75 lines
3.1 KiB
Markdown
75 lines
3.1 KiB
Markdown
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# Simple HTTP health check example
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The GCE Ingress controller adopts the readiness probe from the matching endpoints, provided the readiness probe doesn't require HTTPS or special headers.
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Create the following app:
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```console
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$ kubectl create -f health_check_app.yaml
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replicationcontroller "echoheaders" created
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You have exposed your service on an external port on all nodes in your
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cluster. If you want to expose this service to the external internet, you may
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need to set up firewall rules for the service port(s) (tcp:31165) to serve traffic.
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See http://releases.k8s.io/HEAD/docs/user-guide/services-firewalls.md for more details.
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service "echoheadersx" created
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You have exposed your service on an external port on all nodes in your
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cluster. If you want to expose this service to the external internet, you may
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need to set up firewall rules for the service port(s) (tcp:31020) to serve traffic.
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See http://releases.k8s.io/HEAD/docs/user-guide/services-firewalls.md for more details.
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service "echoheadersy" created
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ingress "echomap" created
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```
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You should soon find an Ingress that is backed by a GCE Loadbalancer.
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```console
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$ kubectl describe ing echomap
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Name: echomap
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Namespace: default
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Address: 107.178.255.228
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Default backend: default-http-backend:80 (10.180.0.9:8080,10.240.0.2:8080)
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Rules:
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Host Path Backends
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---- ---- --------
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foo.bar.com
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/foo echoheadersx:80 (<none>)
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bar.baz.com
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/bar echoheadersy:80 (<none>)
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/foo echoheadersx:80 (<none>)
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Annotations:
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target-proxy: k8s-tp-default-echomap--a9d60e8176d933ee
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url-map: k8s-um-default-echomap--a9d60e8176d933ee
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backends: {"k8s-be-31020--a9d60e8176d933ee":"HEALTHY","k8s-be-31165--a9d60e8176d933ee":"HEALTHY","k8s-be-31686--a9d60e8176d933ee":"HEALTHY"}
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forwarding-rule: k8s-fw-default-echomap--a9d60e8176d933ee
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Events:
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FirstSeen LastSeen Count From SubobjectPath Type Reason Message
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--------- -------- ----- ---- ------------- -------- ------ -------
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17m 17m 1 {loadbalancer-controller } Normal ADD default/echomap
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15m 15m 1 {loadbalancer-controller } Normal CREATE ip: 107.178.255.228
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$ curl 107.178.255.228/foo -H 'Host:foo.bar.com'
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CLIENT VALUES:
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client_address=10.240.0.5
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command=GET
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real path=/foo
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query=nil
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request_version=1.1
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request_uri=http://foo.bar.com:8080/foo
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...
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```
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You can confirm the health check endpoint point it's using one of 2 ways:
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* Through the cloud console: compute > health checks > lookup your health check. It takes the form k8s-be-nodePort-hash, where nodePort in the example above is 31165 and 31020, as shown by the kubectl output.
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* Through gcloud: Run `gcloud compute http-health-checks list`
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## Limitations
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A few points to note:
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* The readiness probe must be exposed on the port matching the `servicePort` specified in the Ingress
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* The readiness probe cannot have special requirements, like headers or HTTPS
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* The probe timeouts are translated to GCE health check timeouts
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* You must create the pods backing the endpoints with the given readiness probe. This *will not* work if you update the replication controller with a different readiness probe.
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