Templates¶

The DB Operator can generate custom templated entries in Secrets and ConfigMaps using database-related data. This feature uses Go templates and can be used in the following way in Databases:

---
kind: Database
spec:
  credentials:
    templates:
      - name: USER_AND_PASSWORD
        template: "{{ .Username }}-{{ .Password }}"
        secret: true

And in DbUsers:

---
kind: DbUser
spec:
  credentials:
    templates:
      - name: USER_AND_PASSWORD
        template: "{{ .Username }}-{{ .Password }}"
        secret: true

Available fields and functions¶

Fields¶

These fields are available for templating:

• Protocol: Depends on the db engine. Possible values are mysql/postgresql
• Hostname: The same value as for the db host in the connection configmap
• Port: The same value as for the db port in the connection configmap
• Database: The same value as for the db name in the creds secret
• Username: The same value as for the dab user in the creds secret
• Password: The same value as for the password in the creds secret

So to create a full connection string, you could use a template like that:

"{{ .Protocol }}://{{ .Username }}:{{ .Password }}@{{ .Hostname }}:{{ .Port }}/{{ .Database }}"

Functions¶

You can also use one of the available functions to retrieve data directly from the data sources accessible to the operator.

• Secret: Query data from the Secret
• ConfigMap: Query data from the ConfigMap
• Query: Get data directly from the database

Secret/ConfigMap¶

When using Secret and ConfigMap you can query the previously created secret to template a new one, e.g.:

spec:
  credentials:
    templates:
      - name: TMPL_1
        template: "test"
        secret: false
      - name: TMPL_2
        template: "{{ .ConfigMap \"TMPL_1\"}}"
        secret: true
      - name: TMPL_3
        template: "{{ .Secret \"TMPL_2\"}}"
        secret: false

This will produce the following entries:

• TMPL_1: test (hardcoded, stored in the ConfigMap)
• TMPL_2: test (read from the ConfigMap and stored in the Secret)
• TMPL_3: test (read from the Secret and stored in the ConfigMap)

Query¶

When using Query you need to make sure that you query returns only one value. For example:

...
    templates:
      - name: POSTGRES_VERSION
        secret: false
        template: "{{ .Query \"SHOW server_version;\" }}"

InstanceVars¶

For values shared across multiple databases on the same instance, you can define instance variables. Once configured on the DbInstance, these variables can also be referenced in Database and DbUser templates.

kind: DbInstance
spec:
  instanceVars:
    TEST_KEY: TEST_VALUE

These variables can be accessed by the Database/DbUser templates like this:

...
    templates:
      - name: DB_INSTANCE_VAR
        secret: false
        template: "{{ .InstanceVar 'TEST_KEY' }}"
...

Then the secret that is created by the operator should contain the following entry: DB_INSTANCE_VAR: TEST_VALUE.

When the value is changed on the instance level, it should also trigger reconciliation of the databases and hence the values should also be updated in the target secrets.