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logoTetrate Service BridgeVersion: 1.10.x

Canary Progressive Delivery Using Flagger

In this document, you will learn how to use Flagger to automate canary deployments with TSB. Flagger is a Kubernetes operator that automates the promotion of canary deployments supporting multiple ingress controllers such as Istio, NGINX, and Gateway API. Flagger supports several metrics provider for canary analysis such as Prometheus, Datadog, and SkyWalking. In following example, we will use SkyWalking as the metrics provider. SkyWalking provides the PromQL service that presents the Prometheus PromQL metrics APIs that can be used by Flagger for canary analysis. If you want to use Prometheus as the metrics provider, you can follow the official Flagger documentation here.

Before you get started, make sure:
✓ TSB is up and running, and GitOps has been enabled for the target cluster
✓ Flagger is installed in the target cluster. You can install Flagger by following official documentation here

GitOps deployment

Please refer Configuring Flux CD for GitOps to understand how to use Flux to deploy your applications. This document will only focus on how to use Flagger to automate canary deployments with TSB.

Deploy Application​

First, let's deploy a sample application to the target cluster. In this example, we will deploy a Bookinfo application.

Bookinfo Reviews

The bookinfo deployment below is modified to only use v1 of the reviews service. This is because we will use v2 of the reviews service as the canary deployment.

Also reviews service is removed because Flagger will automatically generate the reviews service for the canary deployment. See here for more information on what Flagger generates.

kubectl create namespace bookinfo
kubectl label namespace bookinfo istio-injection=enabled
kubectl apply -f https://docs.tetrate.io/examples/flagger/bookinfo.yaml -n bookinfo

Deploy traffic generator. This will send continuous traffic to the bookinfo application.

kubectl apply -f https://docs.tetrate.io/examples/flagger/traffic-gen.yaml

To view topology, go to the TSB UI.

Apply TSB and Flagger Canary configuration​

Next, we will apply the TSB configuration for the bookinfo application. This assumes you already have a Tenant named tetrate. If you don't have a Tenant, you can create one by following the TSB quickstart.

Create a file named bookinfo-tsb.yaml with the following content:

cat <<EOF > bookinfo-tsb.yaml
apiVersion: v1
kind: List
items:
  - apiVersion: tsb.tetrate.io/v2
    kind: Workspace
    metadata:
      name: bookinfo-ws
      namespace: bookinfo
      annotations:
        tsb.tetrate.io/organization: tetrate
        tsb.tetrate.io/tenant: tetrate
    spec:
      namespaceSelector:
        names:
          - "*/bookinfo"
  - apiVersion: traffic.tsb.tetrate.io/v2
    kind: Group
    metadata:
      name: bookinfo-tg
      namespace: bookinfo
      annotations:
        tsb.tetrate.io/organization: tetrate
        tsb.tetrate.io/tenant: tetrate
        tsb.tetrate.io/workspace: bookinfo-ws
    spec:
      configMode: BRIDGED
      namespaceSelector:
        names:
          - "*/bookinfo"
EOF

and apply the configuration:

kubectl apply -f bookinfo-tsb.yaml

Next create then apply canary configuration for the bookinfo application.

cat <<EOF > reviews-canary.yaml
apiVersion: flagger.app/v1beta1
kind: Canary
metadata:
  name: reviews-rollout
  namespace: bookinfo
spec:
  # deployment reference
  targetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: reviews
  service:
    port: 9080
    # delegation: true is REQUIRED when using Flagger with TSB
    delegation: true
  analysis:
    # schedule interval
    interval: 5m
    # max number of failed metric checks before rollback
    threshold: 5
    # max traffic percentage routed to canary percentage (0-100)
    maxWeight: 50
    # canary increment step percentage (0-100)
    stepWeight: 10
EOF

kubectl apply -f reviews-canary.yaml

Above configuration means Flagger will increase traffic to canary by 10% every 5 minutes until it reaches 50%. After it reaches 50%, Flagger will wait for 5 minutes before promoting the canary deployment to primary. Failed metrics checks is not used now, since we are not using any metrics analysis.

VirtualService delegation

One important thing to note is that the delegation: true field in the canary configuration. This field is required when using Flagger with TSB. If Delegation is enabled, Flagger would generate Istio VirtualService without hosts and gateway, making the service compatible with Istio delegation. This is required to avoid conflicts with TSB generated VirtualService.

Then create and apply TSB ServiceRoute that tells TSB to use Flagger generated services for the reviews service.

cat <<EOF > bookinfo-reviews-sr.yaml
apiVersion: traffic.tsb.tetrate.io/v2
kind: ServiceRoute
metadata:
  name: reviews-sr
  namespace: bookinfo
  annotations:
    tsb.tetrate.io/organization: tetrate
    tsb.tetrate.io/tenant: tetrate
    tsb.tetrate.io/workspace: bookinfo-ws
    tsb.tetrate.io/trafficGroup: bookinfo-tg
spec:
  service: bookinfo/reviews.bookinfo.svc.cluster.local
  portLevelSettings:
    - port: 9080
      trafficType: HTTP
  httpRoutes:
    - name: reviews-flagger
      match:
        - name: port-9080
          port: 9080
      flagger:
        canary: reviews-rollout
        namespace: bookinfo
EOF

kubectl apply -f bookinfo-reviews-sr.yaml

At this point, you are ready to trigger the canary deployment.

Trigger Canary Deployment​

Trigger canary deployment by updating the reviews deployment image.

kubectl set image -n bookinfo deployment/reviews reviews=docker.io/istio/examples-bookinfo-reviews-v2:1.18.0

You can check the canary status by describing the Flagger canary object.

k describe canary reviews-rollout -n bookinfo
Name:         reviews-rollout
Namespace:    bookinfo
API Version:  flagger.app/v1beta1
Kind:         Canary
Metadata:
  Creation Timestamp:  2024-02-27T08:15:56Z
  Generation:          1
  Resource Version:    2110146
  UID:                 48b41d3f-a48b-46cc-ae42-9669fc32d5a5
Spec:
  Analysis:
    Interval:     1m
    Max Weight:   50
    Step Weight:  10
    Threshold:    5
  Service:
    Delegation:                 true
    Port:                       9080
  Target Ref:
    API Version:  apps/v1
    Kind:         Deployment
    Name:         reviews
Status:
  Canary Weight:  10
  Conditions:
    Last Transition Time:  2024-02-28T04:23:58Z
    Last Update Time:      2024-02-28T04:23:58Z
    Message:               New revision detected, progressing canary analysis.
    Reason:                Progressing
    Status:                Unknown
    Type:                  Promoted
  Failed Checks:           0
  Iterations:              0
  Last Applied Spec:       7456477c8d
  Last Promoted Spec:      fd4676cc5
  Last Transition Time:    2024-02-28T04:24:58Z
  Phase:                   Progressing
  Tracked Configs:
Events:
  Type    Reason  Age                 From     Message
  ----    ------  ----                ----     -------
  Normal  Synced  3m27s (x3 over 15h)  flagger  New revision detected! Scaling up reviews.bookinfo
  Normal  Synced  2m27s (x3 over 15h)  flagger  Starting canary analysis for reviews.bookinfo
  Normal  Synced  2m27s (x3 over 15h)  flagger  Advance reviews-rollout.bookinfo canary weight 10
  Normal  Synced  87s (x3 over 15h)    flagger  Advance reviews-rollout.bookinfo canary weight 20
  Normal  Synced  27s (x3 over 15h)    flagger  Advance reviews-rollout.bookinfo canary weight 30

And you can see the VirtualService generated by Flagger with incremental traffic split between primary and canary.

kubectl get virtualservice -n bookinfo reviews -o yaml
apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
  annotations:
    helm.toolkit.fluxcd.io/driftDetection: disabled
    kustomize.toolkit.fluxcd.io/reconcile: disabled
  creationTimestamp: "2024-02-27T08:16:58Z"
  generation: 16
  labels:
    app: reviews
  name: reviews
  namespace: bookinfo
  ownerReferences:
  - apiVersion: flagger.app/v1beta1
    blockOwnerDeletion: true
    controller: true
    kind: Canary
    name: reviews-rollout
    uid: 48b41d3f-a48b-46cc-ae42-9669fc32d5a5
  resourceVersion: "2111703"
  uid: 52f6ea39-3b6a-4ef9-857f-848382d7113a
spec:
  hosts: []
  http:
  - route:
    - destination:
        host: reviews-primary
      weight: 70
    - destination:
        host: reviews-canary
      weight: 30

When the canary deployment is successful, canary deployment will be promoted to primary and the previous primary deployment will be deleted.

Observing Canary Rollout in TSB UI​

You can see the canary rollout in TSB UI. You will see following changes in the topology.

Initial state when reviews v1 is primary. Initial state

Canary is progressing. Traffic is split between reviews-primary (that point to v1 workload) and reviews (that point to v2 workload). Canary is progressing

Canary is promoted. reviews-primary is updated to point to v2 workload and v1 workload is deleted. Reviews v2 is making request to ratings service. Canary is promoted

Using SkyWalking Metrics for Canary Analysis​

To use SkyWalking metrics for canary analysis, you need to create a MetricTemplate that defines the metrics query to be used by Flagger.

In the following example, we will create a MetricTemplate that uses SkyWalking PromQL service to query the apdex score of the reviews service. Refer to SkyWalking PromQL service for more information on available query in SkyWalking PromQL service.

cat <<EOF > reviews-metrics-template.yaml
apiVersion: flagger.app/v1beta1
kind: MetricTemplate
metadata:
  name: reviews-metrics-template-apdex
  namespace: istio-system
spec:
  provider:
    type: prometheus
    address: http://oap.istio-system:9090/promql
  query: |
    service_apdex{service='-|reviews|bookinfo|c1|-', layer='MESH'}
EOF

kubectl apply -f reviews-metrics-template.yaml

Then update the canary configuration to use the MetricTemplate.

cat <<EOF > reviews-canary-metrics.yaml
apiVersion: flagger.app/v1beta1
kind: Canary
metadata:
  name: reviews-rollout
  namespace: bookinfo
spec:
  # deployment reference
  targetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: reviews
  service:
    port: 9080
    # delegation: true is REQUIRED when using Flagger with TSB
    delegation: true
  analysis:
    # schedule interval
    interval: 5m
    # max number of failed metric checks before rollback
    threshold: 5
    # max traffic percentage routed to canary percentage (0-100)
    maxWeight: 50
    # canary increment step percentage (0-100)
    stepWeight: 10
    # metrics analysis configuration
    metrics:
    - name: apdex
      templateRef:
        name: apdex
        namespace: istio-system
      thresholdRange:
        min: 99
      interval: 1m
EOF

kubectl apply -f reviews-canary-metrics.yaml

Now, if you update the reviews deployment image, Flagger will use the SkyWalking metrics to analyze the canary deployment. When the canary deployment is successful, canary deployment will be promoted to primary and the previous primary deployment will be deleted. On the other hand, if the canary deployment fails the metrics check, Flagger will rollback the canary deployment to the previous primary deployment.

Following describe canary output shows the canary deployment is failed and Flagger is rolling back the canary deployment.

Status:
  Canary Weight:  0
  Conditions:
    Last Transition Time:  2024-03-21T03:33:44Z
    Last Update Time:      2024-03-21T03:33:44Z
    Message:               Canary analysis failed, Deployment scaled to zero.
    Reason:                Failed
    Status:                False
    Type:                  Promoted
  Failed Checks:           0
  Iterations:              0
  Last Applied Spec:       7bb6f89f7
  Last Promoted Spec:      68d966ff59
  Last Transition Time:    2024-03-21T03:38:44Z
  Phase:                   Failed
  Tracked Configs:
Events:
  Type     Reason  Age                  From     Message
  ----     ------  ----                 ----     -------
  Normal   Synced  12m                  flagger  New revision detected! Restarting analysis for reviews.bookinfo
  Normal   Synced  11m (x4 over 25h)    flagger  Starting canary analysis for reviews.bookinfo
  Normal   Synced  11m (x4 over 25h)    flagger  Advance reviews-rollout.bookinfo canary weight 10
  Warning  Synced  7m36s (x6 over 23h)  flagger  Halt advancement no values found for custom metric: apdex: no values found
  Warning  Synced  6m36s (x5 over 19h)  flagger  Halt reviews-rollout.bookinfo advancement apdex 0.00 < 99
  Warning  Synced  5m36s (x3 over 19h)  flagger  Canary failed! Scaling down reviews-rollout.bookinfo
  Warning  Synced  5m36s (x2 over 19h)  flagger  Rolling back reviews-rollout.bookinfo failed checks threshold reached 5