This is a POC project and not ready for production use !
Introduction
kube-trigger is a controller running in cluster to watches source updates(ConfigMap,Secrets) and apply some actions.
kube-trigger use a CRD TriggerRule to define sources and actions.
Following TriggerRule defines that when configmap changes, trigger a rolling update for statefulset busybox.
apiVersion: app.example.com/v1alpha1
kind: TriggerRule
metadata:
name: example
spec:
actions:
- updatePodTemplate:
objectRef:
kind: StatefulSet
name: busybox
namespace: kubetrigger-statefulset-1560220263
sources:
- objectRef:
kind: ConfigMap
name: cm
namespace: kubetrigger-statefulset-1560220263
Check exmaples for setting up kube-trigger in your cluster.
Why kube-trigger?
Kubernetes has a historical issue that people wants to automatically rollout their configmaps.
A common approach is to write your app to listening to a url or signal to reload itself. And use a sidecar watches config file changes and reload the app.
kube-trigger provide a alternative to do this without using sidecar. For apps that not support reload, kube-trigger can trigger rolling update.
More important, sources and actions in kube-trigger can be extended(eg. source can be a timer to restart pod periodly), which give a more custom ability to achieve your goals.
TODO List
- support rolling update
- support webhook
- support exec
- CRD validations
Design
Development
Prerequisites
- golang environment(1.12, with go mudule enabled)
- docker (used for creating container images, etc.)
- operator-sdk
- kind or minikube (optional)
Build Image
operator-sdk build --verbose <ImageName>
docker push <ImageName>
Testing
Running end-to-end tests on local cluster:
operator-sdk test local ./test/e2e --verbose
