ConfigMap is used to store the configuration of the operator
$ kubectl create -f manifests/configmap.yaml
Deploying the operator
First you need to install the service account definition in your Minikube cluster.
$ kubectl create -f manifests/operator-service-account-rbac.yaml
Next deploy the postgres-operator from the docker image Zalando is using:
$ kubectl create -f manifests/postgres-operator.yaml
If you prefer to build the image yourself follow up down below.
Check if CustomResourceDefinition has been registered
$ kubectl get crd NAME KIND postgresqls.acid.zalan.do CustomResourceDefinition.v1beta1.apiextensions.k8s.io
How to configure PostgreSQL operator
Select the namespace to deploy to
The operator can run in a namespace other than
default. For example, to use
test namespace, run the following before deploying the operator's
$ kubectl create namespace test $ kubectl config set-context $(kubectl config current-context) --namespace=test
kubectl commands will work with the
test namespace. The
operator will run in this namespace and look up needed resources - such as its
config map - there. Please note that the namespace for service accounts and cluster role bindings in operator RBAC rules needs to be adjusted to the non-default value.
Specify the namespace to watch
Watching a namespace for an operator means tracking requests to change Postgresql clusters in the namespace such as "increase the number of Postgresql replicas to 5" and reacting to the requests, in this example by actually scaling up.
By default, the operator watches the namespace it is deployed to. You can
change this by altering the
WATCHED_NAMESPACE env var in the operator
deployment manifest or the
watched_namespace field in the operator configmap.
In the case both are set, the env var takes the precedence. To make the
operator listen to all namespaces, explicitly set the field/env var to "
Note that for an operator to manage pods in the watched namespace, the
operator's service account (as specified in the operator deployment manifest)
has to have appropriate privileges to access the watched namespace. The
operator may not be able to function in the case it watches all namespaces but
lacks access rights to any of them (except Kubernetes system namespaces like
kube-system). The reason is that for multiple namespaces operations such as
'list pods' execute at the cluster scope and fail at the first violation of
The watched namespace also needs to have a (possibly different) service account
in the case database pods need to talk to the Kubernetes API (e.g. when using
Kubernetes-native configuration of Patroni). The operator checks that the
pod_service_account_name exists in the target namespace, and, if not, deploys
pod_service_account_definition from the operator
Config with the default value of:
apiVersion: v1 kind: ServiceAccount metadata: name: operator
In this definition, the operator overwrites the account's name to match
pod_service_account_name and the
default namespace to match the target
namespace. The operator performs no further syncing of this account.
Role-based access control for the operator
manifests/operator-service-account-rbac.yaml defines cluster roles and bindings needed
for the operator to function under access control restrictions. To deploy the
operator with this RBAC policy use:
$ kubectl create -f manifests/configmap.yaml $ kubectl create -f manifests/operator-service-account-rbac.yaml $ kubectl create -f manifests/postgres-operator.yaml $ kubectl create -f manifests/minimal-postgres-manifest.yaml
Note that the service account in
operator-rbac.yaml is named
zalando-postgres-operator. You may have to change the
in the operator configmap and
serviceAccountName in the postgres-operator
This is done intentionally, as to avoid breaking those setups that already work
with the default
operator account. In the future the operator should ideally
be run under the
zalando-postgres-operator service account.
The service account defined in
operator-rbac.yaml acquires some privileges
not really used by the operator (i.e. we only need list and watch on
configmaps), this is also done intentionally to avoid breaking things if
someone decides to configure the same service account in the operator's
configmap to run postgres clusters.
Use taints and tolerations for dedicated PostgreSQL nodes
To ensure Postgres pods are running on nodes without any other application pods, you can use taints and tolerations and configure the required toleration in the operator ConfigMap.
As an example you can set following node taint:
$ kubectl taint nodes <nodeName> postgres=:NoSchedule
And configure the toleration for the PostgreSQL pods by adding following line to the ConfigMap:
apiVersion: v1 kind: ConfigMap metadata: name: postgres-operator data: toleration: "key:postgres,operator:Exists,effect:NoSchedule" ...
Custom Pod Environment Variables
It is possible to configure a config map which is used by the Postgres pods as an additional provider for environment variables.
One use case is to customize the Spilo image and configure it with environment variables. The config map with the additional settings is configured in the operator's main config map:
apiVersion: v1 kind: ConfigMap metadata: name: postgres-operator data: # referencing config map with custom settings pod_environment_configmap: postgres-pod-config ...
apiVersion: v1 kind: ConfigMap metadata: name: postgres-pod-config namespace: default data: MY_CUSTOM_VAR: value
This ConfigMap is then added as a source of environment variables to the Postgres StatefulSet/pods.
Limiting the number of instances in clusters with
As a preventive measure, one can restrict the minimum and the maximum number of
instances permitted by each Postgres cluster managed by the operator. If either
max_instances is set to a non-zero value, the operator may
adjust the number of instances specified in the cluster manifest to match
either the min or the max boundary. For instance, of a cluster manifest has 1
instance and the min_instances is set to 3, the cluster will be created with 3
instances. By default, both parameters are set to -1.
For any Postgresql/Spilo cluster, the operator creates two separate k8s
services: one for the master pod and one for replica pods. To expose these
services to an outer network, one can attach load balancers to them by setting
true in the
cluster manifest. In the case any of these variables are omitted from the
manifest, the operator configmap's settings
enable_replica_load_balancer apply. Note that the operator settings affect
all Postgresql services running in all namespaces watched by the operator.
To limit the range of IP adresses that can reach a load balancer, specify desired ranges in the
allowedSourceRanges field (applies to both master and replica LBs). To prevent exposing LBs to the entire Internet, this field is set at cluster creation time to
127.0.0.1/32 unless overwritten explicitly. If you want to revoke all IP ranges from an existing cluster, please set the
allowedSourceRanges field to
127.0.0.1/32 or to the empty sequence
. Setting the field to
null or omitting entirely may lead to k8s removing this field from the manifest due to the k8s handling of null fields. Then the resultant manifest will not have the necessary change, and the operator will respectively do noting with the existing source ranges.
Running periodic 'autorepair' scans of Kubernetes objects
The Postgres operator periodically scans all Kubernetes objects belonging to
each cluster and repairs all discrepancies between them and the definitions
generated from the current cluster manifest. There are two types of scans: a
sync scan, running every
resync_period seconds for every cluster, and the
repair scan, coming every
repair_period only for those clusters that didn't
report success as a result of the last operation applied to them.
Postgres roles supported by the operator
The operator is capable of maintaining roles of multiple kinds within a Postgres database cluster:
System roles are roles necessary for the proper work of Postgres itself such as a replication role or the initial superuser role. The operator delegates creating such roles to Patroni and only establishes relevant secrets.
Infrastructure roles are roles for processes originating from external systems, e.g. monitoring robots. The operator creates such roles in all PG clusters it manages assuming k8s secrets with the relevant credentials exist beforehand.
Per-cluster robot users are also roles for processes originating from external systems but defined for an individual Postgres cluster in its manifest. A typical example is a role for connections from an application that uses the database.
Human users originate from the Teams API that returns list of the team members given a team id. Operator differentiates between (a) product teams that own a particular Postgres cluster and are granted admin rights to maintain it, and (b) Postgres superuser teams that get the superuser access to all PG databases running in a k8s cluster for the purposes of maintaining and troubleshooting.
Understanding rolling update of Spilo pods
The operator logs reasons for a rolling update with the
info level and a diff between the old and new StatefulSet specs with the
debug level. To benefit from numerous escape characters in the latter log entry, view it in CLI with
echo -e. Note that the resultant message will contain some noise because the
PodTemplate used by the operator is yet to be updated with the default values used internally in Kubernetes.