Enable libcnb Dependabot grouping#592
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Add a `libcnb` Dependabot group so the libcnb-family crates (`libcnb`, `libcnb-*` and `libherokubuildpack`) are updated together in a single PR, rather than split across the general `rust-dependencies` group. Dependabot's grouping docs state that when multiple groups are specified, the first group defined wins: https://docs.github.com/en/code-security/reference/supply-chain-security/dependabot-options-reference#groups-- In practice this is broken: PRs are compared against all groups and can end up in a later group whose settings then prevent the PR being opened - so major libcnb updates were misrouted to `rust-dependencies` and filtered out by its `update-types: ["minor", "patch"]` rule, meaning no PR was opened at all. To work around this, the groups are made non-overlapping by adding a matching `exclude-patterns` to `rust-dependencies`. See: dependabot/dependabot-core#11093 See also: heroku/buildpacks-nodejs#1408 The libcnb-family crate versions have also been pinned to exact versions using the `=` syntax, since these crates have a large impact on the behaviour of the buildpack, so we want to control their version more carefully. (We used to pin to an exact version in many CNBs in the past, but removed the pin as part of trying to work out why Dependabot wasn't updating.) GUS-W-23329202.
Malax
approved these changes
Jul 7, 2026
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Add a
libcnbDependabot group so the libcnb-family crates (libcnb,libcnb-*andlibherokubuildpack) are updated together in a single PR, rather than split across the generalrust-dependenciesgroup.Dependabot's grouping docs state that when multiple groups are specified, the first group defined wins:
https://docs.github.com/en/code-security/reference/supply-chain-security/dependabot-options-reference#groups--
In practice this is broken: PRs are compared against all groups and can end up in a later group whose settings then prevent the PR being opened - so major libcnb updates were misrouted to
rust-dependenciesand filtered out by itsupdate-types: ["minor", "patch"]rule, meaning no PR was opened at all. To work around this, the groups are made non-overlapping by adding a matchingexclude-patternstorust-dependencies.See:
dependabot/dependabot-core#11093
See also: heroku/buildpacks-nodejs#1408
The libcnb-family crate versions have also been pinned to exact versions using the
=syntax, since these crates have a large impact on the behaviour of the buildpack, so we want to control their version more carefully. (We used to pin to an exact version in many CNBs in the past, but removed the pin as part of trying to work out why Dependabot wasn't updating.)GUS-W-23329202.