This adds a `devShell` which unlike `runHydra` doesn't start hydra
automatically and doesn't receive hydra as build input. It is better
suited for interactive development cycles:
```
$ nix-shell -A devShell
$ ./bootstrap
$ configurePhase
$ make
$ # hack hack hack
$ foreman start
# test test test
<C-c>
$ # hack hack hack
```
runHyda automatically starts hydra and postgres:
```
$ nix-shell -A runHydra
```
The shell receives hydra from the working copy as buildInput.
Running hydra, queue-runner, evaluator and postgres is managed
by foreman (https://github.com/ddollar/foreman) and configured
in `Procfile`.
SQLite isn't properly supported by Hydra for a few years now[1], but
Hydra still depends on it. Apart from a slightly bigger closure this can
cause confusion by users since Hydra picks up SQLite rather than
PostgreSQL by default if HYDRA_DBI isn't configured properly[2]
[1] 78974abb69
[2] https://logs.nix.samueldr.com/nixos-dev/2020-04-10#3297342;
Apparentely, buildEnv in 20.03 no longer respects
propagated-build-inputs.
Note that the use of a library function (closePropagation) seems
fundamentally wrong to me - propagated-build-inputs should be used at
runtime, not at evaluation time.
It contains Hydra, PostgreSQL and an frontend proxy. So you can get a
running Hydra instance by doing
$ nixos-container create hydra --flake hydra
$ nixos-container start hydra
The web interface is available on port 80.
Maximilian Bosch