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diff --git a/doc/manual/src/release-notes/rl-0.8.md b/doc/manual/src/release-notes/rl-0.8.md new file mode 100644 index 000000000..626c0c92b --- /dev/null +++ b/doc/manual/src/release-notes/rl-0.8.md @@ -0,0 +1,166 @@ +# Release 0.8 (2005-04-11) + +NOTE: the hashing scheme in Nix 0.8 changed (as detailed below). As a +result, `nix-pull` manifests and channels built for Nix 0.7 and below +will not work anymore. However, the Nix expression language has not +changed, so you can still build from source. Also, existing user +environments continue to work. Nix 0.8 will automatically upgrade the +database schema of previous installations when it is first run. + +If you get the error message + + you have an old-style manifest `/nix/var/nix/manifests/[...]'; please + delete it + +you should delete previously downloaded manifests: + + $ rm /nix/var/nix/manifests/* + +If `nix-channel` gives the error message + + manifest `http://catamaran.labs.cs.uu.nl/dist/nix/channels/[channel]/MANIFEST' + is too old (i.e., for Nix <= 0.7) + +then you should unsubscribe from the offending channel (`nix-channel +--remove +URL`; leave out `/MANIFEST`), and subscribe to the same URL, with +`channels` replaced by `channels-v3` (e.g., +<http://catamaran.labs.cs.uu.nl/dist/nix/channels-v3/nixpkgs-unstable>). + +Nix 0.8 has the following improvements: + + - The cryptographic hashes used in store paths are now 160 bits long, + but encoded in base-32 so that they are still only 32 characters + long (e.g., + `/nix/store/csw87wag8bqlqk7ipllbwypb14xainap-atk-1.9.0`). (This is + actually a 160 bit truncation of a SHA-256 hash.) + + - Big cleanups and simplifications of the basic store semantics. The + notion of “closure store expressions” is gone (and so is the notion + of “successors”); the file system references of a store path are now + just stored in the database. + + For instance, given any store path, you can query its closure: + + $ nix-store -qR $(which firefox) + ... lots of paths ... + + Also, Nix now remembers for each store path the derivation that + built it (the “deriver”): + + $ nix-store -qR $(which firefox) + /nix/store/4b0jx7vq80l9aqcnkszxhymsf1ffa5jd-firefox-1.0.1.drv + + So to see the build-time dependencies, you can do + + $ nix-store -qR $(nix-store -qd $(which firefox)) + + or, in a nicer format: + + $ nix-store -q --tree $(nix-store -qd $(which firefox)) + + File system references are also stored in reverse. For instance, you + can query all paths that directly or indirectly use a certain Glibc: + + $ nix-store -q --referrers-closure \ + /nix/store/8lz9yc6zgmc0vlqmn2ipcpkjlmbi51vv-glibc-2.3.4 + + - The concept of fixed-output derivations has been formalised. + Previously, functions such as `fetchurl` in Nixpkgs used a hack + (namely, explicitly specifying a store path hash) to prevent changes + to, say, the URL of the file from propagating upwards through the + dependency graph, causing rebuilds of everything. This can now be + done cleanly by specifying the `outputHash` and `outputHashAlgo` + attributes. Nix itself checks that the content of the output has the + specified hash. (This is important for maintaining certain + invariants necessary for future work on secure shared stores.) + + - One-click installation :-) It is now possible to install any + top-level component in Nixpkgs directly, through the web — see, + e.g., <http://catamaran.labs.cs.uu.nl/dist/nixpkgs-0.8/>. All you + have to do is associate `/nix/bin/nix-install-package` with the MIME + type `application/nix-package` (or the extension `.nixpkg`), and + clicking on a package link will cause it to be installed, with all + appropriate dependencies. If you just want to install some specific + application, this is easier than subscribing to a channel. + + - `nix-store -r + PATHS` now builds all the derivations PATHS in parallel. Previously + it did them sequentially (though exploiting possible parallelism + between subderivations). This is nice for build farms. + + - `nix-channel` has new operations `--list` and `--remove`. + + - New ways of installing components into user environments: + + - Copy from another user environment: + + $ nix-env -i --from-profile .../other-profile firefox + + - Install a store derivation directly (bypassing the Nix + expression language entirely): + + $ nix-env -i /nix/store/z58v41v21xd3...-aterm-2.3.1.drv + + (This is used to implement `nix-install-package`, which is + therefore immune to evolution in the Nix expression language.) + + - Install an already built store path directly: + + $ nix-env -i /nix/store/hsyj5pbn0d9i...-aterm-2.3.1 + + - Install the result of a Nix expression specified as a + command-line argument: + + $ nix-env -f .../i686-linux.nix -i -E 'x: x.firefoxWrapper' + + The difference with the normal installation mode is that `-E` + does not use the `name` attributes of derivations. Therefore, + this can be used to disambiguate multiple derivations with the + same name. + + - A hash of the contents of a store path is now stored in the database + after a successful build. This allows you to check whether store + paths have been tampered with: `nix-store + --verify --check-contents`. + + - Implemented a concurrent garbage collector. It is now always safe to + run the garbage collector, even if other Nix operations are + happening simultaneously. + + However, there can still be GC races if you use `nix-instantiate` + and `nix-store + --realise` directly to build things. To prevent races, use the + `--add-root` flag of those commands. + + - The garbage collector now finally deletes paths in the right order + (i.e., topologically sorted under the “references” relation), thus + making it safe to interrupt the collector without risking a store + that violates the closure invariant. + + - Likewise, the substitute mechanism now downloads files in the right + order, thus preserving the closure invariant at all times. + + - The result of `nix-build` is now registered as a root of the garbage + collector. If the `./result` link is deleted, the GC root disappears + automatically. + + - The behaviour of the garbage collector can be changed globally by + setting options in `/nix/etc/nix/nix.conf`. + + - `gc-keep-derivations` specifies whether deriver links should be + followed when searching for live paths. + + - `gc-keep-outputs` specifies whether outputs of derivations + should be followed when searching for live paths. + + - `env-keep-derivations` specifies whether user environments + should store the paths of derivations when they are added (thus + keeping the derivations alive). + + - New `nix-env` query flags `--drv-path` and `--out-path`. + + - `fetchurl` allows SHA-1 and SHA-256 in addition to MD5. Just specify + the attribute `sha1` or `sha256` instead of `md5`. + + - Manual updates. |