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flagger/docs/gitbook/tutorials/istio-progressive-delivery.md

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# Istio Canary Deployments
This guide shows you how to use Istio and Flagger to automate canary deployments.
![Flagger Canary Stages](https://raw.githubusercontent.com/fluxcd/flagger/main/docs/diagrams/flagger-canary-steps.png)
## Prerequisites
Flagger requires a Kubernetes cluster **v1.16** or newer and Istio **v1.5** or newer.
Install Istio with telemetry support and Prometheus:
```bash
istioctl manifest install --set profile=default
# Suggestion: Please change release-1.8 in below command, to your real istio version.
kubectl apply -f https://raw.githubusercontent.com/istio/istio/release-1.18/samples/addons/prometheus.yaml
```
Install Flagger in the `istio-system` namespace:
```bash
kubectl apply -k github.com/fluxcd/flagger//kustomize/istio
```
Create an ingress gateway to expose the demo app outside of the mesh:
```yaml
apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
name: public-gateway
namespace: istio-system
spec:
selector:
istio: ingressgateway
servers:
- port:
number: 80
name: http
protocol: HTTP
hosts:
- "*"
```
## Bootstrap
Flagger takes a Kubernetes deployment and optionally a horizontal pod autoscaler \(HPA\), then creates a series of objects \(Kubernetes deployments, ClusterIP services, Istio destination rules and virtual services\). These objects expose the application inside the mesh and drive the canary analysis and promotion.
Create a test namespace with Istio sidecar injection enabled:
```bash
kubectl create ns test
kubectl label namespace test istio-injection=enabled
```
Create a deployment and a horizontal pod autoscaler:
```bash
kubectl apply -k https://github.com/fluxcd/flagger//kustomize/podinfo?ref=main
```
Deploy the load testing service to generate traffic during the canary analysis:
```bash
kubectl apply -k https://github.com/fluxcd/flagger//kustomize/tester?ref=main
```
Create a canary custom resource \(replace example.com with your own domain\):
```yaml
apiVersion: flagger.app/v1beta1
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/v2
kind: HorizontalPodAutoscaler
name: podinfo
service:
# service port number
port: 9898
# container port number or name (optional)
targetPort: 9898
# Istio gateways (optional)
gateways:
- istio-system/public-gateway
# Istio virtual service host names (optional)
hosts:
- app.example.com
# Istio traffic policy (optional)
trafficPolicy:
tls:
# use ISTIO_MUTUAL when mTLS is enabled
mode: DISABLE
# Istio retry policy (optional)
retries:
attempts: 3
perTryTimeout: 1s
retryOn: "gateway-error,connect-failure,refused-stream"
analysis:
# schedule interval (default 60s)
interval: 1m
# 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:
- name: request-success-rate
# minimum req success rate (non 5xx responses)
# percentage (0-100)
thresholdRange:
min: 99
interval: 1m
- name: request-duration
# maximum req duration P99
# milliseconds
thresholdRange:
max: 500
interval: 30s
# testing (optional)
webhooks:
- name: acceptance-test
type: pre-rollout
url: http://flagger-loadtester.test/
timeout: 30s
metadata:
type: bash
cmd: "curl -sd 'test' http://podinfo-canary:9898/token | grep token"
- name: load-test
url: http://flagger-loadtester.test/
timeout: 5s
metadata:
cmd: "hey -z 1m -q 10 -c 2 http://podinfo-canary.test:9898/"
```
**Note** that when using Istio 1.4 you have to replace the `request-duration` with a [metric template](https://docs.flagger.app/dev/upgrade-guide#istio-telemetry-v2).
Save the above resource as podinfo-canary.yaml and then apply it:
```bash
kubectl apply -f ./podinfo-canary.yaml
```
When the canary analysis starts, Flagger will call the pre-rollout webhooks before routing traffic to the canary. The canary analysis will run for five minutes while validating the HTTP metrics and rollout hooks every minute.
![Flagger Canary Process](https://raw.githubusercontent.com/fluxcd/flagger/main/docs/diagrams/flagger-canary-hpa.png)
After a couple of seconds Flagger will create the canary objects:
```bash
# applied
deployment.apps/podinfo
horizontalpodautoscaler.autoscaling/podinfo
canary.flagger.app/podinfo
# generated
deployment.apps/podinfo-primary
horizontalpodautoscaler.autoscaling/podinfo-primary
service/podinfo
service/podinfo-canary
service/podinfo-primary
destinationrule.networking.istio.io/podinfo-canary
destinationrule.networking.istio.io/podinfo-primary
virtualservice.networking.istio.io/podinfo
```
## Automated canary promotion
Trigger a canary deployment by updating the container image:
```bash
kubectl -n test set image deployment/podinfo \
podinfod=ghcr.io/stefanprodan/podinfo:6.0.1
```
Flagger detects that the deployment revision changed and starts a new rollout:
```text
kubectl -n test describe canary/podinfo
Status:
Canary Weight: 0
Failed Checks: 0
Phase: Succeeded
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Synced 3m flagger New revision detected podinfo.test
Normal Synced 3m flagger Scaling up podinfo.test
Warning Synced 3m flagger Waiting for podinfo.test rollout to finish: 0 of 1 updated replicas are available
Normal Synced 3m flagger Advance podinfo.test canary weight 5
Normal Synced 3m flagger Advance podinfo.test canary weight 10
Normal Synced 3m flagger Advance podinfo.test canary weight 15
Normal Synced 2m flagger Advance podinfo.test canary weight 20
Normal Synced 2m flagger Advance podinfo.test canary weight 25
Normal Synced 1m flagger Advance podinfo.test canary weight 30
Normal Synced 1m flagger Advance podinfo.test canary weight 35
Normal Synced 55s flagger Advance podinfo.test canary weight 40
Normal Synced 45s flagger Advance podinfo.test canary weight 45
Normal Synced 35s flagger Advance podinfo.test canary weight 50
Normal Synced 25s flagger Copying podinfo.test template spec to podinfo-primary.test
Warning Synced 15s flagger Waiting for podinfo-primary.test rollout to finish: 1 of 2 updated replicas are available
Normal Synced 5s flagger Promotion completed! Scaling down podinfo.test
```
**Note** that if you apply new changes to the deployment during the canary analysis, Flagger will restart the analysis.
A canary deployment is triggered by changes in any of the following objects:
* Deployment PodSpec \(container image, command, ports, env, resources, etc\)
* ConfigMaps mounted as volumes or mapped to environment variables
* Secrets mounted as volumes or mapped to environment variables
You can monitor all canaries with:
```bash
watch kubectl get canaries --all-namespaces
NAMESPACE NAME STATUS WEIGHT LASTTRANSITIONTIME
test podinfo Progressing 15 2019-01-16T14:05:07Z
prod frontend Succeeded 0 2019-01-15T16:15:07Z
prod backend Failed 0 2019-01-14T17:05:07Z
```
## Automated rollback
During the canary analysis you can generate HTTP 500 errors and high latency to test if Flagger pauses the rollout.
Trigger another canary deployment:
```bash
kubectl -n test set image deployment/podinfo \
podinfod=ghcr.io/stefanprodan/podinfo:6.0.2
```
Exec into the load tester pod with:
```bash
kubectl -n test exec -it flagger-loadtester-xx-xx sh
```
Generate HTTP 500 errors:
```bash
watch curl http://podinfo-canary:9898/status/500
```
Generate latency:
```bash
watch curl http://podinfo-canary:9898/delay/1
```
When the number of failed checks reaches the canary analysis threshold, the traffic is routed back to the primary, the canary is scaled to zero and the rollout is marked as failed.
```text
kubectl -n test describe canary/podinfo
Status:
Canary Weight: 0
Failed Checks: 10
Phase: Failed
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Synced 3m flagger Starting canary deployment for podinfo.test
Normal Synced 3m flagger Advance podinfo.test canary weight 5
Normal Synced 3m flagger Advance podinfo.test canary weight 10
Normal Synced 3m flagger Advance podinfo.test canary weight 15
Normal Synced 3m flagger Halt podinfo.test advancement success rate 69.17% < 99%
Normal Synced 2m flagger Halt podinfo.test advancement success rate 61.39% < 99%
Normal Synced 2m flagger Halt podinfo.test advancement success rate 55.06% < 99%
Normal Synced 2m flagger Halt podinfo.test advancement success rate 47.00% < 99%
Normal Synced 2m flagger (combined from similar events): Halt podinfo.test advancement success rate 38.08% < 99%
Warning Synced 1m flagger Rolling back podinfo.test failed checks threshold reached 10
Warning Synced 1m flagger Canary failed! Scaling down podinfo.test
```
## Session Affinity
While Flagger can perform weighted routing and A/B testing individually, with Istio it can combine the two leading to a Canary
release with session affinity. For more information you can read the [deployment strategies docs](../usage/deployment-strategies.md#canary-release-with-session-affinity).
Create a canary custom resource \(replace app.example.com with your own domain\):
```yaml
apiVersion: flagger.app/v1beta1
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/v2
kind: HorizontalPodAutoscaler
name: podinfo
service:
# service port number
port: 9898
# container port number or name (optional)
targetPort: 9898
# Istio gateways (optional)
gateways:
- istio-system/public-gateway
# Istio virtual service host names (optional)
hosts:
- app.example.com
# Istio traffic policy (optional)
trafficPolicy:
tls:
# use ISTIO_MUTUAL when mTLS is enabled
mode: DISABLE
# Istio retry policy (optional)
retries:
attempts: 3
perTryTimeout: 1s
retryOn: "gateway-error,connect-failure,refused-stream"
analysis:
# schedule interval (default 60s)
interval: 1m
# 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
# session affinity config
sessionAffinity:
# name of the cookie used
cookieName: flagger-cookie
# max age of the cookie (in seconds)
# optional; defaults to 86400
maxAge: 21600
metrics:
- name: request-success-rate
# minimum req success rate (non 5xx responses)
# percentage (0-100)
thresholdRange:
min: 99
interval: 1m
- name: request-duration
# maximum req duration P99
# milliseconds
thresholdRange:
max: 500
interval: 30s
# testing (optional)
webhooks:
- name: acceptance-test
type: pre-rollout
url: http://flagger-loadtester.test/
timeout: 30s
metadata:
type: bash
cmd: "curl -sd 'test' http://podinfo-canary:9898/token | grep token"
- name: load-test
url: http://flagger-loadtester.test/
timeout: 5s
metadata:
cmd: "hey -z 1m -q 10 -c 2 http://podinfo-canary.test:9898/"
```
Save the above resource as podinfo-canary-session-affinity.yaml and then apply it:
```bash
kubectl apply -f ./podinfo-canary-session-affinity.yaml
```
Trigger a canary deployment by updating the container image:
```bash
kubectl -n test set image deployment/podinfo \
podinfod=ghcr.io/stefanprodan/podinfo:6.0.1
```
You can load `app.example.com` in your browser and refresh it until you see the requests being served by `podinfo:6.0.1`.
All subsequent requests after that will be served by `podinfo:6.0.1` and not `podinfo:6.0.0` because of the session affinity
configured by Flagger with Istio.
## Traffic mirroring
![Flagger Canary Traffic Shadowing](https://raw.githubusercontent.com/fluxcd/flagger/main/docs/diagrams/flagger-canary-traffic-mirroring.png)
For applications that perform read operations, Flagger can be configured to drive canary releases with traffic mirroring. Istio traffic mirroring will copy each incoming request, sending one request to the primary and one to the canary service. The response from the primary is sent back to the user and the response from the canary is discarded. Metrics are collected on both requests so that the deployment will only proceed if the canary metrics are within the threshold values.
Note that mirroring should be used for requests that are **idempotent** or capable of being processed twice \(once by the primary and once by the canary\).
You can enable mirroring by replacing `stepWeight/maxWeight` with `iterations` and by setting `analysis.mirror` to `true`:
```yaml
apiVersion: flagger.app/v1beta1
kind: Canary
metadata:
name: podinfo
namespace: test
spec:
analysis:
# schedule interval
interval: 1m
# max number of failed metric checks before rollback
threshold: 5
# total number of iterations
iterations: 10
# enable traffic shadowing
mirror: true
# weight of the traffic mirrored to your canary (defaults to 100%)
mirrorWeight: 100
metrics:
- name: request-success-rate
thresholdRange:
min: 99
interval: 1m
- name: request-duration
thresholdRange:
max: 500
interval: 1m
webhooks:
- name: acceptance-test
type: pre-rollout
url: http://flagger-loadtester.test/
timeout: 30s
metadata:
type: bash
cmd: "curl -sd 'test' http://podinfo-canary:9898/token | grep token"
- name: load-test
url: http://flagger-loadtester.test/
timeout: 5s
metadata:
cmd: "hey -z 1m -q 10 -c 2 http://podinfo.test:9898/"
```
With the above configuration, Flagger will run a canary release with the following steps:
* detect new revision \(deployment spec, secrets or configmaps changes\)
* scale from zero the canary deployment
* wait for the HPA to set the canary minimum replicas
* check canary pods health
* run the acceptance tests
* abort the canary release if tests fail
* start the load tests
* mirror 100% of the traffic from primary to canary
* check request success rate and request duration every minute
* abort the canary release if the metrics check failure threshold is reached
* stop traffic mirroring after the number of iterations is reached
* route live traffic to the canary pods
* promote the canary \(update the primary secrets, configmaps and deployment spec\)
* wait for the primary deployment rollout to finish
* wait for the HPA to set the primary minimum replicas
* check primary pods health
* switch live traffic back to primary
* scale to zero the canary
* send notification with the canary analysis result
The above procedure can be extended with [custom metrics](../usage/metrics.md) checks, [webhooks](../usage/webhooks.md), [manual promotion](../usage/webhooks.md#manual-gating) approval and [Slack or MS Teams](../usage/alerting.md) notifications.
## Canary Deployments for TCP Services
Performing a Canary deployment on a TCP (non HTTP) service is nearly identical to an HTTP Canary. Besides updating your `Gateway` document to support the `TCP` routing, the only difference is you have to set the `appProtocol` field to `TCP` inside of the `service` section of your `Canary` document.
#### Example:
```yaml
apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
name: public-gateway
namespace: istio-system
spec:
selector:
istio: ingressgateway
servers:
- port:
number: 7070
name: tcp-service
protocol: TCP # <== set the protocol to tcp here
hosts:
- "*"
```
```yaml
apiVersion: flagger.app/v1beta1
kind: Canary
# omitted for brevity
spec:
service:
port: 7070
appProtocol: TCP # <== set the appProtocol here
targetPort: 7070
portName: "tcp-service-port"
```
If the `appProtocol` equals `TCP` then Flagger will treat this as a Canary deployment for a `TCP` service. When it creates the `VirtualService` document it will add a `TCP` section to route requests between the `primary` and `canary` services. See Istio documentation for more information on this [spec](https://istio.io/latest/docs/reference/config/networking/virtual-service/#TCPRoute).
The resulting `VirtualService` will include a `tcp` section similar to what is shown below:
```yaml
tcp:
- route:
- destination:
host: tcp-service-primary
port:
number: 7070
weight: 100
- destination:
host: tcp-service-canary
port:
number: 7070
weight: 0
```
Once the Canary analysis begins, Flagger will be able to adjust the weights inside of this `tcp` section to advance the Canary deployment until it either runs into an error (and is halted) or it successfully reaches the end of the analysis and is Promoted.
It is also important to note that if you set `appProtocol` to anything other than `TCP`, for example if you set it to `HTTP`, it will perform the Canary and treat it as an `HTTP` service. The same remains true if you do not set `appProtocol` at all. It will __ONLY__ treat a Canary as a `TCP` service if `appProtocal` equals `TCP`.
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