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Automated Canary deployment using Flagger

Introduction

Flagger is a progressive delivery tool that automates the release process for applications running on Kubernetes. It takes a Kubernetes deployment and creates a series of objects (Kubernetes deployments, ClusterIP services and Contour HTTPProxy) for an application. These objects expose the application in the cluster and drive the canary analysis and promotion.

Lab Prerequisites

Install Flagger

# make sure you are in canary directory
cd $PIB_BASE/labs/advanced-labs/canary

# copy flagger to apps directory
cp -R ./flagger ../../../apps

# add and commit the flagger app
cd $PIB_BASE
git add .
git commit -am "added flagger app"
git push

cd apps/flagger

# check deploy targets (should be [])
flt targets list

# clear the targets if not []
flt targets clear

# add all clusters as a target
flt targets add all

# deploy the changes
flt targets deploy

Check that your GitHub Action is running

Check deployment

  • Once the action completes successfully
# you should see flagger added to your cluster
git pull

# force flux to sync
# flux will sync on a schedule - this command forces it to sync now for debugging
flt sync

# check that flagger is deployed to your cluster
# NOTE: We also deploy prometheus to scrape metrics to monitor Canary deployment
flt check app flagger
flt check app prometheus

Update reference app to use Canary deployment Strategy

  • To update IMDb reference app to use canary deployment template:

    • Update apps/imdb/app.yaml with template value
      template: pib-service-canary

      # deploy imdb with canary template
cd ../imdb
flt targets deploy

    • Once the github action is completed, force flux to sync:

      # force flux to sync
# flux will sync on a schedule - this command forces it to sync now for debugging
git pull
flt sync

      The reference app should be updated with Canary Deployment objects listed:

        deployment.apps/imdb
  deployment.apps/imdb-primary
  deployment.apps/webv-imdb
  service/imdb
  service/imdb-canary
  service/imdb-primary
  service/webv-imdb
  httpproxy.projectcontour.io/imdb

    • Validate primary and canary objects in the cluster:

      flt ssh $MY_CLUSTER
kic pods
kic svc
kubectl get canary -n imdb

# exit from cluster
exit

Observe automated canary promotion

  • Trigger a canary deployment by updating the container image for IMDb:

    • Update apps/imdb/app.yaml with image tag from latest to beta
      image: ghcr.io/cse-labs/pib-imdb:beta

      # deploy imdb with updated version
cd ../imdb
flt targets deploy

    • Once the github action is completed, force flux to sync:

      # force flux to sync
# flux will sync on a schedule - this command forces it to sync now for debugging
git pull
flt sync

  • Observe canary promotion in k9s:

    # start k9s for the cluster
flt ssh $MY_CLUSTER
k9s <enter>

    • Type :canaries <enter> to view canary object

    • Observe status and weight for canary promotion

      • Flagger detects the deployment version change and starts a new rollout with 20% traffic progression
      • Once canary status is updated to Succeeded, 100% of the traffic should be routed to new version

    • Press enter again and scroll to bottom to see events

    • Press escape to go back

    • Exit K9s: :q <enter>

    • Exit from cluster: exit <enter>

Monitoring Canary deployments using Grafana

Flagger comes with a Grafana dashboard made for canary analysis. Install Grafana

# cd to canary directory
cd $PIB_BASE/labs/advanced-labs/canary

# copy flagger to apps directory
cp -R ./flagger-grafana ../../../apps

# add and commit the flagger-grafana app
cd $PIB_BASE
git add .
git commit -am "added flagger-grafana app"
git push

cd apps/flagger-grafana

# check deploy targets (should be [])
flt targets list

# clear the targets if not []
flt targets clear

# add all clusters as a target
flt targets add all

# deploy the changes
flt targets deploy

Once the github action is completed and flux sync is performed, navigate to grafana dashboard by appending /grafana to the host url in the browser tab.

  • Grafana login info
    • admin
    • change-me

Canary Dashboard