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docs: document max inputs/outputs/filters plugin limits #2554

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docs: document max inputs/outputs/filters plugin limits
pierluigilenoci Apr 24, 2026
ebf5753
docs: wrap bitmask in back-ticks per review feedback
pierluigilenoci Apr 24, 2026
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8 changes: 7 additions & 1 deletion administration/configuring-fluent-bit/classic-mode/configuration-file.md
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Expand Up @@ -62,6 +62,8 @@ The `INPUT` section defines a source (related to an input plugin). Each [input p

`Name` is mandatory and tells Fluent Bit which input plugin to load. `Tag` is mandatory for all plugins except for the `input forward` plugin, which provides dynamic tags.

There is no hard-coded limit on the number of `INPUT` sections. The practical maximum depends on available system resources such as memory and file descriptors.

### Example

The following is an example of an `INPUT` section:
Expand All @@ -85,6 +87,8 @@ The `FILTER` section defines a filter (related to an filter plugin). Each filter

`Name` is mandatory and lets Fluent Bit know which filter plugin should be loaded. `Match` or `Match_Regex` is mandatory for all plugins. If both are specified, `Match_Regex` takes precedence.

There is no hard-coded limit on the number of `FILTER` sections. The practical maximum depends on available system resources such as memory.

### Filter example

The following is an example of a `FILTER` section:
Expand All @@ -98,7 +102,7 @@ The following is an example of a `FILTER` section:

## Config output

The `OUTPUT` section specifies a destination that certain records should go to after a `Tag` match. Fluent Bit can route up to 256 `OUTPUT` plugins. The configuration supports the following keys:
The `OUTPUT` section specifies a destination that certain records should go to after a `Tag` match. The configuration supports the following keys:

| Key | Description |
| ----------- | -------------- |
Expand All @@ -107,6 +111,8 @@ The `OUTPUT` section specifies a destination that certain records should go to a
| `Match_Regex` | A regular expression to match against the tags of incoming records. Use this option if you want to use the full regular expression syntax. |
| `Log_Level` | Set the plugin's logging verbosity level. Allowed values are: `off`, `error`, `warn`, `info`, `debug`, and `trace`. Defaults to the `SERVICE` section's `Log_Level`. |

There is no hard-coded limit on the number of `OUTPUT` sections. The routing `bitmask` is dynamically sized at startup based on the number of configured output plugins. The practical maximum depends on available system resources such as memory and file descriptors.

### Output example

The following is an example of an `OUTPUT` section:
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6 changes: 5 additions & 1 deletion administration/configuring-fluent-bit/yaml/pipeline-section.md
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Expand Up @@ -77,6 +77,8 @@ The `inputs` section defines one or more [input plugins](../../../pipeline/input

The `name` parameter is required and defines for Fluent Bit which input plugin should be loaded. The `tag` parameter is required for all plugins except for the `forward` plugin, which provides dynamic tags.

There is no hard-coded limit on the number of input plugins. The practical maximum depends on available system resources such as memory and file descriptors.

### Shared HTTP listener settings for inputs

Some HTTP-based input plugins share the same listener implementation and support the following common settings in addition to their plugin-specific parameters:
Expand Down Expand Up @@ -144,6 +146,8 @@ The `filters` section defines one or more [filters](../../../pipeline/filters.md

The `name` parameter is required and lets Fluent Bit know which filter should be loaded. One of either the `match` or `match_regex` parameters is required. If both are specified, `match_regex` takes precedence.

There is no hard-coded limit on the number of filter plugins. The practical maximum depends on available system resources such as memory.

### Example filter configuration

The following is an example of a `filters` section that contains a `grep` plugin:
Expand All @@ -168,7 +172,7 @@ The `outputs` section defines one or more [output plugins](../../../pipeline/out
| `match_regex` | A regular expression to match against the tags of incoming records. Use this option if you want to use the full regular expression syntax. |
| `log_level` | Set the plugin's logging verbosity level. Allowed values are: `off`, `error`, `warn`, `info`, `debug`, and `trace`. The output log level defaults to the `service` section's `log_level`. |

Fluent Bit can route up to 256 output plugins.
Fluent Bit has no hard-coded limit on the number of output plugins. The routing `bitmask` is dynamically sized at startup based on the number of configured output plugins. The practical maximum depends on available system resources such as memory and file descriptors.

### Outgoing `OAuth 2.0` client credentials settings

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