document env vars

[dberenbaum]

This adds a page with DVC environment variables. It doesn't document all of them since some seem intended to be private, but it documents all those that are mentioned elsewhere in the docs. I don't think this is the ideal place for the page, but I don't want to bog this down in a major reorg of docs like suggested in #4381.

Related:

• fix(dvclive): Note on DVC_STUDIO_URL and DVC_STUDIO_TOKEN env variablesgit  #5012
• Auto push dvc experiments #5029

[dberenbaum]

Open to doing this differently or combining with #5012, but seems like we need somewhere to document all DVC env vars

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[skshetry]

Suggested change

	- `DVC_NO_ANALYTICS`: If `true`, disables
	- `DVC_NO_ANALYTICS`: If set, disables

[dberenbaum]

@skshetry Why is it your preference? I kind of see the logic, but part of me feels it's better to give an example of a valid value for the env var.

[skshetry]

We used DVC_NO_ANALYTICS to take effect on any value because with this envvar, you only want to disable analytics. And, tbh with these envvars, I can never figure out if it should be set as 0/1/true/yes/no.

I am fine with showing an example. I wasn't sure if this was a reference or not. I'm fine with what you have.

[shcheklein]

Are we ready to merge this?

[dberenbaum]

I was waiting to align on the related issues linked above.

Is it worthwhile to document DVC_EXP_AUTO_PUSH in its current state? I initially drafted this PR in part as a precursor to #5035, but I'm not sure we actually want to push people to use this env var. I lean towards dropping it from this PR for now and then I think we could merge.

[dberenbaum]

Also, if it absorbs #5012, let me do one more pass to maybe clarify and incorporate some of the suggestions there from @natikgadzhi.

[dberenbaum]

Dropped DVC_EXP_AUTO_PUSH and DVC_EXP_GIT_REMOTE to keep this simple. Merging now.