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The cpu input plugin, measures the CPU usage by the system and per CPU core in a percentage unit between every second of time. At the moment this plugin is only available for Linux.
The following tables describes the information generated by the plugin. The keys below represent the data used by the overall system, all values associated to the keys are in a percentage unit (0 to 100%):
In addition to the keys reported in the above table, a similar content is created per CPU core. The cores are listed from 0 to N as the Kernel reports:
In order to get the statistics of the CPU usage of your system, you can run the plugin from the command line or through the configuration file:
As described above, the CPU input plugin gathers the overall usage every one second and flushed the information to the output on the fifth second. On this example we used the stdout plugin to demonstrate the output records. In a real use-case you may want to flush this information to some central aggregator such as Fluentd or Elasticsearch.
In your main configuration file append the following Input & Output sections:
The dummy input plugin, generates dummy events. It is useful for testing, debugging, benchmarking and getting started with Fluent Bit.
The plugin supports the following configuration parameters:
You can run the plugin from the command line or through the configuration file:
In your main configuration file append the following Input & Output sections:
The input plugins defines the source from where Fluent Bit can collect data, it can be through a network interface, radio hardware or some built-in metric. As of this version the following input plugins are available:
Forward is the protocol used by and to route messages between peers. This plugin implements the input service to listen for Forward messages.
The plugin supports the following configuration parameters:
In order to receive Forward messages, you can run the plugin from the command line or through the configuration file:
From the command line you can let Fluent Bit listen for Forward messages with the following options:
By default the service will listen an all interfaces (0.0.0.0) through TCP port 24224, optionally you can change this directly, e.g:
In the example the Forward messages will only arrive through network interface under 192.168.3.2 address and TCP Port 9090.
In your main configuration file append the following Input & Output sections:
The MQTT input plugin, allows to retrieve messages/data from MQTT control packets over a TCP connection. The incoming data to receive must be a JSON map.
The plugin supports the following configuration parameters:
In order to start listening for MQTT messages, you can run the plugin from the command line or through the configuration file:
Since the MQTT input plugin let Fluent Bit behave as a server, we need to dispatch some messages using some MQTT client, in the following example mosquitto tool is being used for the purpose:
The following command line will send a message to the MQTT input plugin:
In your main configuration file append the following Input & Output sections:
The netif input plugin, gathers the information about the network traffic of the running system every certain interval of time and reports them.
The plugin supports the following configuration parameters:
In order to monitor network traffic from your system, you can run the plugin from the command line or through the configuration file:
In your main configuration file append the following Input & Output sections:
Note: Total interval (sec) = Interval_Sec + (Interval_Nsec / 1000000000).
e.g. 1.5s = 1s + 500000000ns
The kmsg input plugin reads the Linux Kernel log buffer since the beginning, it gets every record and parse it field as priority, sequence, seconds, useconds, and message.
In order to start getting the Linux Kernel messages, you can run the plugin from the command line or through the configuration file:
As described above, the plugin processed all messages that the Linux Kernel reported, the output has been truncated for clarification.
In your main configuration file append the following Input & Output sections:
Once Fluent Bit is running, you can send some messages using the fluent-cat tool (this tool is provided by :
In we should see the following output:
key
description
cpu_p
CPU usage of the overall system, this value is the summatory of time spent on user and kernel space. The result takes in consideration the numbers of CPU cores in the system.
user_p
CPU usage in User mode, for short it means the CPU usage by user space programs. The result of this value takes in consideration the numbers of CPU cores in the system.
system_p
CPU usage in Kernel mode, for short it means the CPU usage by the Kernel. The result of this value takes in consideration the numbers of CPU cores in the system.
key
description
cpuN.p_cpu
Represents the total CPU usage by core N.
cpuN.p_user
Total CPU spent in user mode or user space programs associated to this core.
cpuN.p_system
Total CPU spent in system or kernel mode associated to this core.
Key
Description
Dummy
Dummy JSON record. Default: {"message":"dummy"}
Rate
Events number generated per second. Default: 1
name
title
description
CPU Usage
measure total CPU usage of the system.
Disk Usage
measure Disk I/Os.
Dummy
generate dummy event.
Exec
executes external program and collects event logs.
Forward
Fluentd forward protocol.
Head
read first part of files.
Health
Check health of TCP services.
Kernel Log Buffer
read the Linux Kernel log buffer messages.
Memory Usage
measure the total amount of memory used on the system.
MQTT
start a MQTT server and receive publish messages.
Network Traffic
measure network traffic.
Process
Check health of Process.
Random
Generate Random samples.
Serial Interface
read data information from the serial interface.
Standard Input
read data from the standard input.
Syslog
read syslog messages from a Unix socket.
Systemd
read logs from Systemd/Journald.
Tail
Tail log files
TCP
Listen for JSON messages over TCP.
Key | Description |
Listen | Listener network interface, default: 0.0.0.0 |
Port | TCP port where listening for connections, default: 1883 |
Key | Description |
Interface | Specify the network interface to monitor. e.g. eth0 |
Interval_Sec | Polling interval (seconds). default: 1 |
Interval_NSec | Polling interval (nanosecond). default: 0 |
Verbose | If true, gather metrics precisely. default: false |
The mem input plugin, gathers the information about the memory and swap usage of the running system every certain interval of time and reports the total amount of memory and the amount of free available.
In order to get memory and swap usage from your system, you can run the plugin from the command line or through the configuration file:
In your main configuration file append the following Input & Output sections:
Key | Description | Default |
Listen | Listener network interface. | 0.0.0.0 |
Port | TCP port to listen for incoming connections. | 24224 |
Buffer_Max_Size | Buffer_Chunk_Size |
Buffer_Chunk_Size | 32KB |
Syslog input plugins allows to collect Syslog messages through a Unix socket server (UDP or TCP) or over the network using TCP or UDP.
The plugin supports the following configuration parameters:
When using Syslog input plugin, Fluent Bit requires access to the parsers.conf file, the path to this file can be specified with the option -R or through the Parsers_File key on the [SERVER] section (more details below).
When udp or unix_udp is used, the buffer size to receive messages is configurable only through the Buffer_Chunk_Size option which defaults to 32kb.
In order to receive Syslog messages, you can run the plugin from the command line or through the configuration file:
From the command line you can let Fluent Bit listen for Forward messages with the following options:
By default the service will create and listen for Syslog messages on the unix socket /tmp/in_syslog
In your main configuration file append the following Input & Output sections:
Once Fluent Bit is running, you can send some messages using the logger tool:
In Fluent Bit we should see the following output:
The following content aims to provide configuration examples for different use cases to integrate Fluent Bit and make it listen for Syslog messages from your systems.
Put the following content in your fluent-bit.conf file:
then start Fluent Bit.
Add a new file to your rsyslog config rules called 60-fluent-bit.conf inside the directory /etc/rsyslog.d/ and add the following content:
then make sure to restart your rsyslog daemon:
Put the following content in your fluent-bit.conf file:
then start Fluent Bit.
Add a new file to your rsyslog config rules called 60-fluent-bit.conf inside the directory /etc/rsyslog.d/ and place the following content:
then make sure to set proper permissions to the socket and restart your rsyslog daemon:
Random input plugin generate very simple random value samples using the device interface /dev/urandom, if not available it will use a unix timestamp as value.
The plugin supports the following configuration parameters:
In order to start generating random samples, you can run the plugin from the command line or through the configuration file:
From the command line you can let Fluent Bit generate the samples with the following options:
In your main configuration file append the following Input & Output sections:
Once Fluent Bit is running, you will see the reports in the output interface similar to this:
Process input plugin allows you to check how health a process is. It does the check by issuing a process every a certain interval of time.
The plugin supports the following configuration parameters:
In order to start performing the checks, you can run the plugin from the command line or through the configuration file:
The following example will check the health of crond process.
In your main configuration file append the following Input & Output sections:
Once Fluent Bit is running, you will see the health of process:
The head input plugin, allows to read events from the head of file. It's behavior is similar to the head command.
The plugin supports the following configuration parameters:
This mode is useful to get a specific line. This is an example to get CPU frequency from /proc/cpuinfo.
/proc/cpuinfo is a special file to get cpu information.
Cpu frequency is "cpu MHz : 2791.009". We can get the line with this configuration file.
Output is
In order to read the head of a file, you can run the plugin from the command line or through the configuration file:
The following example will read events from the /proc/uptime file, tag the records with the uptime name and flush them back to the stdout plugin:
In your main configuration file append the following Input & Output sections:
Note: Total interval (sec) = Interval_Sec + (Interval_Nsec / 1000000000).
e.g. 1.5s = 1s + 500000000ns
The stdin plugin allows to retrieve valid JSON text messages over the standard input interface (stdin). In order to use it, specify the plugin name as the input, e.g:
As input data the stdin plugin recognize the following JSON data formats:
A better example to demonstrate how it works will be through a Bash script that generates messages and writes them to . Write the following content in a file named test.sh:
Give the script execution permission:
Now lets start the script and in the following way:
The exec input plugin, allows to execute external program and collects event logs.
The plugin supports the following configuration parameters:
You can run the plugin from the command line or through the configuration file:
The following example will read events from the output of ls.
In your main configuration file append the following Input & Output sections:
The disk input plugin, gathers the information about the disk usage of the running system every certain interval of time and reports them.
The plugin supports the following configuration parameters:
In order to get disk usage from your system, you can run the plugin from the command line or through the configuration file:
In your main configuration file append the following Input & Output sections:
Note: Total interval (sec) = Interval_Sec + (Interval_Nsec / 1000000000).
e.g. 1.5s = 1s + 500000000ns
Health input plugin allows you to check how healthy a TCP server is. It does the check by issuing a TCP connection every a certain interval of time.
The plugin supports the following configuration parameters:
In order to start performing the checks, you can run the plugin from the command line or through the configuration file:
From the command line you can let Fluent Bit generate the checks with the following options:
In your main configuration file append the following Input & Output sections:
Once Fluent Bit is running, you will see some random values in the output interface similar to this:
The Systemd input plugin allows to collect log messages from the Journald daemon on Linux environments.
The plugin supports the following configuration parameters:
In order to receive Systemd messages, you can run the plugin from the command line or through the configuration file:
From the command line you can let Fluent Bit listen for Systemd messages with the following options:
In the example above we are collecting all messages coming from the Docker service.
In your main configuration file append the following Input & Output sections:
The tcp input plugin allows to listen for JSON messages through a network interface (TCP port).
The plugin supports the following configuration parameters:
In order to receive JSON messages over TCP, you can run the plugin from the command line or through the configuration file:
From the command line you can let Fluent Bit listen for JSON messages with the following options:
By default the service will listen an all interfaces (0.0.0.0) through TCP port 5170, optionally you can change this directly, e.g:
In the example the JSON messages will only arrive through network interface under 192.168.3.2 address and TCP Port 9090.
In your main configuration file append the following Input & Output sections:
Once Fluent Bit is running, you can send some messages using the netcat:
The tail input plugin allows to monitor one or several text files. It have a similar behavior to tail -f shell command.
The plugin reads every matched file in the Path pattern and for every new line found (separated by a \n), it generate a new record. Optionally a database file can be used so the plugin can have a history of tracked files and a state of offsets, this is very useful to resume a state if the service is restarted.
Content:
The plugin supports the following configuration parameters:
Note that if the database parameter db is not specified, by default the plugin will start reading each target file from the beginning.
Additionally the following options exists to configure the handling of multi-lines files:
Docker mode exists to recombine JSON log lines split by the Docker daemon due to its line length limit. To use this feature, configure the tail plugin with the corresponding parser and then enable Docker mode:
In order to tail text or log files, you can run the plugin from the command line or through the configuration file:
From the command line you can let Fluent Bit parse text files with the following options:
In your main configuration file append the following Input & Output sections:
The tail input plugin a feature to save the state of the tracked files, is strongly suggested you enabled this. For this purpose the db property is available, e.g:
When running, the database file /path/to/logs.db will be created, this database is backed by SQLite3 so if you are interested into explore the content, you can open it with the SQLite client tool, e.g:
Make sure to explore when Fluent Bit is not hard working on the database file, otherwise you will see some Error: database is locked messages.
By default SQLite client tool do not format the columns in a human read-way, so to explore in_tail_files table you can create a config file in ~/.sqliterc with the following content:
Rotation with truncation (e.g. logrotate's copytruncate mode) is not supported.
Specify the maximum buffer memory size used to receive a Forward message. The value must be according to the specification.
By default the buffer to store the incoming Forward messages, do not allocate the maximum memory allowed, instead it allocate memory when is required. The rounds of allocations are set by Buffer_Chunk_Size. The value must be according to the specification.
In we should see the following output:
Key
Description
Default
Mode
Defines transport protocol mode: unix_udp (UDP over Unix socket), unix_tcp (TCP over Unix socket), tcp or udp
unix_udp
Listen
If Mode is set to tcp, specify the network interface to bind.
0.0.0.0
Port
If Mode is set to tcp, specify the TCP port to listen for incoming connections.
5140
Path
If Mode is set to unix_tcp or unix_udp, set the absolute path to the Unix socket file.
Parser
Specify an alternative parser for the message. By default, the plugin uses the parser syslog-rfc3164. If your syslog messages have fractional seconds set this Parser value to syslog-rfc5424 instead.
Buffer_Chunk_Size
By default the buffer to store the incoming Syslog messages, do not allocate the maximum memory allowed, instead it allocate memory when is required. The rounds of allocations are set by Chunk_Size in KB. If not set, Chunk_Size is equal to 32 (32KB). Read considerations below when using udp or unix_udp mode.
Buffer_Max_Size
Specify the maximum buffer size in KB to receive a Syslog message. If not set, the default size will be the value of Chunk_Size.
Key
Description
Samples
If set, it will only generate a specific number of samples. By default this value is set to -1, which will generate unlimited samples.
Interval_Sec
Interval in seconds between samples generation. Default value is 1.
Internal_Nsec
Specify a nanoseconds interval for samples generation, it works in conjuntion with the Interval_Sec configuration key. Default value is 0.
Key
Description
Proc_Name
Name of the target Process to check.
Interval_Sec
Interval in seconds between the service checks. Default value is 1.
Internal_Nsec
Specify a nanoseconds interval for service checks, it works in conjuntion with the Interval_Sec configuration key. Default value is 0.
Alert
If enabled, it will only generate messages if the target process is down. By default this option is disabled.
Fd
If enabled, a number of fd is appended to each records. Default value is true.
Mem
If enabled, memory usage of the process is appended to each records. Default value is true.
Key
Description
File
Absolute path to the target file, e.g: /proc/uptime
Buf_Size
Buffer size to read the file.
Interval_Sec
Polling interval (seconds).
Interval_NSec
Polling interval (nanosecond).
Add_Path
If enabled, filepath is appended to each records. Default value is false.
Key
Rename a key. Default: head.
Lines
Line number to read. If the number N is set, in_head reads first N lines like head(1) -n.
Split_line
If enabled, in_head generates key-value pair per line.
Key | Description | Default |
Path | Optional path to the Systemd journal directory, if not set, the plugin will use default paths to read local-only logs. |
Max_Fields | Set a maximum number of fields (keys) allowed per record. | 8000 |
Max_Entries | When Fluent Bit starts, the Journal might have a high number of logs in the queue. In order to avoid delays and reduce memory usage, this option allows to specify the maximum number of log entries that can be processed per round. Once the limit is reached, Fluent Bit will continue processing the remaining log entries once Journald performs the notification. | 5000 |
Systemd_Filter | Allows to perform a query over logs that contains a specific Journald key/value pairs, e.g: _SYSTEMD_UNIT=UNIT. The Systemd_Filter option can be specified multiple times in the input section to apply multiple filters as required. |
Systemd_Filter_Type | Define the filter type when Systemd_Filter is specified multiple times. Allowed values are And and Or. With And a record is matched only when all of the Systemd_Filter have a match. With Or a record is matched when any of the Systemd_Filter has a match. | Or |
Tag | The tag is used to route messages but on Systemd plugin there is an extra functionality: if the tag includes a star/wildcard, it will be expanded with the Systemd Unit file (e.g: host.* => host.UNIT_NAME). |
DB | Specify the absolute path of a database file to keep track of Journald cursor. |
Read_From_Tail | Start reading new entries. Skip entries already stored in Journald. | Off |
Strip_Underscores | Remove the leading underscore of the Journald field (key). For example the Journald field _PID becomes the key PID. | Off |
Key | Description | Default |
Multiline | If enabled, the plugin will try to discover multiline messages and use the proper parsers to compose the outgoing messages. Note that when this option is enabled the Parser option is not used. | Off |
Multiline_Flush | Wait period time in seconds to process queued multiline messages | 4 |
Parser_Firstline | Name of the parser that matchs the beginning of a multiline message. Note that the regular expression defined in the parser must include a group name (named capture) |
Parser_N | Optional-extra parser to interpret and structure multiline entries. This option can be used to define multiple parsers, e.g: Parser_1 ab1, Parser_2 ab2, Parser_N abN. |
Key | Description | Default |
Docker_Mode | If enabled, the plugin will recombine split Docker log lines before passing them to any parser as configured above. This mode cannot be used at the same time as Multiline. | Off |
Docker_Mode_Flush | Wait period time in seconds to flush queued unfinished split lines. | 4 |
Key | Description |
Command | The command to execute. |
Parser | Specify the name of a parser to interpret the entry as a structured message. |
Interval_Sec | Polling interval (seconds). |
Interval_NSec | Polling interval (nanosecond). |
Key | Description |
Interval_Sec | Polling interval (seconds). default: 1 |
Interval_NSec | Polling interval (nanosecond). default: 0 |
Dev_Name | Device name to limit the target. (e.g. sda). If not set, in_disk gathers information from all of disks and partitions. |
Key | Description |
Host | Name of the target host or IP address to check. |
Port | TCP port where to perform the connection check. |
Interval_Sec | Interval in seconds between the service checks. Default value is 1. |
Internal_Nsec | Specify a nanoseconds interval for service checks, it works in conjuntion with the Interval_Sec configuration key. Default value is 0. |
Alert | If enabled, it will only generate messages if the target TCP service is down. By default this option is disabled. |
Add_Host | If enabled, hostname is appended to each records. Default value is false. |
Add_Port | If enabled, port number is appended to each records. Default value is false. |
Key | Description |
Listen | Listener network interface, default: 0.0.0.0. |
Port | TCP port where listening for connections, default: 5170. |
Buffer_Size | Specify the maximum buffer size in KB to receive a JSON message. If not set, the default size will be the value of Chunk_Size. |
Chunk_Size | By default the buffer to store the incoming JSON messages, do not allocate the maximum memory allowed, instead it allocate memory when is required. The rounds of allocations are set by Chunk_Size in KB. If not set, Chunk_Size is equal to 32 (32KB). |
Key | Description | Default |
Buffer_Chunk_Size | 32k |
Buffer_Max_Size | Buffer_Chunk_Size |
Path | Pattern specifying a specific log files or multiple ones through the use of common wildcards. |
Path_Key | If enabled, it appends the name of the monitored file as part of the record. The value assigned becomes the key in the map. |
Exclude_Path | Set one or multiple shell patterns separated by commas to exclude files matching a certain criteria, e.g: exclude_path=*.gz,*.zip |
Refresh_Interval | The interval of refreshing the list of watched files in seconds. | 60 |
Rotate_Wait | Specify the number of extra time in seconds to monitor a file once is rotated in case some pending data is flushed. | 5 |
Ignore_Older | Ignores files that have been last modified before this time in seconds. Supports m,h,d (minutes, hours,days) syntax. Default behavior is to read all specified files. |
Skip_Long_Lines | When a monitored file reach it buffer capacity due to a very long line (Buffer_Max_Size), the default behavior is to stop monitoring that file. Skip_Long_Lines alter that behavior and instruct Fluent Bit to skip long lines and continue processing other lines that fits into the buffer size. | Off |
DB | Specify the database file to keep track of monitored files and offsets. |
DB.Sync | Full |
Mem_Buf_Limit | Set a limit of memory that Tail plugin can use when appending data to the Engine. If the limit is reach, it will be paused; when the data is flushed it resumes. |
Parser | Specify the name of a parser to interpret the entry as a structured message. |
Key | When a message is unstructured (no parser applied), it's appended as a string under the key name log. This option allows to define an alternative name for that key. | log |
Tag | Set a tag (with regex-extract fields) that will be placed on lines read. E.g. |
Tag_Regex | Set a regex to exctract fields from the file. E.g. |
The serial input plugin, allows to retrieve messages/data from a Serial interface.
In order to retrieve messages over the Serial interface, you can run the plugin from the command line or through the configuration file:
The following example loads the input serial plugin where it set a Bitrate of 9600, listen from the /dev/tnt0 interface and use the custom tag data to route the message.
The above interface (/dev/tnt0) is an emulation of the serial interface (more details at bottom), for demonstrative purposes we will write some message to the other end of the interface, in this case /dev/tnt1, e.g:
In Fluent Bit you should see an output like this:
Now using the Separator configuration, we could send multiple messages at once (run this command after starting Fluent Bit):
In your main configuration file append the following Input & Output sections:
The following content is some extra information that will allow you to emulate a serial interface on your Linux system, so you can test this Serial input plugin locally in case you don't have such interface in your computer. The following procedure has been tested on Ubuntu 15.04 running a Linux Kernel 4.0.
Download the sources
Unpack and compile
Copy the new kernel module into the kernel modules directory
Load the module
You should see new serial ports in /dev/ (ls /dev/tnt*) Give appropriate permissions to the new serial ports:
When the module is loaded, it will interconnect the following virtual interfaces:
Set the initial buffer size to read files data. This value is used too to increase buffer size. The value must be according to the specification.
Set the limit of the buffer size per monitored file. When a buffer needs to be increased (e.g: very long lines), this value is used to restrict how much the memory buffer can grow. If reading a file exceed this limit, the file is removed from the monitored file list. The value must be according to the specification.
Set a default synchronization (I/O) method. Values: Extra, Full, Normal, Off. This flag affects how the internal SQLite engine do synchronization to disk, for more details about each option please refer to .
Key
Description
File
Absolute path to the device entry, e.g: /dev/ttyS0
Bitrate
The bitrate for the communication, e.g: 9600, 38400, 115200, etc
Min_Bytes
The serial interface will expect at least Min_Bytes to be available before to process the message (default: 1)
Separator
Allows to specify a separator string that's used to determinate when a message ends.
Format
Specify the format of the incoming data stream. The only option available is 'json'. Note that Format and Separator cannot be used at the same time.