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Merge pull request #31125 from a-robinson/example-petset-cockroachdb

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Automatic merge from submit-queue

Productionize the cockroachdb example a little more

Includes:
* A service for clients to use
* Readiness/liveness probes
* An extended graceful termination period
* Automatic prometheus monitoring (when prometheus is configured to watch for annotations on services, as in [CoreOS's recent blog post](https://coreos.com/blog/prometheus-and-kubernetes-up-and-running.html), for example)

I'm leaving the management of certs to future work, but if anyone that sees this needs help with them in the meantime, don't hesitate to reach out.

Successor to #28446

@bprashanth - if you're still interested in / open to an e2e test (as mentioned in https://github.com/cockroachdb/cockroach/issues/5967#issuecomment-230188807), let me know and I'll put one together. If so, I assume you'd want it as part of the `petset` test group rather than the `examples` tests?

cc @tschottdorf 

**Release note**:
```release-note
NONE
```
This commit is contained in:
Kubernetes Submit Queue
2016-09-10 05:03:51 -07:00
committed by GitHub
parent c7d1e38412 98b6d0672d
commit ee98966ec9
3 changed files with 85 additions and 10 deletions
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43
examples/cockroachdb/README.md
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@@ -72,6 +72,25 @@ steps.
Follow the steps in [minikube.sh](minikube.sh) (or simply run that file).
## Accessing the database
Along with our PetSet configuration, we expose a standard Kubernetes service
that offers a load-balanced virtual IP for clients to access the database
with. In our example, we've called this service `cockroachdb-public`.
Start up a client pod and open up an interactive, (mostly) Postgres-flavor
SQL shell using:
```console
$ kubectl run -it cockroach-client --image=cockroachdb/cockroach --restart=Never --command -- bash
root@cockroach-client # ./cockroach sql --host cockroachdb-public
```
You can see example SQL statements for inserting and querying data in the
included [demo script](demo.sh), but can use almost any Postgres-style SQL
commands. Some more basic examples can be found within
[CockroachDB's documentation](https://www.cockroachlabs.com/docs/learn-cockroachdb-sql.html).
## Simulating failures
When all (or enough) nodes are up, simulate a failure like this:
@@ -80,14 +99,15 @@ When all (or enough) nodes are up, simulate a failure like this:
kubectl exec cockroachdb-0 -- /bin/bash -c "while true; do kill 1; done"
```
On one of the other pods, run `./cockroach sql --host $(hostname)` and use
(mostly) Postgres-flavor SQL. The example runs with three-fold replication,
so it can tolerate one failure of any given node at a time.
Note also that there is a brief period of time immediately after the creation
of the cluster during which the three-fold replication is established, and
during which killing a node may lead to unavailability.
You can then reconnect to the database as demonstrated above and verify
that no data was lost. The example runs with three-fold replication, so
it can tolerate one failure of any given node at a time. Note also that
there is a brief period of time immediately after the creation of the
cluster during which the three-fold replication is established, and during
which killing a node may lead to unavailability.
There is also a [demo script](demo.sh).
The [demo script](demo.sh) gives an example of killing one instance of the
database and ensuring the other replicas have all data that was written.
## Scaling up or down
@@ -96,6 +116,15 @@ volume claim first). If you ran `minikube.sh`, there's a spare volume so you
can immediately scale up by one. Convince yourself that the new node
immediately serves reads and writes.
## Cleaning up when you're done
Because all of the resources in this example have been tagged with the label `app=cockroachdb`,
we can clean up everything that we created in one quick command using a selector on that label:
```shell
kubectl delete petsets,pods,persistentvolumes,persistentvolumeclaims,services -l app=cockroachdb
```
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