---
title: MQTT input
description: Use the MQTT input to read data transmitted using lightweight messaging protocol for small and mobile devices, optimized for high-latency or unreliable...
url: https://www.elastic.co/elastic/docs-builder/docs/3016/reference/beats/filebeat/filebeat-input-mqtt
products:
  - Beats
  - Filebeat
applies_to:
  - Elastic Cloud Serverless: Generally available
  - Elastic Stack: Generally available
---

# MQTT input
Use the `MQTT` input to read data transmitted using lightweight messaging protocol for small and mobile devices, optimized for high-latency or unreliable networks.
This input connects to the MQTT broker, subscribes to selected topics and parses data into common message lines. Everything happens before line filtering, multiline, and JSON decoding, so this input can be used in combination with those settings.
Example configuration:
```yaml
filebeat.inputs:
- type: mqtt
  hosts: 
    - tcp://broker:1883
    - ssl://secure_broker:8883
  topics: 
    - sample_topic
```

All other settings are optional.

## Configuration options

The `mqtt` input supports the following configuration options plus the [Common options](#filebeat-input-mqtt-common-options) described later.

### `hosts`

A list of MQTT brokers to connect to.

### `topics`

A list of topics to subscribe to and read from.

### `qos`

An agreement level between the sender of a message and the receiver of a message that defines the guarantee of delivery.
There are 3 QoS levels in MQTT. Defaults to `0`:
- At most once (`0`),
- At least once (`1`),
- Exactly once (`2`).


### `client_id`

A unique identifier of each MQTT client connecting to a MQTT broker.

### `username`

A client username used for authentication provided on the application level by the MQTT protocol.

### `password`

A client password used for authentication provided on the application level by the MQTT protocol.

### `clean_session`

The `clean_session` flag indicates whether the client wants to establish a persistent session with the broker. The default is `true`.
When `clean_session` is set to false, the session is considered to be persistent. The broker stores all subscriptions for the client and all missed messages for the client that subscribed with a Quality of Service (QoS) level 1 or 2.
In contrast, when `clean_session` is set to true, the broker doesn’t retain any information for the client and discards any previous state from any persistent session.

### `ssl`

Configuration options for SSL parameters like the certificate, key and the certificate authorities to use.
See [SSL](https://www.elastic.co/elastic/docs-builder/docs/3016/reference/beats/filebeat/configuration-ssl) for more information.

## Common options

The following configuration options are supported by all inputs.

#### `enabled`

Use the `enabled` option to enable and disable inputs. By default, enabled is set to true.

#### `tags`

A list of tags that Filebeat includes in the `tags` field of each published event. Tags make it easy to select specific events in Kibana or apply conditional filtering in Logstash. These tags will be appended to the list of tags specified in the general configuration.
Example:
```yaml
filebeat.inputs:
- type: mqtt
  . . .
  tags: ["json"]
```


#### `fields`

Optional fields that you can specify to add additional information to the output. For example, you might add fields that you can use for filtering log data. Fields can be scalar values, arrays, dictionaries, or any nested combination of these. By default, the fields that you specify here will be grouped under a `fields` sub-dictionary in the output document. To store the custom fields as top-level fields, set the `fields_under_root` option to true. If a duplicate field is declared in the general configuration, then its value will be overwritten by the value declared here.
```yaml
filebeat.inputs:
- type: mqtt
  . . .
  fields:
    app_id: query_engine_12
```


#### `fields_under_root`

If this option is set to true, the custom [fields](#filebeat-input-mqtt-fields) are stored as top-level fields in the output document instead of being grouped under a `fields` sub-dictionary. If the custom field names conflict with other field names added by Filebeat, then the custom fields overwrite the other fields.

#### `processors`

A list of processors to apply to the input data.
See [Processors](https://www.elastic.co/elastic/docs-builder/docs/3016/reference/beats/filebeat/filtering-enhancing-data) for information about specifying processors in your config.

#### `pipeline`

The ingest pipeline ID to set for the events generated by this input.
<note>
  The pipeline ID can also be configured in the Elasticsearch output, but this option usually results in simpler configuration files. If the pipeline is configured both in the input and output, the option from the input is used.
</note>

<important>
  The `pipeline` is always lowercased. If `pipeline: Foo-Bar`, then the pipeline name in Elasticsearch needs to be defined as `foo-bar`.
</important>


#### `keep_null`

If this option is set to true, fields with `null` values will be published in the output document. By default, `keep_null` is set to `false`.

#### `index`

If present, this formatted string overrides the index for events from this input (for elasticsearch outputs), or sets the `raw_index` field of the event’s metadata (for other outputs). This string can only refer to the agent name and version and the event timestamp; for access to dynamic fields, use `output.elasticsearch.index` or a processor.
Example value: `"%{[agent.name]}-myindex-%{+yyyy.MM.dd}"` might expand to `"filebeat-myindex-2019.11.01"`.

#### `publisher_pipeline.disable_host`

By default, all events contain `host.name`. This option can be set to `true` to disable the addition of this field to all events. The default value is `false`.