Update dispatch.sr.ht docs with new env vars

1 files changed, 28 insertions, 0 deletions

diff --git a/dispatch.sr.ht/github.md b/dispatch.sr.ht/github.md
index 318ba12..200b7e5 100644
--- a/dispatch.sr.ht/github.md
+++ b/dispatch.sr.ht/github.md
@@ -28,3 +28,31 @@ attempts to merge will succeed *even if the branch protection rules are unmet*.
 You must enable the "Include administrators" option to prevent this.
 
 ![Screenshot of "Include administrators" option](https://sr.ht/7VYq.png)
+
+# Build environment
+
+dispatch.sr.ht will check out the specific commit you pushed when submitting
+builds, and will rewrite the upstream clone URL to the fork when building pull
+requests.
+
+## Configuring your sources list
+
+Do not include `.git` at the end of your git clone URLs.
+
+## Environment variables
+
+The following environment variables are set when building commits:
+
+- `GITHUB_DELIVERY`: the webhook delivery UUID that triggered this build
+- `GITHUB_EVENT`: the event type ("push") that triggered this build
+- `GITHUB_REF`: the ref (e.g. "refs/heads/master") that was updated
+- `GITHUB_REPO`: the full name (e.g. "username/repo_name") of the GitHub repo
+
+The following environment variables are set when building pull requests:
+
+- `GITHUB_DELIVERY`: the webhook delivery UUID that triggered this build
+- `GITHUB_EVENT`: the event type ("push") that triggered this build
+- `GITHUB_PR_NUMBER`: the pull request number
+- `GITHUB_PR_TITLE`: the title of the pull request
+- `GITHUB_BASE_REPO`: the full name (e.g. "username/repo_name") of the base repo
+- `GITHUB_HEAD_REPO`: the full name (e.g. "username/repo_name") of the head repo (fork)