Installing Erlang with kerl

30 Jan 2019 17:04 direnv erlang

At Electric Imp, on developer PCs, we manage our Erlang versions with kerl.

Assuming you have kerl available in your path (and you’ve installed the prerequisites), installing a version of Erlang is simple:

kerl update releases
kerl build 21.2 21.2
kerl install 21.2 $HOME/.kerl/erlangs/21.2

You can tweak the Erlang build by setting the KERL_CONFIGURE_OPTIONS environment variable. We don’t bother. If we did, we’d probably put a suffix on the build name and install directory.

The installation directory (~/.kerl/erlangs) was chosen to be similar to where kiex installs Elixir versions.

We prefer building from github, using a tag:

kerl build git OTP-21.2.4 OTP-21.2.4
kerl install OTP-21.2.4 $HOME/.kerl/erlangs/OTP-21.2.4

This gives us the option of installing a patched fork, which has been necessary in the past.

Note that you can set (e.g.) MAKEFLAGS=-j6 kerl build ... which will make the build quicker.

In this case, the build name and installation directory are named after the tag (OTP-21.2.4), which makes it easier to tell which versions were built from releases or from tags.

To activate the installation, you can do as kerl says:

. $HOME/.kerl/erlangs/OTP-21.2.4/activate

…or you can use direnv

If you’re running short of disk space, you can delete old builds:

kerl cleanup all

This doesn’t delete the installed versions.