Publish Events to MQTT

AIStor supports publishing bucket notification events to MQTT server/broker endpoint.

Prerequisites

MQTT 3.1 or 3.1.1 Server/Broker

This procedure assumes an existing MQTT 3.1 or 3.1.1 server/broker to which the AIStor Server has connectivity. See the mqtt.org software listing for a list of MQTT-compatible server/brokers.

If the MQTT service requires authentication, you must provide an appropriate username and password during the configuration process to grant AIStor access to the service.
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 an MQTT endpoint to an AIStor Server

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

Add the MQTT endpoint to AIStor.

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

The following example code sets all environment variables related to configuring an MQTT service endpoint. The minimum required variables are:
- MINIO_NOTIFY_MQTT_ENABLE
- MINIO_NOTIFY_MQTT_BROKER
- MINIO_NOTIFY_MQTT_TOPIC
- MINIO_NOTIFY_MQTT_USERNAME
  
  Required if the MQTT server/broker enforces authentication/authorization
- MINIO_NOTIFY_MQTT_PASSWORD
  
  Required if the MQTT server/broker enforces authentication/authorization
The full list of available variables is:
```
export MINIO_NOTIFY_MQTT_ENABLE_<IDENTIFIER>="on"
export MINIO_NOTIFY_MQTT_BROKER_<IDENTIFIER>="ENDPOINT"
export MINIO_NOTIFY_MQTT_TOPIC_<IDENTIFIER>="TOPIC"
export MINIO_NOTIFY_MQTT_USERNAME_<IDENTIFIER>="<string>"
export MINIO_NOTIFY_MQTT_PASSWORD_<IDENTIFIER>="<string>"
export MINIO_NOTIFY_MQTT_QOS_<IDENTIFIER>="<string>"
export MINIO_NOTIFY_MQTT_KEEP_ALIVE_INTERVAL_<IDENTIFIER>="<string>"
export MINIO_NOTIFY_MQTT_RECONNECT_INTERVAL_<IDENTIFIER>="<string>"
export MINIO_NOTIFY_MQTT_QUEUE_DIR_<IDENTIFIER>="<string>"
export MINIO_NOTIFY_MQTT_QUEUE_LIMIT_<IDENTIFIER>="<string>"
export MINIO_NOTIFY_MQTT_COMMENT_<IDENTIFIER>="<string>"
```
- Replace <IDENTIFIER> with a unique descriptive string for the MQTT service endpoint. Use the same <IDENTIFIER> value for all environment variables related to the new MQTT service endpoint. The following examples assume an identifier of PRIMARY.
  
  If the specified <IDENTIFIER> matches an existing MQTT service endpoint on the AIStor Server, the new settings override any existing settings for that endpoint. Use mc admin config get notify_mqtt to review the currently configured MQTT endpoints on the AIStor Server.
- Replace <ENDPOINT> with the URL of the MQTT service endpoint. For example:
  
  tcp://hostname:port
- Replace TOPIC with the MQTT topic to which AIStor associates events published to the server/broker.
See MQTT Service for Bucket Notifications for complete documentation on each environment variable.
Configuration Settings
AIStor supports adding or updating MQTT endpoints on a running minio server process using the mc admin config set command and the notify_mqtt configuration key. You must restart the minio server process to apply any new or updated configuration settings.

The following example code sets all settings related to configuring an MQTT service endpoint. The following configuration settings are the minimum required for an MQTT server/broker endpoint:
- broker
- topic
- username
  
  Required if the MQTT server/broker enforces authentication/authorization
- password
  
  Required if the MQTT server/broker enforces authentication/authorization
The full list of available configuration settings is:
```
mc admin config set ALIAS/ notify_mqtt:IDENTIFIER \
   broker="ENDPOINT" \
   topic="TOPIC" \
   username="username" \
   password="password" \
   qos="<integer>" \
   keep_alive_interval="60s|m|h|d"
   reconnect_interval="60s|m|h|d"
   queue_dir="<string>" \
   queue_limit="<string>" \
   comment="<string>"
```
- Replace IDENTIFIER with a unique descriptive string for the MQTT service endpoint. The following examples in this procedure assume an identifier of PRIMARY.
  
  If the specified IDENTIFIER matches an existing MQTT service endpoint on the AIStor Server, the new settings override any existing settings for that endpoint. Use mc admin config get notify_mqtt to review the currently configured MQTT endpoints on the AIStor Server.
- Replace ENDPOINT with the URL of the MQTT service endpoint. For example:
  
  tcp://hostname:port
- Replace TOPIC with the MQTT topic to which AIStor associates events published to the server/broker.
See MQTT 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 MQTT target similar to the following:
```
SQS ARNs: arn:minio:sqs::primary:mqtt
```
You must specify the ARN resource when configuring bucket notifications with the associated MQTT deployment as a target.
Configure bucket notifications using the MQTT endpoint as a target.

Use the mc event add command to add a new bucket notification event with the configured MQTT service as a target:
```
mc event add ALIAS/BUCKET arn:minio:sqs::primary:mqtt \
  --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:MQTT
```
Validate the configured events.

Perform an action on the bucket for which you configured the new event and check the MQTT 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 an MQTT endpoint in an AIStor Server

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

List configured MQTT endpoints in the deployment.

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

The command output resembles the following:
```
notify_mqtt:primary  broker="tcp://mqtt-primary.example.net:port" password="" queue_dir="" queue_limit="0" reconnect_interval="0s"  keep_alive_interval="0s" qos="0" topic="" username=""
notify_mqtt:secondary  broker="tcp://mqtt-primary.example.net:port" password="" queue_dir="" queue_limit="0" reconnect_interval="0s"  keep_alive_interval="0s" qos="0" topic="" username=""
```
The notify_mqtt key is the top-level configuration key for an MQTT Notification Settings. The broker key specifies the MQTT server/broker endpoint for the given notify_mqtt key. The notify_mqtt:<IDENTIFIER> suffix describes the unique identifier for that MQTT service endpoint.

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

Use the mc admin config set command to set the new configuration for the MQTT service endpoint:
```
mc admin config set ALIAS/ notify_mqtt:<IDENTIFIER> \
   url="MQTT://user:password@hostname:port" \
   exchange="<string>" \
   exchange_type="<string>" \
   routing_key="<string>" \
   mandatory="<string>" \
   durable="<string>" \
   no_wait="<string>" \
   internal="<string>" \
   auto_deleted="<string>" \
   delivery_mode="<string>" \
   queue_dir="<string>" \
   queue_limit="<string>" \
   comment="<string>"
```
The following configuration settings are the minimum required for an MQTT server/broker endpoint:
- broker
- topic
- username
  
  Required if the MQTT server/broker enforces authentication/authorization
- password
  
  Required if the MQTT server/broker enforces authentication/authorization
All other configuration settings are optional. See MQTT Notification Settings for a complete list of MQTT 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 MQTT target similar to the following:
```
SQS ARNs: arn:minio:sqs::primary:mqtt
```
Validate the changes.

Perform an action on a bucket which has an event configuration using the updated MQTT service endpoint and check the MQTT 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
```