NIX_REMOTE_SYSTEMS path must be absolute (#957)

Once upon a time, I wrote my bachelors thesis about functional
deployment mechanisms.

I had to evaluate several szenarios where package management and
deployment were relevant. One szenario was to do distributed builds
over several machines.

I told myself: Weee, nix can do this! And with nix, this is actually
save, as you do not have side effects when building!

So I started. I use a cloud to set up four virtual machines where I
wanted to do the build. A fifth machine was used as master to distribute
the builds. All was good.

I created the necessary SSH keys, made sure every machine was reachable
by the master and configured the build in my remotes.conf.

When I started to try to build weechat from source, the build failed. It
failed, telling me

    error: unable to start any build; either increase ‘--max-jobs’ or enable distributed builds

And I started to dig around. I digged long and good. But I wasn't able
to find the issue.

I double and triple checked my environment variables, my settings, the
SSH key and everything.

I reached out to fellow Nixers by asking on the nixos IRC channel. And I
got help. But we weren't able to find the issue, either.

So I became frustrated. I re-did all the environment variables.

And suddenly,... it worked! What did I change? Well... I made the
environment variables which contained pathes contain absolute pathes
rather than relatives.

And because I like to share my knowledge, this should be put into the
documentation, so others do not bang their heads against the wall
because something is not documented somewhere.
This commit is contained in:
Matthias Beyer 2016-07-21 11:19:21 +02:00 committed by Domen Kožar
parent 2d5a99baf0
commit 2ec9d2fb02

View file

@ -44,7 +44,8 @@ outputs and perform the remote build. To use it, you should set
<envar>NIX_BUILD_HOOK</envar> to <envar>NIX_BUILD_HOOK</envar> to
<filename><replaceable>prefix</replaceable>/libexec/nix/build-remote.pl</filename>. <filename><replaceable>prefix</replaceable>/libexec/nix/build-remote.pl</filename>.
You should also define a list of available build machines and point You should also define a list of available build machines and point
the environment variable <envar>NIX_REMOTE_SYSTEMS</envar> to it. An the environment variable <envar>NIX_REMOTE_SYSTEMS</envar> to it (the
path has to be absolute, otherwise nix will fail to distribute the build). An
example configuration is shown in <xref linkend='ex-remote-systems' example configuration is shown in <xref linkend='ex-remote-systems'
/>. Each line in the file specifies a machine, with the following />. Each line in the file specifies a machine, with the following
bits of information: bits of information: