License Scanning

Trivy scans any container image for license files and offers an opinionated view on the risk associated with the license.

License are classified using the Google License Classification -

Forbidden
Restricted
Reciprocal
Notice
Permissive
Unencumbered
Unknown

Tip

Licenses that Trivy fails to recognize are classified as UNKNOWN. As those licenses may be in violation, it is recommended to check those unknown licenses as well.

By default, Trivy scans licenses for packages installed by apk, apt-get, dnf, npm, pip, gem, etc. Check out the coverage document for details.

To enable extended license scanning, you can use --license-full. In addition to package licenses, Trivy scans source code files, Markdown documents, text files and LICENSE documents to identify license usage within the image or filesystem.

By default, Trivy only classifies licenses that are matched with a confidence level of 0.9 or more by the classifer. To configure the confidence level, you can use --license-confidence-level. This enables us to classify licenses that might be matched with a lower confidence level by the classifer.

Note

The full license scanning is expensive. It takes a while.

Currently, the standard license scanning doesn't support filesystem and repository scanning.

License scanning	Image	Rootfs	Filesystem	Repository
Standard	✅	✅	-	-
Full (--license-full)	✅	✅	✅	✅

License checking classifies the identified licenses and map the classification to severity.

Classification	Severity
Forbidden	CRITICAL
Restricted	HIGH
Reciprocal	MEDIUM
Notice	LOW
Permissive	LOW
Unencumbered	LOW
Unknown	UNKNOWN

Quick start

This section shows how to scan license in container image and filesystem.

Standard scanning

Specify an image name with --scanners license.

$ trivy image --scanners license --severity UNKNOWN,HIGH,CRITICAL alpine:3.15
2022-07-13T17:28:39.526+0300    INFO    License scanning is enabled

OS Packages (license)
=====================
Total: 6 (UNKNOWN: 0, HIGH: 6, CRITICAL: 0)

┌───────────────────┬─────────┬────────────────┬──────────┐
│      Package      │ License │ Classification │ Severity │
├───────────────────┼─────────┼────────────────┼──────────┤
│ alpine-baselayout │ GPL-2.0 │ Restricted     │ HIGH     │
├───────────────────┤         │                │          │
│ apk-tools         │         │                │          │
├───────────────────┤         │                │          │
│ busybox           │         │                │          │
├───────────────────┤         │                │          │
│ musl-utils        │         │                │          │
├───────────────────┤         │                │          │
│ scanelf           │         │                │          │
├───────────────────┤         │                │          │
│ ssl_client        │         │                │          │
└───────────────────┴─────────┴────────────────┴──────────┘

Full scanning

Specify --license-full

$ trivy image --scanners license --severity UNKNOWN,HIGH,CRITICAL --license-full grafana/grafana
2022-07-13T17:48:40.905+0300    INFO    Full license scanning is enabled

OS Packages (license)
=====================
Total: 20 (UNKNOWN: 9, HIGH: 11, CRITICAL: 0)

┌───────────────────┬───────────────────┬────────────────┬──────────┐
│      Package      │      License      │ Classification │ Severity │
├───────────────────┼───────────────────┼────────────────┼──────────┤
│ alpine-baselayout │ GPL-2.0           │ Restricted     │ HIGH     │
├───────────────────┤                   │                │          │
│ apk-tools         │                   │                │          │
├───────────────────┼───────────────────┤                │          │
│ bash              │ GPL-3.0           │                │          │
├───────────────────┼───────────────────┼────────────────┼──────────┤
│ keyutils-libs     │ GPL-2.0           │ Restricted     │ HIGH     │
│                   ├───────────────────┼────────────────┼──────────┤
│                   │ LGPL-2.0-or-later │ Non Standard   │ UNKNOWN  │
├───────────────────┼───────────────────┤                │          │
│ libaio            │ LGPL-2.1-or-later │                │          │
├───────────────────┼───────────────────┼────────────────┼──────────┤
│ libcom_err        │ GPL-2.0           │ Restricted     │ HIGH     │
│                   ├───────────────────┼────────────────┼──────────┤
│                   │ LGPL-2.0-or-later │ Non Standard   │ UNKNOWN  │
├───────────────────┼───────────────────┼────────────────┼──────────┤
│ tzdata            │ Public-Domain     │ Non Standard   │ UNKNOWN  │
└───────────────────┴───────────────────┴────────────────┴──────────┘

Loose File License(s) (license)
===============================
Total: 6 (UNKNOWN: 4, HIGH: 0, CRITICAL: 2)

┌────────────────┬──────────┬──────────────┬──────────────────────────────────────────────────────────────┐
│ Classification │ Severity │   License    │                        File Location                         │
├────────────────┼──────────┼──────────────┼──────────────────────────────────────────────────────────────┤
│ Forbidden      │ CRITICAL │ AGPL-3.0     │ /usr/share/grafana/LICENSE                                   │
│                │          │              │                                                              │
│                │          │              │                                                              │
├────────────────┼──────────┼──────────────┼──────────────────────────────────────────────────────────────┤
│ Non Standard   │ UNKNOWN  │ BSD-0-Clause │ /usr/share/grafana/public/build/5069.d6aae9dd11d49c741a80.j- │
│                │          │              │ s.LICENSE.txt                                                │
│                │          │              ├──────────────────────────────────────────────────────────────┤
│                │          │              │ /usr/share/grafana/public/build/6444.d6aae9dd11d49c741a80.j- │
│                │          │              │ s.LICENSE.txt                                                │
│                │          │              ├──────────────────────────────────────────────────────────────┤
│                │          │              │ /usr/share/grafana/public/build/7889.d6aae9dd11d49c741a80.j- │
│                │          │              │ s.LICENSE.txt                                                │
│                │          │              ├──────────────────────────────────────────────────────────────┤
│                │          │              │ /usr/share/grafana/public/build/canvasPanel.d6aae9dd11d49c7- │
│                │          │              │ 41a80.js.LICENSE.txt                                         │
└────────────────┴──────────┴──────────────┴──────────────────────────────────────────────────────────────┘

Configuration

Trivy has number of configuration flags for use with license scanning;

Ignored Licenses

Trivy license scanning can ignore licenses that are identified to explicitly remove them from the results using the --ignored-licenses flag;

$ trivy image --scanners license --ignored-licenses MPL-2.0,MIT --severity HIGH grafana/grafana:latest
2022-07-13T18:15:28.605Z        INFO    License scanning is enabled

OS Packages (license)
=====================
Total: 2 (HIGH: 2, CRITICAL: 0)

┌───────────────────┬─────────┬────────────────┬──────────┐
│      Package      │ License │ Classification │ Severity │
├───────────────────┼─────────┼────────────────┼──────────┤
│ alpine-baselayout │ GPL-2.0 │ Restricted     │ HIGH     │
├───────────────────┤         │                │          │
│ ssl_client        │         │                │          │
└───────────────────┴─────────┴────────────────┴──────────┘

Configuring Classifier Confidence Level

You can use the --license-confidence-level flag to adjust the confidence level between 0.0 to 1.0 (default 0.9). For example, when you run the scanner with the default confidence level on SPDX license list data, it is able to detect only 258 licenses.

$ trivy fs --scanners license --license-full <path/to/spdx/list/data>
2023-04-18T10:05:13.601-0700    INFO    Full license scanning is enabled

Loose File License(s) (license)
===============================
Total: 258 (UNKNOWN: 70, LOW: 90, MEDIUM: 18, HIGH: 58, CRITICAL: 22)

However, by configuring the confidence level to 0.8, the scanner is now able to detect 282 licenses.

$ trivy fs --scanners license --license-full --license-confidence-level 0.8 <path/to/spdx/list/data>
2023-04-18T10:21:39.637-0700    INFO    Full license scanning is enabled

Loose File License(s) (license)
===============================
Total: 282 (UNKNOWN: 81, LOW: 97, MEDIUM: 24, HIGH: 58, CRITICAL: 22)

Custom Classification

You can generate the default config by the --generate-default-config flag and customize the license classification. For example, if you want to forbid only AGPL-3.0, you can leave it under forbidden and move other licenses to another classification.

$ trivy image --generate-default-config
$ vim trivy.yaml
license:
  forbidden:
  - AGPL-3.0

  restricted:
  - AGPL-1.0
  - CC-BY-NC-1.0
  - CC-BY-NC-2.0
  - CC-BY-NC-2.5
  - CC-BY-NC-3.0
  - CC-BY-NC-4.0
  - CC-BY-NC-ND-1.0
  - CC-BY-NC-ND-2.0
  - CC-BY-NC-ND-2.5
  - CC-BY-NC-ND-3.0
  - CC-BY-NC-ND-4.0
  - CC-BY-NC-SA-1.0
  - CC-BY-NC-SA-2.0
  - CC-BY-NC-SA-2.5
  - CC-BY-NC-SA-3.0
  - CC-BY-NC-SA-4.0
  - Commons-Clause
  - Facebook-2-Clause
  - Facebook-3-Clause
  - Facebook-Examples
  - WTFPL
  - BCL
  - CC-BY-ND-1.0
  - CC-BY-ND-2.0
  - CC-BY-ND-2.5
  - CC-BY-ND-3.0
  - CC-BY-ND-4.0
  - CC-BY-SA-1.0
  - CC-BY-SA-2.0
  - CC-BY-SA-2.5
  - CC-BY-SA-3.0
  - CC-BY-SA-4.0
  - GPL-1.0
  - GPL-2.0
  - GPL-2.0-with-autoconf-exception
  - GPL-2.0-with-bison-exception
  - GPL-2.0-with-classpath-exception
  - GPL-2.0-with-font-exception
  - GPL-2.0-with-GCC-exception
  - GPL-3.0
  - GPL-3.0-with-autoconf-exception
  - GPL-3.0-with-GCC-exception
  - LGPL-2.0
  - LGPL-2.1
  - LGPL-3.0
  - NPL-1.0
  - NPL-1.1
  - OSL-1.0
  - OSL-1.1
  - OSL-2.0
  - OSL-2.1
  - OSL-3.0
  - QPL-1.0
  - Sleepycat

  reciprocal:
  - APSL-1.0
  - APSL-1.1
  - APSL-1.2
  - APSL-2.0
  - CDDL-1.0
  - CDDL-1.1
  - CPL-1.0
  - EPL-1.0
  - EPL-2.0
  - FreeImage
  - IPL-1.0
  - MPL-1.0
  - MPL-1.1
  - MPL-2.0
  - Ruby

  notice:
  - AFL-1.1
  - AFL-1.2
  - AFL-2.0
  - AFL-2.1
  - AFL-3.0
  - Apache-1.0
  - Apache-1.1
  - Apache-2.0
  - Artistic-1.0-cl8
  - Artistic-1.0-Perl
  - Artistic-1.0
  - Artistic-2.0
  - BSL-1.0
  - BSD-2-Clause-FreeBSD
  - BSD-2-Clause-NetBSD
  - BSD-2-Clause
  - BSD-3-Clause-Attribution
  - BSD-3-Clause-Clear
  - BSD-3-Clause-LBNL
  - BSD-3-Clause
  - BSD-4-Clause
  - BSD-4-Clause-UC
  - BSD-Protection
  - CC-BY-1.0
  - CC-BY-2.0
  - CC-BY-2.5
  - CC-BY-3.0
  - CC-BY-4.0
  - FTL
  - ISC
  - ImageMagick
  - Libpng
  - Lil-1.0
  - Linux-OpenIB
  - LPL-1.02
  - LPL-1.0
  - MS-PL
  - MIT
  - NCSA
  - OpenSSL
  - PHP-3.01
  - PHP-3.0
  - PIL
  - Python-2.0
  - Python-2.0-complete
  - PostgreSQL
  - SGI-B-1.0
  - SGI-B-1.1
  - SGI-B-2.0
  - Unicode-DFS-2015
  - Unicode-DFS-2016
  - Unicode-TOU
  - UPL-1.0
  - W3C-19980720
  - W3C-20150513
  - W3C
  - X11
  - Xnet
  - Zend-2.0
  - zlib-acknowledgement
  - Zlib
  - ZPL-1.1
  - ZPL-2.0
  - ZPL-2.1

  unencumbered:
  - CC0-1.0
  - Unlicense
  - 0BSD

  permissive: []