Head
The head input plugin, allows to read events from the head of file. It's behavior is similar to the head command.
Configuration Parameters
The plugin supports the following configuration parameters:
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. |
Split Line Mode
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
Getting Started
In order to read the head of a file, you can run the plugin from the command line or through the configuration file:
Command Line
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:
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
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