Add a generic OpenShift template

[tdiesler]

On OpenShift 3.6, with

oc new-app wildflyext/example-camel-rest

the pod was stuck in state pending for more than 5min. Then, after 13min it magically started running. We may want to use a template for more predictable behaviour.

Ideally, user experience should not suffer.

[ppalaga]

Running oc new-app wildflyext/example-camel-rest against a cluster that does not have the image cached may indeed result in a few minutes delay between the pod scheduling and its reaching the "up" state. The wildflyext/example-camel-rest image is as big as ~1G and pulling it simply takes some time.

I'd say this is normal and I do not see how a template might help. @tdiesler do you have any specific idea how a template could help here?

I think the only thing we can do is to note in the documentation that pulling may take a few minutes. We could perhaps also describe a way to check that the image is really being pulled so that users can be sure that there is no other problem.

kubernetes/kubernetes#19077 says that image pulling state can be seen in the output of oc get events

oc get events                                                                                                                                                                                                                  Thu Mar 15 14:41:50 2018

LASTSEEN   FIRSTSEEN   COUNT     NAME                          KIND                    SUBOBJECT                             TYPE      REASON                  SOURCE                        MESSAGE
26s        26s         1         example-camel-rest-1-66fg9    Pod                                                           Normal    Scheduled               default-scheduler             Successfully assigned example-camel-rest-1-66fg9 to localhost
26s        26s         1         example-camel-rest-1-66fg9    Pod                                                           Normal    SuccessfulMountVolume   kubelet, localhost            MountVolume.SetUp succeeded for volume "default-token-fxfx7"
25s        25s         1         example-camel-rest-1-66fg9    Pod                     spec.containers{example-camel-rest}   Normal    Pulling                 kubelet, localhost            pulling image "wildflyext/example-camel-rest@sha256:7ece79d64298c34dd
2b0212f8ea137fb8788463434796b46bbcac75837c6b127"
1m         1m          1         example-camel-rest-1-deploy   Pod                                                           Normal    Scheduled               default-scheduler             Successfully assigned example-camel-rest-1-deploy to localhost
1m         1m          1         example-camel-rest-1-deploy   Pod                                                           Normal    SuccessfulMountVolume   kubelet, localhost            MountVolume.SetUp succeeded for volume "deployer-token-5nmsv"
1m         1m          1         example-camel-rest-1-deploy   Pod                     spec.containers{deployment}           Normal    Pulling                 kubelet, localhost            pulling image "openshift/origin-deployer:v3.7.1"
33s        33s         1         example-camel-rest-1-deploy   Pod                     spec.containers{deployment}           Normal    Pulled                  kubelet, localhost            Successfully pulled image "openshift/origin-deployer:v3.7.1"
33s        33s         1         example-camel-rest-1-deploy   Pod                     spec.containers{deployment}           Normal    Created                 kubelet, localhost            Created container
32s        32s         1         example-camel-rest-1-deploy   Pod                     spec.containers{deployment}           Normal    Started                 kubelet, localhost            Started container
29s        29s         1         example-camel-rest-1          ReplicationController                                         Normal    SuccessfulCreate        replication-controller        Created pod: example-camel-rest-1-66fg9
1m         1m          1         example-camel-rest            DeploymentConfig                                              Normal    DeploymentCreated       deploymentconfig-controller   Created new replication controller "example-camel-rest-1" for version
 1

Note the pulling image "wildflyext/example-camel-rest@sha256:7ece79d64298c34dd in the above output.

[jamesnetherton]

I think the original purpose of having this issue was to address #1392.

By default, there are no liveness / readiness probes configured so OpenShift has no concrete means of knowing whether the pod should be considered up and ready.

It may be that my work in 7c9c673 is enough to satisfy this.

Although, having a template would mean that we could define probes without the user having to do it manually.

[ppalaga]

OK, let me prepare a template with health checks