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Blue/Green Deployment
We can create our "blue" deployment by saving the following yaml to a file
blue.yaml.apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: nginx-1.10
spec:
replicas: 3
template:
metadata:
labels:
name: nginx
version: "1.10"
spec:
containers:
- name: nginx
image: nginx:1.10
ports:
- name: http
containerPort: 80
You can then create the deployment using the kubectl command.
$ kubectl apply -f blue.yaml
Save this to
service.yaml.apiVersion: v1
kind: Service
metadata:
name: nginx
labels:
name: nginx
spec:
ports:
- name: http
port: 80
targetPort: 80
selector:
name: nginx
version: "1.10"
type: LoadBalancer
Creating the service will create a load balancer that is accessible outside the cluster.
$ kubectl apply -f service.yaml
For the "green" deployment we will deploy a new deployment in parallel wit the "blue" deployment. If the following is in
green.yaml...apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: nginx-1.11
spec:
replicas: 3
template:
metadata:
labels:
name: nginx
version: "1.11"
spec:
containers:
- name: nginx
image: nginx:1.11
ports:
- name: http
containerPort: 80
... I can create the new deployment like so.
$ kubectl apply -f green.yaml
To cut over to the "green" deployment we will update the selector for the service. Edit the
service.yaml and change the selector version to "1.11". That will make it so that it matches the pods on the "green" deployment.apiVersion: v1
kind: Service
metadata:
name: nginx
labels:
name: nginx
spec:
ports:
- name: http
port: 80
targetPort: 80
selector:
name: nginx
version: "1.11"
type: LoadBalancer
This apply will update the existing
nginx service in place.$ kubectl apply -f service.yaml
Automating
#!/bin/bash
# bg-deploy.sh <servicename> <version> <green-deployment.yaml>
# Deployment name should be <service>-<version>
DEPLOYMENTNAME=$1-$2
SERVICE=$1
VERSION=$2
DEPLOYMENTFILE=$3
kubectl apply -f $DEPLOYMENTFILE
# Wait until the Deployment is ready by checking the MinimumReplicasAvailable condition.
READY=$(kubectl get deploy $DEPLOYMENTNAME -o json | jq '.status.conditions[] | select(.reason == "MinimumReplicasAvailable") | .status' | tr -d '"')
while [[ "$READY" != "True" ]]; do
READY=$(kubectl get deploy $DEPLOYMENTNAME -o json | jq '.status.conditions[] | select(.reason == "MinimumReplicasAvailable") | .status' | tr -d '"')
sleep 5
done
# Update the service selector with the new version
kubectl patch svc $SERVICE -p "{\"spec\":{\"selector\": {\"name\": \"${SERVICE}\", \"version\": \"${VERSION}\"}}}"
echo "Done."
References
Last modified 4yr ago