PostgreSQL

Detailed information on the PostgreSQL configuration store component

Component format

To set up an PostgreSQL configuration store, create a component of type configuration.postgresql

apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
  name: <NAME>
spec:
  type: configuration.postgresql
  version: v1
  metadata:
    # Connection string
    - name: connectionString
      value: "host=localhost user=postgres password=example port=5432 connect_timeout=10 database=config"
    # Name of the table which holds configuration information
    - name: table
      value: "[your_configuration_table_name]" 
    # Timeout for database operations, in seconds (optional)
    #- name: timeoutInSeconds
    #  value: 20
    # Name of the table where to store the state (optional)
    #- name: tableName
    #  value: "state"
    # Name of the table where to store metadata used by Dapr (optional)
    #- name: metadataTableName
    #  value: "dapr_metadata"
    # Cleanup interval in seconds, to remove expired rows (optional)
    #- name: cleanupIntervalInSeconds
    #  value: 3600
    # Maximum number of connections pooled by this component (optional)
    #- name: maxConns
    #  value: 0
    # Max idle time for connections before they're closed (optional)
    #- name: connectionMaxIdleTime
    #  value: 0
    # Controls the default mode for executing queries. (optional)
    #- name: queryExecMode
    #  value: ""
    # Uncomment this if you wish to use PostgreSQL as a state store for actors (optional)
    #- name: actorStateStore
    #  value: "true"

Warning

The above example uses secrets as plain strings. It is recommended to use a secret store for the secrets as described here.

Spec metadata fields

Authenticate using a connection string

The following metadata options are required to authenticate using a PostgreSQL connection string.

Authenticate using Microsoft Entra ID

Authenticating with Microsoft Entra ID is supported with Azure Database for PostgreSQL. All authentication methods supported by Dapr can be used, including client credentials (“service principal”) and Managed Identity.

Authenticate using AWS IAM

Authenticating with AWS IAM is supported with all versions of PostgreSQL type components. The user specified in the connection string must be an already existing user in the DB, and an AWS IAM enabled user granted the rds_iam database role. Authentication is based on the AWS authentication configuration file, or the AccessKey/SecretKey provided. The AWS authentication token will be dynamically rotated before it’s expiration time with AWS.

Other metadata options

Set up PostgreSQL as Configuration Store

1. Start the PostgreSQL Database

2. Connect to the PostgreSQL database and setup a configuration table with following schema:

   Field	Datatype	Nullable	Details
   KEY	VARCHAR	N	Holds “Key” of the configuration attribute
   VALUE	VARCHAR	N	Holds Value of the configuration attribute
   VERSION	VARCHAR	N	Holds version of the configuration attribute
   METADATA	JSON	Y	Holds Metadata as JSON

   CREATE TABLE IF NOT EXISTS table_name (
     KEY VARCHAR NOT NULL,
     VALUE VARCHAR NOT NULL,
     VERSION VARCHAR NOT NULL,
     METADATA JSON
   );

3. Create a TRIGGER on configuration table. An example function to create a TRIGGER is as follows:

   CREATE OR REPLACE FUNCTION notify_event() RETURNS TRIGGER AS $$
       DECLARE 
           data json;
           notification json;
       BEGIN
           IF (TG_OP = 'DELETE') THEN
               data = row_to_json(OLD);
           ELSE
               data = row_to_json(NEW);
           END IF;
           notification = json_build_object(
                             'table',TG_TABLE_NAME,
                             'action', TG_OP,
                             'data', data);
           PERFORM pg_notify('config',notification::text);
           RETURN NULL; 
       END;
   $$ LANGUAGE plpgsql;

4. Create the trigger with data encapsulated in the field labeled as data:

   notification = json_build_object(
     'table',TG_TABLE_NAME,
     'action', TG_OP,
     'data', data
   );

5. The channel mentioned as attribute to pg_notify should be used when subscribing for configuration notifications

6. Since this is a generic created trigger, map this trigger to configuration table

   CREATE TRIGGER config
   AFTER INSERT OR UPDATE OR DELETE ON configtable
       FOR EACH ROW EXECUTE PROCEDURE notify_event();

7. In the subscribe request add an additional metadata field with key as pgNotifyChannel and value should be set to same channel name mentioned in pg_notify. From the above example, it should be set to config

Note

When calling subscribe API, metadata.pgNotifyChannel should be used to specify the name of the channel to listen for notifications from PostgreSQL configuration store.

Any number of keys can be added to a subscription request. Each subscription uses an exclusive database connection. It is strongly recommended to subscribe to multiple keys within a single subscription. This helps optimize the number of connections to the database.

Example of subscribe HTTP API:

curl -l 'http://<host>:<dapr-http-port>/configuration/mypostgresql/subscribe?key=<keyname1>&key=<keyname2>&metadata.pgNotifyChannel=<channel name>'

Related links

• Basic schema for a Dapr component
• Configuration building block

Last modified October 11, 2024: Fixed typo (#4389) (fe17926)