This guide aims to give you a quick look and feel for using the Postgres Operator on a local Kubernetes environment.
Since the Postgres Operator is designed for the Kubernetes (K8s) framework, hence set it up first. For local tests we recommend to use one of the following solutions:
To interact with the K8s infrastructure install its CLI runtime kubectl.
This quickstart assumes that you have started minikube or created a local kind
cluster. Note that you can also use built-in K8s support in the Docker Desktop
for Mac to follow the steps of this tutorial. You would have to replace
minikube start and minikube delete with your launch actions for the Docker
built-in K8s support.
Configuring the Postgres Operator is only possible before deploying a new
Postgres cluster. This can work in two ways: via a ConfigMap or a custom
OperatorConfiguration object. More details on configuration can be found
here.
The Postgres Operator can be deployed in the following ways:
The Postgres Operator can be installed simply by applying yaml manifests. Note,
we provide the /manifests directory as an example only; you should consider
adjusting the manifests to your K8s environment (e.g. namespaces).
# First, clone the repository and change to the directory
git clone https://github.com/zalando/postgres-operator.git
cd postgres-operator
# apply the manifests in the following order
kubectl create -f manifests/configmap.yaml # configuration
kubectl create -f manifests/operator-service-account-rbac.yaml # identity and permissions
kubectl create -f manifests/postgres-operator.yaml # deployment
kubectl create -f manifests/api-service.yaml # operator API to be used by UI
There is a Kustomization manifest that combines the mentioned resources (except for the CRD) - it can be used with kubectl 1.14 or newer as easy as:
kubectl apply -k github.com/zalando/postgres-operator/manifests
For convenience, we have automated starting the operator with minikube using the
run_operator_locally script. It applies the acid-minimal-cluster.
manifest.
./run_operator_locally.sh
To install the Postgres Operator in OpenShift you have to change the config
parameter kubernetes_use_configmaps to "true". Otherwise, the operator
and Patroni will store leader and config keys in Endpoints that are not
supported in OpenShift. This requires also a slightly different set of rules
for the postgres-operator and postgres-pod cluster roles.
oc create -f manifests/operator-service-account-rbac-openshift.yaml
Alternatively, the operator can be installed by using the provided
Helm chart which saves you the manual steps. The charts
for both the Postgres Operator and its UI are hosted via the gh-pages branch.
They only work only with Helm v3. Helm v2 support was dropped with v1.8.0.
# add repo for postgres-operator
helm repo add postgres-operator-charts https://opensource.zalando.com/postgres-operator/charts/postgres-operator
# install the postgres-operator
helm install postgres-operator postgres-operator-charts/postgres-operator
# add repo for postgres-operator-ui
helm repo add postgres-operator-ui-charts https://opensource.zalando.com/postgres-operator/charts/postgres-operator-ui
# install the postgres-operator-ui
helm install postgres-operator-ui postgres-operator-ui-charts/postgres-operator-ui
Starting the operator may take a few seconds. Check if the operator pod is running before applying a Postgres cluster manifest.
# if you've created the operator using yaml manifests
kubectl get pod -l name=postgres-operator
# if you've created the operator using helm chart
kubectl get pod -l app.kubernetes.io/name=postgres-operator
If the operator doesn’t get into Running state, either check the latest K8s
events of the deployment or pod with kubectl describe or inspect the operator
logs:
kubectl logs "$(kubectl get pod -l name=postgres-operator --output='name')"
In the following paragraphs we describe how to access and manage PostgreSQL clusters from the command line with kubectl. But it can also be done from the browser-based Postgres Operator UI. Before deploying the UI make sure the operator is running and its REST API is reachable through a K8s service. The URL to this API must be configured in the deployment manifest of the UI.
To deploy the UI simply apply all its manifests files or use the UI helm chart:
# manual deployment
kubectl apply -f ui/manifests/
# or kustomization
kubectl apply -k github.com/zalando/postgres-operator/ui/manifests
# or helm chart
helm install postgres-operator-ui ./charts/postgres-operator-ui
Like with the operator, check if the UI pod gets into Running state:
# if you've created the operator using yaml manifests
kubectl get pod -l name=postgres-operator-ui
# if you've created the operator using helm chart
kubectl get pod -l app.kubernetes.io/name=postgres-operator-ui
You can now access the web interface by port forwarding the UI pod (mind the
label selector) and enter localhost:8081 in your browser:
kubectl port-forward svc/postgres-operator-ui 8081:80
Available option are explained in detail in the UI docs.
If the operator pod is running it listens to new events regarding postgresql
resources. Now, it’s time to submit your first Postgres cluster manifest.
# create a Postgres cluster
kubectl create -f manifests/minimal-postgres-manifest.yaml
After the cluster manifest is submitted and passed the validation the operator
will create Service and Endpoint resources and a StatefulSet which spins up new
Pod(s) given the number of instances specified in the manifest. All resources
are named like the cluster. The database pods can be identified by their number
suffix, starting from -0. They run the Spilo
container image by Zalando. As for the services and endpoints, there will be one
for the master pod and another one for all the replicas (-repl suffix). Check
if all components are coming up. Use the label application=spilo to filter and
list the label spilo-role to see who is currently the master.
# check the deployed cluster
kubectl get postgresql
# check created database pods
kubectl get pods -l application=spilo -L spilo-role
# check created service resources
kubectl get svc -l application=spilo -L spilo-role
You can create a port-forward on a database pod to connect to Postgres. See the user guide for instructions. With minikube it’s also easy to retrieve the connections string from the K8s service that is pointing to the master pod:
export HOST_PORT=$(minikube service acid-minimal-cluster --url | sed 's,.*/,,')
export PGHOST=$(echo $HOST_PORT | cut -d: -f 1)
export PGPORT=$(echo $HOST_PORT | cut -d: -f 2)
Retrieve the password from the K8s Secret that is created in your cluster. Non-encrypted connections are rejected by default, so set the SSL mode to require:
export PGPASSWORD=$(kubectl get secret postgres.acid-minimal-cluster.credentials.postgresql.acid.zalan.do -o 'jsonpath={.data.password}' | base64 -d)
export PGSSLMODE=require
psql -U postgres
To delete a Postgres cluster simply delete the postgresql custom resource.
kubectl delete postgresql acid-minimal-cluster
This should remove the associated StatefulSet, database Pods, Services and Endpoints. The PersistentVolumes are released and the PodDisruptionBudget is deleted. Secrets however are not deleted and backups will remain in place.
When deleting a cluster while it is still starting up or got stuck during that
phase it can happen
that the postgresql resource is deleted leaving orphaned components behind.
This can cause troubles when creating a new Postgres cluster. For a fresh setup
you can delete your local minikube or kind cluster and start again.