| name | license-scan |
| description | Scan dependency licenses with ol by combining resolved package-manager inputs with an optional CycloneDX/SPDX SBOM, judge coverage, then enforce the intended SPDX policy with check, reviewed baselines, and CI. Supports single-language, polyglot, and monorepo builds, including input alignment, evidence collection, unresolved-result diagnosis, baseline composition, and license-regression detection. |
ol License Scan
Scan what the build actually resolved. Judge coverage before reading licenses. Apply policy last.
Repositories are polyglot until proven otherwise: find every in-scope ecosystem before choosing inputs.
Lifecycle
ol scan --input . --format json > ol-report.json
ol check --report ol-report.json --allow-licenses <approved-SPDX-ids>
- Scan into canonical JSON and keep it. Every later step reads that file, not a new scan.
- Judge coverage. Exit
0 means the command ran, not that the audit is complete.
- Check without a baseline so every violation is visible.
- Triage by population, not row by row.
- Baseline only reviewed evidence that stays unresolved.
- Verify steady state, then run the same check in CI.
Read references/policy-workflow.md before creating or updating a baseline.
Scope and inputs
- Run
ol scan --help as the version-specific option reference.
- Name the auditable subject: a release artifact, application, workspace, subtree, or whole repository. Ask when the choice changes compliance meaning.
- Find every ecosystem in that subject, including inside ignored build directories. Do not stop at the first one.
- Read references/ecosystem-inputs.md for each ecosystem's supported input and how to produce it.
ol scan --input . discovers every supported resolved input recursively and is the normal starting point. It also finds test fixtures, vendored trees, and unrelated sample projects, which are not dependencies of the subject. The Input discovery line is the detector: an ecosystem you did not expect, or a detected-file count far above the number of projects you know about, means the scan reached beyond the subject. Narrow it with --exclude-input-path or explicit paths.
Never pass an unresolved manifest alone — package.json, Cargo.toml, *.csproj, go.mod, requirements files. They state requests, not the graph the build selected. ol reports such a file as an ignored candidate and names the command that produces the real input; act on that rather than scanning the manifest.
Adding an SBOM
An SBOM is a second input, not a replacement. Add one when ol has no adapter for an ecosystem in the subject, or when CI must not install that ecosystem's resolver.
Where a resolved input exists, it is the stronger evidence: only a resolved input records the installed location that lets ol read licenses out of package artifacts. Adding an SBOM there usually changes nothing and can add components that are not dependencies — see references/sbom-generators.md.
ol accepts at most one SBOM per scan, and every input must describe the same commit, configuration, platform, and feature set. For separate independently shipped products, scan each subject separately rather than manufacturing one repository-wide result.
Run the scan
Keep external evidence enabled for the primary result. --no-external-evidence is for an explicitly offline comparison; label such a result incomplete.
Use --refresh only when stale evidence is suspected, and lower --concurrency when a service rate-limits. In CI, persist --cache-dir between runs: a cold cache costs hundreds of GitHub requests on a large repository, and GITHUB_TOKEN allows 1,000 per hour per repository.
For a centrally maintained read-only seed, distribute an Ol cache archive instead of granting consuming workflows cache-write access. In GitHub Actions, unpack it into a fresh per-job directory such as $RUNNER_TEMP/ol-cache before scan. The scan may add missing evidence there without modifying the archive, and the temporary directory is discarded with the job. The trusted updater follows the same fresh-directory pattern, refreshes its selected dependency population, then runs ol cache pack <archive> --cache-dir <directory> --max-age <duration>; the age bound keeps evidence no updater refreshed from accumulating forever. Keep the committed seed near the recommended 1 MiB size; pack warns above 1 MiB and rejects output above 8 MiB. Use ol cache prune --cache-dir <persistent-directory> --max-age <duration> only when intentionally retaining a writable cache directory across runs.
GitHub authentication
ol does not read GITHUB_TOKEN. Set OL_GITHUB_TOKEN in the scan process environment only, never on the command line, and never echo or store it.
OL_GITHUB_TOKEN="$(gh auth token)" ol scan ...
$env:OL_GITHUB_TOKEN = gh auth token
ol scan ...
Remove-Item Env:OL_GITHUB_TOKEN
Judge coverage first
Read these before any license, cheapest first.
| Signal | Question it answers |
|---|
metadata.inputDiscovery (Input discovery line: detected files, ignored candidates, incomplete input sets; excluded paths are metadata.inputScope) | Did every ecosystem in the subject get scanned, and only those? An ignored candidate is an unscanned ecosystem. |
summary.supply (Supplied by line; --verbose splits it per ecosystem) | Did the second input earn its place? A large sbomOnly count means the generator catalogued things that are not dependencies. |
warnings, including input_declares_no_components | Did an input resolve nothing? Every count zero reads exactly like a clean project. |
metadata.packageMetadata, packageArtifacts, declaredGitHubFiles, sourceRepository | Separate collector failure from component status. fetchErrorCount above zero means the run is degraded. |
metadata.network.githubAuth | Was the intended authentication mode used? |
In a polyglot scan, read these per ecosystem. One healthy ecosystem hides a missing graph in another.
If a combined scan surprises you, rerun the same scope with each input alone and identify which one changed the evidence. Keep the combined result; do not discard inconvenient evidence.
Triage violations by population
ol check exits 0 pass, 2 policy violations, 3 inconclusive — the run proved nothing, so fix the pipeline or retry rather than treat it as a licensing fact. A CI job that collapses 2 and 3 cannot tell a registry outage from a forbidden license. Two things reach 3: every finding was a collection failure, or the report carries input_declares_no_components and there was nothing to evaluate at all.
Violations name a Mechanism and end with an Unresolved mechanisms tally. Read the tally first. A hundred unresolved rows are usually a few populations, and one decision covers each.
| Mechanism | What it means | Action |
|---|
declared_license_location_not_collected | The publisher named a URL ol does not fetch. | Open the Reference URL. Legacy NuGet licenseUrl values often lead to no license at all; then the component is inherently unresolved. |
declared_license_file_not_collected | A license file ships inside the package. | Open that path in the published package. |
license_not_recognized | A repository license file exists that GitHub could not classify. | Open the Reference URL. |
license_not_detected | The repository was read and holds no license file. | Ask the publisher, or accept it as unresolved. |
external_evidence_not_collected | Collection was never attempted for this component. | Expected under --no-external-evidence or --skip-evidence-packages; rerun with collection before concluding anything. |
package_metadata_not_found | The registry said the package is not published there. | Expected for private-feed packages. |
package_metadata_no_purl | The component carries no package identity, so nothing can ever be asked. | A generator problem, not a collection problem. Fix the generator's scope or cataloger selection. |
unsupported_package_metadata, package_metadata_unversioned_purl | ol has no provider for that ecosystem, or the purl names no single version. | Fix the input, or accept the limitation. |
- on a license is not allowed row | The license resolved; policy rejected it. | Allow-list decision, never a baseline one. |
--allow-dev-licenses relaxes only components a resolver proved development-only. An input that determines no usage — an SBOM, Yarn, NuGet, Go, pip, Bundler — abstains rather than cancelling that proof, but a component no input classified stays unknown and is never relaxed.
Policy and baseline
Do not invent an allow-list; obtain the intended one. Resolved-but-rejected licenses belong in the allow-list. Only unknown, ambiguous, conflict, and invalid may be baselined, and error never is.
--baseline is repeatable and the files compose: a component is acknowledged when any of them states it. Use one shared file for a population several repositories share and a local file for what only this repository accepts.
ol check --report ol-report.json --allow-licenses <ids> --baseline <shared> --baseline <local>
--update-baseline rewrites the last file with what the earlier ones do not already acknowledge, and never touches the earlier ones. Never run it in CI: a failing check is the review gate.
Detect regressions
check answers "does the current state satisfy policy". It cannot say what a change did, so every pre-existing violation blocks every pull request until it is resolved. Commit a report and compare:
ol diff --previous before.json --current after.json
This is what surfaces a dependency whose license changed between versions. --sarif on check writes the same violations for code scanning, with dependency paths.
Report
State the ol version, the auditable subject, the ecosystems found and any excluded, the exact input-generation commands, coverage signals above, component and status counts per ecosystem, unresolved mechanisms with counts, collector health, limitations, and the next action. For policy work also state the allow-list source, initial violations, baseline paths and acknowledged counts, steady-state exit code, and the exact CI command.
Keep the canonical JSON before producing any filtered view. --dependency filters presentation, not analysis.
