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alice-sawatzky and k8s-ci-robot [incubator/patroni] add schedulerName option (#15574)
* [incubator/patroni] add schedulerName option

Signed-off-by: Alice Sawatzky <alice.sawatzky@farmersedge.ca>

* [incubator/patroni] minor version bump

Signed-off-by: Alice Sawatzky <alice.sawatzky@farmersedge.ca>

* [incubator/patroni] use `if` instead of `with`

Signed-off-by: Alice Sawatzky <alice.sawatzky@farmersedge.ca>
Latest commit c2264da Aug 14, 2019

README.md

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

StatefulSet Caveats

Todo

  • Make namespace configurable

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-p16
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
kubernetes.dcs.enable Using Kubernetes as DCS true
kubernetes.configmaps.enable Using Kubernetes configmaps instead of endpoints false
etcd.enable Using etcd as DCS false
etcd.deployChart Deploy etcd chart false
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...
consul.enable Using Consul as DCS false
consul.deployChart Deploy Consul chart false
consul.host Host name of consul cluster nil
env Extra custom environment variables {}
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 []
affinityTemplate A template string to use to generate the affinity settings Anti-affinity preferred on hostname
affinity Affinity settings. Overrides affinityTemplate if set. {}
schedulerName Alternate scheduler name nil
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
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