How to run initialization SQL commands at cluster creation time¶

The Operator can execute a custom sequence of PostgreSQL commands when creating the databse cluster. This sequence can include both SQL commands and meta-commands of the PostgreSQL interactive shell (psql). This feature may be useful to push any customizations to the cluster: modify user roles, change error handling, set and use variables, etc.

psql interactive terminal will execute these initialization statements when the cluster is created, after creating custom users and databases specifed in the Custom Resource.

To set SQL initialization sequence you need creating a special ConfigMap with it, and reference this ConfigMap in the databaseInitSQL subsection of your Custom Resource options.

The following example uses initialization SQL command to add a new role to a PostgreSQL database cluster:

Create YAML manifest for the ConfigMap as follows:
my_init.yaml
```
apiVersion: v1
kind: ConfigMap
metadata:
  name: cluster1-init-sql
  namespace: postgres-operator
data:
  init.sql: CREATE ROLE someonenew WITH createdb superuser login password 'someonenew'; 
```
The namespace field should point to the namespace of your database cluster, and the init.sql key contains the sequence of commands, which will be passed to the psql.

Create the ConfigMap by applying your manifest:
```
$ kubectl apply -f my_init.yaml
```
Update the databaseInitSQL part of the deploy/cr.yaml Custom Resource manifest as follows:
```
...
databaseInitSQL:
  key: init.sql
  name: cluster1-init-sql
...
```
Now, SQL commands will be executed when you create the cluster by apply the manifest:
```
$ kubectl apply -f deploy/cr.yaml -n postgres-operator
```

The psql command is executed the standard input and the file flag (psql -f -). If the command returns 0 exit code, SQL will not be run again. When psql returns with an error exit code, the Operator will continue attempting to execute it as part of its reconcile loop until success. You can fix errors in the SQL sequence, for example by interactive kubectl edit configmap cluster1-init-sql -n postgres-namespace command.

Note

You can use following psql meta-command to make sure that any SQL errors would make psql to return the error code:

\set ON_ERROR_STOP
\echo Any error will lead to exit code 3

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Last update: 2024-10-08