Can env vars be referenced in shibboleth2.xml?

[Peter Schober]

* Wessel, Keith <kwessel at illinois.edu> [2020-09-29 22:02]:
> But, since I have two containers running together to separate out
> shibd and Apache

"It is generally recommended that you separate areas of concern by
using one service per container."[1]
A webserver and its modules could be considered to be "one area of
concern" or "one service". The fact that the Shib SP also comes with
shibd is an implementation detail that may not justify splitting up
your web server into multiple containers.
Specifying --init to Docker run isn't sufficient as the default init
process (tini) can only spawn a single child. s6-overlay[2] seems to
be a popular choice, though.

Other than the above I'd probably use additional tooling to bake all
the desired settings for the SP into the container, instead of having
them applied at run-time within the container based on environment
variables. That'll work with any kind of config or setting, no matter
whether it can be set from within Apache httpd or not.

-peter

[1] https://docs.docker.com/config/containers/multi-service_container/
[2] https://github.com/just-containers/s6-overlay