monitor_agent
The
in_monitor_agent Input plugin exports Fluentd's internal metrics via REST API.It is included in Fluentd's core.
<source>
@type monitor_agent
bind 0.0.0.0
port 24220
</source>
This configuration launches HTTP server with 24220 port and get metrics:
$ curl http://host:24220/api/plugins.json
Also you can fetch the same data in LTSV format:
$ curl http://host:24220/api/plugins
Refer to the Configuration File article for the basic structure and syntax of the configuration file.
The value must be
monitor_agent.type | default | version |
|---|---|---|
integer | 24220 | 0.14.0 |
The port to listen to.
type | default | version |
|---|---|---|
string | 0.0.0.0 (all addresses) | 0.14.0 |
The bind address to listen to.
type | default | version |
|---|---|---|
string | nil | 0.14.0 |
If you set this parameter, this plugin emits metrics as records. See "Reuse plugins" section.
type | default | version |
|---|---|---|
integer | 60 | 0.14.0 |
The interval time between event emits. This will be used when
tag is configured.type | default | version |
|---|---|---|
bool | true | 0.14.0 |
You can set this option to false to remove the
config field from the response.type | default | version |
|---|---|---|
bool | true | 0.14.11 |
You can set this option to false to remove the
retry field from the response.Here is a configuration example using
in_monitor_agent:<source>
@type monitor_agent
@id in_monitor_agent
include_config false
</source>
<source>
@type forward
@id in_forward
</source>
<match test.**>
@type elasticsearch
@id out_es
</match>
When using this plugin, we strongly recommend setting
@id on each plugin in use. This makes the task to identify which record corresponds to which plugin much easier. Without @id, Fluentd uses object_id as the unique identifier, so you cannot identify a record just by looking at its plugin_id field.Here is how the output looks like in JSON:
{
"plugins": [
{
"plugin_id": "in_monitor_agent",
"plugin_category": "input",
"type": "monitor_agent",
"output_plugin": false,
"retry_count": null
},
{
"plugin_id": "in_forward",
"plugin_category": "input",
"type": "forward",
"output_plugin": false,
"retry_count": null
},
{
"plugin_id": "out_es",
"plugin_category": "output",
"type": "elasticsearch",
"output_plugin": true,
"buffer_queue_length": 0,
"buffer_total_queued_size": 0,
"retry_count": 0,
"retry": {}
}
]
}
If the plugin is an output plugin with the buffer settings, the metrics include the buffer related fields.
If the output plugin is in retry status, additional fields are added to
retry. For example, if the Elasticsearch plugin fails to flush the buffer.Here is the response:
{
"plugin_id": "out_es",
"plugin_category": "output",
"type": "elasticsearch",
"output_plugin": true,
"buffer_queue_length": 1,
"buffer_total_queued_size": 0,
"retry_count": 3,
"retry": {
"start": "2018-01-30 22:42:47 +0900",
"steps": 2,
"next_time": "2018-01-30 22:42:52 +0900"
}
}
steps field in retry show the number of flush failures, so next is the third try. retry_count is the total number of flush failures. This value is cleared when fluentd restarts, not when retry succeeds.This plugin supports a number of query parameters with which you can customize the output format of HTTP responses. For example, you can append
debug=1 to the request URL to get the verbose internal metrics:$ curl http://localhost:24220/api/plugins.json?debug=1
The following list shows the available query parameters:
Parameter | Value | Explanation |
|---|---|---|
debug | Constant | Expose additional internal metrics. Note that sensitive configuration value (password and so on) will be shown without obfuscating |
with_ivars | Variable names | Expose the specified instance variables of each plugin |
with_config | Boolean | Override the configuration option with_config |
with_retry | Boolean | Override the configuration option with_retry |
tag | Event tag | Only show plugins that matches the specified tag |
@id | Plugin id | Filter plugins by plugin id |
@type | Plugin type | Filter plugins by plugin type |
You can emit the internal metrics as events by setting the
tag.For example:
<source>
@type monitor_agent
tag debug.monitor
emit_interval 60
port 24230
</source>
Note that
in_monitor_agent produces separate records for each plugin. Thus, using this configuration, you will receive events like below once per minute:2018-01-30 22:53:29.591560000 +0900 debug.monitor: { "plugin_id":"object:3ffd9988bea0","plugin_category":"input","type":"monitor_agent","output_plugin":false,"retry_count":null}
2018-01-30 22:53:29.591560000 +0900 debug.monitor: { "plugin_id":"in_forward","plugin_category":"input","type":"forward","output_plugin":false,"retry_count":null}
2018-01-30 22:53:29.591560000 +0900 debug.monitor: { "plugin_id":"out_out","plugin_category":"output","type":"stdout","output_plugin":true,"retry_count":0}
If you use this plugin under the multi-process environment, the HTTP server will be launched in each worker. Port is assigned sequentially. For example, with this configuration:
<system>
workers 3
</system>
<source>
@type monitor_agent
port 24230
</source>
Three (3) HTTP servers will be launched with:
- port 24230 for worker 0
- port 24231 for worker 1
- port 24232 for worker 2
If this article is incorrect or outdated, or omits critical information, please let us know. Fluentd is an open-source project under Cloud Native Computing Foundation (CNCF). All components are available under the Apache 2 License.
Last modified 8mo ago