To use the local Nix store (default):
store_mode = direct
To use a local binary cache:
store_mode = local-binary-cache
binary_cache_dir = /var/lib/hydra/binary-cache
To use an S3 bucket:
store_mode = s3-binary-cache
binary_cache_s3_bucket = my-nix-bucket
Also, respect binary_cache_{secret,public}_key_file for signing the
binary cache.
The queue runner no longer uses this field, and it doesn't provide
very interesting historical data (mostly SSH failures), but it takes
up a lot of space. Also, it contained some bad UTF-8 which was
preventing an upgrade to Postgres 9.5, so a good occasion to get rid
of it.
The required configuration in hydra.conf:
enable_google_login = 1
google_client_id = 238429sdjkds....apps.googleusercontent.com
and optionally persona_allowed_domains to restrict to one or more
domains.
This is necessary given the current size of the Nixpkgs/NixOS
jobsets. Once we have a Nix store + Postgres on SSD, we can reduce
this again.
Should really make this configurable...
The uid split a while back caused the web interface to create GC roots
in /nix/var/nix/gcroots/per-user/hydra-www, where they wouldn't be
purged by hydra-update-gc-roots. Thus restarted builds would
accumulate forever. The fix is to keep the roots in a shared directory
with gid=hydra.
Regression introduced by 1fdc258de0.
The commit introduced a channel/custom PathPart which uses the new
custom channel expressions, but I forgot to remove CaptureArgs, so the
URL really is channel/latest/ignored-value.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Reported-by: Peter Simons <simons@cryp.to>
This removes the "busy", "locker" and "logfile" columns, which are no
longer used by the queue runner. The "Running builds" page now only
shows builds that have an active build step.
Previously, priority bumps could take a long time to get noticed if
getQueuedBuilds() was busy processing zillions of queue
additions. (This was made worse by the reintroduction of substitute
checking.)
We have this set in upgrade-42.sql, so it's better to stay consistent
with the basic SQL file to avoid problems with new Hydra installations.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Reported-by: Eelco Dolstra <eelco.dolstra@logicblox.com>
There is still a tiny window between the calls to nix-prefetch-* and
addTempRoot. This could be eliminated by adding a "-o" option to
nix-prefetch-*, or by not using those scripts at all (and use
addToStore directly).
This allows Hydra to use binaries from available binary caches. It
makes the queue monitor thread quite a bit slower, so if you don't
want to use binary caches, it's better to add "--option
build-use-substitutes false" to the hydra-queue-runner invocation.
Fixed#243.
The last paragraph states about package installation of the "following"
jobs, but it only applies to generic channels, so let's only display it
there.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
So this is the final part which is needed in order to be able to deliver
custom channels, everything else is now just polishing.
We do this by simply redirecting to the build product download URL and
we use binary_cache_url the same way as in NixChannel.pm.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
We should now get an overview and help text on how to add a particular
channel and also a bit of information about the builds that are required
for a channel to get upgraded.
Right now we only select the latest successful build in the latest
successful evaluation, so if someone wants to have more information about
which channel has failed, (s)he still has to look at the "Channels" tab
of the jobset.
We can make this more fancy at some later point if this is really
needed, because right now we're only interested in the latest build,
because it's the only thing necessary to deliver the channel contents.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
It's actually lower-case _despite_ the spelling in the SQL file(s),
because the schema auto-generator from DBIx::Class doesn't take it into
account because it's working on SQLite and the latter seems to ignore
case.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
We want to have contents and detauls of channel expressions as well and
we already have that in product.type == file, so why not reuse the same
for the channel expression?
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
We now have a searchBuildsAndEvalsForJobset, which creates such a
mapping for us, so we don't need to duplicate code in jobs_tab and
channels_tab.
Also, we're going to use this for the overview of a particular channel
as well, so it makes sense to put it in CatalystUtils instead of
directly in Jobset.pm.
Instead of eval->jobs, it's now eval->builds, because it's really an
aggregate over the builds schema, rather than the job schema.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
We only allow channel/latest anyway, so it really doesn't make sense to
explicitly specify this in the PathPart and provide other dispatcher
once we have more than just "latest", which greatly simplifies the
dispatch tree.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
We now have a column for that, so no need for counting rows which was a
bit inefficient anyway, because we only would have needed the first row
in the result.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Now that we have our dedicated "Channels" tab, there is no need anymore
to show redundant information.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
We now no longer need that additional join of the build outputs and can
solely use the isChannel column of the Builds table to determine whether
it's a channel build.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
This is to properly separate channels from regular jobs and also make
sure that we can always iterate on them, no matter whether the build has
failed. The reason why we were not able to do this until now was because
we were iterating on the build products, and whenever some constituent
of a channel job has failed, we didn't get a build output.
So whenever there is a meta.isHydraChannel, we can now properly
distinguish it from the other jobs.
I still don't have any clue, why "make -C src/sql update-dbix" without
*any* modifications tries to create additional schema definitions. But
I've checked the md5sums of the existing schema definitions and they
don't seem to match, so it seems that they already have been tampered
with.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Now we can provide different channel expressions for one particular
channel build. Not sure yet how this would be useful, but I found it
more appropriate to use a type instead of a subtype of "file".
This should get us consistent with the provious commit.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
This is to get a bit more consistency among channel builds but doesn't
do a radical change on the display. Ideally we may want to have a
channel overview with all the constituents and a small help showing how
the user can add the channel.
Unfortunately, this also introduces an inconsistency: We previously used
the *subtype* "channel", but now we're expecting "channel" as the type
of the product, so we need to change this for the channels overview as
well.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
It's very similar to "jobs" and the code is pretty much the same, except
that we don't do filtering on it. At least it doesn't waste space for a
filter option when there are usually WAY less channel jobs than ordinary
jobs.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Currently I'm using a (not very well) downscaled version of the NixOS
logo, so we want to replace it by a proper image ASAP.
Other than that, the idea is to have something like this in
hydra-build-products:
file channel $out/channel.tar.bz2
Right now of course, it's only displayed at the corresponding builds, so
we might want to have aggregates on all channels for a project, jobset
or maybe even single jobs?
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
They will show up in machineTypes as (e.g.) x86_64-linux:local instead
of x86_64-linux. This is to prevent the Hydra provisioner from
creating machines for steps that are supposed to be executed locally.
It's easier for the Hydra provisioner to put host public keys in the
machines file than to separately manage the known_hosts file
(especially when the provisioner runs on a different machine).
This is necessary because the required system type can become
available later (e.g. by being provisioned by the
auto-scaler). However, in the future, we may want to fail steps if
they have been unsupported for more than a certain amount of time.
For example, steps that require the "kvm" feature may require a
different kind of machine to be provisioned. This can also be used to
require performance-sensitive tests to run on a particular kind of
machine, e.g., by setting requiredSystemFeatures to something like
"ec2-i2.8xlarge".
"hydra-queue-runner --status" now prints how many runnable and running
build steps exist for each machine type. This allows additional
machines to be provisioned based on the Hydra load.
If there is no input named 'inputs', hydra-eval-jobs now passes in a set
of lists, where each attribute corresponds to an input defined in the
jobset specification and each list element is a different input alt, as
an argument named 'inputs'.
Among other things, this allows for generic hydra expressions to be
shared amongst projects with similar structures but different sets of
specific inputs.
Builds can now emit metrics that Hydra will store in its database and
render as time series via flot charts. Typical applications are to
keep track of performance indicators, coverage percentages, artifact
sizes, and so on.
For example, a coverage build can emit the coverage percentage as
follows:
echo "lineCoverage $pct %" > $out/nix-support/hydra-metrics
Graphs of all metrics for a job can be seen at
http://.../job/<project>/<jobset>/<job>#tabs-charts
Specific metrics are also visible at
http://.../job/<project>/<jobset>/<job>/metric/<metric>
The latter URL also allows getting the data in JSON format (e.g. via
"curl -H 'Accept: application/json'").
If Hydra isn't hosted on https://example.com/ but something like
https://example.com/hydra/, the URL for /api/scmdiff would have ended up
on /api/scmdiff rather than /hydra/api/scmdiff.
This is because we didn't use the URI resolver from the controller,
hence we're using it now to build up the whole URL including the query
string.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Without an index on (machine, stoptime desc), this requires a
sequential scan. And adding a whole index for this seems
overkill. (Possibly the queue runner could maintain this info more
efficiently.)
This prevents a race where multiple threads see that machine X is
missing path P, and start sending it concurrently. Nix handles this
correctly, but it's still wasteful (especially for the case where P ==
GHC).
A more refined scheme would be to have per machine, per path locks.
Derivations with "preferLocalBuild = true" can now be executed on
specific machines (typically localhost) by setting the mandary system
features field to include "local". For example:
localhost x86_64-linux,i686-linux - 10 100 - local
says that "localhost" can *only* do builds with "preferLocalBuild =
true". The speed factor of 100 will make the machine almost always win
over other machines.
Otherwise we never recover from reset daemon connections, e.g.
hydra-queue-runner[16106]: while loading build 599369: cannot start daemon worker: reading from file: Connection reset by peer
hydra-queue-runner[16106]: while loading build 599236: writing to file: Broken pipe
...
The error is now handled queueMonitor(), causing the next call to
queueMonitorLoop() to create a new connection.
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.
Having a hundred threads doing I/O at the same time is bad on magnetic
disks because of the excessive disk seeks. So allow only 4 threads to
copy closures in parallel.
While sorting machines by load, the load of a machine
(machine->currentJobs) can be changed by other threads. If that
happens, the comparator is no longer a proper ordering, in which case
std::sort() can segfault. So we now make a copy of currentJobs before
sorting.
There is a slight possibility that the queue monitor and a builder
thread simultaneously decide to mark a build as finished. That's fine,
as long as we ensure the DB update is idempotent (as ensured by doing
"update Builds set finished = 1 ... where finished = 0").
If a build A depends on a derivation that is the top-level derivation
of some build B, then we should process B before A (meaning we
shouldn't make the derivation runnable before B has been
added). Otherwise, the derivation will be "accounted" to A rather than
B (so the build step will show up in the wrong build).
Aborted builds are now put back on the runnable queue and retried
after a certain time interval (currently 60 seconds for the first
retry, then tripled on each subsequent retry).
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.
It just makes things unnecessarily complicated. We can just exit
without cleaning anything up, since the only thing to do is unmark
builds and build steps as busy. But we can do that by having systemd
call "hydra-queue-runner --unlock" from ExecStopPost.
If multiple threads create a step for the same build, they could get
the same "max(stepnr)" and allocate conflicting new step numbers. So
lock the BuildSteps table while doing this. We could use a different
isolation level, but this is easier.
This removes the need for Nix's build-remote.pl.
Build logs are now written to $HYDRA_DATA/build-logs because
hydra-queue-runner doesn't have write permission to /nix/var/log.
When visiting the tail-reload page, for a short amount of time the
"unscrolled" version is shown. To circumvent that, let's scroll down
immediately at the first possibility to fill the gap between the loading
of the document and the first AJAX request coming in.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
There are quite a lot of build outputs which have lines with a length
exceeding the width of the taillog <pre/> and thus visually produce more
lines than 50. This causes the tail "box" to change height frequently
and to get to the bottom you need to scroll down.
We now set a fixed line-height to 120% of the font size and cap the
maximum height based on that value (50 * 1.2 = 60). It's probably not
nice to override the line-height, but max-lines is currently only
available using browser-specific property names. But after all it's just
for the tail output, if people complain about the line-height, we can
still change it :-)
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
We're just implicitly escaping the tail content by not using .load() but
explicitly setting the text content using .text(), so that escaping
isn't needed on our side.
This should get rid of a few formatting errors and possibly XSS if
someone manages to place JS code in the tail of a build and manages to
lurk a user to that tail output.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Like eval IDs, build IDs don't convey useful information.
Also, make the job name link to the build rather than the job. When
people click on a build, they expect to go to the build page, not the
job page.
Scheduling is mostly based on jobset shares these days. So showing and
sorting by priority just wastes space and gives the incorrect
impression that Hydra executes builds in the order shown on the queue
page.
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.
...
There is no point in indexing rows with common column values like
"finished = 1", since those are the majority of the table. Only the
exceptions ("finished = 0") are interesting. Having smaller tables
should make updates/insertions faster.
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.
This adds a Hydra plugin for users to submit their open source projects
to the Coverity Scan system for analysis.
First, add a <coverityscan> section to your Hydra config, including the
access token, project name, and email, and a regex specifying jobs to
upload:
<coverityscan>
project = testrix
jobs = foobar:.*:coverity.*
email = aseipp@pobox.com
token = ${builtins.readFile ./coverity-token}
</coverityscan>
This will upload the scan results for any job whose name matches
'coverity.*' in any jobset in the Hydra 'foobar' project, for the
Coverity Scan project named 'testrix'.
Note that one upload will occur per job matched by the regular
expression - so be careful with how many builds you upload.
The jobs which are matched by the jobs specification must have a file in
their output path of the form:
$out/tarballs/...-cov-int.(xz|lzma|zip|bz2|tgz)
The file must have the 'cov-int' directory produced by `cov-build` in
the root.
(You can also output something into
$out/nix-support/hydra-build-products for the Hydra UI.)
This file will be found in the store, and uploaded to the service
directly using your access credentials. Note the exact extension: don't
use .tar.xz, only use .xz specifically.
Signed-off-by: Austin Seipp <aseipp@pobox.com>
Fixes errors like:
Caught exception in engine "Wide character in syswrite at /nix/store/498lwsrn5kkdh1q8kn3vcpd3457w6m7a-hydra-perl-deps/lib/perl5/site_perl/5.16.3/Starman/Server.pm line 547."
Note that these errors didn't happen if the database encoding was set
to SQL_ASCII (which was the case for hydra.nixos.org, explaining why
it didn't get these errors). However, now the encoding must be
UTF8. To change it, do:
update pg_database set encoding = pg_char_to_encoding('UTF8') where datname = 'hydra';
This gets rid of the warning:
DBIx::Class::Storage::DBI::select_single(): Query returned more than one row. SQL that returns multiple rows is DEPRECATED for ->find and ->single at /home/eelco/Dev/hydra/src/script/../lib/Hydra/Controller/Project.pm line 15
In the dashboard and on the job page, indicate whether the job appears
in the latest jobset eval. That way, the user gets some indication if
a job has accidentally disappeared (e.g. due to an evaluation error).
Use the following in your hydra.conf to make your instance a
private Hydra instance (public is the default):
private 1
Currently, this will not allow you to use the API, channels
and the binary cache when running in private mode. We will add
solutions for these functionalities later.
This requires adding the following to hydra.conf:
binary_cache_key_name = <key-name>
binary_cache_private_key_file = <path-to-private-key>
e.g.
binary_cache_key_name = hydra.nixos.org-1
binary_cache_private_key_file = /home/hydra/cache-key.sec
All successful, non-garbage-collected builds in the evaluation are
passed in a attribute set. So if you declare a Hydra input named
‘foo’ of type ‘eval’, you get a set with members ‘foo.<jobname>’. For
instance, if you passed a Nixpkgs eval as an input named ‘nixpkgs’,
then you could get the Firefox build for x86_64-linux as
‘nixpkgs.firefox.x86_64-linux’.
Inputs of type ‘eval’ can be specified in three ways:
* As the number of the evaluation.
* As a jobset identifier (‘<project>:<jobset>’), which will yield the
latest finished evaluation of that jobset. Note that there is no
guarantee that any job in that evaluation has succeeded, so it might
not be very useful.
* As a job identifier (‘<project>:<jobset>:<job>’), which will yield
the latest finished evaluation of that jobset in which <job>
succeeded. In conjunction with aggregate jobs, this allows you to
make sure that the evaluation contains the desired builds.
For users who only have the "create-projects" role, actually display the
item in the menu as the only option.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
This reverts commit 2d7e106d29.
Unfortunately some jobsets still depend on this behaviour. They could
probably do something like "assert system == input.system; ..." but
changing them all is undesirable.
Include information about who changed the build status in notification
emails, and enable optional per-input notification of said committers.
Conflicts due to two branches modifying the database schema.
Signed-off-by: Shea Levy <shea@shealevy.com>
Conflicts:
src/lib/Hydra/Schema/Jobsets.pm
src/sql/upgrade-23.sql
Currently the dashboard allows users to get a quick overview of the
status of jobs they're interested in, but more will be added,
e.g. viewing all your jobsets or all jobs of which you're a
maintainer.
There are jobsets that are evaluated only once, that is, after they've
been evaluated, they're disabled automatically. This is primarily
useful for doing releases: for instance, doing an evaluation with
"officialRelease" set to "true" should be done only once.
If there are builds in the queue that depend on another scheduled
build, then hydra-queue-runner will start the dependency first and
block the dependent builds. This is implemented in
findBuildDependencyInQueue. However, if there are tens of thousands
of such dependent builds, since each call to
findBuildDependencyInQueue may take a second or so, hydra-queue-runner
will spend hours just deciding which builds *not* to do. Thus very
little progress is made.
So now, when a build is started, we immediately check which builds are
"blocked" by it (i.e. depend on it), and remove such builds from
consideration.
We can just show the normal "edit jobset" page for the original jobset
and then do a PUT request to create a new jobset.
Also simplified updating the jobset inputs. We can just delete all of
them and recreate them from the user parameters. That's safe because
it's done in a transaction.
It's now a dropdown menu in the tabs thingy, which subsumes the
"Reproduce locally" button. This makes the actions in the menu a bit
more visible, IMHO.
This commit is provided by (zsh syntax):
sed -i 's|/static[^"]*|[% c.uri_for("&") %]|;s/\[% size %\]/${size}/' **/*.tt
And the reason for this change is to make it easier to change the base
path with headers like X-Request-Base to be served within a URI prefix,
especially when behind a reverse proxy.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Pick the jobset that has used the smallest fraction of its share,
rather than the jobset furthest below its share in absolute terms.
This gives jobsets with a small share a quicker start (but they
will also run out of their share quicker).
Each jobset now has a "scheduling share" that determines how much of
the build farm's time it is entitled to. For instance, if a jobset
has 100 shares and the total number of shares of all jobsets is 1000,
it's entitled to 10% of the build farm's time. When there is a free
build slot for a given system type, the queue runner will select the
jobset that is furthest below its scheduling share over a certain time
window (currently, the last day). Withing that jobset, it will pick
the build with the highest priority.
So meta.schedulingPriority now only determines the order of builds
within a jobset, not between jobsets. This makes it much easier to
prioritise one jobset over another (e.g. nixpkgs:trunk over
nixpkgs:stdenv).
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>
We now keep *all* unfinished evaluations of a jobset, in addition to
the <keepnr> most recent finished evaluations.
The main motivation is to ensure that mirror-{nixos,nixpkgs} work
properly: if building an evaluation takes too long, some of its builds
may already have been garbage-collected by the time the others finish.
We had Postgres barfing with this error:
DBIx::Class::Storage::DBI::_dbh_execute(): DBI Exception: DBD::Pg::st execute failed: ERROR: stack depth limit exceeded
because the ‘drvpath => [ @dependentDrvs ]’ in failDependents can
cause a query of unbounded size. (In this specific case there was a
failure of Bison, which has > 10000 dependent derivations.) So now we
just get all scheduled builds from the DB.
Due to the fixed-output derivation hashing scheme, there can be
multiple derivations of the same output path. But build logs are
indexed by derivation path. Thus, we may not be able to find the
log of a build or build step using its derivation. So as a fallback,
Hydra now looks for other derivations with the same output paths.
They're mostly redundant since there is a faster "jobs" tab on
the jobset pages now. The only thing the latter lacks is the
ability to see status change times, but those are quite expensive
to compute, and are visible on build pages if you really need them.
PostgreSQL and Perl have different sort orders, in particular when
comparing job names such as "aspell.x86_64-linux" and
"aspellDicts.cs.i686-freebsd". This confused the evaluation
comparison code, causing some jobs to appear as "removed".
So now we do all the sorting in Perl.
Fixes#105.
Aggregate constituents are derivations. However there can be multiple
builds in an evaluation that have the same derivation, i.e. they can
alias each other (e.g. "emacs", "emacs24" and "emacs24Packages.emacs"
in Nixpkgs). Previously we picked a build arbitrarily for the
AggregateConstituents table. Now we pick the one with the shortest
name (e.g. "emacs").
We now keep all builds in the N most recent evaluations of a jobset,
rather than the N most recent builds of every job. Note that this
means that typically fewer builds will be kept (since jobs may be
unchanged across evaluations).
For presentation purposes, we need to know what builds are part of an
aggregate build. So at evaluation time, look at the "members"
attribute, find the corresponding builds in the eval, and create a
mapping in the AggregateMembers table.
It redirects to the latest successful build from a finished
evaluation. This is mostly useful for the Nixpkgs/NixOS mirroring
script, which need the latest finished evaluation in which some
aggregate job (such as ‘tested’ in NixOS) succeeded.
The NrBuilds table tracks the value of ‘select count(*) from Builds
where finished = 0’, keeping it up to date via a trigger. This is
necessary to make the /all page fast, since otherwise it needs to do a
sequential scan on the Builds table.
Doing a chdir in the parent is evil. For instance, we had Hydra core
dumps ending up in the cloned directory. Therefore, the function
‘run’ allows doing a chdir in the child. The function ‘grab’ returns
the child's stdout and throws an exception if the child fails.
