redis-lua-debugger

rld is a non-interactive debugger for Lua scripts running in Redis. See this post for a runtime example.

rld's features include:

• Easy & native installation, only ~6KB payload.
• Prints output to local and remote consoles.
• Traces the execution of code lines.
• State-of-the-art automatic watch mechanism reports new variables and value changes.
• Reports function calls, returns and arguments and does on-the-fly profiling.

Basic usage

1. Load rld.lua to Redis once (e.g. redis-cli --eval rld.lua).
2. Add this line at the beginning of your Lua script: rld.start().
3. Run your code as usual (e.g. redis-cli --eval prog.lua).
4. View rld's output in Redis' log file or by subscribing to the rld channel.

API

• rld.start() - starts the debugger
• rld.stop() - stops the debugger
• rld.troff() / rld.tron() - toggles tracing off/on
• rld.options - debugger options, see source for details

TODO

• Instead of auto-watch, watch explicit variables by regex (i.e. default is .*)
• Publish to different channels according to topic (trace, variables,...)
• Add options arguments to start()

Known Issues

• This script is not compatible with Redis v3 and above (https://github.com/antirez/redis/commit/30278061cc834b4073b004cb1a2bfb0f195734f7)
• Last line of user script doesn't trigger auto-watch change printouts
• Function names are shown without global context (e.g. redis.call becomes call)
• rld functions are also traced (e.g. calling rld.stop/troff/tron from @user_script)
• Replication breaker: while the rld script is replicated, it is never run on the slave explicitly and therefore doesn't register in _G. This causes user scripts to break in the slave when trying to invoke rld.

Contributing

1. Fork it.
2. Change it.
3. Make a pull request.

License

See the LICENSE file.

DISCLAIMER

This script is highly experimental - use at your own risk! (and never in production ;))