This rewrites the top-level loop of hydra-evaluator in C++. The Perl
stuff is moved into hydra-eval-jobset. (Rewriting the entire evaluator
would be nice but is a bit too much work.) The new version has some
advantages:
* It can run multiple jobset evaluations in parallel.
* It uses PostgreSQL notifications so it doesn't have to poll the
database. So if a jobset is triggered via the web interface or from
a GitHub / Bitbucket webhook, evaluation of the jobset will start
almost instantaneously (assuming the evaluator is not at its
concurrency limit).
* It imposes a timeout on evaluations. So if e.g. hydra-eval-jobset
hangs connecting to a Mercurial server, it will eventually be
killed.
In your hydra config, you can add an arbitrary number of <s3config>
sections, with the following options:
* name (required): Bucket name
* jobs (required): A regex to match job names (in project:jobset:job
format) that should be backed up to this bucket
* compression_type: bzip2 (default), xz, or none
* prefix: String to prepend to all hydra-created s3 keys (if this is
meant to represent a directory, you should include the trailing slash,
e.g. "cache/"). Default "".
After each build with an output (i.e. successful or failed-with-output
builds), the output path and its closure are uploaded to the bucket as
.nar files, with corresponding .narinfos to enable use as a binary
cache.
This plugin requires that s3 credentials be available. It uses
Net::Amazon::S3, which as of this commit the nixpkgs version can
retrieve s3 credentials from the AWS_ACCESS_KEY_ID and
AWS_SECRET_ACCESS_KEY environment variables, or from ec2 instance
metadata when using an IAM role.
This commit also adds a hydra-s3-backup-collect-garbage program, which
uses hydra's gc roots directory to determine which paths are live, and
then deletes all files except nix-cache-info and any .nar or .narinfo
files corresponding to live paths. hydra-s3-backup-collect-garbage
respects the prefix configuration option, so it won't delete anything
outside of the hierarchy you give it, and it has the same credential
requirements as the plugin. Probably a timer unit running the garbage
collection periodically should be added to hydra-module.nix
Note that two of the added tests fail, due to a bug in the interaction
between Net::Amazon::S3 and fake-s3. Those behaviors work against real
s3 though, so I'm committing this even with the broken tests.
Signed-off-by: Shea Levy <shea@shealevy.com>
