SBoM dependency graph ingestion overview

Overview

The process starts after all SBoM::Occurence models have been ingested because we ingest them in slices and it would be tricky to process that in slices as well.

All work happens in a background worker which will be added in a subsequent MR so that we do not increase the time it takes to ingest an SBoM report. This means that there will be a delay between when the SBoM report is ingested and before the dependency graph is updated.

All record pertaining to dependency graphs are stored in sbom_graph_paths database table and has foreign keys to sbom_occurrences as well as projects for easier filtering.

Details

1. The database table is designed as a closure table
2. When a dependency is transitive then the corresponding Sbom::Occurrence#ancestors will contain entries.
3. When a dependency is a direct dependency then the corresponding Sbom::Occurrence#ancestors will contain an {}.
4. Dependencies can be both direct and transitive.
5. There can be more than one version of a given dependency in a project (for example Node allows that).
6. There can be more than one Sbom::Occurrence for a given dependency version, for example in monorepos. These Sbom::Occurrence rows should have a different input_file_path and source_id (however we will not use source_id when building the dependency tree to avoid SQL JOIN).