flagger

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Published: Mar 25, 2019 License: Apache-2.0

README

flagger

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Flagger is a Kubernetes operator that automates the promotion of canary deployments using Istio or App Mesh routing for traffic shifting and Prometheus metrics for canary analysis. The canary analysis can be extended with webhooks for running acceptance tests, load tests or any other custom validation.

Flagger implements a control loop that gradually shifts traffic to the canary while measuring key performance indicators like HTTP requests success rate, requests average duration and pods health. Based on analysis of the KPIs a canary is promoted or aborted, and the analysis result is published to Slack.

flagger-overview

Documentation

Flagger documentation can be found at docs.flagger.app

Install

Before installing Flagger make sure you have Istio setup up with Prometheus enabled. If you are new to Istio you can follow my Istio service mesh walk-through.

Deploy Flagger in the istio-system namespace using Helm:

# add the Helm repository
helm repo add flagger https://flagger.app

# install or upgrade
helm upgrade -i flagger flagger/flagger \
--namespace=istio-system \
--set metricsServer=http://prometheus.istio-system:9090 

Flagger is compatible with Kubernetes >1.11.0 and Istio >1.0.0.

Canary CRD

Flagger takes a Kubernetes deployment and optionally a horizontal pod autoscaler (HPA), then creates a series of objects (Kubernetes deployments, ClusterIP services and Istio virtual services). These objects expose the application on the mesh and drive the canary analysis and promotion.

Flagger keeps track of ConfigMaps and Secrets referenced by a Kubernetes Deployment and triggers a canary analysis if any of those objects change. When promoting a workload in production, both code (container images) and configuration (config maps and secrets) are being synchronised.

For a deployment named podinfo, a canary promotion can be defined using Flagger's custom resource:

apiVersion: flagger.app/v1alpha3
kind: Canary
metadata:
  name: podinfo
  namespace: test
spec:
  # deployment reference
  targetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: podinfo
  # the maximum time in seconds for the canary deployment
  # to make progress before it is rollback (default 600s)
  progressDeadlineSeconds: 60
  # HPA reference (optional)
  autoscalerRef:
    apiVersion: autoscaling/v2beta1
    kind: HorizontalPodAutoscaler
    name: podinfo
  service:
    # container port
    port: 9898
    # Istio gateways (optional)
    gateways:
    - public-gateway.istio-system.svc.cluster.local
    # Istio virtual service host names (optional)
    hosts:
    - podinfo.example.com
    # HTTP match conditions (optional)
    match:
      - uri:
          prefix: /
    # HTTP rewrite (optional)
    rewrite:
      uri: /
    # Envoy timeout and retry policy (optional)
    headers:
      request:
        add:
          x-envoy-upstream-rq-timeout-ms: "15000"
          x-envoy-max-retries: "10"
          x-envoy-retry-on: "gateway-error,connect-failure,refused-stream"
    # cross-origin resource sharing policy (optional)
    corsPolicy:
      allowOrigin:
        - example.com
  # promote the canary without analysing it (default false)
  skipAnalysis: false
  # define the canary analysis timing and KPIs
  canaryAnalysis:
    # schedule interval (default 60s)
    interval: 1m
    # max number of failed metric checks before rollback
    threshold: 10
    # max traffic percentage routed to canary
    # percentage (0-100)
    maxWeight: 50
    # canary increment step
    # percentage (0-100)
    stepWeight: 5
    # Istio Prometheus checks
    metrics:
    # builtin Istio checks
    - name: istio_requests_total
      # minimum req success rate (non 5xx responses)
      # percentage (0-100)
      threshold: 99
      interval: 1m
    - name: istio_request_duration_seconds_bucket
      # maximum req duration P99
      # milliseconds
      threshold: 500
      interval: 30s
    # custom check
    - name: "kafka lag"
      threshold: 100
      query: |
        avg_over_time(
          kafka_consumergroup_lag{
            consumergroup=~"podinfo-consumer-.*",
            topic="podinfo"
          }[1m]
        )
    # external checks (optional)
    webhooks:
      - name: load-test
        url: http://flagger-loadtester.test/
        timeout: 5s
        metadata:
          cmd: "hey -z 1m -q 10 -c 2 http://podinfo.test:9898/"

For more details on how the canary analysis and promotion works please read the docs.

Roadmap
  • Integrate with other service mesh technologies like Linkerd v2 or Consul Mesh
  • Add support for comparing the canary metrics to the primary ones and do the validation based on the derivation between the two
Contributing

Flagger is Apache 2.0 licensed and accepts contributions via GitHub pull requests.

When submitting bug reports please include as much details as possible:

  • which Flagger version
  • which Flagger CRD version
  • which Kubernetes/Istio version
  • what configuration (canary, virtual service and workloads definitions)
  • what happened (Flagger, Istio Pilot and Proxy logs)
Getting Help

If you have any questions about Flagger and progressive delivery:

Your feedback is always welcome!

Directories

Path Synopsis
cmd
pkg
apis/appmesh/v1alpha1
Package v1alpha1 is the v1alpha1 version of the API.
Package v1alpha1 is the v1alpha1 version of the API.
apis/flagger/v1alpha3
Package v1alpha3 is the v1alpha3 version of the API.
Package v1alpha3 is the v1alpha3 version of the API.
apis/istio/v1alpha3
+k8s:deepcopy-gen=package +groupName=networking.istio.io proto: https://github.com/istio/api/blob/master/networking/v1alpha3/virtual_service.proto
+k8s:deepcopy-gen=package +groupName=networking.istio.io proto: https://github.com/istio/api/blob/master/networking/v1alpha3/virtual_service.proto
client/clientset/versioned
This package has the automatically generated clientset.
This package has the automatically generated clientset.
client/clientset/versioned/fake
This package has the automatically generated fake clientset.
This package has the automatically generated fake clientset.
client/clientset/versioned/scheme
This package contains the scheme of the automatically generated clientset.
This package contains the scheme of the automatically generated clientset.
client/clientset/versioned/typed/appmesh/v1alpha1
This package has the automatically generated typed clients.
This package has the automatically generated typed clients.
client/clientset/versioned/typed/appmesh/v1alpha1/fake
Package fake has the automatically generated clients.
Package fake has the automatically generated clients.
client/clientset/versioned/typed/flagger/v1alpha3
This package has the automatically generated typed clients.
This package has the automatically generated typed clients.
client/clientset/versioned/typed/flagger/v1alpha3/fake
Package fake has the automatically generated clients.
Package fake has the automatically generated clients.
client/clientset/versioned/typed/istio/v1alpha3
This package has the automatically generated typed clients.
This package has the automatically generated typed clients.
client/clientset/versioned/typed/istio/v1alpha3/fake
Package fake has the automatically generated clients.
Package fake has the automatically generated clients.

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