diff options
Diffstat (limited to 'doc/stdenv/meta.chapter.md')
| -rw-r--r-- | doc/stdenv/meta.chapter.md | 50 |
1 files changed, 31 insertions, 19 deletions
diff --git a/doc/stdenv/meta.chapter.md b/doc/stdenv/meta.chapter.md index 4a3b04b8f6e4..7f57eda791ea 100644 --- a/doc/stdenv/meta.chapter.md +++ b/doc/stdenv/meta.chapter.md @@ -3,17 +3,19 @@ Nix packages can declare *meta-attributes* that contain information about a package such as a description, its homepage, its license, and so on. For instance, the GNU Hello package has a `meta` declaration like this: ```nix -meta = { - description = "A program that produces a familiar, friendly greeting"; - longDescription = '' - GNU Hello is a program that prints "Hello, world!" when you run it. - It is fully customizable. - ''; - homepage = "https://www.gnu.org/software/hello/manual/"; - license = lib.licenses.gpl3Plus; - maintainers = with lib.maintainers; [ eelco ]; - platforms = lib.platforms.all; -}; +{ + meta = { + description = "A program that produces a familiar, friendly greeting"; + longDescription = '' + GNU Hello is a program that prints "Hello, world!" when you run it. + It is fully customizable. + ''; + homepage = "https://www.gnu.org/software/hello/manual/"; + license = lib.licenses.gpl3Plus; + maintainers = with lib.maintainers; [ eelco ]; + platforms = lib.platforms.all; + }; +} ``` Meta-attributes are not passed to the builder of the package. Thus, a change to a meta-attribute doesn’t trigger a recompilation of the package. @@ -82,7 +84,9 @@ The *priority* of the package, used by `nix-env` to resolve file name conflicts The list of Nix platform types on which the package is supported. Hydra builds packages according to the platform specified. If no platform is specified, the package does not have prebuilt binaries. An example is: ```nix -meta.platforms = lib.platforms.linux; +{ + meta.platforms = lib.platforms.linux; +} ``` Attribute Set `lib.platforms` defines [various common lists](https://github.com/NixOS/nixpkgs/blob/master/lib/systems/doubles.nix) of platforms types. @@ -95,8 +99,10 @@ In general it is preferable to set `meta.platforms = lib.platforms.all` and then For example, a package which requires dynamic linking and cannot be linked statically could use this: ```nix -meta.platforms = lib.platforms.all; -meta.badPlatforms = [ lib.systems.inspect.patterns.isStatic ]; +{ + meta.platforms = lib.platforms.all; + meta.badPlatforms = [ lib.systems.inspect.patterns.isStatic ]; +} ``` The [`lib.meta.availableOn`](https://github.com/NixOS/nixpkgs/blob/b03ac42b0734da3e7be9bf8d94433a5195734b19/lib/meta.nix#L95-L106) function can be used to test whether or not a package is available (i.e. buildable) on a given platform. @@ -136,7 +142,7 @@ For more on how to write and run package tests, see [](#sec-package-tests). The NixOS tests are available as `nixosTests` in parameters of derivations. For instance, the OpenSMTPD derivation includes lines similar to: ```nix -{ /* ... */, nixosTests }: +{ /* ... , */ nixosTests }: { # ... passthru.tests = { @@ -194,8 +200,10 @@ To be effective, it must be presented directly to an evaluation process that han The list of Nix platform types for which the [Hydra](https://github.com/nixos/hydra) [instance at `hydra.nixos.org`](https://nixos.org/hydra) will build the package. (Hydra is the Nix-based continuous build system.) It defaults to the value of `meta.platforms`. Thus, the only reason to set `meta.hydraPlatforms` is if you want `hydra.nixos.org` to build the package on a subset of `meta.platforms`, or not at all, e.g. ```nix -meta.platforms = lib.platforms.linux; -meta.hydraPlatforms = []; +{ + meta.platforms = lib.platforms.linux; + meta.hydraPlatforms = []; +} ``` ### `broken` {#var-meta-broken} @@ -209,13 +217,17 @@ This means that `broken` can be used to express constraints, for example: - Does not cross compile ```nix - meta.broken = !(stdenv.buildPlatform.canExecute stdenv.hostPlatform) + { + meta.broken = !(stdenv.buildPlatform.canExecute stdenv.hostPlatform); + } ``` - Broken if all of a certain set of its dependencies are broken ```nix - meta.broken = lib.all (map (p: p.meta.broken) [ glibc musl ]) + { + meta.broken = lib.all (map (p: p.meta.broken) [ glibc musl ]); + } ``` This makes `broken` strictly more powerful than `meta.badPlatforms`. |