Small Docker image for Asterisk on Alpine Linux

WARNING. New versions of Asterisk redefine memory management functions (malloc, free), which is incompatible with MUSL libc used by Alpine.

Goals

• Create a minimal Docker image for Asterisk
• Build it from source to make it easy to build any versions, including rcs, betas or git master
• Use the bundled pjproject, not the one from the repositories
  • It's the officially recommended way to install pjsip
  • 2.5.5 currently available in Alpine repositories has multiple critical security vulnerabilities (AST-2017-009, AST-2017-003, AST-2017-002)
  • The bundled version is maintained by the Asterisk development team, as of today it's 2.7.1 for Asterisk 13 and 15, with some patches backported from the upstream.

Limitations

• No support for databases except for sqlite, no odbc modules
• Some rarely used channel drivers and other features are not built:
  • channel drivers: MGCP, Skinny, Unistim
  • DUNDi
  • some other applications and modules

Example usage

docker run -it --rm \
  --network=host \
  --name=asterisk \
  --mount type=bind,source=/etc/asterisk,destination=/etc/asterisk,ro=true \
  --mount type=bind,source=/var/lib/asterisk/sounds,destination=/var/lib/asterisk/sounds,ro=true \
  --mount type=bind,source=/var/lib/asterisk/moh,destination=/var/lib/asterisk/moh,ro=true \
  --mount type=bind,source=/var/log/asterisk,destination=/var/log/asterisk \
  ipoddubny/alpine-asterisk \
  /usr/sbin/asterisk -cvvvvf

References

• Alpine Asterisk package source: https://git.alpinelinux.org/cgit/aports/tree/main/asterisk
• Asterisk in an Alpine Linux LXC container: https://paulgorman.org/technical/asterisk-alpine-lxc.txt