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https://github.com/maksim-paskal/service-leader-election
https://github.com/maksim-paskal/service-leader-election
Last synced: 5 days ago
JSON representation
- Host: GitHub
- URL: https://github.com/maksim-paskal/service-leader-election
- Owner: maksim-paskal
- Created: 2022-06-18T15:29:38.000Z (over 2 years ago)
- Default Branch: main
- Last Pushed: 2023-10-11T23:36:24.000Z (about 1 year ago)
- Last Synced: 2024-06-21T09:49:29.670Z (7 months ago)
- Language: Go
- Size: 87.9 KB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# Sidecar to switch trafic to leader pod
Inspired by article [Simple leader election with Kubernetes and Docker](https://kubernetes.io/blog/2016/01/simple-leader-election-with-kubernetes/)
This tool can switch traffic to leader pod, for example if your application can not be running in multiple pods, but you want to make it more reliable, you can run your application in multiple replicas, but traffic will be process only by one of this pod.
## How it works
for example you have 3 replicas of your application, and you have a service, by default service will be proxy all traffic to all of your pods
```bash
NAME READY STATUS RESTARTS AGE
pod/service-leader-election-689f7875f6-fgmjb 1/1 Running 0 9m10s
pod/service-leader-election-689f7875f6-nsdcg 1/1 Running 0 9m10s
pod/service-leader-election-689f7875f6-zp4wp 1/1 Running 0 9m10s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/service-leader-election ClusterIP 10.100.54.205 28086/TCP 9m11s
```
this sidecar:
1) label your pod with additional label `service-leader-election=`
2) elects leader between your pods
3) switch your service to leader pod
after election all traffic will be processed only by one of your pods
## Installation
you need additional serviceaccount that can get pod and service information and also can make a patch
```yaml
apiVersion: v1
kind: ServiceAccount
metadata:
name: service-leader-election
---
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
name: service-leader-election-role
rules:
- apiGroups: [""]
resources: ["pods","services"]
verbs: ["get", "patch"]
- apiGroups: ["coordination.k8s.io"]
resources: ["leases"]
verbs: ["*"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: service-leader-election
roleRef:
kind: Role
name: service-leader-election-role
apiGroup: rbac.authorization.k8s.io
subjects:
- kind: ServiceAccount
name: service-leader-election
namespace: {{ .Release.Namespace }}
```
add additional sidecar to your deployment
```yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: app
labels:
app: app
spec:
...
spec:
serviceAccountName: service-leader-election
containers:
- name: service-leader-election
image: paskalmaksim/service-leader-election:latest
imagePullPolicy: Always
args:
args:
- -lease-name=lockname
- -service-name=servicename
resources:
limits:
cpu: 50m
memory: 100Mi
livenessProbe:
httpGet:
path: /healthz
port: 28086
initialDelaySeconds: 15
periodSeconds: 20
env:
- name: POD_NAME
valueFrom:
fieldRef:
fieldPath: metadata.name
- name: POD_NAMESPACE
valueFrom:
fieldRef:
fieldPath: metadata.namespace
```