# improg: Program integration input module

Module Name: | improg
Authors: | Jean-Philippe Hilaire <jean-philippe.hilaire@pmu.fr> & Philippe Duveau <philippe.duveau@free.fr>

## Purpose

This module allows rsyslog to spawn external command(s) and consume message from pipe(s) (stdout of the external process).

Limitation: Be careful when you rely on stdio like printf(…) or fprintf(stdout,…) - the buffering they apply can prevent your message go out timely to improg and may make your process seem stuck. Either disable buffering or be sure to do an fflush() when ready with the current output.

The input module consume pipes form all external programs in a mono-threaded runInput method. This means that data treatments will be serialized.

Optionally, the module manage the external program through keyword sent to it using a second pipe to stdin of the external process.

An operational sample in C can be found @ “github.com/pduveau/jsonperfmon”

Also a bash’s script is provided as tests/improg-simul.sh. The echo and read (built-in) can be used to communicate with the module. External commands can not be used to communicate. printf is unable to send data directly to the module but can used through a variable and echo.

## Compile

To successfully compile improg module.

> ./configure –enable-improg …

## Configuration Parameters

### Action Parameters

#### Binary

type | mandatory | format | default
--- | --- | --- | ---
string | yes | command arguments… |

Command line : external program and arguments

#### Tag

type | mandatory | format | default
--- | --- | --- | ---
string | yes |  | none

The tag to be assigned to messages read from this file. If you would like to see the colon after the tag, you need to include it when you assign a tag value, like so: `tag="myTagValue:"`.

#### Facility

type | mandatory | format | default
--- | --- | --- | ---
string | no | facility|number | local0

The syslog facility to be assigned to messages read from this file. Can be specified in textual form (e.g. `local0`, `local1`, …) or as numbers (e.g. 16 for `local0`). Textual form is suggested.

#### Severity

type | mandatory | format | default
--- | --- | --- | ---
string | no | severity|number | notice

The syslog severity to be assigned to lines read. Can be specified in textual form (e.g. `info`, `warning`, …) or as numbers (e.g. 6 for `info`). Textual form is suggested.

#### confirmMessages

type | mandatory | format | default
--- | --- | --- | ---
binary | no | on|off | on

Specifies whether the external program needs feedback from rsyslog via stdin. When this switch is set to “on”, rsyslog confirms each received message. This feature facilitates error handling: instead of having to implement a retry logic, the external program can rely on the rsyslog queueing capabilities. The program receives a line with the word `ACK` from its standard input.

Also, the program receives a `STOP` when rsyslog ask the module to stop.

#### signalOnClose

type | mandatory | format | default
--- | --- | --- | ---
binary | no | on|off | off

Specifies whether a TERM signal must be sent to the external program before closing it (when either the worker thread has been unscheduled, a restart of the program is being forced, or rsyslog is about to shutdown).

#### closeTimeout

type | mandatory | format | default
--- | --- | --- | ---
number | no |  | 200

Specifies whether a KILL signal must be sent to the external program in case it does not terminate within the timeout indicated by closeTimeout (when either the worker thread has been unscheduled, a restart of the program is being forced, or rsyslog is about to shutdown).

#### killUnresponsive

type | mandatory | format | default
--- | --- | --- | ---
binary | no | on|off | on

Specifies whether a KILL signal must be sent to the external program in case it does not terminate within the timeout indicated by closeTimeout (when either the worker thread has been unscheduled, a restart of the program is being forced, or rsyslog is about to shutdown).

## Stop sequence

1. If confirmMessages is set to on, a STOP is written in stdin of the child.

2. If signalOnClose is set to “on”, a TERM signal is sent to the child.

3. The pipes with the child process are closed (the child will receive EOF on stdin),

4. Then, rsyslog waits for the child process to terminate during closeTimeout,

5. If the child has not terminated within the timeout, a KILL signal is sent to it.

Support: rsyslog Assistant | GitHub Discussions | GitHub Issues: rsyslog source project

Contributing: Source & docs: rsyslog source project

© 2008–2025 Rainer Gerhards and others. Licensed under the Apache License 2.0.