This flag
* Disables substituters.
* Sets the tarball-ttl to infinity (ensuring e.g. that the flake
registry and any downloaded flakes are considered current).
* Disables retrying downloads and sets the connection timeout to the
minimum. (So it doesn't completely disable downloads at the moment.)
This allows many programs (e.g. gcc, clang, cmake) to print colorized
log output (assuming $TERM is set to a value like "xterm").
There are other ways to get colors, in particular setting
CLICOLOR_FORCE, but they're less widely supported and can break
programs that parse tool output.
In a daemon-based Nix setup, some options cannot be overridden by a
client unless the client's user is considered trusted.
Currently, if an untrusted user tries to override one of those
options, we are silently ignoring it.
This can be pretty confusing in certain situations.
e.g. a user thinks he disabled the sandbox when in reality he did not.
We are now sending a warning message letting know the user some options
have been ignored.
Related to #1761.
This exploits the hermetic nature of flake evaluation to speed up
repeated evaluations of a flake output attribute.
For example (doing 'nix build' on an already present package):
$ time nix build nixpkgs:firefox
real 0m1.497s
user 0m1.160s
sys 0m0.139s
$ time nix build nixpkgs:firefox
real 0m0.052s
user 0m0.038s
sys 0m0.007s
The cache is ~/.cache/nix/eval-cache-v1.sqlite, which has entries like
INSERT INTO Attributes VALUES(
X'92a907d4efe933af2a46959b082cdff176aa5bfeb47a98fabd234809a67ab195',
'packages.firefox',
1,
'/nix/store/pbalzf8x19hckr8cwdv62rd6g0lqgc38-firefox-67.0.drv /nix/store/g6q0gx0v6xvdnizp8lrcw7c4gdkzana0-firefox-67.0 out');
where the hash 92a9... is a fingerprint over the flake store path and
the contents of the lockfile. Because flakes are evaluated in pure
mode, this uniquely identifies the evaluation result.
As long as the flake input is locked, it is now only fetched when it
is evaluated (e.g. "nixpkgs" is fetched when
"inputs.nixpkgs.<something>" is evaluated).
This required adding an "id" attribute to the members of "inputs" in
lockfiles, e.g.
"inputs": {
"nixpkgs/release-19.03": {
"id": "nixpkgs",
"inputs": {},
"narHash": "sha256-eYtxncIMFVmOHaHBtTdPGcs/AnJqKqA6tHCm0UmPYQU=",
"nonFlakeInputs": {},
"uri": "github:edolstra/nixpkgs/e9d5882bb861dc48f8d46960e7c820efdbe8f9c1"
}
}
because the flake ID needs to be known beforehand to construct the
"inputs" attrset.
Fixes#2913.
This is like 'nix run', except that the command to execute is defined
in a flake output, e.g.
defaultApp = {
type = "app";
program = "${packages.blender_2_80}/bin/blender";
};
Thus you can do
$ nix app blender-bin
to start Blender from the 'blender-bin' flake.
In the future, we can extend this with sandboxing. (For example we
would want to be able to specify that Blender should not have network
access by default and should only have access to certain paths in the
user's home directory.)
This is primarily useful for version string generation, where we need
a monotonically increasing number. The revcount is the preferred thing
to use, but isn't available for GitHub flakes (since it requires
fetching the entire history). The last commit timestamp OTOH can be
extracted from GitHub tarballs.
This ensures that flakes don't get garbage-collected, which is
important to get nix-channel-like behaviour.
For example, running
$ nix build hydra:
will create a GC root
~/.cache/nix/flake-closures/hydra -> /nix/store/xarfiqcwa4w8r4qpz1a769xxs8c3phgn-flake-closure
where the contents/references of the linked file in the store are the
flake source trees used by the 'hydra' flake:
/nix/store/n6d5f5lkpfjbmkyby0nlg8y1wbkmbc7i-source
/nix/store/vbkg4zy1qd29fnhflsv9k2j9jnbqd5m2-source
/nix/store/z46xni7d47s5wk694359mq9ay353ar94-source
Note that this in itself is not enough to allow offline use; the
fetcher for the flakeref (e.g. fetchGit or downloadCached) must not
fail if it cannot fetch the latest version of the file, so long as it
knows a cached version.
Issue #2868.
This causes 'nix' to print build log output to stderr rather than
showing the last log line in the progress bar. Log lines are prefixed
by the name of the derivation (minus the version string), e.g.
binutils> make[1]: Leaving directory '/build/binutils-2.31.1'
binutils-wrapper> unpacking sources
binutils-wrapper> patching sources
...
binutils-wrapper> Using dynamic linker: '/nix/store/kr51dlsj9v5cr4n8700jliyz8v5b2q7q-bootstrap-stage0-glibc/lib/ld-linux-x86-64.so.2'
bootstrap-stage2-gcc-wrapper> unpacking sources
...
linux-headers> unpacking sources
linux-headers> unpacking source archive /nix/store/8javli69jhj3bkql2c35gsj5vl91p382-linux-4.19.16.tar.xz
