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Productionize the cockroachdb example a little more

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Includes:
* A service for clients to use
* Readiness/liveness probes
* An extended graceful termination period
* Easy clean-up of all created resources
This commit is contained in:
Alex Robinson
2016-08-18 17:13:28 -04:00
parent 01cf564eaa
commit 98b6d0672d
3 changed files with 83 additions and 15 deletions
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43
examples/cockroachdb/README.md
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@@ -67,6 +67,25 @@ 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:
@@ -75,14 +94,15 @@ 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
@@ -91,6 +111,15 @@ 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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