base-resolver

base-resolver is a V2 component that:

1. implements the Package Resolver FIDL protocol fuchsia.pkg.PackageResolver (though it does not implement the GetHash method. GetHash is used to determine which version of a package the ephemeral resolver (pkg-resolver) would resolve. The base-resolver always resolves the version from base, so clients should never need to use this method.)
2. implements the Component Resolver FIDL protocol fuchsia.component.resolution.Resolver and exposes this protocol as a resolver capability.

The responsibility of base-resolver is to resolve URLs to packages that are located in blobfs and are part of the “base” set of packages.

It does this by:

1. Using fuchsia.boot/Arguments to determine the hash of the system_image package.
2. Reading the static packages manifest of the system_image package to discover the mapping from base package URLs to hashes.
3. Using an RX* handle to blobfs and the package-directory library to serve the package directories directly out of blobfs.

Building

The base-resolver component should be part of the core product configuration and be buildable by any fx set invocation.

Running

This component is not packaged in the traditional way. Instead, its binary and manifest are included in the Zircon Boot Image (ZBI) and are accessible via bootfs.

To launch this component, include it as a child in the component topology using the URL fuchsia-boot:///#meta/base-resolver.cm, and include its exposed resolver capability in an environment.

{% includecode gerrit_repo="fuchsia/fuchsia" gerrit_path="src/sys/base-resolver/tests/meta/integration-test.cml" region_tag="environment"}

Testing

Unit tests for base-resolver are available in the base-resolver-unittests package.

$ fx test base-resolver-unittests

Integration tests for base-resolver are available in the base-resolver-tests package (which uses base-resolver as a component resolver) and the base-resolver-integration-tests package, which uses RealmBuilder to fake the dependencies.

$ fx test base-resolver-tests base-resolver-integration-tests