mirror of https://github.com/istio/istio.io.git
285 lines
12 KiB
Markdown
285 lines
12 KiB
Markdown
---
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title: Circuit Breaking
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description: This task shows you how to configure circuit breaking for connections, requests, and outlier detection.
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weight: 50
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keywords: [traffic-management,circuit-breaking]
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owner: istio/wg-networking-maintainers
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test: yes
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---
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This task shows you how to configure circuit breaking for connections, requests,
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and outlier detection.
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Circuit breaking is an important pattern for creating resilient microservice
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applications. Circuit breaking allows you to write applications that limit the impact of failures, latency spikes, and other undesirable effects of network peculiarities.
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In this task, you will configure circuit breaking rules and then test the
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configuration by intentionally "tripping" the circuit breaker.
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## Before you begin
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* Setup Istio by following the instructions in the
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[Installation guide](/docs/setup/).
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{{< boilerplate start-httpbin-service >}}
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The `httpbin` application serves as the backend service for this task.
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## Configuring the circuit breaker
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1. Create a [destination rule](/docs/reference/config/networking/destination-rule/) to apply circuit breaking settings
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when calling the `httpbin` service:
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{{< warning >}}
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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.
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Otherwise requests will generate 503 errors as described [here](/docs/ops/common-problems/network-issues/#503-errors-after-setting-destination-rule).
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{{< /warning >}}
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{{< text bash >}}
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$ kubectl apply -f - <<EOF
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apiVersion: networking.istio.io/v1
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kind: DestinationRule
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metadata:
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name: httpbin
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spec:
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host: httpbin
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trafficPolicy:
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connectionPool:
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tcp:
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maxConnections: 1
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http:
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http1MaxPendingRequests: 1
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maxRequestsPerConnection: 1
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outlierDetection:
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consecutive5xxErrors: 1
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interval: 1s
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baseEjectionTime: 3m
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maxEjectionPercent: 100
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EOF
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{{< /text >}}
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1. Verify the destination rule was created correctly:
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{{< text bash yaml >}}
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$ kubectl get destinationrule httpbin -o yaml
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apiVersion: networking.istio.io/v1
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kind: DestinationRule
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...
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spec:
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host: httpbin
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trafficPolicy:
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connectionPool:
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http:
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http1MaxPendingRequests: 1
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maxRequestsPerConnection: 1
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tcp:
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maxConnections: 1
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outlierDetection:
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baseEjectionTime: 3m
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consecutive5xxErrors: 1
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interval: 1s
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maxEjectionPercent: 100
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{{< /text >}}
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## Adding a client
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Create a client to send traffic to the `httpbin` service. The client is
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a simple load-testing client called [fortio](https://github.com/istio/fortio).
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Fortio lets you control the number of connections, concurrency, and
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delays for outgoing HTTP calls. You will use this client to "trip" the circuit breaker
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policies you set in the `DestinationRule`.
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1. Inject the client with the Istio sidecar proxy so network interactions are
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governed by Istio.
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If you have enabled [automatic sidecar injection](/docs/setup/additional-setup/sidecar-injection/#automatic-sidecar-injection), deploy the `fortio` service:
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{{< text bash >}}
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$ kubectl apply -f @samples/httpbin/sample-client/fortio-deploy.yaml@
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{{< /text >}}
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Otherwise, you have to manually inject the sidecar before deploying the `fortio` application:
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{{< text bash >}}
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$ kubectl apply -f <(istioctl kube-inject -f @samples/httpbin/sample-client/fortio-deploy.yaml@)
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{{< /text >}}
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1. Log in to the client pod and use the fortio tool to call `httpbin`.
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Pass in `curl` to indicate that you just want to make one call:
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{{< text bash >}}
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$ export FORTIO_POD=$(kubectl get pods -l app=fortio -o 'jsonpath={.items[0].metadata.name}')
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$ kubectl exec "$FORTIO_POD" -c fortio -- /usr/bin/fortio curl -quiet http://httpbin:8000/get
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HTTP/1.1 200 OK
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server: envoy
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date: Tue, 25 Feb 2020 20:25:52 GMT
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content-type: application/json
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content-length: 586
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access-control-allow-origin: *
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access-control-allow-credentials: true
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x-envoy-upstream-service-time: 36
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{
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"args": {},
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"headers": {
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"Content-Length": "0",
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"Host": "httpbin:8000",
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"User-Agent": "fortio.org/fortio-1.3.1",
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"X-B3-Parentspanid": "8fc453fb1dec2c22",
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"X-B3-Sampled": "1",
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"X-B3-Spanid": "071d7f06bc94943c",
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"X-B3-Traceid": "86a929a0e76cda378fc453fb1dec2c22",
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"X-Forwarded-Client-Cert": "By=spiffe://cluster.local/ns/default/sa/httpbin;Hash=68bbaedefe01ef4cb99e17358ff63e92d04a4ce831a35ab9a31d3c8e06adb038;Subject=\"\";URI=spiffe://cluster.local/ns/default/sa/default"
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},
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"origin": "127.0.0.1",
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"url": "http://httpbin:8000/get"
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}
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{{< /text >}}
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You can see the request succeeded! Now, it's time to break something.
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## Tripping the circuit breaker
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In the `DestinationRule` settings, you specified `maxConnections: 1` and
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`http1MaxPendingRequests: 1`. These rules indicate that if you exceed more than
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one connection and request concurrently, you should see some failures when the
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`istio-proxy` opens the circuit for further requests and connections.
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1. Call the service with two concurrent connections (`-c 2`) and send 20 requests
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(`-n 20`):
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{{< text bash >}}
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$ kubectl exec "$FORTIO_POD" -c fortio -- /usr/bin/fortio load -c 2 -qps 0 -n 20 -loglevel Warning http://httpbin:8000/get
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20:33:46 I logger.go:97> Log level is now 3 Warning (was 2 Info)
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Fortio 1.3.1 running at 0 queries per second, 6->6 procs, for 20 calls: http://httpbin:8000/get
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Starting at max qps with 2 thread(s) [gomax 6] for exactly 20 calls (10 per thread + 0)
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20:33:46 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:33:47 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:33:47 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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Ended after 59.8524ms : 20 calls. qps=334.16
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Aggregated Function Time : count 20 avg 0.0056869 +/- 0.003869 min 0.000499 max 0.0144329 sum 0.113738
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# range, mid point, percentile, count
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>= 0.000499 <= 0.001 , 0.0007495 , 10.00, 2
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> 0.001 <= 0.002 , 0.0015 , 15.00, 1
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> 0.003 <= 0.004 , 0.0035 , 45.00, 6
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> 0.004 <= 0.005 , 0.0045 , 55.00, 2
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> 0.005 <= 0.006 , 0.0055 , 60.00, 1
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> 0.006 <= 0.007 , 0.0065 , 70.00, 2
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> 0.007 <= 0.008 , 0.0075 , 80.00, 2
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> 0.008 <= 0.009 , 0.0085 , 85.00, 1
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> 0.011 <= 0.012 , 0.0115 , 90.00, 1
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> 0.012 <= 0.014 , 0.013 , 95.00, 1
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> 0.014 <= 0.0144329 , 0.0142165 , 100.00, 1
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# target 50% 0.0045
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# target 75% 0.0075
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# target 90% 0.012
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# target 99% 0.0143463
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# target 99.9% 0.0144242
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Sockets used: 4 (for perfect keepalive, would be 2)
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Code 200 : 17 (85.0 %)
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Code 503 : 3 (15.0 %)
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Response Header Sizes : count 20 avg 195.65 +/- 82.19 min 0 max 231 sum 3913
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Response Body/Total Sizes : count 20 avg 729.9 +/- 205.4 min 241 max 817 sum 14598
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All done 20 calls (plus 0 warmup) 5.687 ms avg, 334.2 qps
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{{< /text >}}
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It's interesting to see that almost all requests made it through! The `istio-proxy`
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does allow for some leeway.
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{{< text plain >}}
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Code 200 : 17 (85.0 %)
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Code 503 : 3 (15.0 %)
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{{< /text >}}
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1. Bring the number of concurrent connections up to 3:
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{{< text bash >}}
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$ kubectl exec "$FORTIO_POD" -c fortio -- /usr/bin/fortio load -c 3 -qps 0 -n 30 -loglevel Warning http://httpbin:8000/get
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20:32:30 I logger.go:97> Log level is now 3 Warning (was 2 Info)
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Fortio 1.3.1 running at 0 queries per second, 6->6 procs, for 30 calls: http://httpbin:8000/get
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Starting at max qps with 3 thread(s) [gomax 6] for exactly 30 calls (10 per thread + 0)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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Ended after 51.9946ms : 30 calls. qps=576.98
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Aggregated Function Time : count 30 avg 0.0040001633 +/- 0.003447 min 0.0004298 max 0.015943 sum 0.1200049
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# range, mid point, percentile, count
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>= 0.0004298 <= 0.001 , 0.0007149 , 16.67, 5
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> 0.001 <= 0.002 , 0.0015 , 36.67, 6
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> 0.002 <= 0.003 , 0.0025 , 50.00, 4
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> 0.003 <= 0.004 , 0.0035 , 60.00, 3
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> 0.004 <= 0.005 , 0.0045 , 66.67, 2
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> 0.005 <= 0.006 , 0.0055 , 76.67, 3
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> 0.006 <= 0.007 , 0.0065 , 83.33, 2
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> 0.007 <= 0.008 , 0.0075 , 86.67, 1
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> 0.008 <= 0.009 , 0.0085 , 90.00, 1
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> 0.009 <= 0.01 , 0.0095 , 96.67, 2
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> 0.014 <= 0.015943 , 0.0149715 , 100.00, 1
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# target 50% 0.003
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# target 75% 0.00583333
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# target 90% 0.009
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# target 99% 0.0153601
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# target 99.9% 0.0158847
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Sockets used: 20 (for perfect keepalive, would be 3)
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Code 200 : 11 (36.7 %)
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Code 503 : 19 (63.3 %)
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Response Header Sizes : count 30 avg 84.366667 +/- 110.9 min 0 max 231 sum 2531
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Response Body/Total Sizes : count 30 avg 451.86667 +/- 277.1 min 241 max 817 sum 13556
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All done 30 calls (plus 0 warmup) 4.000 ms avg, 577.0 qps
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{{< /text >}}
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Now you start to see the expected circuit breaking behavior. Only 36.7% of the
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requests succeeded and the rest were trapped by circuit breaking:
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{{< text plain >}}
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Code 200 : 11 (36.7 %)
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Code 503 : 19 (63.3 %)
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{{< /text >}}
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1. Query the `istio-proxy` stats to see more:
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{{< text bash >}}
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$ kubectl exec "$FORTIO_POD" -c istio-proxy -- pilot-agent request GET stats | grep httpbin | grep pending
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cluster.outbound|8000||httpbin.default.svc.cluster.local;.circuit_breakers.default.remaining_pending: 1
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cluster.outbound|8000||httpbin.default.svc.cluster.local;.circuit_breakers.default.rq_pending_open: 0
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cluster.outbound|8000||httpbin.default.svc.cluster.local;.circuit_breakers.high.rq_pending_open: 0
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cluster.outbound|8000||httpbin.default.svc.cluster.local;.upstream_rq_pending_active: 0
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cluster.outbound|8000||httpbin.default.svc.cluster.local;.upstream_rq_pending_failure_eject: 0
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cluster.outbound|8000||httpbin.default.svc.cluster.local;.upstream_rq_pending_overflow: 21
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cluster.outbound|8000||httpbin.default.svc.cluster.local;.upstream_rq_pending_total: 29
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{{< /text >}}
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You can see `21` for the `upstream_rq_pending_overflow` value which means `21`
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calls so far have been flagged for circuit breaking.
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## Cleaning up
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1. Remove the rules:
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{{< text bash >}}
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$ kubectl delete destinationrule httpbin
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{{< /text >}}
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1. Shutdown the [httpbin]({{< github_tree >}}/samples/httpbin) service and client:
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{{< text bash >}}
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$ kubectl delete -f @samples/httpbin/sample-client/fortio-deploy.yaml@
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$ kubectl delete -f @samples/httpbin/httpbin.yaml@
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{{< /text >}}
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