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---
title: Mirroring
description: This task demonstrates the traffic mirroring/shadowing capabilities of Istio.
weight: 60
keywords: [traffic-management,mirroring]
---
This task demonstrates the traffic mirroring capabilities of Istio.
Traffic mirroring, also called shadowing, is a powerful concept that allows
feature teams to bring changes to production with as little risk as possible.
Mirroring sends a copy of live traffic to a mirrored service. The mirrored
traffic happens out of band of the critical request path for the primary service.
In this task, you will first force all traffic to `v1` of a test service. Then,
you will apply a rule to mirror a portion of traffic to `v2`.
## Before you begin
* Set up Istio by following the instructions in the
[Installation guide](/docs/setup/).
* Start by deploying two versions of the [httpbin]({{< github_tree >}}/samples/httpbin) service that have access logging enabled:
**httpbin-v1:**
{{< text 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", "0.0.0.0:80", "httpbin:app"]
ports:
- containerPort: 80
EOF
{{< /text >}}
**httpbin-v2:**
{{< text 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", "0.0.0.0:80", "httpbin:app"]
ports:
- containerPort: 80
EOF
{{< /text >}}
**httpbin Kubernetes service:**
{{< text bash >}}
$ kubectl create -f - <<EOF
apiVersion: v1
kind: Service
metadata:
name: httpbin
labels:
app: httpbin
spec:
ports:
- name: http
port: 8000
targetPort: 80
selector:
app: httpbin
EOF
{{< /text >}}
* Start the `sleep` service so you can use `curl` to provide load:
**sleep service:**
{{< text 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
{{< /text >}}
## Creating a default routing policy
By default Kubernetes load balances across both versions of the `httpbin` service.
In this step, you will change that behavior so that all traffic goes to `v1`.
1. Create a default route rule to route all traffic to `v1` of the service:
{{< warning >}}
If you installed/configured Istio with mutual TLS authentication enabled, you must add a TLS traffic policy `mode: ISTIO_MUTUAL` to the `DestinationRule` before applying it. Otherwise requests will generate 503 errors as described [here](/docs/ops/traffic-management/troubleshooting/#503-errors-after-setting-destination-rule).
{{< /warning >}}
{{< text bash >}}
$ kubectl apply -f - <<EOF
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
{{< /text >}}
Now all traffic goes to the `httpbin:v1` service.
1. Send some traffic to the service:
{{< text bash 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:8000/headers' | python -m json.tool
{
"headers": {
"Accept": "*/*",
"Content-Length": "0",
"Host": "httpbin:8000",
"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"
}
}
{{< /text >}}
1. Check the logs for `v1` and `v2` of the `httpbin` pods. You should see access
log entries for `v1` and none for `v2`:
{{< text bash >}}
$ 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"
{{< /text >}}
{{< text bash >}}
$ export V2_POD=$(kubectl get pod -l app=httpbin,version=v2 -o jsonpath={.items..metadata.name})
$ kubectl logs -f $V2_POD -c httpbin
<none>
{{< /text >}}
## Mirroring traffic to v2
1. Change the route rule to mirror traffic to v2:
{{< text bash >}}
$ kubectl apply -f - <<EOF
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
{{< /text >}}
This route rule sends 100% of the traffic to `v1`. The last stanza specifies
that you want to mirror to the `httpbin:v2` service. When traffic gets mirrored,
the requests are sent to the mirrored service with their Host/Authority headers
appended with `-shadow`. For example, `cluster-1` becomes `cluster-1-shadow`.
Also, it is important to note that these requests are mirrored as "fire and
forget", which means that the responses are discarded.
1. Send in traffic:
{{< text bash >}}
$ kubectl exec -it $SLEEP_POD -c sleep -- sh -c 'curl http://httpbin:8000/headers' | python -m json.tool
{{< /text >}}
Now, you should see access logging for both `v1` and `v2`. The access logs
created in `v2` are the mirrored requests that are actually going to `v1`.
{{< text bash >}}
$ 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"
{{< /text >}}
{{< text bash >}}
$ 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"
{{< /text >}}
1. If you want to examine traffic internals, run the following commands on another console:
{{< text bash >}}
$ export SLEEP_POD=$(kubectl get pod -l app=sleep -o jsonpath={.items..metadata.name})
$ export V1_POD_IP=$(kubectl get pod -l app=httpbin -l version=v1 -o jsonpath={.items..status.podIP})
$ export V2_POD_IP=$(kubectl get pod -l app=httpbin -l version=v2 -o jsonpath={.items..status.podIP})
$ kubectl exec -it $SLEEP_POD -c istio-proxy -- sudo tcpdump -A -s 0 host $V1_POD_IP or host $V2_POD_IP
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
05:47:50.159513 IP sleep-7b9f8bfcd-2djx5.38836 > 10-233-75-11.httpbin.default.svc.cluster.local.80: Flags [P.], seq 4039989036:4039989832, ack 3139734980, win 254, options [nop,nop,TS val 77427918 ecr 76730809], length 796: HTTP: GET /headers HTTP/1.1
E..P2.X.X.X.
.K.
.K....P..W,.$.......+.....
..t.....GET /headers HTTP/1.1
host: httpbin:8000
user-agent: curl/7.35.0
accept: */*
x-forwarded-proto: http
x-request-id: 571c0fd6-98d4-4c93-af79-6a2fe2945847
x-envoy-decorator-operation: httpbin.default.svc.cluster.local:8000/*
x-b3-traceid: 82f3e0a76dcebca2
x-b3-spanid: 82f3e0a76dcebca2
x-b3-sampled: 0
x-istio-attributes: Cj8KGGRlc3RpbmF0aW9uLnNlcnZpY2UuaG9zdBIjEiFodHRwYmluLmRlZmF1bHQuc3ZjLmNsdXN0ZXIubG9jYWwKPQoXZGVzdGluYXRpb24uc2VydmljZS51aWQSIhIgaXN0aW86Ly9kZWZhdWx0L3NlcnZpY2VzL2h0dHBiaW4KKgodZGVzdGluYXRpb24uc2VydmljZS5uYW1lc3BhY2USCRIHZGVmYXVsdAolChhkZXN0aW5hdGlvbi5zZXJ2aWNlLm5hbWUSCRIHaHR0cGJpbgo6Cgpzb3VyY2UudWlkEiwSKmt1YmVybmV0ZXM6Ly9zbGVlcC03YjlmOGJmY2QtMmRqeDUuZGVmYXVsdAo6ChNkZXN0aW5hdGlvbi5zZXJ2aWNlEiMSIWh0dHBiaW4uZGVmYXVsdC5zdmMuY2x1c3Rlci5sb2NhbA==
content-length: 0
05:47:50.159609 IP sleep-7b9f8bfcd-2djx5.49560 > 10-233-71-7.httpbin.default.svc.cluster.local.80: Flags [P.], seq 296287713:296288571, ack 4029574162, win 254, options [nop,nop,TS val 77427918 ecr 76732809], length 858: HTTP: GET /headers HTTP/1.1
E.....X.X...
.K.
.G....P......l......e.....
..t.....GET /headers HTTP/1.1
host: httpbin-shadow:8000
user-agent: curl/7.35.0
accept: */*
x-forwarded-proto: http
x-request-id: 571c0fd6-98d4-4c93-af79-6a2fe2945847
x-envoy-decorator-operation: httpbin.default.svc.cluster.local:8000/*
x-b3-traceid: 82f3e0a76dcebca2
x-b3-spanid: 82f3e0a76dcebca2
x-b3-sampled: 0
x-istio-attributes: Cj8KGGRlc3RpbmF0aW9uLnNlcnZpY2UuaG9zdBIjEiFodHRwYmluLmRlZmF1bHQuc3ZjLmNsdXN0ZXIubG9jYWwKPQoXZGVzdGluYXRpb24uc2VydmljZS51aWQSIhIgaXN0aW86Ly9kZWZhdWx0L3NlcnZpY2VzL2h0dHBiaW4KKgodZGVzdGluYXRpb24uc2VydmljZS5uYW1lc3BhY2USCRIHZGVmYXVsdAolChhkZXN0aW5hdGlvbi5zZXJ2aWNlLm5hbWUSCRIHaHR0cGJpbgo6Cgpzb3VyY2UudWlkEiwSKmt1YmVybmV0ZXM6Ly9zbGVlcC03YjlmOGJmY2QtMmRqeDUuZGVmYXVsdAo6ChNkZXN0aW5hdGlvbi5zZXJ2aWNlEiMSIWh0dHBiaW4uZGVmYXVsdC5zdmMuY2x1c3Rlci5sb2NhbA==
x-envoy-internal: true
x-forwarded-for: 10.233.75.12
content-length: 0
05:47:50.166734 IP 10-233-75-11.httpbin.default.svc.cluster.local.80 > sleep-7b9f8bfcd-2djx5.38836: Flags [P.], seq 1:472, ack 796, win 276, options [nop,nop,TS val 77427925 ecr 77427918], length 471: HTTP: HTTP/1.1 200 OK
E....3X.?...
.K.
.K..P...$....ZH...........
..t...t.HTTP/1.1 200 OK
server: envoy
date: Fri, 15 Feb 2019 05:47:50 GMT
content-type: application/json
content-length: 241
access-control-allow-origin: *
access-control-allow-credentials: true
x-envoy-upstream-service-time: 3
{
"headers": {
"Accept": "*/*",
"Content-Length": "0",
"Host": "httpbin:8000",
"User-Agent": "curl/7.35.0",
"X-B3-Sampled": "0",
"X-B3-Spanid": "82f3e0a76dcebca2",
"X-B3-Traceid": "82f3e0a76dcebca2"
}
}
05:47:50.166789 IP sleep-7b9f8bfcd-2djx5.38836 > 10-233-75-11.httpbin.default.svc.cluster.local.80: Flags [.], ack 472, win 262, options [nop,nop,TS val 77427925 ecr 77427925], length 0
E..42.X.X.\.
.K.
.K....P..ZH.$.............
..t...t.
05:47:50.167234 IP 10-233-71-7.httpbin.default.svc.cluster.local.80 > sleep-7b9f8bfcd-2djx5.49560: Flags [P.], seq 1:512, ack 858, win 280, options [nop,nop,TS val 77429926 ecr 77427918], length 511: HTTP: HTTP/1.1 200 OK
E..3..X.>...
.G.
.K..P....l....;...........
..|...t.HTTP/1.1 200 OK
server: envoy
date: Fri, 15 Feb 2019 05:47:49 GMT
content-type: application/json
content-length: 281
access-control-allow-origin: *
access-control-allow-credentials: true
x-envoy-upstream-service-time: 3
{
"headers": {
"Accept": "*/*",
"Content-Length": "0",
"Host": "httpbin-shadow:8000",
"User-Agent": "curl/7.35.0",
"X-B3-Sampled": "0",
"X-B3-Spanid": "82f3e0a76dcebca2",
"X-B3-Traceid": "82f3e0a76dcebca2",
"X-Envoy-Internal": "true"
}
}
05:47:50.167253 IP sleep-7b9f8bfcd-2djx5.49560 > 10-233-71-7.httpbin.default.svc.cluster.local.80: Flags [.], ack 512, win 262, options [nop,nop,TS val 77427926 ecr 77429926], length 0
E..4..X.X...
.K.
.G....P...;..n............
..t...|.
{{< /text >}}
You can see request and response contents of the traffic.
## Cleaning up
1. Remove the rules:
{{< text bash >}}
$ kubectl delete virtualservice httpbin
$ kubectl delete destinationrule httpbin
{{< /text >}}
1. Shutdown the [httpbin]({{< github_tree >}}/samples/httpbin) service and client:
{{< text bash >}}
$ kubectl delete deploy httpbin-v1 httpbin-v2 sleep
$ kubectl delete svc httpbin
{{< /text >}}
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