Fallback for os env vars

[vdraceil]

[watcher:test]
cmd = python test.py
numprocesses = $(circus.env.NUM_TEST_PROCESSES)

Now, if I set os.environ["NUM_TEST_PROCESSES"] = 3, I'll have 3 "test" processes running
but if that env var is not set, what happens?
can a default be provided - like $(circus.env.NUM_TEST_PROCESSES, 1) ?
there's nothing on the docs for this, but is this even possible with circus?

If I use [env] or [env:XXX] sections, those will get precedence no matter what I set in os.environ

[biozz]

Hi, @vdraceil!

Let's break it down.

but if that env var is not set, what happens?

With the config you provided - there will be an exception, because the variables are not interpolated if either [env] section or copy_env is specified.

This config should properly handle your environment variables if set.

[watcher:test]
cmd = python test.py
numprocesses = $(circus.env.NUM_TEST_PROCESSES)
copy_env = True

can a default be provided - like $(circus.env.NUM_TEST_PROCESSES, 1) ?

Unfortunately, no, there is no such feature at the moment. But it is a good suggestion. Although, it might require changing the signature of replace_gnu_args method, which can be a pain.

Another solution could be falling back to default values, not sure why it is not done yet.

there's nothing on the docs for this

I agree, the docs could use some polishing and more notes about environment variables. I will try to do something about that.