Support standard build envs for CI / Git integrations

[pi0]

CI/CD pipelines often provide variables such as deployment URL, git hash, git branch, etc. We might expose standard exports that can scan them.

Some providers:

Vercel

https://vercel.com/docs/projects/environment-variables/system-environment-variables

VERCEL_URL, VERCEL_BRANCH_URL, VERCEL_GIT_PROVIDER, VERCEL_GIT_REPO_SLUG, VERCEL_GIT_REPO_OWNER, VERCEL_GIT_REPO_ID, VERCEL_GIT_COMMIT_REF, VERCEL_GIT_COMMIT_SHA, VERCEL_GIT_COMMIT_MESSAGE, VERCEL_GIT_COMMIT_AUTHOR_LOGIN, VERCEL_GIT_COMMIT_AUTHOR_NAME, VERCEL_GIT_PREVIOUS_SHA

Netlify

https://docs.netlify.com/configure-builds/environment-variables/

REPOSITORY_URL, BRANCH, HEAD, COMMIT_REF, CACHED_COMMIT_REF, CACHED_COMMIT_REF, PULL_REQUEST, REVIEW_ID, URL, DEPLOY_URL, DEPLOY_PRIME_URL

Github Actions

https://docs.github.com/en/actions/learn-github-actions/variables#default-environment-variables

GITHUB_SHA, GITHUB_ACTOR, GITHUB_API_URL, GITHUB_BASE_REF, GITHUB_HEAD_REF, GITHUB_REF, GITHUB_REF_NAME, GITHUB_REPOSITORY, GITHUB_REPOSITORY_OWNER, GITHUB_REPOSITORY_OWNER_ID, GITHUB_WORKFLOW_SHA

Gitlab CI

https://docs.gitlab.com/ee/ci/variables/predefined_variables.html

CI_COMMIT_AUTHOR, CI_COMMIT_BEFORE_SHA, CI_COMMIT_BRANCH, CI_COMMIT_DESCRIPTION, CI_COMMIT_MESSAGE, CI_COMMIT_REF_NAME, CI_COMMIT_SHA, CI_COMMIT_SHORT_SHA, CI_COMMIT_TAG, CI_ENVIRONMENT_URL, CI_PAGES_URL,

Cloudflare pages

https://developers.cloudflare.com/pages/configuration/build-configuration/#environment-variables

CF_PAGES, CF_PAGES_COMMIT_SHA, CF_PAGES_BRANCH, CF_PAGES_URL

[harlan-zw]

Following.

Also, fwiw the URL becomes ambiguous across platforms, sometimes it's the specific URL for that deployment (https://<deployid>.host.com) verse the configured domain (https://mydomain.com).

[pi0]

Yes indeed... I'm not sure if any of these platforms give access to the alias of main domain and if they do we might expose two vars for canonical domain. (BTW talking about our usecase of generatic permanent URLs for something like og-image, I would say this is even safer to rely on deploy-pinned URL)