+++
title = "Packaging Practices"
+++
# Packaging Practices

The primary goal of `ypkg` is ease of maintenance. In order to do so we ensure packages in the binary repository adhere to a strict set of conventions and practices.

The next few sections will detail these.

## Package naming

The `ypkg` tool does not allow for custom subpackages or subpackage naming, and will enforce its own policy. This can be eased somewhat through the use of `patterns`, however the available subpackage names are limited.

We request you use (where possible) the upstream source name for your package. Subpackage names (when generated) are constructed by using the `name` value first, then applying the subpackage name as such:

`pkgname-$subpackage`

Subpackages are fully automatic with `ypkg`, and are created based on file patterns. All subpackages automatically depend on the main package, to ensure correct operation. In the following explanations, `$lib` is used to refer to the host 
library directory, i.e. `lib` or `lib64` (or `lib32` on `emul32` builds)

### The devel subpackage

This is invariably created for packages that provide libraries and development headers. The following rules will result in files being placed in a `devel` subpackage:

```
/usr/include
/usr/$lib/lib*.so
/usr/$lib/lib*.a
/usr/share/man2/
/usr/share/man3/
/usr/share/pkgconfig
/usr/$lib/pkgconfig
/usr/share/cmake
/usr/share/vala
```

Note that for some packages, `/usr/$lib/lib*.so` files are not symlinks. In this instance, the main package will be broken with no library files present. This can quickly be determined by looking at the resulting .xml file generated after running the build. 
If this happens, simply override with `patterns` or set `libsplit` to “no”.

**A note on static archives**: Unless it is absolutely unavoidable, you should disable static libraries within your build. This is usually fixed by adding `--disable-static` to your configure routine. If `*.a` files are shown in your packaging request, it will be 
questioned, as they can pose a greater security risk if packages link against these static archives.

### The docs subpackage

Currently there is only one pattern which is forced into a `docs` subpackage:

```
/usr/share/gtk-doc
```

If required, you can use `patterns` to move other files into the `docs` subpackage, making it smaller.

### The 32bit subpackage

This subpackage is only generated during an `emul32` build. The folowing paths will automatically be placed into a `32bit` subpackage

```
/usr/lib32/lib*.so
/usr/lib32/lib*.so.*
/usr/lib32/lib*.a
```

Note the same static archive rules apply to `32bit` packages. These packages aren’t as heavily split as we try to discourage their use, though they must be provided in some instances.

### The utils subpackage

This is not an automatic subpackage, you must use `patterns` to utilise it. It is provided for instances that it may not be suitable to have binaries present, i.e. for a library package.

## Maintenance

When submitting a change `package.yml`, it must be accompanied by its corresponding `pspec_*.xml` file, which was generated at build time. This machine file allows the repository maintainers to evaluate the package condition.

When providing a new version of a package, or a fix, always ensure you increment the `release` number by 1. This ensures that users of your package are correctly updated to the latest version.

Never submit a package without having first tested it, and ensuring it builds within `solbuild`, a clean chroot environment.

## Generating a Package.yml

Making a package.yml file is not necessarily a manual process. In fact, [once you have common setup](/articles/packaging/building-a-package/en), you already have a script capable of generating a package.yml file based 
on the source archive URL.

You can generate a package.yml by using `common/Scripts/yauto.py URL_TO_ARCHIVE`. We recommend creation an alias in your `.bashrc` or `.zshrc`, so you can access it wherever you are. For example:

``` bash
alias fetchYml="$HOME/repository/common/Scripts/yauto.py"
```

## Patching / extra files

Files that may be required during the build can be accessed via the `$pkgfiles` variable. Note that you must store your files in the `./files` directory relative to your `package.yml`

Both patches and extra files (such as systemd units) are stored in this directory. Note that if your patch is to address a **CVE**, you must use the following naming scheme: `./files/security/cve-xxxx-xxxx.patch`

Where `xxxx-xxxx` is replaced with the full CVE ID. Complying with this simple rule ensures that we can know at any time the security status of packages when using tools such as `cve-check-tool`

### Applying a patch

It is common practice to apply the patch within the `setup` section of your build staging. We can achieve this using the `%patch` macro, and the `$pkgfiles` variable. In this example, the required file is located 
at `./files/0002-Sample-commit-2.patch`

``` bash
%patch -p1 < $pkgfiles/0002-Sample-commit-2.patch
```

Note you use the macro as you would normally use the patch command, however use of the macro ensures it performs a clean batch-mode patch.

If you are using compressed patches, i.e. for the `bash` or `readline` packages, you can pipe the call through `zcat` or similar:

``` bash
zcat $pkgfiles/bash43-032.gz | %patch -p0
```

#### Handling multiple patches 

In the event you need to apply multiple patches, such as a multitude of CVE patches, it may be sensible to use our `%apply_patches` macro, which will apply all the patches listed in a `series` file in your package's `./files` folder. Example below:

``` bash
security/cve-xxxx-xxxx.patch
fix-silliness.patch
```

Both of the files above will be applied using `-p1`. If you need to use stripping num, like `-p4`, you can do something like:

``` bash
security/cve-xxxx-xxxx.patch -p4
fix-silliness.patch
```

## Installing extra files

We recommend using patches where possible first, as they ensure correct maintainence and will be updated across package versions. If you must install extra files into the directory, please use the `install` 
command, ensuring you set the correct permissions. Again, files are accessible from the `./files/` directory, relative to `package.yml`.

This is an example of installing a custom profile file, seen in the `bash` package:

``` bash
install -m 0644 $pkgfiles/profile $installdir/etc/profile
```

### Build dependencies 

Most software packages that you build will in one way or another, depend on another software package to provide specific functionality. This is usually achieved by using a library.

Any package that is submitted to our repositories is always built in a clean chroot environment, therefore any dependencies required to build that package in a reproducible and sane fashion, must be listed.

This is achieved by populating the `builddeps` key with a list of build dependencies. We support two kinds of build dependencies: explicitly named, or `pkgconfig` dependencies.

We prefer the use of `pkgconfig` dependencies. Most modern software will use the `pkg-config` tool (package configuration) to determine which files are required to build the current software. This may include 
compiler flags, library to link against and where the package headers are located.

An obvious advantage to supporting `pkgconfig` dependencies is that there is a 1:1 mapping between the name requested by the build and the name used within the `package.yml`. Instead of trying to hunt down 
the package providing that dependency, you simply list the same name. Any package in the repository will export information about the `.pc` files (for `pkg-config`) it contains, enabling you to use those as a build dependency.

A secondary advantage is that this allows for easily switching or replacing a providing package. When no `pkgconfig` name is available (some packages do not provide these, or it doesn’t make sense for them to), you 
may use the explicit package name. Always ensure you select the correct package, i.e. the `-devel` subpackage. This provides the necessary symlinks and headers to build packages.

#### Using pkgconfig dependencies 

In the `builddeps` list, simply use the `pkgconfig(name)` syntax. For example, to add gtk+-3.0 to the build dependencies, we would do the following:

``` yaml
builddeps:
    - pkgconfig(gtk+-3.0)
```

At build time the appropriate provider package is selected, in this instance `libgtk-3-devel`

You can determine if there are pkgconfigs available from a -devel package by doing `eopkg info (name)` and looking for the `Provides` key.

Example:

``` bash
$ eopkg info libgtk-3-devel
```

In output:

``` bash
Provides: pkgconfig(gtk+-3.0) pkgconfig(gdk-3.0) pkgconfig(gdk-wayland-3.0) pkgconfig(gail-3.0) pkgconfig(gdk-x11-3.0) pkgconfig(gtk+-unix-print-3.0)
pkgconfig(gtk+-wayland-3.0) pkgconfig(gtk+-x11-3.0) 
```

### Using explict named dependencies

As may be obvious, simply list the package name. Note we discourage this when a `pkgconfig` dependency is available.

``` yaml
builddeps:
    - stk-devel
```

## Runtime dependencies

Runtime dependencies are extra packages that a package needs in order to function correctly. A common example of this is other libraries. Solus `eopkg` packages will automatically add any binary dependencies at 
runtime, so that you do not have to.

All `devel` subpackages automatically depend on their parent package. On top of this, if they provide a `.pc` pkg-config file, we export this information, and automatically determine the packages this particular 
package would need to be able to build against correctly. As such, the majority of dependencies for builds are automatically resolved.

In certain instances, binary dependencies aren’t enough. An example of this might be an extra Python package, or a font, something that is not accounted for by binary checks.

To account for this, you may add extra explicit runtime dependencies to your package. These are taken from the optional `rundeps` ypkg key.

This key uses the `dict(s)` type, and the default key is the current package `name`. You may express a different subpackage to apply dependencies to by using that name as a key, i.e. `devel`, or `docs`.

This would add the “python-gobject” runtime dependency to the main package:

```
rundeps:
    - python-gobject
```

This would add the same dependency, as well as adding it to the `devel` subpackage:

```
rundeps:
    - python-gobject
    - devel: python-gobject
```

Remember this uses the `dict(s)` type, which is very flexible. You can equally express this as follows (adding more deps as an example):

```
rundeps:
    - python-gobject
    - devel:
        - somepackage
        - someotherpackage
```

## Patterns

In most instances, `ypkg` will assign the correct location for files, whether it be in the main `name` package, or a subpackage. However there may be instances where the default does not match the intended behaviour.

In these instances it is possible to override the default assignment by way of patterns. These are simply a list of paths or globs to ensure a particular file, or set of files, end up in the desired location.

The `patterns` key expects a `dict(s)` argument. The default key for each pattern is assumed to be the `name` of the package, so omitting the name would place files into the main package. The value should be a 
path or pattern you wish to match, ensuring files go to a specific location.

In this example from libjpeg-turbo, we move all documentation into the `docs` subpackage:

```
patterns:
    - docs: [/usr/share/man]
```
This example, taken from the wayland package, ensures the binaries from `/usr/bin` and the `/usr/share/wayland` are located in the `devel` subpackage:

```
patterns:
    - devel:
        - /usr/bin
        - /usr/share/wayland
```

## Replace / rename

In some situations, it may be required to replace one package with another, or to rename an existing package. In these instances you should coordinate with a repository maintainer to ensure the replaced package is 
marked **Obsolete** within the index. This will ensure correct upgrade paths for users.

Note that to retire a package, you must also coordinate with a repository maintainer. An **Obsolete** package is removed by the package manager when the user upgrades. As such, correct upgrade paths need to be 
established.

The `replaces` ypkg key uses the `dict(s)` type, and the default key is assumed to be the current package `name`.

In this example, we rename the `libgeoclue*` packages to use the correct names, and ensure a working upgrade path.

```
replaces:
    - devel: libgeoclue-devel
    - libgeoclue
```

The `name` of this package is **geoclue**, and the new package names are now:

- geoclue
- geoclue-devel

Given the `replaces` values above, **geoclue** now replaces **libgeoclue**, and **geoclue-devel** replaces **libgeoclue-devel**. This is entirely transparent to the user, with a seamless update replacing the old 
packages with the new renamed packages.

The repository maintainer marked the old names as **Obsolete** in the index.