Publish Events to PostgreSQL

AIStor supports publishing bucket notification events to PostgreSQL. AIStor supports PostgreSQL 9.5 and later only.

Prerequisites

PostgreSQL 9.5 and later

AIStor relies on features introduced with PostgreSQL 9.5.
The AIStor mc Command Line Tool

This procedure uses the mc command line tool for certain actions. See the mc Quickstart for installation instructions.

Add a PostgreSQL Endpoint to an AIStor Server

The following procedure adds a new PostgreSQL service endpoint for supporting bucket notifications in an AIStor Server.

Add the PostgreSQL endpoint to AIStor.

You can configure a new PostgreSQL service endpoint using either environment variables or by setting runtime configuration settings.
Environment Variables
AIStor supports specifying the PostgreSQL service endpoint and associated configuration settings using environment variables. The minio server process applies the specified settings on its next startup.

The minimum required variables are:
The following example code sets all environment variables related to configuring a PostgreSQL service endpoint.
```
export MINIO_NOTIFY_POSTGRES_ENABLE_<IDENTIFIER>="on"
export MINIO_NOTIFY_POSTGRES_CONNECTION_STRING_<IDENTIFIER>="host=postgresql-endpoint.example.net port=4222"
export MINIO_NOTIFY_POSTGRES_TABLE_<IDENTIFIER>="minioevents"
export MINIO_NOTIFY_POSTGRES_FORMAT_<IDENTIFIER>="namespace|access"
export MINIO_NOTIFY_POSTGRES_MAX_OPEN_CONNECTIONS_<IDENTIFIER>="2"
export MINIO_NOTIFY_POSTGRES_QUEUE_DIR_<IDENTIFIER>="/opt/minio/events"
export MINIO_NOTIFY_POSTGRES_QUEUE_LIMIT_<IDENTIFIER>="100000"
export MINIO_NOTIFY_POSTGRES_COMMENT_<IDENTIFIER>="PostgreSQL Notification Event Logging for MinIO"
```
- Replace <IDENTIFIER> with a unique descriptive string for the PostgreSQL service endpoint. Use the same <IDENTIFIER> value for all environment variables related to the new target service endpoint. The following examples assume an identifier of PRIMARY.
  
  If the specified <IDENTIFIER> matches an existing PostgreSQL service endpoint on the AIStor Server, the new settings override any existing settings for that endpoint. Use mc admin config get notify_postgres to review the currently configured PostgreSQL endpoints on the AIStor Server.
- Replace <ENDPOINT> with the PostgreSQL Connection String for PostgreSQL service endpoint. AIStor supports key=value format for the connection string. For example:
  
  "host=https://postgresql.example.com port=5432 ..."
  
  For more complete documentation on supported PostgreSQL connection string parameters, see PostgreSQL Connection String.
See PostgreSQL Service for Bucket Notifications for complete documentation on each environment variable.
Configuration Settings
AIStor supports adding or updating PostgreSQL endpoints on a running minio server process using the mc admin config set command and the notify_postgres configuration key. You must restart the minio server process to apply any new or updated configuration settings.

The minimum required setting are:
The following example code sets all settings related to configuring a PostgreSQL service endpoint.
```
mc admin config set ALIAS/ notify_postgres:IDENTIFIER \
   connection_string="ENDPOINT" \
   table="<string>" \
   format="<string>" \
   max_open_connections="<string>" \
   queue_dir="<string>" \
   queue_limit="<string>" \
   comment="<string>"
```
- Replace IDENTIFIER with a unique descriptive string for the PostgreSQL service endpoint. The following examples in this procedure assume an identifier of PRIMARY.
  
  If the specified IDENTIFIER matches an existing PostgreSQL service endpoint on the AIStor Server, the new settings override any existing settings for that endpoint. Use mc admin config get notify_postgres to review the currently configured PostgreSQL endpoints on the AIStor Server.
- Replace <ENDPOINT> with the PostgreSQL URI connection string of the PostgreSQL service endpoint. AIStor supports key=value format for the PostgreSQL connection string. For example:
  
  "host=https://postgresql.example.com port=5432 ..."
  
  For more complete documentation on supported PostgreSQL connection string parameters, see PostgreSQL Connection String.
See PostgreSQL Bucket Notification Configuration Settings for complete documentation on each setting.
If you define both environment variables and configuration settings for the deployment, the settings defined by environment variables are used.
Restart the AIStor Server.

You must restart the AIStor Server to apply the configuration changes. Use the mc admin service restart command to restart the deployment.
```
mc admin service restart ALIAS
```
Replace ALIAS with the alias of the deployment to restart.

The minio server process prints a line on startup for each configured PostgreSQL target similar to the following:
```
SQS ARNs: arn:minio:sqs::primary:postgresql
```
You must specify the ARN resource when configuring bucket notifications with the associated PostgreSQL deployment as a target.
Configure bucket notifications using the PostgreSQL endpoint as a target

Use the mc event add command to add a new bucket notification event with the configured PostgreSQL service as a target:
```
mc event add ALIAS/BUCKET arn:minio:sqs::primary:postgresql \
  --event EVENTS
```
- Replace ALIAS with the alias of an AIStor Server.
- Replace BUCKET with the name of the bucket in which to configure the event.
- Replace EVENTS with a comma-separated list of events for which AIStor triggers notifications.
Use mc event ls to view all configured bucket events for a given notification target:
```
mc event ls ALIAS/BUCKET arn:minio:sqs::primary:postgresql
```
Validate the configured events.

Perform an action on the bucket for which you configured the new event and check the PostgreSQL service for the notification data. The action required depends on which events were specified when configuring the bucket notification.

For example, if the bucket notification configuration includes the s3:ObjectCreated:Put event, you can use the mc cp command to create a new object in the bucket and trigger a notification.
```
mc cp ~/data/new-object.txt ALIAS/BUCKET
```

Update a PostgreSQL endpoint in an AIStor Server

The following procedure updates an existing PostgreSQL service endpoint for supporting bucket notifications in an AIStor Server.

List configured PostgreSQL endpoints in the deployment.

Use the mc admin config get command to list the currently configured PostgreSQL service endpoints in the deployment:
```
mc admin config get ALIAS/ notify_postgres
```
Replace ALIAS with the alias of the AIStor Server.

The command output resembles the following:
```
notify_postgres:primary queue_dir="" connection_string="postgresql://" queue_limit="0"  table="" format="namespace"
notify_postgres:secondary queue_dir="" connection_string="" queue_limit="0"  table="" format="namespace"
```
The notify_postgres key is the top-level configuration key for a PostgreSQL Notification Settings. The connection_string key specifies the PostgreSQL service endpoint for the given notify_postgres key. The notify_postgres:<IDENTIFIER> suffix describes the unique identifier for that PostgreSQL service endpoint.

Note the identifier for the PostgreSQL service endpoint you want to update for the next step.
Update the PostgreSQL endpoint.

Use the mc admin config set command to set the new configuration for the PostgreSQL service endpoint:
```
mc admin config set ALIAS/ notify_postgres:IDENTIFIER \
   connection_string="ENDPOINT" \
   table="<string>" \
   format="<string>" \
   max_open_connections="<string>" \
   queue_dir="<string>" \
   queue_limit="<string>" \
   comment="<string>"
```
The following configuration settings are the minimum required for a PostgreSQL service endpoint:
All other configuration settings are optional. See PostgreSQL Notification Settings for a complete list of PostgreSQL configuration settings.
Restart the AIStor Server.

You must restart the AIStor Server to apply the configuration changes. Use the mc admin service restart command to restart the deployment.
```
mc admin service restart ALIAS
```
Replace ALIAS with the alias of the deployment to restart.

The minio server process prints a line on startup for each configured PostgreSQL target similar to the following:
```
SQS ARNs: arn:minio:sqs::primary:postgresql
```
Validate the changes.

Perform an action on a bucket which has an event configuration using the updated PostgreSQL service endpoint and check the PostgreSQL service for the notification data. The action required depends on which events were specified when configuring the bucket notification.

For example, if the bucket notification configuration includes the s3:ObjectCreated:Put event, you can use the mc cp command to create a new object in the bucket and trigger a notification.
```
mc cp ~/data/new-object.txt ALIAS/BUCKET
```