deprecated-helm-charts/incubator/patroni

Patroni Helm Chart

This directory contains a Kubernetes chart to deploy a five node Patroni cluster using a Spilo and a StatefulSet.

Prerequisites Details

• Kubernetes 1.5+
• PV support on the underlying infrastructure

StatefulSet Details

• https://kubernetes.io/docs/concepts/workloads/controllers/statefulset/

StatefulSet Caveats

• https://kubernetes.io/docs/concepts/workloads/controllers/statefulset/#limitations

Todo

• Make namespace configurable
• K8S native DCS

Chart Details

This chart will do the following:

• Implement a HA scalable PostgreSQL 10 cluster using a Kubernetes StatefulSet.

Installing the Chart

To install the chart with the release name my-release:

$ helm repo add incubator https://kubernetes-charts-incubator.storage.googleapis.com/
$ helm dependency update
$ helm install --name my-release incubator/patroni

To install the chart with randomly generated passwords:

$ helm install --name my-release incubator/patroni \
  --set credentials.superuser="$(< /dev/urandom tr -dc _A-Z-a-z-0-9 | head -c32)",credentials.admin="$(< /dev/urandom tr -dc _A-Z-a-z-0-9 | head -c32)",credentials.standby="$(< /dev/urandom tr -dc _A-Z-a-z-0-9 | head -c32)"

Connecting to PostgreSQL

Your access point is a cluster IP. In order to access it spin up another pod:

$ kubectl run -i --tty --rm psql --image=postgres --restart=Never -- bash -il

Then, from inside the pod, connect to PostgreSQL:

$ psql -U admin -h my-release-patroni.default.svc.cluster.local postgres
<admin password from values.yaml>
postgres=>

Configuration

The following table lists the configurable parameters of the patroni chart and their default values.

Parameter	Description	Default
nameOverride	Override the name of the chart	nil
fullnameOverride	Override the fullname of the chart	nil
replicaCount	Amount of pods to spawn	5
image.repository	The image to pull	registry.opensource.zalan.do/acid/spilo-10
image.tag	The version of the image to pull	1.4-p6
image.pullPolicy	The pull policy	IfNotPresent
credentials.superuser	Password of the superuser	tea
credentials.admin	Password of the admin	cola
credentials.standby	Password of the replication user	pinacolada
etcd.enable	Using etcd as DCS	true
etcd.deployChart	Deploy etcd chart	true
etcd.host	Host name of etcd cluster	nil
etcd.discovery	Domain name of etcd cluster	nil
zookeeper.enable	Using ZooKeeper as DCS	false
zookeeper.deployChart	Deploy ZooKeeper chart	false
zookeeper.hosts	List of ZooKeeper cluster members	host1:port1,host2:port,etc...
walE.enable	Use of Wal-E tool for base backup/restore	false
walE.scheduleCronJob	Schedule of Wal-E backups	00 01 * * *
walE.retainBackups	Number of base backups to retain	2
walE.s3Bucket:	Amazon S3 bucket used for wal-e backups	nil
walE.gcsBucket	GCS storage used for Wal-E backups	nil
walE.kubernetesSecret	K8s secret name for provider bucket	nil
walE.backupThresholdMegabytes	Maximum size of the WAL segments accumulated after the base backup to consider WAL-E restore instead of pg_basebackup	1024
walE.backupThresholdPercentage	Maximum ratio (in percents) of the accumulated WAL files to the base backup to consider WAL-E restore instead of pg_basebackup	30
resources	Any resources you wish to assign to the pod	{}
nodeSelector	Node label to use for scheduling	{}
tolerations	List of node taints to tolerate	[]
affinity	Affinity settings	Preferred on hostname
persistentVolume.accessModes	Persistent Volume access modes	[ReadWriteOnce]
persistentVolume.annotations	Annotations for Persistent Volume Claim`	{}
persistentVolume.mountPath	Persistent Volume mount root path	/home/postgres/pgdata
persistentVolume.size	Persistent Volume size	2Gi
persistentVolume.storageClass	Persistent Volume Storage Class	volume.alpha.kubernetes.io/storage-class: default
persistentVolume.subPath	Subdirectory of Persistent Volume to mount	""
rbac.create	Create required role and rolebindings	true
serviceAccount.create	If true, create a new service account	true
serviceAccount.name	Service account to be used. If not set and serviceAccount.create is true, a name is generated using the fullname template	nil

Specify each parameter using the --set key=value[,key=value] argument to helm install.

Alternatively, a YAML file that specifies the values for the parameters can be provided while installing the chart. For example,

$ helm install --name my-release -f values.yaml incubator/patroni

Tip

: You can use the default values.yaml

Cleanup

To remove the spawned pods you can run a simple helm delete <release-name>.

Helm will however preserve created persistent volume claims, to also remove them execute the commands below.

$ release=<release-name>
$ helm delete $release
$ kubectl delete pvc -l release=$release

Internals

Patroni is responsible for electing a PostgreSQL master pod by leveraging the DCS of your choice. After election it adds a spilo-role=master label to the elected master and set the label to spilo-role=replica for all replicas. Simultaneously it will update the <release-name>-patroni endpoint to let the service route traffic to the elected master.

$ kubectl get pods -l spilo-role -L spilo-role
NAME                   READY     STATUS    RESTARTS   AGE       SPILO-ROLE
my-release-patroni-0   1/1       Running   0          9m        replica
my-release-patroni-1   1/1       Running   0          9m        master
my-release-patroni-2   1/1       Running   0          8m        replica
my-release-patroni-3   1/1       Running   0          8m        replica
my-release-patroni-4   1/1       Running   0          8m        replica