This makes things more efficient (we don't need to use an SSH master
connection, and we only start a single remote process) and gets rid of
locking issues (the remote nix-store process will keep inputs and
outputs locked as long as they're needed).
It also makes it more or less secure to connect directly to the root
account on the build machine, using a forced command
(e.g. ‘command="nix-store --serve --write"’). This bypasses the Nix
daemon and is therefore more efficient.
Also, don't call nix-store to import the output paths.
If derivation declares multiple outputs and first (default) output
if not "out", then "nix-instantiate" calls return path with output
names appended after "!". Than suffix must be stripped before
ant path checks are done.
This allows you to easily set up a build environment containing the
specified packages from Nixpkgs. For example:
$ nix-shell -p sqlite xorg.libX11 hello
will start a shell in which the given packages are present.
The flag ‘--check’ to ‘nix-store -r’ or ‘nix-build’ will cause Nix to
redo the build of a derivation whose output paths are already valid.
If the new output differs from the original output, an error is
printed. This makes it easier to test if a build is deterministic.
(Obviously this cannot catch all sources of non-determinism, but it
catches the most common one, namely the current time.)
For example:
$ nix-build '<nixpkgs>' -A patchelf
...
$ nix-build '<nixpkgs>' -A patchelf --check
error: derivation `/nix/store/1ipvxsdnbhl1rw6siz6x92s7sc8nwkkb-patchelf-0.6' may not be deterministic: hash mismatch in output `/nix/store/4pc1dmw5xkwmc6q3gdc9i5nbjl4dkjpp-patchelf-0.6.drv'
The --check build fails if not all outputs are valid. Thus the first
call to nix-build is necessary to ensure that all outputs are valid.
The current outputs are left untouched: the new outputs are either put
in a chroot or diverted to a different location in the store using
hash rewriting.
The tarball can now be unpacked anywhere. The installation script
uses "sudo" to create /nix if it doesn't exist. It also fetches the
nixpkgs-unstable channel.
NAR info files in binary caches can now have a cryptographic signature
that Nix will verify before using the corresponding NAR file.
To create a private/public key pair for signing and verifying a binary
cache, do:
$ openssl genrsa -out ./cache-key.sec 2048
$ openssl rsa -in ./cache-key.sec -pubout > ./cache-key.pub
You should also come up with a symbolic name for the key, such as
"cache.example.org-1". This will be used by clients to look up the
public key. (It's a good idea to number keys, in case you ever need
to revoke/replace one.)
To create a binary cache signed with the private key:
$ nix-push --dest /path/to/binary-cache --key ./cache-key.sec --key-name cache.example.org-1
The public key (cache-key.pub) should be distributed to the clients.
They should have a nix.conf should contain something like:
signed-binary-caches = *
binary-cache-public-key-cache.example.org-1 = /path/to/cache-key.pub
If all works well, then if Nix fetches something from the signed
binary cache, you will see a message like:
*** Downloading ‘http://cache.example.org/nar/7dppcj5sc1nda7l54rjc0g5l1hamj09j-subversion-1.7.11’ (signed by ‘cache.example.org-1’) to ‘/nix/store/7dppcj5sc1nda7l54rjc0g5l1hamj09j-subversion-1.7.11’...
On the other hand, if the signature is wrong, you get a message like
NAR info file `http://cache.example.org/7dppcj5sc1nda7l54rjc0g5l1hamj09j.narinfo' has an invalid signature; ignoring
Signatures are implemented as a single line appended to the NAR info
file, which looks like this:
Signature: 1;cache.example.org-1;HQ9Xzyanq9iV...muQ==
Thus the signature has 3 fields: a version (currently "1"), the ID of
key, and the base64-encoded signature of the SHA-256 hash of the
contents of the NAR info file up to but not including the Signature
line.
Issue #75.
This reverts commit 194e3374b8.
Checking the command line for GC roots means that
$ nix-store --delete $path
will fail because $path is now a root because it's mentioned on the
command line.
Ever since SQLite in Nixpkgs was updated to 3.8.0.2, Nix has randomly
segfaulted on Darwin:
http://hydra.nixos.org/build/6175515http://hydra.nixos.org/build/6611038
It turns out that this is because the binary cache substituter somehow
ends up loading two versions of SQLite: the one in Nixpkgs and the
other from /usr/lib/libsqlite3.dylib. It's not exactly clear why the
latter is loaded, but it appears to be because WWW::Curl indirectly loads
/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation,
which in turn seems to load /usr/lib/libsqlite3.dylib. This leads to
a segfault when Perl exits:
#0 0x00000001010375f4 in sqlite3_finalize ()
#1 0x000000010125806e in sqlite_st_destroy ()
#2 0x000000010124bc30 in XS_DBD__SQLite__st_DESTROY ()
#3 0x00000001001c8155 in XS_DBI_dispatch ()
...
#14 0x0000000100023224 in perl_destruct ()
#15 0x0000000100000d6a in main ()
...
The workaround is to explicitly load DBD::SQLite before WWW::Curl.
nix-shell with the --command flag might be used non-interactively, but
if bash starts non-interactively (i.e. with stdin or stderr not a
terminal), it won't source the script given in --rcfile. However, in
that case it *will* source the script found in $BASH_ENV, so we can use
that instead.
Also, don't source ~/.bashrc in a non-interactive shell (detectable by
checking the PS1 env var)
Signed-off-by: Shea Levy <shea@shealevy.com>
Nixpkgs's stdenv setup script sets the "nullglob" option, but doing so
breaks Bash completion on NixOS (when ‘programs.bash.enableCompletion’
is set) and on Ubuntu. So clear that flag afterwards. Of course,
this may break stdenv functions in subtle ways...
Nixpkgs' stdenv disables dependency tracking by default. That makes
sense for one-time builds, but in an interactive environment we expect
repeated "make" invocations to do the right thing.
This reverts commit 69b8f9980f.
The timeout should be enforced remotely. Otherwise, if the garbage
collector is running either locally or remotely, if will block the
build or closure copying for some time. If the garbage collector
takes too long, the build may time out, which is not what we want.
Also, on heavily loaded systems, copying large paths to and from the
remote machine can take a long time, also potentially resulting in a
timeout.
For instance, it's pointless to keep copy-from-other-stores running if
there are no other stores, or download-using-manifests if there are no
manifests. This also speeds things up because we don't send queries
to those substituters.
Previously, if a binary cache is hanging/unreachable/slow,
download-from-binary-cache.pl would also hang without any indication
to the user. Now, if fetching a URL takes more than 5 seconds, it
will print a message to that effect.
Amazon S3 returns HTTP status code 403 if a file doesn't exist and the
user has no permission to list the contents of the bucket. So treat
it as 404 (meaning it's cached in the NARExistence table).
The "$UID != 0" makes no sense: if the local side has write access to
the Nix store (which is always the case) then it doesn't matter if
we're root - we can import unsigned paths either way.
Otherwise it will set the parent's stdin to non-blocking mode, causing
the subsequent read of the set of inputs/outputs to fail randomly.
That's insane.
Before selecting a machine, build-remote.pl will try to run the
command "nix-builds-inhibited" on the machine. If this command exists
and returns a 0 exit code, then the machine won't be used. It's up to
the user to provide this command, but it would typically be a script
that checks whether there is enough disk space and whether the load is
not too high.
Don't pass --timeout / --max-silent-time to the remote builder.
Instead, let the local Nix process terminate the build if it exceeds a
timeout. The remote builder will be killed as a side-effect. This
gives better error reporting (since the timeout message from the
remote side wasn't properly propagated) and handles non-Nix problems
like SSH hangs.
This allows providing additional binary caches, useful in scripts like
Hydra's build reproduction scripts, in particular because untrusted
caches are ignored.
