github/kubernetes
1
0
Fork 0
mirror of https://github.com/k3s-io/kubernetes.git synced 2025-08-11 21:12:07 +00:00
Code Issues Projects Releases Wiki Activity

Intial draft on SeedProvider docs

Browse Source
This commit is contained in:
chrislovecnm 2016-04-14 17:12:38 -06:00
parent 1d96b4c55b
commit 82092f9ed0
1 changed files with 61 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

61
examples/cassandra/java/README.md Normal file
View File

@ -0,0 +1,61 @@
<!-- BEGIN MUNGE: UNVERSIONED_WARNING -->
<!-- BEGIN STRIP_FOR_RELEASE -->
<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
width="25" height="25">
<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
width="25" height="25">
<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
width="25" height="25">
<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
width="25" height="25">
<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
width="25" height="25">
<h2>PLEASE NOTE: This document applies to the HEAD of the source tree</h2>
If you are using a released version of Kubernetes, you should
refer to the docs that go with that version.
<!-- TAG RELEASE_LINK, added by the munger automatically -->
<strong>
The latest release of this document can be found
[here](http://releases.k8s.io/release-1.2/examples/README.md).
Documentation for other releases can be found at
[releases.k8s.io](http://releases.k8s.io).
</strong>
--
<!-- END STRIP_FOR_RELEASE -->
<!-- END MUNGE: UNVERSIONED_WARNING -->
# Cassandra on Kubernetes Custom Seed Provider: releases.k8s.io/HEAD
Within any deployment of Cassandra a Seed Provider is used to for node discovery and communication. When a Cassandra node first starts it must discover which nodes, or seeds, for the information about the Cassandra nodes in the ring / rack / datacenter.
This Java project provides a custom Seed Provider which communicates with the Kubernetes API to discover the required information. This provider is bundled with the Docker provided in this example.
# Configuring the Seed Provider
The following environment variables may be used to override the default configurations:
| ENV VAR | DEFAULT VALUE | NOTES |
| ------------- |:-------------: |:-------------:|
| KUBERNETES_PORT_443_TCP_ADDR | kubernetes.default.svc.cluster.local | The hostname of the API server |
| KUBERNETES_PORT_443_TCP_PORT | 443 | API port number |
| CASSANDRA_SERVICE | cassandra | Default service name for lookup |
| POD_NAMESPACE | default | Default pod service namespace |
# Using
This seed provider is packaged with the Cassandra example docker. See the [_Pods_](../../docs/../user-guide/pods.md) documentation on how to configure and or customize environment variables when deploying a new pod to K8s. Also see the [_EXAMPLE_](../README.md) documentation on how to configure and deploy the Cassandra demo.
If no endpoints are discovered from the API the seeds configured in the cassandra.yaml file are used.
# Provider limitations
This Cassandra Provider implements `SeedProvider`. and utilizes `SimpleSnitch`. This limits a Cassandra Ring to a single Cassandra Datacenter and ignores Rack setup. Datastax provides more documentation on the use of [_SNITCHES_](https://docs.datastax.com/en/cassandra/3.x/cassandra/architecture/archSnitchesAbout.html). Further development is planned to
expand this capability.
This in affect makes every node a seed provider, which is not a recommended best practice. This increases maintenance and reduces gossip performance.