channels: Dependencies listed in '.guix-channel' can have an introduction.

Suggested by Ricardo Wurmus and Simon Tournier.

* guix/channels.scm (sexp->channel-introduction): New procedure.
(read-channel-metadata): Use it.
(profile-channels)[sexp->channel-introduction]: Remove.
* tests/channels.scm ("latest-channel-instances, authenticate dependency"):
New test.
* doc/guix.texi (Channels)[Declaring Channel Dependencies]: Augment example.

1 files changed, 9 insertions, 1 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index c3dd977860..7823367605 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -4160,7 +4160,15 @@ The meta-data file should contain a simple S-expression like this:
  (dependencies
   (channel
    (name some-collection)
-   (url "https://example.org/first-collection.git"))
+   (url "https://example.org/first-collection.git")
+
+   ;; The 'introduction' bit below is optional: you would
+   ;; provide it for dependencies that can be authenticated.
+   (introduction
+    (channel-introduction
+      (version 0)
+      (commit "a8883b58dc82e167c96506cf05095f37c2c2c6cd")
+      (signer "CABB A931 C0FF EEC6 900D  0CFB 090B 1199 3D9A EBB5"))))
   (channel
    (name some-other-collection)
    (url "https://example.org/second-collection.git")