Without this, if (failed or aborted) derivations have been
garbage-collected, there is no way to restart them, which is very
annoying. Now we set a forceEval flag in the jobset to cause it to be
re-evaluated even if none of the inputs have changed.
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.
This prevents the server from gradually filling up due to store paths
fetched by hydra-server that then get turned into a GC root by
hydra-update-gc-roots.
This allows fully declarative project specifications. This is best
illustrated by example:
* I create a new project, setting the declarative spec file to
"spec.json" and the declarative input to a git repo pointing
at git://github.com/shlevy/declarative-hydra-example.git
* hydra creates a special ".jobsets" jobset alongside the project
* Just before evaluating the ".jobsets" jobset, hydra fetches
declarative-hydra-example.git, reads spec.json as a jobset spec,
and updates the jobset's configuration accordingly:
{
"enabled": 1,
"hidden": false,
"description": "Jobsets",
"nixexprinput": "src",
"nixexprpath": "default.nix",
"checkinterval": 300,
"schedulingshares": 100,
"enableemail": false,
"emailoverride": "",
"keepnr": 3,
"inputs": {
"src": { "type": "git", "value": "git://github.com/shlevy/declarative-hydra-example.git", "emailresponsible": false },
"nixpkgs": { "type": "git", "value": "git://github.com/NixOS/nixpkgs.git release-16.03", "emailresponsible": false }
}
}
* When the "jobsets" job of the ".jobsets" jobset completes, hydra
reads its output as a JSON representation of a dictionary of
jobset specs and creates a jobset named "master" configured
accordingly (In this example, this is the same configuration as
.jobsets itself, except using release.nix instead of default.nix):
{
"enabled": 1,
"hidden": false,
"description": "js",
"nixexprinput": "src",
"nixexprpath": "release.nix",
"checkinterval": 300,
"schedulingshares": 100,
"enableemail": false,
"emailoverride": "",
"keepnr": 3,
"inputs": {
"src": { "type": "git", "value": "git://github.com/shlevy/declarative-hydra-example.git", "emailresponsible": false },
"nixpkgs": { "type": "git", "value": "git://github.com/NixOS/nixpkgs.git release-16.03", "emailresponsible": false }
}
}
This is currently done by a separate program that periodically
calls "hydra-queue-runner --status". Eventually, I'll do this
in the queue runner directly.
Fixes#220.
Hydra-queue-runner now no longer polls the queue periodically, but
instead sleeps until it receives a notification from PostgreSQL about
a change to the queue (build added, build cancelled or build
restarted).
Also, for the "build added" case, we now only check for builds with an
ID greater than the previous greatest ID. This is much more efficient
if the queue is large.
These give warnings in Perl >= 5.18:
given is experimental at /home/hydra/src/hydra/src/lib/Hydra/Helper/CatalystUtils.pm line 241.
when is experimental at /home/hydra/src/hydra/src/lib/Hydra/Helper/CatalystUtils.pm line 242.
...
This incorporates the following two commits from <nixpkgs>:
NixOS/nixpkgs@f83af95f8aNixOS/nixpkgs@5e7a1cf955
Hydra was the original reason why I was fixing tempdir creation in the
first place. Seeing that Hydra ships its own versions of these scripts,
we need to patch them here as well.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
If hydra-eval-jobs creates a new root, and hydra-update-gc-roots runs
before hydra-evaluator has had a chance to add the corresponding build
to the database, then hydra-update-gc-roots will remove the root. If
subsequently the Nix garbage collector kicks in, it may remove the
build's .drv file before the build is performed. Since evaluation of
the Nixpkgs and NixOS jobsets nowadays takes a lot of time (e.g. an
hour), the probability of this happening is fairly high.
The quick fix is not to delete roots that are less than a day old. So
long as evaluation doesn't take longer than a day, this should be fine
;-)
Fixes#166.
