If a repo is dirty, it used to return a `rev` object with an "empty"
sha1 (0000000000000000000000000000000000000000). Please note that this
only applies for `builtins.fetchGit` and *not* for `builtins.fetchTree{
type = "git"; }`.
The original idea was to implement a git-fetcher in Nix's core that
supports content hashes[1]. In #3549[2] it has been suggested to
actually use `fetchTree` for this since it's a fairly generic wrapper
over the new fetcher-API[3] and already supports content-hashes.
This patch implements a new git-fetcher based on `fetchTree` by
incorporating the following changes:
* Removed the original `fetchGit`-implementation and replaced it with an
alias on the `fetchTree` implementation.
* Ensured that the `git`-fetcher from `libfetchers` always computes a
content-hash and returns an "empty" revision on dirty trees (the
latter one is needed to retain backwards-compatibility).
* The hash-mismatch error in the fetcher-API exits with code 102 as it
usually happens whenever a hash-mismatch is detected by Nix.
* Removed the `flakes`-feature-flag: I didn't see a reason why this API
is so tightly coupled to the flakes-API and at least `fetchGit` should
remain usable without any feature-flags.
* It's only possible to specify a `narHash` for a `git`-tree if either a
`ref` or a `rev` is given[4].
* It's now possible to specify an URL without a protocol. If it's missing,
`file://` is automatically added as it was the case in the original
`fetchGit`-implementation.
[1] https://github.com/NixOS/nix/pull/3216
[2] https://github.com/NixOS/nix/pull/3549#issuecomment-625194383
[3] https://github.com/NixOS/nix/pull/3459
[4] https://github.com/NixOS/nix/pull/3216#issuecomment-553956703
This further continues with the dependency inverstion. Also I just went
ahead and exposed `parseDerivation`: it seems like the more proper
building block, and not a bad thing to expose if we are trying to be
less wedded to drv files on disk anywas.
On nix-env -qa -f '<nixpkgs>', this reduces maximum RSS by 20970 KiB
and runtime by 0.8%. This is mostly because we're not parsing the hash
part as a hash anymore (just validating that it consists of base-32
characters).
Also, replace storePathToHash() by StorePath::hashPart().
This function was used in only one place, where it could easily be
replaced by readDerivation() since it's not
performance-critical. (This function appears to have been modelled
after queryDerivationOutputs(), which exists only to make the garbage
collector faster.)
This fixes an issue where lockfile generation was not idempotent:
after updating a lockfile, a "follows" node would end up pointing to a
new copy of the node, rather than to the original node.
fetchTarball, fetchTree, and fetchGit all have *optional* hash attrs.
This means that we need to be careful with what we allow to avoid
accidentally making these defaults. When ‘hash = ""’ we assume the
empty hash is wanted.
follow up of https://github.com/NixOS/nix/pull/3544
This allows hash="" so that it can be used for debugging purposes. For
instance, this gives you an error message like:
warning: found empty hash, assuming you wanted 'sha256:0000000000000000000000000000000000000000000000000000'
hash mismatch in fixed-output derivation '/nix/store/asx6qw1r1xk6iak6y6jph4n58h4hdmbm-nix':
wanted: sha256:0000000000000000000000000000000000000000000000000000
got: sha256:0fpfhipl9v1mfzw2ffmxiyyzqwlkvww22bh9wcy4qrfslb4jm429
Needed so that we can include it as a logger in loggers.cc without
adding a dependency on nix
This also requires moving names.hh to libutil to prevent a circular
dependency between libmain and libexpr
The initial contents of the flake is specified by the
'templates.<name>' or 'defaultTemplate' output of another flake. E.g.
outputs = { self }: {
templates = {
nixos-container = {
path = ./nixos-container;
description = "An example of a NixOS container";
};
};
};
allows
$ nix flake init -t templates#nixos-container
Also add a command 'nix flake new', which is identical to 'nix flake
init' except that it initializes a specified directory rather than the
current directory.
Instead, `Hash` uses `std::optional<HashType>`. In the future, we may
also make `Hash` itself require a known hash type, encoraging people to
use `std::optional<Hash>` instead.
Caches tree in addition to lockedRef, and explicitly writes out the logic for different combinations of cached/uncached flakes and indirect/resolved/locked flakes. This eliminates uneccessary calls to lookupInFlakeCache, fetchTree, maybeLookupFlake, and flakeCache.push_back
The attributes previously stored in TreeInfo (narHash, revCount,
lastModified) are now stored in Input. This makes it less arbitrary
what attributes are stored where.
As a result, the lock file format has changed. An entry like
"info": {
"lastModified": 1585405475,
"narHash": "sha256-bESW0n4KgPmZ0luxvwJ+UyATrC6iIltVCsGdLiphVeE="
},
"locked": {
"owner": "NixOS",
"repo": "nixpkgs",
"rev": "b88ff468e9850410070d4e0ccd68c7011f15b2be",
"type": "github"
},
is now stored as
"locked": {
"owner": "NixOS",
"repo": "nixpkgs",
"rev": "b88ff468e9850410070d4e0ccd68c7011f15b2be",
"type": "github",
"lastModified": 1585405475,
"narHash": "sha256-bESW0n4KgPmZ0luxvwJ+UyATrC6iIltVCsGdLiphVeE="
},
The 'Input' class is now a dumb set of attributes. All the fetcher
implementations subclass InputScheme, not Input. This simplifies the
API.
Also, fix substitution of flake inputs. This was broken since lazy
flake fetching started using fetchTree internally.
In particular, doing 'nix build /path/to/dir' now works if
/path/to/dir is not a Git tree (it only has to contain a flake.nix
file).
Also, 'nix flake init' no longer requires a Git tree (but it will do a
'git add flake.nix' if it's a Git tree)
Maximilian Bosch
Jonas Chevalier