Triggering a new workflow from another workflow? - github-actions

Question

Can I trigger a new workflow from another workflow?
I'm trying to run a workflow after the first workflow has pushed a new release and it seems to ignore it.

Answer 1

Found the answer here:
An action in a workflow run can't trigger a new workflow run. For example, if an action pushes code using the repository's GITHUB_TOKEN, a new workflow will not run even when the repository contains a workflow configured to run when push events occur.
EDIT:
The quote above might be confusing. When I add a Personal Access Token (PAT) to the checkout action with repo permissions granted (and not repository's GITHUB_TOKEN), the following commands DO trigger other workflows:
- name: Checkout Repo
uses: actions/checkout#v2
with:
token: ${{ secrets.PAT_TOKEN }}
(In my case, running semnatic-release after this checkout, which creates a new release with a new tag - did trigger another workflow that runs only if a tag was created)

Answer 2

As described here, you can trigger another workflow using the workflow_run event.
For example we could think of two workflow definitions like this (the only prerequisite is, that both reside in the same repository - but I'am sure, there's also an event for other repos as well):
release.yml
name: CI release
on: [push]
jobs:
build:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout#v2
- name: Release artifact
run: ...
do-something-different.yml
name: Do anything after the release of the first workflow
on:
workflow_run:
workflows: ["CI release"]
types:
- completed
jobs:
notify:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout#v2
- name: Do something
run: ...
A crucial point here is that the name: CI release definition of the first yaml file must exactly match the workflow_run: workflows: ["CI release"] definition in the second yaml file. Another point is that this approach needs to be done on the default branch (which is mostly main or master) as the docs state:
Note: This event will only trigger a workflow run if the workflow file
is on the default branch.

Answer 3

If you don't want to use a general Personal Access Token (which has access to all of your repos), you can generate a dedicated SSH keypair for this purpose and add it to the repository as a Deploy Key. This is done as follows:
Generate an SSH keypair:
ssh-keygen -N "" -f deploy_key -C "github-actions"
Add the private key (generated file deploy_key) as an encryped secret, e.g. COMMIT_KEY to the GitHub project.
Add the public key (generated file deploy_key.pub) as a deploy key with write access to the GitHub project. Tick the Allow write access checkbox.
When checking out the source code in your workflow, add the SSH key:
- name: Checkout
uses: actions/checkout#v3
with:
ssh-key: "${{secrets.COMMIT_KEY}}"
Subsequent push actions in the same workflow will then trigger any configured GitHub workflow as if they were pushed manually.