Nix-channel revision/url -meta data

Help
1

Hello

in
nix repl

:l <nixpkgs>
 config

it is possible to inspect what inside the channel

What interests me are the meta data
like in
nix-shell -p nix-prefetch-git --run ' nix-prefetch-git https://github.com/nixos/nixpkgs-channels.git refs/heads/nixos-unstable '

{
“url”: “GitHub - NixOS/nixpkgs-channels: DEPRECATED! Use NixOS/nixpkgs repository instead.”,
“rev”: “84d74ae9c9cbed73274b8e4e00be14688ffc93fe”,
“date”: “2020-09-26T18:54:09-07:00”,
“sha256”: “0ww70kl08rpcsxb9xdx8m48vz41dpss4hh3vvsmswll35l158x0v”,
}

but from/for the current channel[s] of the OS

1 Like
2

You can try inspecting the derivation:

$ nix show-derivation $(nix-store --query --deriver $(nix-instantiate --eval --expr '<nixpkgs>'))
{ 
  "/nix/store/zvxv9sl4232w8irhpxd7b5hp6h2iljfd-nixos-19.09.2520.289466dd6a1.drv": {
    "inputSrcs": [
      "/nix/store/a6zdbsflqj152v16l8xds18yakckls2p-nix-2.1.1",
      "/nix/store/hg88w6nh54z2i8qa7zljxdvj2bkavw0x-nixexprs.tar.xz",
      "/nix/store/sfdmj74sfra43h215r3b9glp3q1l14hd-unpack-channel.sh"
    ],
...
3

thanks for your answer

  • is it possible to get the rev(ision) hash and date as well?
4

I notice there’s a svn-revision file in there that contains the git commit.

$ cat `nix-instantiate --eval -E '<nixpkgs>'`/svn-revision
.2520.289466dd6a1

289466dd6a1 is the nixpkgs commit hash.

I’m not sure about the date.

5

that is interesting.
But then how to match it with references from https://channels.nix.gsc.io/nixos-20.09/history-v2?

6

It appears to be there, I just haven’t updated my channel in a long time. The hash I found above (289466dd6a1) shows up here as 289466dd6a11c65a7de4a954d6ebf66c1ad07652 1592518222 1592908512

https://channels.nix.gsc.io/nixos-19.09/history-v2

7

but I cannot find my channel

nix-channel --list  
home-manager https://github.com/rycee/home-manager/archive/release-20.09.tar.gz
nixos https://nixos.org/channels/nixos-20.09

cat `nix-instantiate --eval -E '<nixpkgs>'`/svn-revision
beta992.7badbf18c45

is not listed.

8

nix-instantiate --eval -E '(import <nixpkgs> {}).lib.version'
(that was what i forgot :- )

1 Like
9

I’m not sure how history-v2 gets generated. Looking at https://channels.nix.gsc.io/nixos-20.09/ it seems to have a timestamp of 29-Sep-2020 which is before 7badbf18c45 was merged.

I didn’t know about lib.version, I’m going to start using that.

1 Like
10

if i wasn’t confused about channels before, I am now ;-).

I wonder why

nix-channel --list

doesn’t show
nixos https://nixos.org/channels/nixos-20.03 version:14.04.526.dbadfad

for mere uninitiated nix foo masters?

might be friendlier… but arn’t channels being currently nuked from orbit in favour of flakes?

flakespic
flakespic704×251 88.3 KB

11

There’s other use cases for channels, such as production systems where you want the underlying package set to update for you with security updates.

yep

nix-repl> :l
Added 12565 variables.

nix-repl> lib.version
"21.03.git.0932db581d2"

nix-repl> :l <nixpkgs>
Added 12274 variables.

nix-repl> lib.version
"20.09pre239318.c59ea8b8a0e"

for “doing a release”, the parameters are passed into the jobset so they are correct:

# pkgs/top-level/release.nix
{ nixpkgs ? { outPath = (import ../../lib).cleanSource ../..; revCount = 1234; shortRev = "abcdef"; revision = "0000000000000000000000000000000000000000"; }
1 Like
12

lib.version seems the way to get it, i presume this is the same thing nix-info -m shows?

nix-shell -p nix-info --run "nix-info -m"

 - system: `"x86_64-linux"`
 - host os: `Linux 5.4.66, NixOS, 20.03.3011.13a15f262a2 (Markhor)`
 - multi-user?: `yes`
 - sandbox: `yes`
 - version: `nix-env (Nix) 2.3.6`
 - channels(root): `"nixos-20.03.3011.13a15f262a2"`
 - nixpkgs: `/nix/var/nix/profiles/per-user/root/channels/nixos`
2 Likes