Previously the acknowledgement calls from Docker were receiving a
404 (which apparently doesn't bother it?!). This corrects the URL,
which meant that acknowledgement had to move inside of the
registryHandler.
Uses the structured errors feature introduced in the Nix code to
return more sensible errors to clients. For now this is quite limited,
but already a lot better than before:
* packages that could not be found result in 404s
* all other errors result in 500s
This way the registry clients will not attempt to interpret the
returned garbage data/empty response as something useful.
Adds environment variables with which users can configure the package
set source to use. Not setting a source lets Nix default to a recent
NixOS channel (currently nixos-19.03).
Instead of just dispatching on URL regexes, use handlers to split the
routes into registry-related handlers and otherwise(tm).
For now the otherwise(tm) consists of a file server serving the static
directory, rather than just a plain match on the index route.
Previously the code had hardcoded paths to runtime data (the Nix
builder & web files), which have now been moved into configuration
options.
Additionally configuration for the application is now centralised in a
single config struct, an instance of which is passed around the
application.
This makes it possible to implement a wrapper in Nix that will
configure the runtime data locations automatically.
