Installing MacPorts on CI systems

GitHub Actions is great and allows you to test your GitHub projects on OSX.
However, OSX images on GitHub Actions only come with HomeBrew installed.
If, like me, you want to use MacPorts,
you should install it on the fly everytime.
For a few projects I am working on I copied around scripts installing MacPorts. I now decided to share here a generic script called macports-ci that could be used in multiple projects.
The script is checked frequently on GitHub Actions,
so you should be able to see from the status image above whether it is working or not.
I recommend using curl -LO as explained below to always use the latest version from the master branch.
In case I have to test some feature, I will do it on separate branches so as to keep master branch stable.

Installing MacPorts

Put the following commands in your workflow

 - curl -LO https://raw.githubusercontent.com/GiovanniBussi/macports-ci/master/macports-ci
 - source ./macports-ci install

If you prefer, you can directly include the macports-ci file in your github repository. However, I recommend always using curl -LO to obtain
the latest version.

Notice that in the original version of this script it was necessary to also set some enviroment variables (COLUMNS and PATH). In case you execute the script in the old way (./macports-ci) or in case you execute it in a separate shell you might have to take care of these variables.
See notes below.
Also notice that as of July 15, 2020, when used in a GitHub workflow, the script also exports the variable using ::set-env. This means that you can install MacPorts in one step and use it in the following steps. As of October 17, this has been fixed to use @latest/actions/reference/workflow-commands-for-github-actions#environment-files">environment files (see issue 14).

The source macports-ci install script can be run with a few options:

 --prefix=/other/prefix
     Install MacPorts in a different location. Default is `/opt/local`.
 --source
     Install MacPorts from source (slower). It is implicit when
     using `--prefix` with a prefix different from `/opt/local`.
 --binary
     Install MacPorts from a pkg (faster, this is the default).
 --version=2.4.1
     Require a specific MacPorts version. Notice that
     MacPorts is anyway updated with a `selfupdate` command.
 --sync=rsync
     Specify sync mode. Mode can be either `rsync`,
     `tarball` (default), or `github`.
 --keep-brew
     Do not uninstall HomeBrew (currently this is the default)
 --remove-brew
     Uninstall HomeBrew (experimental)

Notice that the source macports-ci install script will take care of a number of things, including:

Uninstalling HomeBrew (only if --remove-brew option is used). This is an experimental feature. Notice that
travis relies on some library installed by HomeBrew so some feature might not work (I noticed a problem in saving caches).
Finding which version of OSX you have so as to identify the correct MacPorts image
when using binary installation from pkg.
Trying to use port selfupdate multiple times until it succeeds.
Fixing the environment setting COLUMNS to the appropriate value (except if you execute the script in the old way, see below).
Fixing the environment prepending /opt/local/bin to the PATH (except if you execute the script in the old way, see below). This will make sure that the port command is in the path.

Using your local Portfiles

In case you just need ports to install tools that are used in your project,
you are done. If you want to also setup a
local Portfile repository to test your own Portfiles you might do the following:

 - source macports-ci localports path/to/local/port/dir

After this command, you will be able to install packages described in your local Portfiles using commands such as port install portname.
Notice that local Portfiles will take the precedence with respect to official Portfiles.

Enabling ccache

Ccache could be used to significantly speed up your builds, especially if you build similar sources multiple times. However, notice that it will add an initial slowdown to install ccache itself. This would be more significant if you install on a non-default prefix, such that ccache itself (and its required libraries) are installed from source. Thus, using ccache is not recommended when building on non-default prefix.

In case you want to enable ccache to be available to port install commands, you should modify your workflow following these instructions. First, add the following step:

  - uses: actions/cache@v2
    with:
        path: ~/.macports-ci-ccache
        key: ccache-macports-${{ github.sha }}
        restore-keys: ccache-macports-

This will inform GitHub Actions that there is a directory to be cached. Then, add the following command after you installed MacPorts and before executing port install commands:

- source macports-ci ccache

This will install ccache, retrieve the cache, and make sure ccache is used for compiling further packages.
Finally, add the following command after you executed the relevant port install commands:

- source macports-ci ccache --save

This will store the ccache cache in a place where it can be seen by GitHub Actions.

Executing the script in the old way

Originally this script was designed to be executed as ./macports-ci (rather than source macports-ci). Executing the script has some limitations. In particular, you should adjust the environment variables COLUMNS and PATH for the next commands to work correctly. A typical set of instructions was:

- export COLUMNS=80
- curl -LO https://raw.githubusercontent.com/GiovanniBussi/macports-ci/master/macports-ci
- chmod +x ./macports-ci
- ./macports-ci install
- export PATH="/opt/local/bin:$PATH"

As of April 30, 2018 it is possible to source the script rather than executing it:

 - curl -LO https://raw.githubusercontent.com/GiovanniBussi/macports-ci/master/macports-ci
 - source ./macports-ci install

As of July 24, 2018, sourcing the script set both the COLUMNS and the PATH variables to the correct values. At this point, sourcing the script rather then executing it is recommended. Executing the script in the old way will still be supported.

Notice that if instead of running the source command directly in your workflow file you decide to include it in some external auxiliary scripts, you might still need to set the environment variables COLUMNS and PATH in the workflow file.

Real life usage

You can find some sample usage in the workflows of these repositories:

Feedbacks

I would like to keep this script up to date and to make it as robust as possible so that other projects can just use it without too much worries.
In case you find any problem or you think you can improve this script, please open an
issue
or a pull request.

Todo

There are a few additional improvements that could be implemented:

Allow users to cache the /opt/local directory. I am afraid this is not feasible, since MacPorts also does a number of other things under the hood that are difficult to track (e.g. it adds a new user).
Make use of sudo command optional. Inside ./macports-ci, need of sudo could be detected trying to touch a file in the prefix path.
Personalize ccache, e.g. allowing the user to specify cache size.