On 05/25/2016 05:31 AM, Amador Pahim wrote:
Hi folks,
We have requests to handle the environment variables that we can set to
the tests. This is the RFC in that regard, with a summary of the ideas
already exposed in the original request and some additional planning.
The original request is here:
https://trello.com/c/Ddcly0oG/312-mechanism-to-provide-environment-variables-to-tests-run-on-a-virtual-machine-remote
Motivation
==========
Avocado tests are executed in a fork process or even in a remote
machine. Regardless the fact that Avocado is hard coded to set some
environment variables, they are for internal consumption and user is not
allowed to control/configure its behavior.
You mean this:
http://avocado-framework.readthedocs.io/en/latest/WritingTests.html#environment-variables-for-simple-tests
Right? Basically, the fact that Avocado sets some of the job/test state
as environment variables, that can be used by SIMPLE tests.
The motivation is the request to provide users an interface to set
and/or keep environment variables for test consumption.
Use cases
=========
1) Use the command line or the config file to set the environment
variables in tests processes environment; access those variables from
inside the test.
2) Copy from current environment some environment variable(s) to the
tests processes environment; access those variables from inside the test.
Proposal
========
- To create a command line option, under the `run` command, to set
environment variables that will be available in tests environment process:
$ avocado run --test-env='FOO=BAR,FOO1=BAR1' passtest.py
I can relate to this use case...
- To create an option in config file with a dictionary of environment
variables to set in test process environment. It can be used as a
replacement or complement to the command line option (with lower priority):
[tests.env]
test_env_vars = {'FOO': 'BAR', 'FOO1': 'BAR1'}
... while putting those in a config file does not seem like something
one would do.
In all cases, and more explicitly in the config file example, this is
only really necessary if/when the environment variable to pass to the
test actually harms Avocado (considering a local execution, that is, in
a forked process).
So, if Avocado and the test, share the use of environment variables by
the same name, then this is a must. Also in the case of execution in
other "runners", such as remote/vm, this can be quite valuable.
- Create an option in config file with a list of environment variable
names to copy from avocado main process environment to the test process
environment (similar to env_keep in the /etc/sudoers file):
[tests.env]
env_keep = ['FOO', 'FOO1', 'FOO2']
Right, this makes sense. But it also brings the point that we may
actually change the default behavior of keeping environment variables
from Avocado in the tests' process. That is, they would get a much
cleaner environment by default. While this sounds cleaner, it may break
a lot of expectations.
For every configuration entry point, the setting have to be respected in
local and remote executions.
Drawbacks
=========
While setting an environment variable, user will be able to change the
behavior of a test and probably the behavior of Avocado itself. Maybe
even the OS behavior as well. We should:
- Warn users about the danger when using such options.
I fail to see where an environment variable, to be set by Avocado in the
test process, can or should impact Avocado itself. If it does, then
we'd probably be doing something wrong. I'm not sure we need warnings
that exceed documenting the intended behavior.
- Protect Avocado environment variables from overwriting.
About protecting the Avocado's own environment variables: agreed.
Looking forward to read your comments.
Overall, this is definitely welcome. Let's discuss possible
implementation issues, such as remote/vm support, because it wouldn't be
nice to introduce something like this with too many caveats.
Cheers,
- Cleber.
Best Regards,
--
Amador Pahim
_______________________________________________
Avocado-devel mailing list
Avocado-devel@redhat.com
https://www.redhat.com/mailman/listinfo/avocado-devel
--
Cleber Rosa
[ Sr Software Engineer - Virtualization Team - Red Hat ]
[ Avocado Test Framework - avocado-framework.github.io ]
_______________________________________________
Avocado-devel mailing list
Avocado-devel@redhat.com
https://www.redhat.com/mailman/listinfo/avocado-devel
