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Publish Events to MQTT

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

Add an MQTT Endpoint to a MinIO Deployment

The following procedure adds a new MQTT service endpoint for supporting bucket notifications in a MinIO deployment.

Important

This procedure requires restarting all minio server processes associated to the deployment at the same time. There is typically a brief period of time during which API operations are interrupted or may fail.

Applications using an S3-compatible SDK with built-in retry logic or which implement manual retry logic typically experience no notable interruption in services. For applications which cannot use retry-logic, consider scheduling a maintenance period to minimize interruption of services while performing this procedure.

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 MinIO deployment 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 MinIO access to the service.

MinIO mc Command Line Tool

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

1) Add the MQTT Endpoint to MinIO

You can configure a new MQTT service endpoint using either environment variables or by setting runtime configuration settings.

MinIO 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:

set MINIO_NOTIFY_MQTT_ENABLE_<IDENTIFIER>="on"
set MINIO_NOTIFY_MQTT_BROKER_<IDENTIFIER>="ENDPOINT"
set MINIO_NOTIFY_MQTT_TOPIC_<IDENTIFIER>="TOPIC"
set MINIO_NOTIFY_MQTT_USERNAME_<IDENTIFIER>="<string>"
set MINIO_NOTIFY_MQTT_PASSWORD_<IDENTIFIER>="<string>"
set MINIO_NOTIFY_MQTT_QOS_<IDENTIFIER>="<string>"
set MINIO_NOTIFY_MQTT_KEEP_ALIVE_INTERVAL_<IDENTIFIER>="<string>"
set MINIO_NOTIFY_MQTT_RECONNECT_INTERVAL_<IDENTIFIER>="<string>"
set MINIO_NOTIFY_MQTT_QUEUE_DIR_<IDENTIFIER>="<string>"
set MINIO_NOTIFY_MQTT_QUEUE_LIMIT_<IDENTIFIER>="<string>"
set 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 MinIO deployment, 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 MinIO deployment.

  • Replace <ENDPOINT> with the URL of the MQTT service endpoint. For example:

    tcp://hostname:port

  • Replace TOPIC with the MQTT topic to which MinIO associates events published to the server/broker.

See MQTT Service for Bucket Notifications for complete documentation on each environment variable.

MinIO 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

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 MinIO deployment, 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 MinIO deployment.

  • Replace ENDPOINT with the URL of the MQTT service endpoint. For example:

    tcp://hostname:port

  • Replace TOPIC with the MQTT topic to which MinIO associates events published to the server/broker.

See MQTT Bucket Notification Configuration Settings for complete documentation on each setting.

2) Restart the MinIO Deployment

You must restart the MinIO deployment to apply the configuration changes. Use the mc admin service restart command to restart the deployment.

Important

MinIO restarts all minio server processes associated to the deployment at the same time. Applications may experience a brief period of downtime during the restart process.

Consider scheduling the restart during a maintenance period to minimize interruption of services.

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.

3) 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 a MinIO deployment.

  • 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 MinIO triggers notifications.

Use mc event list to view all configured bucket events for a given notification target:

mc event list ALIAS/BUCKET arn:minio:sqs::primary:MQTT

4) 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 a MinIO Deployment

The following procedure updates an existing MQTT service endpoint for supporting bucket notifications in a MinIO deployment.

Important

This procedure requires restarting all minio server processes associated to the deployment at the same time. There is typically a brief period of time during which API operations are interrupted or may fail.

Applications using an S3-compatible SDK with built-in retry logic or which implement manual retry logic typically experience no notable interruption in services. For applications which cannot use retry-logic, consider scheduling a maintenance period to minimize interruption of services while performing this procedure.

Prerequisites

MQTT 3.1 or 3.1.1 Server/Broker Endpoint

This procedure assumes an existing MQTT 3.1 or 3.1.1 server/broker to which the MinIO deployment 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 MinIO access to the service.

MinIO mc Command Line Tool

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

1) 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 MinIO deployment.

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 Service for Bucket Notifications. 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.

2) 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 Service for Bucket Notifications for a complete list of MQTT configuration settings.

3) Restart the MinIO Deployment

You must restart the MinIO deployment to apply the configuration changes. Use the mc admin service restart command to restart the deployment.

Important

MinIO restarts all minio server processes associated to the deployment at the same time. Applications may experience a brief period of downtime during the restart process.

Consider scheduling the restart during a maintenance period to minimize interruption of services.

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

3) 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