In Nix the protocol was slightly altered[1] to also contain more
information about realisations. This however wasn't read from the pipe
that was used to read from the store.
After the `cmdBuildDerivation` command which caused this issue, Hydra
will issue a `cmdQueryPathInfos` that tries to read from the remote
store as well. However, there's still left over to read from the
previous command and thus Nix fails to properly allocate the expected
string.
[1] See rev a2b69660a9b326b95d48bd222993c5225bbd5b5f
Fixes#898
The queue runner used to special-case `localhost` as a remote builder:
Rather than using the normal remote-build (using the
`cmdBuildDerivation` command), it was using the (generally less
efficient, except when running against localhost) `cmdBuildPaths`
command because the latter didn't require a privileged Nix user (so made
testing easier − allowing to run hydra in a container in particular).
However:
1. this means that the build loop can follow two discint code paths depending
on the setup, the irony being that the most commonly used one in production
(the “non-localhost” case) isn't the one used in the testsuite (because all
the tests run against a local store);
2. It turns out that the “localhost” version is buggy in relatively obvious
ways − in particular a failure in a fixed-output derivation or a hash
mismatch isn't reported properly;
3. If the “run in a container” use-case is indeed that important, it can be
(partially) restored using a chroot store (which wouldn't behave excactly
the same way of course, but would be more than good-enough for testing)
This would start happening if the network connection between the Hydra
server and the remote build server breaks after sucessfully importing
at least one output of a derivation, but before having finished
importing all outputs.
Fixes#816.
Recently a few internal APIs have changed[1]. The `outputPaths` function
has been removed and a lot of data structures are modeled with
`std::optional` which broke compilation.
This patch updates the code in `hydra-queue-runner` accordingly to make
sure that Hydra compiles again.
[1] https://github.com/NixOS/nix/pull/3883
In a NixOS container, cmdBuildDerivation doesn't work because we're
not privileged. But we also don't need it because the store already
has the derivation.
Also, don't copy from/to the store since this gives errors about
missing signatures.
The hydra-queue-runner opens a connection to the builder. If the
builder is 'localhost' it starts `nix-store`, otherwise it starts
'ssh'.
Currently, if the hydra-queue-runner can not start `nix-store` (not in
the PATH for instance), the error message is:
cannot connect to ‘localhost’: error: cannot start ssh: No such file
or directory
This is not useful since ssh is actually not started:/
With this patch the error message is now:
cannot connect to ‘localhost’: error: cannot start nix-store: No such file
or directory
Thus, we no longer hold the send lock while substituting missing paths
on the build machine. This is a good thing in particular for macOS
builders which have a tendency to hang forever in curl downloads.
Setting
xxx-jobset-repeats = patchelf:master:2
will cause Hydra to perform every build step in the specified jobset 2
additional times (i.e. 3 times in total). Non-determinism is not fatal
unless the derivation has the attribute "isDeterministic = true"; we
just note the lack of determinism in the Hydra database. This will
allow us to get stats about the (lack of) reproducibility of all of
Nixpkgs.
Builds can now specify the attribute "isDeterministic = true" to tell
Hydra to build with build-repeat > 0. If there is a mismatch between
rounds, the step / build fails with a suitable status.
Maybe this should be a meta attribute, but that makes it invisible to
hydra-queue-runner, and it seems reasonable to make a claim of
mandatory determinism part of the derivation (since e.g. enabling this
flag should trigger a rebuild).
We now take into account the memory necessary for compressing the NAR
being exported to the binary cache, plus xz compression overhead.
Also, we now release the memory tokens for the NAR accessor *after*
releasing the NAR accessor. Previously the memory for the NAR accessor
might still be in use while another thread does an allocation, causing
the maximum to be exceeded temporarily.
Also, use notify_all instead of notify_one to wake up memory token
waiters. This is not very nice, but not every waiter is requesting the
same number of tokens, so some might be able to proceed.
This was a bad idea because pthread_cancel() is unsalvageable broken
in C++. Destructors are not allowed to throw exceptions (especially in
C++11), but pthread_cancel() can cause a __cxxabiv1::__forced_unwind
exception inside any destructor that invokes a cancellation
point. (This exception can be caught but *must* be rethrown.) So let's
just kill the builder process instead.
‘basicDrv.inputSrcs’ also contains the outputs of inputDrvs. These
don't necessarily exist in the local store, so copying them may cause
an exception. We should only copy the real inputSrcs.
The maximum output size per build step (as the sum of the NARs of each
output) can be set via hydra.conf, e.g.
max-output-size = 1000000000
The default is 2 GiB.
Also refactored the build error / status handling a bit.
