Channel details of profile generation

[Phil]

Hi all,

I've been writing a script that given a date/time and a profile will
return the details of that profile at that date/time, including the
channels used to create the profile.

Initially I though this would be as easy as:

guix pull -p my-profile -l

But this seems to crash:

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blah@phil:~$ guix pull -p my-profile -l
\Generation 1   Dec 22 2020 17:24:53\
  my-test-repo 1.49-3.f08de71
\Generation 2   Dec 22 2020 17:50:28\
  guix 13d532a
    repository URL: https://git.savannah.gnu.org/git/guix.git
    branch: master
    commit: \13d532a91178be7b6919b85685b150f941116dfc\
  foo-packages 8fc6134
    repository URL: ssh://git@localgit:7999/foo/foo-packages.git
    branch: master
    commit: 3dc613449f59ba8a8fdc35cadb7667ddaaf7fd9b
Backtrace:
          11 (primitive-load "/home/blah/.config/guix/current/bin/…")
In guix/ui.scm:
  2127:12 10 (run-guix-command _ . _)
In ice-9/boot-9.scm:
  1736:10  9 (with-exception-handler _ _ #:unwind? _ # _)
  1731:15  8 (with-exception-handler #<procedure 7fa030b82b40 at ic…> …)
  1731:15  7 (with-exception-handler #<procedure 7fa030b82b10 at ic…> …)
  1731:15  6 (with-exception-handler #<procedure 7fa030c46390 at ic…> …)
In guix/scripts/pull.scm:
    636:4  5 (_)
In guix/memoization.scm:
    100:0  4 (_ #<hash-table 7fa030b4c780 0/31> "guix-profiles/py-t…" …)
In guix/scripts/pull.scm:
   538:21  3 (_)
In guix/inferior.scm:
    256:2  2 (inferior-available-packages #f)
   251:13  1 (send-inferior-request (defined? (quote #)) #f)
In ice-9/boot-9.scm:
  1669:16  0 (raise-exception _ #:continuable? _)

ice-9/boot-9.scm:1669:16: In procedure raise-exception:
In procedure struct-vtable: Wrong type argument in position 1 (expecting 
struct): #f
blah@phil:~$ 

________________________________


This was a bit unexpected as you can call 'guix describe' with a profile
(although you only get channel infomation if you leave off the -p switch).


So instead I decided to write my own script.

I've left how I work out the generation running on a given profile at a
given datetime - but this is easy enough to do (look for nearest
generation-time less than the provided datetime).

Armed with this, the following looked like a good starting place:

(display-profile-content my-profile generation-number)

With me providing a profile and generation I want details on.

There are 2 versions of the display-profile-content function; one in
(guix ui) and one in (guix scripts describe).


https://github.com/guix-mirror/guix/blob/d482569c2289647e666228cad238552b18f09410/guix/scripts/describe.scm#L232
https://github.com/guix-mirror/guix/blob/d482569c2289647e666228cad238552b18f09410/guix/ui.scm#L1947

The ui.scm version doesn't have the details I want, but the describe.scm
one looked promising.

However the match sequence in display-profile-content in describe.scm is
looking for 'source not 'provenance - which if I look at the manifest
under the profile won't match?  Also it only seemed to match against the
first 'repository - which is no good if a private channel is used by the 
profile.

So whilst display-profile-content correctly displays information from
display-generation, the for-each over the manifest entries doesn't
yield any url/branch/commit info - at least for what I want to do.

I also looked at the profile-channels function but drew a blank there
too.

The code at describe.scm was close enough that I could fairly easily
repurpose it (see below).

However my questions are:

Os there not already a cannonical way to do this in Guix?  If yes, what is it?

If no is my approach below sane, or is what I'm trying to achieve
ill-conceived in any way?

Finally, what's the intended difference between 'source and 'provenance?

To my mind - If a profile generation has a manifest which contains
branch/commit details of the branches packages were created with - it
seems reasonable and useful to report that information?

Thanks,
Phil.

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(format #t "~%~%Package/Channel Details:~%")
(define my-manifest
  (manifest-entries
   (profile-manifest (generation-file-name my-profile generation-number))))

(for-each (lambda (entry)
            (format #t "  ~a ~a~%"
                    (manifest-entry-name entry)
                    (manifest-entry-version entry))
            (match (assq 'provenance (manifest-entry-properties entry))
              (('provenance ('repository ('version 0)
                                         ('url url)
                                         ('branch branch)
                                         ('commit commit)
                                         _ ...) ...)
               (let ((repo-triples (zip url branch commit)))
                 (map (lambda (triple)
                        (apply format
                               (append (list #t "     URL: ~a~%     Branch: 
~a~%     Commit: ~a~%~%") triple))) repo-triples)))
              (_ #f))) (reverse my-manifest))


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