istio
/
istio.io
mirror of https://github.com/istio/istio.io.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity
istio.io/content/docs/tasks/traffic-management/mirroring.md

250 lines
7.7 KiB
Markdown
Raw Blame History

---
title: Mirroring
description: This task demonstrates the traffic shadowing/mirroring capabilities of Istio
weight: 60
---
> This task uses the new [v1alpha3 traffic management API](/blog/2018/v1alpha3-routing/). The old API has been deprecated and will be removed in the next Istio release. If you need to use the old version, follow the docs [here](https://archive.istio.io/v0.7/docs/tasks/traffic-management/).
This task demonstrates the traffic shadowing/mirroring capabilities of Istio. Traffic mirroring is a powerful concept that allows feature teams to bring changes to production with as little risk as possible. Mirroring brings a copy of live traffic to a mirrored service and happens out of band of the critical request path for the primary service.
## Before you begin
* Setup Istio by following the instructions in the
[Installation guide](/docs/setup/).
* Start two versions of the `httpbin` service that have access logging enabled
httpbin-v1:
```bash
cat <<EOF | istioctl kube-inject -f - | kubectl create -f -
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: httpbin-v1
spec:
replicas: 1
template:
metadata:
labels:
app: httpbin
version: v1
spec:
containers:
- image: docker.io/kennethreitz/httpbin
imagePullPolicy: IfNotPresent
name: httpbin
command: ["gunicorn", "--access-logfile", "-", "-b", "0.0.0.0:8080", "httpbin:app"]
ports:
- containerPort: 8080
EOF
```
httpbin-v2:
```bash
cat <<EOF | istioctl kube-inject -f - | kubectl create -f -
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: httpbin-v2
spec:
replicas: 1
template:
metadata:
labels:
app: httpbin
version: v2
spec:
containers:
- image: docker.io/kennethreitz/httpbin
imagePullPolicy: IfNotPresent
name: httpbin
command: ["gunicorn", "--access-logfile", "-", "-b", "0.0.0.0:8080", "httpbin:app"]
ports:
- containerPort: 8080
EOF
```
httpbin Kubernetes service:
```bash
cat <<EOF | kubectl create -f -
apiVersion: v1
kind: Service
metadata:
name: httpbin
labels:
app: httpbin
spec:
ports:
- name: http
port: 8080
selector:
app: httpbin
EOF
```
* Start the `sleep` service so we can use `curl` to provide load
sleep service:
```bash
cat <<EOF | istioctl kube-inject -f - | kubectl create -f -
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: sleep
spec:
replicas: 1
template:
metadata:
labels:
app: sleep
spec:
containers:
- name: sleep
image: tutum/curl
command: ["/bin/sleep","infinity"]
imagePullPolicy: IfNotPresent
EOF
```
## Mirroring
Let's set up a scenario to demonstrate the traffic-mirroring capabilities of Istio. We have two versions of our `httpbin` service. By default Kubernetes will load balance across both versions of the service. We'll use Istio to force all traffic to v1 of the `httpbin` service.
### Creating default routing policy
1. Create a default route rule to route all traffic to `v1` of our `httpbin` service:
```bash
cat <<EOF | istioctl create -f -
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
name: httpbin
spec:
hosts:
- httpbin
http:
- route:
- destination:
host: httpbin
subset: v1
weight: 100
---
apiVersion: networking.istio.io/v1alpha3
kind: DestinationRule
metadata:
name: httpbin
spec:
host: httpbin
subsets:
- name: v1
labels:
version: v1
- name: v2
labels:
version: v2
EOF
```
Now all traffic should go to `httpbin v1` service. Let's try sending in some traffic:
```command-output-as-json
$ export SLEEP_POD=$(kubectl get pod -l app=sleep -o jsonpath={.items..metadata.name})
$ kubectl exec -it $SLEEP_POD -c sleep -- sh -c 'curl http://httpbin:8080/headers'
{
"headers": {
"Accept": "*/*",
"Content-Length": "0",
"Host": "httpbin:8080",
"User-Agent": "curl/7.35.0",
"X-B3-Sampled": "1",
"X-B3-Spanid": "eca3d7ed8f2e6a0a",
"X-B3-Traceid": "eca3d7ed8f2e6a0a",
"X-Ot-Span-Context": "eca3d7ed8f2e6a0a;eca3d7ed8f2e6a0a;0000000000000000"
}
}
```
If we check the logs for `v1` and `v2` of our `httpbin` pods, we should see access log entries for only `v1`:
```command
$ export V1_POD=$(kubectl get pod -l app=httpbin,version=v1 -o jsonpath={.items..metadata.name})
$ kubectl logs -f $V1_POD -c httpbin
127.0.0.1 - - [07/Mar/2018:19:02:43 +0000] "GET /headers HTTP/1.1" 200 321 "-" "curl/7.35.0"
```
```command
$ export V2_POD=$(kubectl get pod -l app=httpbin,version=v2 -o jsonpath={.items..metadata.name})
$ kubectl logs -f $V2_POD -c httpbin
<none>
```
1. Change the route rule to mirror traffic to v2
```bash
cat <<EOF | istioctl replace -f -
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
name: httpbin
spec:
hosts:
- httpbin
http:
- route:
- destination:
host: httpbin
subset: v1
weight: 100
mirror:
host: httpbin
subset: v2
EOF
```
This route rule specifies we route 100% of the traffic to v1. The last stanza specifies we want to mirror to the `httpbin v2` service. When traffic gets mirrored, the requests are sent to the mirrored service with its Host/Authority header appended with *-shadow*. For example, *cluster-1* becomes *cluster-1-shadow*. Also important to realize is that these requests are mirrored as "fire and forget", i.e., the responses are discarded.
Now if we send in traffic:
```command
$ kubectl exec -it $SLEEP_POD -c sleep -- sh -c 'curl http://httpbin:8080/headers'
```
We should see access logging for both `v1` and `v2`. The access logs created in `v2` is the mirrored requests that are actually going to `v1`.
```command
$ kubectl logs -f $V1_POD -c httpbin
127.0.0.1 - - [07/Mar/2018:19:02:43 +0000] "GET /headers HTTP/1.1" 200 321 "-" "curl/7.35.0"
127.0.0.1 - - [07/Mar/2018:19:26:44 +0000] "GET /headers HTTP/1.1" 200 321 "-" "curl/7.35.0"
```
```command
$ kubectl logs -f $V2_POD -c httpbin
127.0.0.1 - - [07/Mar/2018:19:26:44 +0000] "GET /headers HTTP/1.1" 200 361 "-" "curl/7.35.0"
```
## Cleaning up
1. Remove the rules.
```command
$ istioctl delete virtualservice httpbin
$ istioctl delete destinationrule httpbin
```
1. Shutdown the [httpbin](https://github.com/istio/istio/tree/master/samples/httpbin) service and client.
```command
$ kubectl delete deploy httpbin-v1 httpbin-v2 sleep
$ kubectl delete svc httpbin
```
## What's next
Check out the [Mirroring configuration](/docs/reference/config/istio.networking.v1alpha3/#HTTPRoute.mirror) reference documentation.
Reference in New Issue View Git Blame Copy Permalink