GitHub Actions¶

There are two ways that you can use Iter8 with GitHub Actions. You can run Iter8 CLI within a GitHub Actions workflow and you can also use Iter8 to trigger a GitHub Actions workflow from an experiment.

Use Iter8 in a GitHub Actions workflow¶

Install the latest version of the Iter8 CLI using iter8-tools/iter8@v0.13. Once installed, the Iter8 CLI can be used as documented in various tutorials. For example:

# Install Iter8 CLI
- uses: iter8-tools/iter8@v0.13
# Launch an experiment inside Kubernetes
# This assumes that your Kubernetes cluster is accessible from the GitHub Actions pipeline
- run: |
    iter8 k launch --set "tasks={http}" \
    --set http.url=http://httpbin.org/get \
    --set runner=job

Trigger a GitHub Actions workflow from an Iter8 experiment¶

Iter8 provides a github task that sends a repository_dispatch which can trigger the workflows in the default branch of a GitHub repository.

Example¶

In this example, you will run the Your First Experiment but at the end of the experiment, Iter8 will trigger a workflow on GitHub.

In this simple example, the workflow will simply print out the experiment report that it will receive with the repository_dispatch. In a more sophisticated scenario, the workflow could, for example, read from the experiment report and based on whether or not task failured or metrics did not meet SLOs, determine what to do next. In a GitOps scenario, it could make changes to the Git repository, promote winners, or restart pipelines among other things.

To summarize what will happen, you will create a new GitHub repository, add a workflow that will respond to the github task, set up and run an experiment, and check if the workflow was triggered.

The github task requires the name of a repository, the name of the owner, as well as an authentication token in order to send the repository_dispatch. To see a full list of the github task parameters, see here.

Create a new repository on GitHub.
Add the following workflow.
```
name: iter8 `github` task test
on:
  repository_dispatch:
    types: iter8
jobs:
  my-job:
    runs-on: ubuntu-latest
    steps:
      - run: 'echo "payload: ${{ toJson(github.event.client_payload) }}"'
```
Note that this workflow has one job that will print out the client_payload. The default github task payload is configured with client_payload set to experiment report. This means that this job will simply print out the entire experiment report.

Also note that the on.repository_dispatch.types is set to iter8. The default github task payload is configured with event_type set to iter8. This indicates that once the repository_dispatch has been sent, only workflows on the default branch with on.repository_dispatch.types set to iter8 will be triggered.
Create a GitHub personal access token for the token parameter.
Ensure that you have a Kubernetes cluster and the kubectl CLI. You can create a local Kubernetes cluster using tools like Kind or Minikube.

Deploy the sample HTTP service in the Kubernetes cluster.

kubectl create deploy httpbin --image=kennethreitz/httpbin --port=80
kubectl expose deploy httpbin --port=80

Launch the experiment with the github task with the appropriate values.

iter8 k launch \
--set "tasks={http,assess,github}" \
--set http.url=http://httpbin.default/get \
--set assess.SLOs.upper.http/latency-mean=50 \
--set assess.SLOs.upper.http/error-count=0 \
--set github.owner=<GitHub owner> \
--set github.repo=<GitHub repository> \
--set github.token=<GitHub token> \
--set runner=job

Verify that the workflow has been triggered after the experiment has completed.

Some variations and extensions of the github task

The default github task payload sends the entirety of the experiment report. In your workflow, you can read from the report and use that data for control flow or use snippets of that data in different actions. For example, you can check to see if there have been any task failures during the experiment and perform different actions.
You do not need to use the default github task payload. You can provide your own payload by overriding the default of the payloadTemplateURL. For example, instead of sending the entirety of the experiment report, you can create a payload template that only sends a subset.

Try a multi-loop experiment with an if parameter to control when the github task is run.

A multi-loop experiment will allow you to run the tasks on a recurring basis, allowing you to monitor your app over a course of time. For example:

iter8 k launch \
--set "tasks={http,assess,github}" \
--set http.url=http://httpbin.default/get \
--set assess.SLOs.upper.http/latency-mean=50 \
--set assess.SLOs.upper.http/error-count=0 \
--set github.owner=<GitHub owner> \
--set github.repo=<GitHub repository> \
--set github.token=<GitHub token> \
--set runner=cronjob \
--set cronjobSchedule="*/1 * * * *"

This will run http, assess, and github tasks every minute. If you would like to run the github task only during the 10^th loop, use the if parameter.

  iter8 k launch \
  --set "tasks={http,assess,github}" \
  --set http.url=http://httpbin.default/get \
  --set assess.SLOs.upper.http/latency-mean=50 \
  --set assess.SLOs.upper.http/error-count=0 \
  --set github.owner=<GitHub owner> \
  --set github.repo=<GitHub repository> \
  --set github.token=<GitHub token> \
  --set github.if="Result.NumLoops == 10"
  --set runner=cronjob \
  --set cronjobSchedule="*/1 * * * *"