Saturday, October 18, 2014

Kamailio 4.2 Tips: #5 - Read configuration file from standard input

Kamailio is reading configuration file by default from Linux standard paths:

  • /etc/kamailio/kamailio.cfg - when installed via packages (e.g., deb, rpm)
  • /usr/local/etc/kamailio/kamailio.cfg - when installed from souces
A custom path to a configuration file can be given using -f command line parameter:

kamailio -f /path/to/kamailio.cfg

Actually it doesn't even matter the file name, can be anything, not only kamailio.cfg. As a side note, with this option, you can run multiple instances of Kamailio on same box, from same installation file, just be sure you have configs with different listen socket (e.g., different IP address or port or protocol).

Kamailio 4.2 adds the option to read the configuration file from standard input: the value for -f parameter has to be - (dash line). It is very unlikely than one would like to type the configuration file via keyboard, but can be useful to pipe the output of another application to Kamailio. That application has to print to terminal (standard output) a Kamailio configuration file) to Kamailio.

This can be useful for:
  • keep configuration files on a centralided system and get it only when starting Kamailio -- could increase the security by not storing locally a file that has credentials to connect to database
  • write an application that embeds kamailio.cfg and prints it based on a key -- the key can be used also for encrypting the embedded kamailio.cfg, increasing the security
For example, next is the command to get latest kamailio.cfg from Kamailio repository with wget and start Kamailio without storing the configuration file locally:

wget -qO- --no-check-certificate \ \
   | kamailio -f -

Note: the command expects Kamailio to be installed from source code (i.e., with modules in /usr/local/lib/kamailio/modules).

Enjoy it!

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