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Documentation -> Manuals -> Manual 3.3 -> Templating opensips.cfg FilesThis page has been visited 3001 times. Pages for other versions: devel 3.5 3.4 Older versions: 3.3 3.2 3.1 3.0
Table of Content (hide) 1. Generic Preprocessing SupportOpenSIPS 3.0+ releases offer script writers full support for piping the opensips.cfg file (including any other files imported by it) to a generic preprocessing command. This may be useful in scenarios where opensips.cfg must be parameterized (e.g. listening interfaces, ports, DB connectors, etc.) and deployed to multiple servers, in an automated fashion. The system administrator may achieve this using the "-p <cmdline>" (preprocessor) option. For example: opensips -f opensips.cfg -p /bin/cat ... is a basic use of the "-p" option, by supplying it with an "echo" preprocessor that receives input via standard input and mirrors it to standard output. From here, it's just a matter of choosing a templating language which fits the deployment requirements. Some basic substitutions can be done using, for example, sed: opensips -f opensips.cfg -p "/bin/sed s/PRIVATE_IP/10.0.0.10/g" 2. Common Templating Languages + ExamplesBelow are some examples of using more advanced templating languages on top of opensips.cfg, for cases where the target environment requires complex decision-making (if statements which enable/disable features, for loops over multiple listening interfaces, etc.). 2.1 GNU m4GNU m4 is a simplistic preprocessor with a mild learning curve, equipped with textual substitution, if statements and file includes among the most notable features. Here is an example integration with opensips.cfg: listen = udp:PRIVATE_IP:5060 loadmodule "proto_udp.so" opensips.cfg.m4
divert(-1) define(`PRIVATE_IP', `127.0.0.1') divert(0)dnl env.m4
opensips -f opensips.cfg.m4 -p "m4 env.m4 -" 2.2 Jinja2Jinja2 is a modern templating language with a rich feature set, including textual replacement, if statements, for loops, a plethora of filters, file includes, and the list goes on! Unlike m4, Jinja2 does not currently have a standalone binary, rather it is provided via a Python package. Here is a way of integrating it with opensips.cfg:
listen = udp:{{ private_ip }}:5060 loadmodule "proto_udp.so" opensips.cfg.j2
import sys import json from jinja2 import Template t = Template("".join(sys.stdin.readlines())) with open('env.json') as f: print(t.render(json.load(f))) opensips-preproc.py
{ "private_ip": "127.0.0.1" } env.json
opensips -f opensips.cfg.j2 -p "python opensips-preproc.py" 2.3 Embedded RubyEmbedded Ruby (ERB) provides an easy to use, powerful templating system for Ruby. Using ERB, actual Ruby code can be added to any plain text document for the purposes of generating document information details and/or flow control. Let's see how it integrates with opensips.cfg!
listen = udp:<%= private_ip %>:5060 loadmodule "proto_udp.so" opensips.cfg.erb
#!/usr/bin/env ruby require 'erb' require './env.rb' template = ERB.new($stdin.read, nil, '-') $stdout.write template.result($erb_context) ~/src/opensips-preproc.rb
$erb_context = binding private_ip = '127.0.0.1' env.rb
opensips -f opensips.cfg.erb -p "ruby opensips-preproc.rb" 3. Debugging Preprocessor OutputSince the output of the preprocessor is never written to any file and is just consumed by OpenSIPS on each run, script developers may still visualize and debug the generated file during development by using a wrapper script over the preprocessing command such as the following: #!/bin/bash m4 env.m4 - | tee >(grep -v __OSSPP_ >/tmp/opensips.cfg) ~/src/preprocessor.sh
opensips -f opensips.cfg.m4 -p ~/src/preprocessor.sh
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