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nodejs: Receive JSON messages from nodejs applications

1: nodejs() source options

Using the nodejs() driver, AxoSyslog can receive application logs directly from nodejs applications that use the widespread Winston logging API. The AxoSyslog application automatically adds the .nodejs.winston. prefix to the name of the fields the extracted from the message.

To use the nodejs() driver, the scl.conf file must be included in your AxoSyslog configuration:

   @include "scl.conf"

The nodejs() driver is actually a reusable configuration snippet configured to receive log messages using the network() driver, and process its JSON contents. For details on using or writing such configuration snippets, see Reusing configuration blocks. You can find the source of the nodejs configuration snippet on GitHub.

Example: Using the nodejs() driver

The following example uses the default settings of the driver, listening for messages on port 9003 of every IP address of the AxoSyslog host.

   @include "scl.conf"
    source apps { nodejs(); };

The following example listens only on IP address 192.168.1.1, port 9999.

   @include "scl.conf"
    source apps {
        nodejs(
            localip(192.168.1.1)
            port(9999)
        )
    };

Note For details on the parameters of the nodejs() driver, see nodejs() source options.

1 - nodejs() source options

The nodejs() driver has the following options.

hook-commands()

Description: This option makes it possible to execute external programs when the relevant driver is initialized or torn down. The hook-commands() can be used with all source and destination drivers with the exception of the usertty() and internal() drivers.

Note The AxoSyslog application must be able to start and restart the external program, and have the necessary permissions to do so. For example, if your host is running AppArmor or SELinux, you might have to modify your AppArmor or SELinux configuration to enable AxoSyslog to execute external applications.

Using `hook-commands()` when AxoSyslog starts or stops

To execute an external program when AxoSyslog starts or stops, use the following options:

`startup()`

Type:	string
Default:	N/A

Description: Defines the external program that is executed as AxoSyslog starts.

`shutdown()`

Type:	string
Default:	N/A

Description: Defines the external program that is executed as AxoSyslog stops.

Using the hook-commands() when AxoSyslog reloads

To execute an external program when the AxoSyslog configuration is initiated or torn down, for example, on startup/shutdown or during a AxoSyslog reload, use the following options:

`setup()`

Type:	string
Default:	N/A

Description: Defines an external program that is executed when the AxoSyslog configuration is initiated, for example, on startup or during a AxoSyslog reload.

`teardown()`

Type:	string
Default:	N/A

Description: Defines an external program that is executed when the AxoSyslog configuration is stopped or torn down, for example, on shutdown or during a AxoSyslog reload.

Example: Using hook-commands() with a network source

In the following example, the hook-commands() is used with the network() driver and it opens an iptables port automatically as AxoSyslog is started/stopped.

The assumption in this example is that the LOGCHAIN chain is part of a larger ruleset that routes traffic to it. Whenever the AxoSyslog created rule is there, packets can flow, otherwise the port is closed.

source {
    network(transport(udp)
    hook-commands(
          startup("iptables -I LOGCHAIN 1 -p udp --dport 514 -j ACCEPT")
          shutdown("iptables -D LOGCHAIN 1")
        )
     );
};

ip() or localip()


Type:	string
Default:	0.0.0.0

Description: The IP address to bind to. By default, AxoSyslog listens on every available interface. Note that this is not the address where messages are accepted from.

If you specify a multicast bind address and use the udp transport, AxoSyslog automatically joins the necessary multicast group. TCP does not support multicasting.

port() or localport()


Type:	number
Default:	9003

Description: The port number to bind to.