Local cargo config

This repository ships with a .cargo/config.toml that replaces the crates.io registry with packaged crates located in /usr/share/cargo/registry.

A similar config is also applied building with dh_cargo. Cargo.lock needs to be deleted when switching between packaged crates and crates.io, since the checksums are not compatible.

To reference new dependencies (or updated versions) that are not yet packaged, the dependency needs to point directly to a path or git source.

Quickly installing all packages from apt

To a void too many manual installations when mk-build-deps etc. fail, a quick way to install all the main packages of this workspace is to run:

# apt install $(make list-packages)

Steps for Releases

• Run ./bump.sh <CRATE> [patch|minor|major|<VERSION>]
  • Fill out changelog
  • Confirm bump commit
• Build packages with make <crate>-deb.
  • Don't forget to commit updated d/control!

Adding Crates

1. At the top level:

   • Generate the crate: cargo new --lib the-name
   • Sort the crate into Cargo.toml's workspace.members

2. In the new crate's Cargo.toml:

   • In [package] set:

     authors.workspace = true
     edition.workspace = true
     exclude.workspace = true
     homepage.workspace = true
     license.workspace = true
     repository.workspace = true
     rust-version.workspace = true
     

     If a separate exclude is need it, separate it out as its own block above the inherited fields.

   • Add a meaningful description

   • Copy debian/copyright and debian/debcargo.toml from another subcrate.

3. In the new crate's lib.rs, add the following preamble on top:

   #![cfg_attr(docsrs, feature(doc_cfg, doc_auto_cfg))]
   

4. Ideally (but optionally) in the new crate's lib.rs, add the following preamble on top as well:

   #![deny(unsafe_op_in_unsafe_fn)]
   #![deny(missing_docs)]
   

Adding a new Dependency

1. At the top level:
   • Add it to [workspace.dependencies] specifying the version and any features that should be enabled throughout the workspace
2. In each member's Cargo.toml:
   • Add it to the desired dependencies section with workspace = true and no version specified.
   • If this member requires additional features, add only the extra features to the member dependency.

Updating a Dependency's Version

1. At the top level:
   • Bump the version in [workspace.dependencies] as desired.
   • Check for deprecations or breakage throughout the workspace.

Notes on Workspace Inheritance

Common metadata (like authors, license, ..) are inherited throughout the workspace. If new fields are added that are identical for all crates, they should be defined in the top-level Cargo.toml file's [workspace.package] section, and inherited in all members explicitly by setting FIELD.workspace = true in the member's [package] section.

Dependency information is also inherited throughout the workspace, allowing a single dependency specification in the top-level Cargo.toml file to be used by all members.

Some restrictions apply:

• features can only be added in members, never removed (this includes default_features = false!)
  • the base feature set at the workspace level should be the minimum (possibly empty!) set required by all members
• workspace dependency specifications cannot include optional
  • if needed, the optional flag needs to be set at the member level when using a workspace dependency

Working with other projects while changing to single crates here

When crates from this workspace need changes caused by requirements in projects outside of this repository, it can often be annoying to keep building and installing .deb files.

Additionally, doing so often requires complete rebuilds as cargo will not pick up file changes of external dependencies.

One way to fix this is by actually changing the version. Since we cut away anything starting at the first hyphen in the version, we need to use a + (build metadata) version suffix.

Eg. turn 5.0.0 into 5.0.0+test8.

There are 2 faster ways:

Adding a #[patch.crates-io] section to the other project.

Note, however, that this requires ALL crates from this workspace to be listed, otherwise multiple conflicting versions of the same crate AND even the same numerical version might be built, causing weird errors.

The advantage, however, is that cargo will pick up on file changes and rebuild the crate on changes.

An in-between: system extensions

An easy way to quickly get the new package "installed" temporarily, such that real apt package upgrades are unaffected is as a system-extension.

The easiest way — if no other extensions are used — is to just symlink the extensions/ directory to /run as root via:

# ln -s ${THIS_DIR}/extensions /run/extensions

This does not persist across reboots. (Note: that the extensions/ directory does not need to exist for the above to work.)

Once this is done, trying a new version of a crate works by:

1. Bump the version: eg. 5.0.0+test8 -> 5.0.0+test9 While this is technically optional (the sysext would then replace (temporarily) the installed version as long as the sysext is active), just like with .deb files, not doing this causes cargo to consider the crate to be unchanged and it will not rebuild its code.
2. here: $ make ${crate}-sysext (rebuilds extensions/${crate}.raw)
3. as root: # systemd-sysext refresh (activates current extensions images)
4. in the other project: $ cargo update && cargo build

In the last step, cargo sees that there's a newer version of the crate available and use that.