Service
The service section defines global properties of the service. The available configuration keys are:
flush
Sets the flush time in seconds.nanoseconds. The engine loop uses a flush timeout to define when to flush the records ingested by input plugins through the defined output plugins.
1
grace
Sets the grace time in seconds as an integer value. The engine loop uses a grace timeout to define the wait time on exit.
5
daemon
Specifies whether Fluent Bit should run as a daemon (background process). Possible values: yes, no, on, and off. Don't enable when using a Systemd-based unit, such as the one provided in Fluent Bit packages.
off
dns.mode
Sets the primary transport layer protocol used by the asynchronous DNS resolver. Can be overridden on a per-plugin basis.
UDP
log_file
Absolute path for an optional log file. By default, all logs are redirected to the standard error interface (stderr).
none
log_level
Sets the logging verbosity level. Possible values: off, error, warn, info, debug, and trace. Values are cumulative. For example, if debug is set, it will include error, warning, info, and debug. The trace mode is only available if Fluent Bit was built with the WITH_TRACE option enabled.
info
plugins_file
Path for a plugins configuration file. This file specifies the paths to custom plugins (.so files) that Fluent Bit can load at runtime. Plugins can be declared directly in the plugins section of YAML configuration files.
none
streams_file
Path for the stream processor configuration file. This file defines the rules and operations for stream processing in Fluent Bit. Stream processor configurations can also be defined directly in the streams section of YAML configuration files.
none
http_server
Enables the built-in HTTP server.
off
http_listen
Sets the listening interface for the HTTP Server when it's enabled.
0.0.0.0
http_port
Sets the TCP port for the HTTP server.
2020
coro_stack_size
Sets the coroutines stack size in bytes. The value must be greater than the page size of the running system. Setting the value too small (for example, 4096) can cause coroutine threads to overrun the stack buffer. For best results, don't change this parameter from its default value.
24576
scheduler.cap
Sets a maximum retry time in seconds.
2000
scheduler.base
Sets the base of exponential backoff.
5
json.convert_nan_to_null
If enabled, NaN is converted to null when Fluent Bit converts msgpack to JSON.
false
json.escape_unicode
Controls how Fluent Bit serializes non‑ASCII / multi‑byte Unicode characters in JSON strings. When enabled, Unicode characters are escaped as \uXXXX sequences (characters outside BMP become surrogate pairs). When disabled, Fluent Bit emits raw UTF‑8 bytes.
true
sp.convert_from_str_to_num
If enabled, the stream processor converts strings that represent numbers to a numeric type.
true
windows.maxstdio
If specified, adjusts the limit of stdio. Only provided for Windows. Values from 512 to 2048 are allowed.
512
Storage configuration
The following storage-related keys can be set as children to the storage key:
storage.path
Set a location in the file system to store streams and chunks of data. Required for filesystem buffering.
none
storage.sync
Configure the synchronization mode used to store data in the file system. Accepted values: normal or full.
normal
storage.checksum
Enable data integrity check when writing and reading data from the filesystem. Accepted values: off or on.
off
storage.max_chunks_up
Set the maximum number of chunks that can be up in memory when using filesystem storage.
128
storage.backlog.mem_limit
Set the memory limit for backlog data chunks.
5M
storage.backlog.flush_on_shutdown
Attempt to flush all backlog chunks during shutdown. Accepted values: off or on.
off
storage.metrics
Enable storage layer metrics on the HTTP endpoint. Accepted values: off or on.
off
storage.delete_irrecoverable_chunks
Delete irrecoverable chunks during runtime and at startup. Accepted values: off or on.
off
storage.keep.rejected
Enable the Dead Letter Queue (DLQ) to preserve chunks that fail to be delivered. Accepted values: off or on.
off
storage.rejected.path
Subdirectory name under storage.path for storing rejected chunks.
rejected
For scheduler and retry details, see scheduling and retries.
For storage and buffering details, see buffering and storage.
Configuration example
The following configuration example that defines a service section with hot reloading enabled and a pipeline with a random input and stdout output:
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