feat(yarn): set http proxy config from environment variables

[rarkins]

Changes

Runs yarn global config commands to set http(s) proxy if the environment variables are set.

Context

Yarn does not recognize the environment variables natively

Documentation (please check one with an [x])

• [=x] I have updated the documentation, or
• No documentation update is required

How I've tested my work (please select one)

I have verified these changes via:

• Code inspection only, or
• Newly added/modified unit tests, or
• No unit tests but ran on a real repository, or
• Both unit tests + ran on a real repository

[rarkins]

I could verify that these proxy commands were run, and that Yarn install picked them up, although curiously Yarn didn't error when the proxy was invalid - it happily downloaded directly and continued.

[renovate-release]

🎉 This PR is included in version 37.232.0 🎉

The release is available on:

• GitHub release
• npm package (@latest dist-tag)
• 37.232.0

Your semantic-release bot 📦🚀

[lukeapage]

This breaks our setup because we want a proxy for renovate, but we don't want a proxy for yarn because its using internal servers. and because yarn doesn't support no-proxy, we can't tell yarn not to use a proxy :/

It seems ridiculous but would you be open to a config option that stops this feature happening?

[viceice]

please open a new discussion and reference this PR and the corresponding issue.

[fgreinacher]

This breaks our setup because we want a proxy for renovate, but we don't want a proxy for yarn because its using internal servers. and because yarn doesn't support no-proxy, we can't tell yarn not to use a proxy :/

It seems ridiculous but would you be open to a config option that stops this feature happening?

This discussion continues at #27983.