lint: Add 'archival' checker.

* guix/lint.scm (check-archival): New procedure.
(%network-dependent-checkers): Add 'archival' checker.
* tests/lint.scm ("archival: missing content")
("archival: content available")
("archival: missing revision")
("archival: revision available")
("archival: rate limit reached"): New tests.
* doc/guix.texi (Invoking guix lint): Document it.

1 files changed, 25 insertions, 0 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index 0510f57c23..de02ad8687 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -9249,6 +9249,31 @@ Parse the @code{source} URL to determine if a tarball from GitHub is
 autogenerated or if it is a release tarball.  Unfortunately GitHub's
 autogenerated tarballs are sometimes regenerated.
 
+@item archival
+@cindex Software Heritage, source code archive
+@cindex archival of source code, Software Heritage
+Checks whether the package's source code is archived at
+@uref{https://www.softwareheritage.org, Software Heritage}.
+
+When the source code that is not archived comes from a version-control system
+(VCS)---e.g., it's obtained with @code{git-fetch}, send Software Heritage a
+``save'' request so that it eventually archives it.  This ensures that the
+source will remain available in the long term, and that Guix can fall back to
+Software Heritage should the source code disappear from its original host.
+The status of recent ``save'' requests can be
+@uref{https://archive.softwareheritage.org/save/#requests, viewed on-line}.
+
+When source code is a tarball obtained with @code{url-fetch}, simply print a
+message when it is not archived.  As of this writing, Software Heritage does
+not allow requests to save arbitrary tarballs; we are working on ways to
+ensure that non-VCS source code is also archived.
+
+Software Heritage
+@uref{https://archive.softwareheritage.org/api/#rate-limiting, limits the
+request rate per IP address}.  When the limit is reached, @command{guix lint}
+prints a message and the @code{archival} checker stops doing anything until
+that limit has been reset.
+
 @item cve
 @cindex security vulnerabilities
 @cindex CVE, Common Vulnerabilities and Exposures