Use the PackageSource.CacheKey function introduced in the previous
commit to determine the key at which a manifest should be cached in
the local cache.
Due to this change, manifests for moving target sources are no longer
cached and the recency threshold logic has been removed.
Introduces three new types representing each of the possible package
sources and moves the logic for specifying the package source to the
server.
Concrete changes:
* Determining whether a specified git reference is a commit vs. a
branch/tag is now done in the server, and is done more precisely by
using a regular expression.
* Package sources now have a new `CacheKey` function which can be used
to retrieve a key under which a build manifest can be cached *if*
the package source is not a moving target (i.e. a full git commit
hash of either nixpkgs or a private repository).
This function is not yet used.
* Users *must* now specify a package source, Nixery no longer defaults
to anything and will fail to launch if no source is configured.
Adds a NIX_TIMEOUT environment variable which can be set to a number
of seconds that is the maximum allowed time each Nix builder can run.
By default this is set to 60 seconds, which should be plenty for most
use-cases as Nixery is not expected to be performing builds of
uncached binaries in most production cases.
Currently the errors Nix throws on a build timeout are not separated
from other types of errors, meaning that users will see a generic 500
server error in case of a timeout.
This fixes#47
Before this change, Nixery would pass on the image name unmodified to
Nix which would lead it to cache-bust the manifest and configuration
layers for images that are content-identical but have different
package ordering.
This fixes#38.
Implements a cache that keeps track of:
a) Manifests that have already been built (for up to 6 hours)
b) Layers that have already been seen (and uploaded to GCS)
This significantly speeds up response times for images that are full
or partial matches with previous images served by an instance.
ALl the ones except for build-image.nix are considered trivial. On the
latter, nixfmt makes some useful changes but by-and-large it is not
ready for that code yet.
Instead of requiring the server component to be made aware of the
location of the Nix builder via environment variables, this commit
introduces a wrapper script for the builder that can simply exist on
the builders $PATH.
This is one step towards a slightly nicer out-of-the-box experience
when using `nix-build -A nixery-bin`.
