Dockerfile + shell scripts to generate systemd/fleet environment files.
When running systemd units via Fleet on CoreOS, it is often necessary to compute certain values when launching a Docker container. Rather than embedding this logic into the unit itself, we use the 'enviornment file' pattern to compute these values inside a Docker container. The values are written to an environment file under
/etc/env.d. Thus, the main unit can simply load this envionrment file and avoid embedding complicated scripting inside it.
The currently supported environment variable computations are:
bootstrap: use an etcd cluster to bootstrap another distributed service, such as Consul or RethinkDB.
discover: discover a paricular service via Consul