If you still have your old CS 1.5 installation around and want to play online with your friends, just use this image or build it yourself with a modified configuration.
This uses and old Ubuntu (14.04) i386 installation. This has two reasons. Newer glibc version (~ >=2.25) won't work with the hlds executables and it's easier to compile the shared libraries for a pure i386 system.
Copy the necessary files to files directory and run.
$ docker build . -t slangenmaier/counterstrike-15
The installation files are mirrored here: https://github.com/stefan-langenmaier/counterstrike-15/releases/tag/initial-release
The rcon_password is hardcoded so you probably want to change that. Look into the install.sh for that.
If you want to run with an open console execute the following:
$ docker run -it --rm -p 27015:27015/udp slangenmaier/counterstrike-15
The hl boom fix is not enabled. It's segfaulting for me.