libraries are - installed by default.</para></listitem> - </varlistentry> - - <varlistentry> - <term><literal>extraBuildCommands</literal></term> - - <listitem><para>Additional commands to be executed for finalizing the - directory structure.</para></listitem> - </varlistentry> - - <varlistentry> - <term><literal>extraBuildCommandsMulti</literal></term> - - <listitem><para>Like <literal>extraBuildCommands</literal>, but - executed only on multilib architectures.</para></listitem> - </varlistentry> - - <varlistentry> - <term><literal>extraOutputsToInstall</literal></term> - - <listitem><para>Additional derivation outputs to be linked for both - target and multi-architecture packages.</para></listitem> - </varlistentry> - - <varlistentry> - <term><literal>extraInstallCommands</literal></term> - - <listitem><para>Additional commands to be executed for finalizing the - derivation with runner script.</para></listitem> - </varlistentry> - - <varlistentry> - <term><literal>runScript</literal></term> - - <listitem><para>A command that would be executed inside the sandbox and - passed all the command line arguments. It defaults to - <literal>bash</literal>.</para></listitem> - </varlistentry> + <varlistentry> + <term><literal>name</literal> + </term> + <listitem> + <para> + Environment name. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><literal>targetPkgs</literal> + </term> + <listitem> + <para> + Packages to be installed for the main host's architecture (i.e. x86_64 on + x86_64 installations). Along with libraries binaries are also installed. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><literal>multiPkgs</literal> + </term> + <listitem> + <para> + Packages to be installed for all architectures supported by a host (i.e. + i686 and x86_64 on x86_64 installations). Only libraries are installed by + default. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><literal>extraBuildCommands</literal> + </term> + <listitem> + <para> + Additional commands to be executed for finalizing the directory + structure. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><literal>extraBuildCommandsMulti</literal> + </term> + <listitem> + <para> + Like <literal>extraBuildCommands</literal>, but executed only on multilib + architectures. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><literal>extraOutputsToInstall</literal> + </term> + <listitem> + <para> + Additional derivation outputs to be linked for both target and + multi-architecture packages. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><literal>extraInstallCommands</literal> + </term> + <listitem> + <para> + Additional commands to be executed for finalizing the derivation with + runner script. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><literal>runScript</literal> + </term> + <listitem> + <para> + A command that would be executed inside the sandbox and passed all the + command line arguments. It defaults to <literal>bash</literal>. + </para> + </listitem> + </varlistentry> </variablelist> <para> - One can create a simple environment using a <literal>shell.nix</literal> - like that: + One can create a simple environment using a <literal>shell.nix</literal> + like that: </para> <programlisting><![CDATA[ @@ -413,50 +429,49 @@ merge:"diff3" ]]></programlisting> <para> - Running <literal>nix-shell</literal> would then drop you into a shell with - these libraries and binaries available. You can use this to run - closed-source applications which expect FHS structure without hassles: - simply change <literal>runScript</literal> to the application path, - e.g. <filename>./bin/start.sh</filename> -- relative paths are supported. - </para> -</section> - -<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>. + Running <literal>nix-shell</literal> would then drop you into a shell with + these libraries and binaries available. You can use this to run + closed-source applications which expect FHS structure without hassles: + simply change <literal>runScript</literal> to the application path, e.g. + <filename>./bin/start.sh</filename> -- relative paths are supported. </para> + </section> + <section xml:id="sec-pkgs-dockerTools"> + <title>pkgs.dockerTools</title> <para> - The parameters of <varname>buildImage</varname> with relative example values are - described below: + <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> - <example xml:id='ex-dockerTools-buildImage'><title>Docker build</title> - <programlisting> + <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' /> @@ -480,154 +495,148 @@ merge:"diff3" }; } </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'> + </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>latest</literal>. + </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> + |