# imhttp: http input module

Module Name: | imhttp
Author: | Nelson Yen

## Purpose

Provides the ability to receive adhoc and plaintext syslog messages via http. The format of messages accepted, depends on configuration. imhttp exposes the capabilities and the underlying options of the http library used, which currently is civetweb.

Civetweb documentation:

- Civetweb User Manual

- Civetweb Configuration Options

## Notable Features

- basicAuthFile

- Error Messages

## Configuration Parameters

Note

Parameter names are case-insensitive.

### Module Parameters

#### Ports

type | mandatory | format | default
--- | --- | --- | ---
string | no | ports | 8080

Configures “listening_ports” in the civetweb library. This option may also be configured using the liboptions (below) however, this option will take precendence.

- Civetweb listening_ports

#### documentroot

type | mandatory | format | default
--- | --- | --- | ---
string | no | none | .

Configures “document_root” in the civetweb library. This option may also be configured using liboptions, however this option will take precedence.

- Civetweb document_root

#### liboptions

type | mandatory | format | default
--- | --- | --- | ---
string | no | none | none

Configures civetweb library “Options”.

- Civetweb Options

### Input Parameters

These parameters can be used with the “input()” statement. They apply to the input they are specified with.

#### Endpoint

type | mandatory | format | default
--- | --- | --- | ---
string | yes | path that begins with ‘/’ | none

Sets a request path for an http input. Path should always start with a ‘/’.

#### DisableLFDelimiter

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

By default LF is used to delimit msg frames, for data is sent in batches. Set this to ‘on’ if this behavior is not needed.

#### Name

type | mandatory | format | default
--- | --- | --- | ---
string | no |  | imhttp

Sets a name for the inputname property. If no name is set “imhttp” is used by default. Setting a name is not strictly necessary, but can be useful to apply filtering based on which input the message was received from.

#### Ruleset

type | mandatory | format | default
--- | --- | --- | ---
string | no |  | default ruleset

Binds specified ruleset to this input. If not set, the default ruleset is bound.

#### SupportOctetCountedFraming

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

Useful to send data using syslog style message framing, disabled by default. Message framing is described by RFC 6587 .

#### RateLimit.Interval

type | mandatory | format | default
--- | --- | --- | ---
integer | no | none | 0

Specifies the rate-limiting interval in seconds. Set it to a number of seconds to activate rate-limiting.

#### RateLimit.Burst

type | mandatory | format | default
--- | --- | --- | ---
integer | no | none | 10000

Specifies the rate-limiting burst in number of messages.

#### flowControl

type | mandatory | format | default
--- | --- | --- | ---
binary | no | none | on

Flow control is used to throttle the sender if the receiver queue is near-full preserving some space for input that can not be throttled.

#### addmetadata

type | mandatory | format | default
--- | --- | --- | ---
binary | no | none | off

Enables metadata injection into $!metadata property. Currently, only header data is supported. The following metadata will be injected into the following properties:

- $!metadata!httpheaders: http header data will be injected here as key-value pairs. All header names will automatically be lowercased for case-insensitive access.

- $!metadata!queryparams: query parameters from the http request will be injected here as key-value pairs. All header names will automatically be lowercased for case-insensitive access.

#### basicAuthFile

type | mandatory | format | default
--- | --- | --- | ---
string | no | none |

Enables access control to this endpoint using http basic authentication. Option is disabled by default. To enable it, set this option to a htpasswd file, which can be generated using a standard htpasswd tool.

See also:

- HTTP Authorization

- HTTP Basic Authentication

- htpasswd utility

#### basicAuthFile

type | mandatory | format | default
--- | --- | --- | ---
string | no | none | none

Configures a htpasswd file and enables basic authentication on http request received on this input. If this option is not set, basic authentation will not be enabled.

## Statistic Counter

This plugin maintains global imhttp statistics. The statistic’s origin and name is “imhttp” and is accumulated for all inputs. The statistic has the following counters:

- submitted - Total number of messages successfully submitted for processing since startup.

- failed - Total number of messages failed since startup, due to processing a request.

- discarded - Total number of messages discarded since startup, due to rate limiting or similar.

## Error Messages

When a message is to long it will be truncated and an error will show the remaining length of the message and the beginning of it. It will be easier to comprehend the truncation.

## Caveats/Known Bugs

- module currently only a single http instance, however multiple ports may be bound.

## Examples

### Example 1

This sets up a http server instance on port 8080 with two inputs. One input path at ‘/postrequest’, and another at ‘/postrequest2’:

    # ports=8080
    # document root='.'
    module(load="imhttp") # needs to be done just once

    # Input using default LF delimited framing
    # For example, the following http request, with data body "Msg0001\nMsg0002\nMsg0003"
    ##
    # - curl -si http://localhost:$IMHTTP_PORT/postrequest -d $'Msg0001\nMsg0002\nMsg0003'
    ##
    # Results in the 3 message objects being submitted into rsyslog queues.
    # - Message object with `msg` property set to `Msg0001`
    # - Message object with `msg` property set to `Msg0002`
    # - Message object with `msg` property set to `Msg0003`

    input(type="imhttp"
          name="myinput1"
          endpoint="/postrequest"
          ruleset="postrequest_rs")

    # define 2nd input path, using octet-counted framing,
    # and routing to different ruleset
    input(type="imhttp"
          name="myinput2"
          endpoint="/postrequest2"
          SupportOctetCountedFraming="on"
          ruleset="postrequest_rs")

    # handle the messages in ruleset
    ruleset(name="postrequest_rs") {
       action(type="omfile" file="/var/log/http_messages" template="myformat")
    }

### Example 2

This sets up a http server instance on ports 80 and 443s (use ‘s’ to indicate ssl) with an input path at ‘/postrequest’:

    # ports=8080, 443 (ssl)
    # document root='.'
    module(load="imhttp" ports=8080,443s)
    input(type="imhttp"
          endpoint="/postrequest"
          ruleset="postrequest_rs")

### Example 3

imhttp can also support the underlying options of Civetweb using the liboptions option.

    module(load="imhttp"
           liboptions=[
             "error_log_file=my_log_file_path",
             "access_log_file=my_http_access_log_path",
           ])

    input(type="imhttp"
          endpoint="/postrequest"
          ruleset="postrequest_rs"
          )

See also

Help with configuring/using `Rsyslog`:

- Mailing list - best route for general questions

- GitHub: rsyslog source project - detailed questions, reporting issues that are believed to be bugs with `Rsyslog`

- Stack Exchange (View, Ask) - experimental support from rsyslog community

See also

Contributing to `Rsyslog`:

- Source project: rsyslog project README.

- Documentation: rsyslog-doc project README

Copyright 2008-2020 Rainer Gerhards (Großrinderfeld), and Others.