CircleCI is a really useful tool for ensuring that your builds go through correctly, that all the libraries and dependencies are accessible and compatible when building clean, and so on.
The way we configure CircleCI builds is by creating a config.yml file, where we detail the build steps. Today there was a particular step in the config file of the project I’m currently part of that was causing the build to fail. The line in this case was requesting the installation of erlang but wasn’t specifying the version number, therefore the latest version would be always installed. The line in cause looks like this:
- run: sudo apt-get -y install esl-erlang
The issue? Erlang 24.0 has just been released and overnight the builds started to fail, due to one of the libraries that we’re using is not yet compatible with the latest version of Erlang.. So the options were to either upgrade to Erlang 24.0 or to force the config file to look for a specific version that we know works well. And, by choosing to keep with the version that we know works, today I learnt how to install a specific version of Erlang:
- run: sudo apt-get -y install esl-erlang=1:23.1.5-1
Bear in mind that you’ll have to type in the exact version, with whatever - and : you see in there.
