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multiple-services

README.md

Blue/green deployment to release multiple services simultaneously

In this example, we release a new version of 2 services simultaneously using the blue/green deployment strategy. Traefik in used as Ingress controller, this example would also work with the Nginx Ingress controller.

Steps to follow

  1. service a and b are serving traffic
  2. deploy new version of both services
  3. wait for all services to be ready
  4. switch incoming traffic from version 1 to version 2
  5. shutdown version 1

In practice

Install the latest version of Helm, then install Traefik:

# Deploy Traefik with Helm
$ helm install \
    --name=traefik \
    --version=1.60.0 \
    --set rbac.enabled=true \
    stable/traefik

# Deploy version 1 of application a and b and the ingress
$ kubectl apply -f app-a-v1.yaml -f app-b-v1.yaml -f ingress-v1.yaml

# Test if the deployment was successful
$ ingress=$(minikube service traefik --url | head -n1)
$ curl $ingress -H 'Host: a.domain.com'
Host: my-app-a-v1-66fb8d6f99-hs8jr, Version: v1.0.0

$ curl $ingress -H 'Host: b.domain.com'
Host: my-app-b-v1-5766557f99-dpghc, Version: v1.0.0

# To see the deployment in action, open a new terminal and run the following
# command
$ watch kubectl get po

# Then deploy version 2 of both applications
$ kubectl apply -f app-a-v2.yaml -f app-b-v2.yaml

# Wait for both applications to be running
$ kubectl rollout status deploy my-app-a-v2 -w
deployment "my-app-a-v2" successfully rolled out

$ kubectl rollout status deploy my-app-b-v2 -w
deployment "my-app-b-v2" successfully rolled out

# Check the status of the deployment, then when all the pods are ready, you can
# update the ingress
$ kubectl apply -f ingress-v2.yaml

# Test if the deployment was successful
$ curl $ingress -H 'Host: a.domain.com'
Host: my-app-a-v2-6b58d47c5f-nmzds, Version: v2.0.0

$ curl $ingress -H 'Host: b.domain.com'
Host: my-app-b-v2-5c9dc59959-hp5kh, Version: v2.0.0

# In case you need to rollback to the previous version
$ kubectl apply -f ingress-v1.yaml

# If everything is working as expected, you can then delete the v1.0.0
# deployment
$ kubectl delete -f ./app-a-v1.yaml -f ./app-b-v1.yaml

Cleanup

$ kubectl delete all -l app=my-app
$ helm del --purge traefik