You need to merge changes without losing track of what happened. You also need to enforce rules so no commits bypass review. This is where Git rebase meets Open Policy Agent (OPA). Together, they let you control commit history and validate policies before code lands in your main branch.
Why Git Rebase Matters
Git rebase rewrites commit history. It creates a linear sequence of commits by applying them on top of another base commit. This keeps your repository history clean and easy to read. It eliminates unnecessary merge commits and makes git log tell a clear story.
But with power comes risk. Rebase can drop commits, conflict silently, or alter commits without notice if misused. You need guardrails.
Why Open Policy Agent Fits
Open Policy Agent is a policy engine for enforceable rules. With OPA, you can define policies in Rego that run as part of your Git workflow. These rules can enforce commit message formats, require passing CI checks, or block rebases onto protected commits.
By combining OPA policies with Git hooks or CI pipelines, you can control how rebase operations affect your main branch. The policy engine becomes part of your version control process, not an afterthought.
Integrating Git Rebase and OPA
Use pre-receive or update hooks in Git server environments to trigger OPA evaluations. For every rebase push, the hook sends commit metadata to OPA. Rego policies check whether:
- Commits follow required conventions
- No rebased commits skip review
- Merge policies are respected
- Commit authors match verified identities
If the policy fails, the rebase is rejected before it can cause damage. This guarantees that every rebase aligns with your organization's governance.
Example Rego Policy for Git Rebase
package git.policy
deny[msg] {
input.operation == "rebase"
some commit
commit := input.commits[_]
not valid_commit(commit)
msg := sprintf("Invalid commit during rebase: %s", [commit.hash])
}
valid_commit(c) {
startswith(c.message, "JIRA-")
c.author_verified == true
}
This example blocks rebases that contain commits without a JIRA ticket ID or an unverified author.
Best Practices
- Treat rebase like an operation requiring review
- Test policies locally before putting them in your pipeline
- Use clear and minimal rules, then expand as needed
- Audit OPA logs to track rejected rebases
Clean history is valuable. But safe history is essential. Git rebase with OPA is how you get both.
See how this can run in minutes with automated OPA policy checks on Git workflows at hoop.dev.