Debugging Plugins

[patrickserrano]

This is more of a question than an issue, but is there any documentation available or tips you can provide for debugging plugin code? Using VS Code, I can get Monstache running with a plugin and can set breakpoints in the Monstache code but I can't figure out how to step into the plugin code.

Any tips or advice would be extremely helpful, thanks!

[patrickserrano]

I'm going to close this as I assume my issues are related to go-delve/delve#1628

[hikrr]

@patrickserrano
How did you set your launch.json to include -buildmode=plugin.
Or if you have an .so plugin, how will you set your 'launch.json' like you mentioned before. (I puts xxx.so in "args" in launch.json. And after debugging, it said 2021/11/23 00:26:33 cannot load plugin wc.so)

Did you have sample launch.json file for reference?

Thanks in advance!

[patrickserrano]

@stagmoose I can post one tomorrow when I'm on my work laptop.

With that said, as of this summer there was a limitation with the debugger on macOS that prevents stepping through code inside a Go plugin.

We worked around that by just littering our plugin with print statements while we did our dev work and taking them out when we pushed to production ¯_(ツ)_/¯

[hikrr]

@patrickserrano
Great! Thanks for your reply!

[patrickserrano]

@stagmoose here's the launch.json file. It looks like it's calling a pre-launch task which was building the plugin, but oddly enough I cannot find that task anywhere in the commit history of the repo :/ With that said, you should be fine if you just replace that with a task that build the plugin for you.

A few things to note, we passed a .env file with the connection strings and we were logging to a file because VS Code was very unhappy when we had verbose logging turned on in Monstache.

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "Launch Monstache with Plugin",
      "type": "go",
      "request": "launch",
      "preLaunchTask": "Build Plugin",
      "mode": "auto",
      "program": "${workspaceFolder}/src/monstache",
      "env": {
        "MONSTACHE_LOG_DIR": "${workspaceFolder}/logs"
      },
      "envFile": "${workspaceFolder}/debug.env",
      "args": [
        "-mapper-plugin-path",
        "./plugin.so",
        "-f",
        "../../config/config.toml",
        "--enable-http-server"
      ],
      "showLog": false,
      "trace": "error"
    }
  ]
}

I should also note that we're not really using launch.json for this project anymore, and instead have rolled a set of custom tasks to build and run a container with monstache. We're deploying to k8s, so building and testing in the container locally is closer to how it would run when deployed. So far it's been great, just took some time to get our ES cluster configured to handle the load generated by the plugin.

[hikrr]

@patrickserrano
Thanks for your long explanation! You're so kind~
I'll try things out!