Error in gargoyle-process-monitor when starting gargoyle

[mightybyte]

When I start up an app that I'm trying to use gargoyle with, I get this error:

gargoyle-postgres-monitor: createProcess: runInteractiveProcess: exec: does not exist (No such file or directory)

This is running on Linux (ubuntu) using a binary compiled with nix-build. In other runs I've also seen it fail with the above message but s/gargoyle-postgres-monitor/pg_ctl/.

[ryantrinkle]

I think we've gotta do three things here:

• Make this warning a bit more prominent: "Note that gargoyle-psql assumes that PostgreSQL executables such as psql are available on the PATH. A custom 'Gargoyle' is required to use non-standard PostgreSQL installations."
• Make this error message more indicative of what's happening
• Word the warning a bit more clearly

[mightybyte]

Also...do you have a story for using both? I've got CI infrastructure running builds with both Nix and Stack. It would be nice if it could be done without the user having to use CPP.

[ryantrinkle]

Interesting point! I'm not sure what the right way to pass that parameter would be. gargoyle-postgres-nix basically means "i want to capture the version of postgres at compile time", whereas gargoyle-postgres means "i want to capture the version of postgres at runtime". Even in the latter case, it can be provided by nix! And actually, I'm not sure the -nix version truly depends on nix - maybe it's just a compile/runtime distinction.

None of that really clarifies for me how the decision should be made, but perhaps if you start from where it is actually made (in your CI/build system), there's a path that makes sense to getting that info to gargoyle.

[mightybyte]

Also, my main motivation for using Gargoyle in the first place was to make it so users of my application don't have to do any postgres installation. I'd like them to just be able to run it and be off to the races. But I also don't know that I want to impose Nix on them. The burden of installing Nix for some users might be higher than that of installing Postgres. I'm not sure what this implies for binary distribution. I guess my vague hope was that it would all be compiled into the binary. But maybe that's not realistic.