Is there a way to restrict what branch an action can be run on?

Question

When running a github action manually, I can choose which branch to run it against. This seems like a bad idea for some actions. Especially actions along the lines of DeployToProduction - where I only ever want that to be run against the main branch.

Is there any way to restrict it to only run against main - while still making the action manually-triggered?

An example of a manually-triggered action that I have might look something like this:

---
name: DeployToStaging
on:
  workflow_dispatch:
jobs: 
  ...

Answer 1

I had the same issue and I solved it with a condition:

if: github.ref == 'refs/heads/master'

steps:
...

in this way the user can see that the action is skipped when selecting a different branch.

Answer 2

Two alternative ways to check for this with an if condition without having to hard-code branch names include:

# Only run for the default branch
if: github.ref_name == github.event.repository.default_branch

# Older syntax for GitHub Enterprise Server where ref_name isn't available
if: github.ref == format('refs/heads/{0}', github.event.repository.default_branch)

and:

# Only run for protected branches
if: github.ref_protected == true