public_git
/
actions-runner-controller
mirror of https://github.com/actions-runner-controller/actions-runner-controller.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity

Merge pull request #1285 from actions-runner-controller/docs/runnersets 

docs: add limitations to runnersets + reorder
This commit is contained in:
Yusuke Kuoka 2022-04-03 18:18:54 +09:00 committed by GitHub
parent 1d9347f418 14f9e7229e
commit 85dea9b67c
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 18 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
README.md
View File

@ -19,6 +19,7 @@ ToC:
- [Enterprise Runners](#enterprise-runners)
- [RunnerDeployments](#runnerdeployments)
- [RunnerSets](#runnersets)
- [Persistent Runners](#persistent-runners)
- [Autoscaling](#autoscaling)
- [Anti-Flapping Configuration](#anti-flapping-configuration)
- [Pull Driven Scaling](#pull-driven-scaling)
@ -32,7 +33,6 @@ ToC:
- [Runner Groups](#runner-groups)
- [Runner Entrypoint Features](#runner-entrypoint-features)
- [Using IRSA (IAM Roles for Service Accounts) in EKS](#using-irsa-iam-roles-for-service-accounts-in-eks)
- [Persistent Runners](#persistent-runners)
- [Software Installed in the Runner Image](#software-installed-in-the-runner-image)
- [Using without cert-manager](#using-without-cert-manager)
- [Troubleshooting](#troubleshooting)
@ -367,6 +367,8 @@ example-runnerdeploy2475ht2qbr mumoshu/actions-runner-controller-ci Running
> This feature requires controller version => [v0.20.0](https://github.com/actions-runner-controller/actions-runner-controller/releases/tag/v0.20.0)
_Ensure you see the limitations before using this kind!!!!!_
For scenarios where you require the advantages of a `StatefulSet`, for example persistent storage, ARC implements a runner based on Kubernete's StatefulSets, the RunnerSet.
A basic `RunnerSet` would look like this:
@ -450,6 +452,21 @@ Under the hood, `RunnerSet` relies on Kubernetes's `StatefulSet` and Mutating We
**Limitations**
* For autoscaling the `RunnerSet` kind only supports pull driven scaling or the `workflow_job` event for webhook driven scaling.
* Whilst `RunnerSets` support all runner modes as well as autoscaling, currently PVs are **NOT** automatically cleaned up as they are still bound to their respective PVCs when a runner is deleted by the controller. This has **major** implications when using `RunnerSets` in the standard runner mode, `ephemeral: true`, see [persistent runners](#persistent-runners) for more details. As a result of this, using the default ephemeral configuration or implementing autoscaling for your `RunnerSets`, you will get a build up of PVCs and PVs without some sort of custom solution for cleaning up.
### Persistent Runners
Every runner managed by ARC is "ephemeral" by default. The life of an ephemeral runner managed by ARC looks like this- ARC creates a runner pod for the runner. As it's an ephemeral runner, the `--ephemeral` flag is passed to the `actions/runner` agent that runs within the `runner` container of the runner pod.
`--ephemeral` is an `actions/runner` feature that instructs the runner to stop and de-register itself after the first job run.
Once the ephemeral runner has completed running a workflow job, it stops with a status code of 0, hence the runner pod is marked as completed, removed by ARC.
As it's removed after a workflow job run, the runner pod is never reused across multiple GitHub Actions workflow jobs, providing you a clean environment per each workflow job.
Although not generally recommended, it's possible to disable passing `--ephemeral` flag by explicitly setting `ephemeral: false` in the `RunnerDeployment` or `RunnerSet` spec. When disabled, your runner becomes "persistent". A persistent runner does not stop after workflow job ends, and in this mode `actions/runner` is known to clean only runner's work dir after each job. Whilst this can seem helpful it creates a non-deterministic environment which is not ideal for a CI/CD environment. Between runs your actions cache, docker images stored in the `dind` and layer cache, globally installed packages etc are retained across multiple workflow job runs which can cause issues which are hard to debug and inconsistent.
Persistent runners are available as an option for some edge cases however they are not preferred as they can create challenges around providing a deterministic and secure environment.
### Autoscaling
@ -1311,21 +1328,6 @@ spec:
securityContext:
fsGroup: 1000
```
### Persistent Runners
Every runner managed by ARC is "ephemeral" by default. The life of an ephemeral runner managed by ARC looks like this- ARC creates a runner pod for the runner. As it's an ephemeral runner, the `--ephemeral` flag is passed to the `actions/runner` agent that runs within the `runner` container of the runner pod.
`--ephemeral` is an `actions/runner` feature that instructs the runner to stop and de-register itself after the first job run.
Once the ephemeral runner has completed running a workflow job, it stops with a status code of 0, hence the runner pod is marked as completed, removed by ARC.
As it's removed after a workflow job run, the runner pod is never reused across multiple GitHub Actions workflow jobs, providing you a clean environment per each workflow job.
Although not recommended, it's possible to disable passing `--ephemeral` flag by explicitly setting `ephemeral: false` in the `RunnerDeployment` or `RunnerSet` spec. When disabled, your runner becomes "persistent". A persistent runner does not stop after workflow job ends, and in this mode `actions/runner` is known to clean only runner's work dir after each job. That means your runner's environment, including various actions cache, docker images stored in the `dind` and layer cache, is retained across multiple workflow job runs.
Persistent runners are available as an option for some edge cases however they are not preferred as they can create challenges around providing a deterministic and secure environment.
### Software Installed in the Runner Image
**Cloud Tooling**<br />