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exec
The
out_exec TimeSliced Output plugin passes events to an external program. The program receives the path to a file containing the incoming events as its last argument. The file format is tab-separated values (TSV) by default.It is included in Fluentd's core.
<match pattern>
@type exec
command cmd arg arg
<format>
@type tsv
keys k1,k2,k3
</format>
<inject>
tag_key k1
time_key k2
time_format %Y-%m-%d %H:%M:%S
</inject>
</match>
Please see the Configuration File article for the basic structure and syntax of the configuration file.
This example illustrates how to run FizzBuzz with
out_exec.We assume that the input file is specified by the last argument in the command line (
ARGV[-1]). The following script fizzbuzz.py runs FizzBuzz against the new-line delimited sequence of natural numbers (1, 2, 3...) and writes the output to foobar.out:#!/usr/bin/env python
import sys
input = file(sys.argv[-1])
output = file("foobar.out", "a")
for line in input:
fizzbuzz = int(line.split("\t")[0])
s = ''
if fizzbuzz%3 == 0:
s += 'fizz'
if fizzbuzz%5 == 0:
s += 'buzz'
if len(s) > 0:
output.write(s+"\n")
else:
output.write(str(fizzbuzz)+"\n")
output.close
Note that this program is written in Python. For
out_exec (as well as out_exec_filter and in_exec), the program can be written in any language, not just Ruby.Then, configure Fluentd as follows:
<source>
@type forward
</source>
<match fizzbuzz>
@type exec
command python /path/to/fizzbuzz.py
<buffer>
@type file
path /path/to/buffer_path
flush_interval 5s # for debugging/checking
</buffer>
<format>
@type tsv
keys fizzbuzz
</format>
</match>
The
@type tsv and keys fizzbuzz in <format> tells Fluentd to extract the fizzbuzz field and output it as TSV. This simple example has a single key, but you can of course extract multiple fields and use format json to output newline-delimited JSON.The intermediate TSV is at
/path/to/buffer_path, and the command python /path/to/fizzbuzz.py /path/to/buffer_path is run. This is why in fizzbuzz.py, it is reading the file at sys.argv[-1].If you start Fluentd and run this command:
$ for i in `seq 15`; do echo "{\"fizzbuzz\":$i}" | fluent-cat fizzbuzz; done
Then, after 5 seconds, you get a file named
foobar.out:$ cat foobar.out
1
2
fizz
4
buzz
fizz
7
8
fizz
buzz
11
fizz
13
14
fizzbuzz
- Asynchronous
The value must be
exec.type | default | version |
string | Nothing | 0.14.0 |
The command (program) to execute. The
exec plugin passes the path of flushed buffer chunk as the last argument.If you set
command parameter like this:command cmd arg arg
The actual command execution is:
cmd arg arg /path/to/file
If
cmd does not exist in PATH, you need to specify the absolute path, e.g. /path/to/cmd.type | default | version |
time | 270 | 0.14.9 |
Command (program) execution timeout.
type | default | version |
string | tsv | 0.14.9 |
The format used to map the incoming events to the program input.
Overwrites the default value in this plugin.
type | default | version |
string | string | 0.14.9 |
Overwrites the default value in this plugin.
type | default | version |
bool | false | 0.14.9 |
Overwrites the default value in this plugin.
type | default | version |
time | 300 | 0.14.9 |
Overwrites the default value in this plugin.
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 2yr ago