Red Light Green Light

A git-centric policy management and enforcement tool designed to accelerate your CI/CD pipelines

Quick Start

Try out the hosted version at https://rl.gl. Note that documents expire after 30 days.

For an example of real-world rlgl policy in action, check out the policy used to validate unit test reports for libffi on Github Actions builds: https://github.com/libffi/rlgl-policy.

Download and install one of the cli tools hosted at https://rl.gl. Now login to the server like so...

$ rlgl login https://rl.gl

You'll get a message back asking you to create a personal API key. Follow those instructions, and try again...

$ rlgl login --key=MY_PERSONAL_KEY https://rl.gl

If you require the use of a proxy, specify like so:

$ rlgl login --proxy=https://myproxy.example.com:8080 --key=MY_PERSONAL_KEY https://rl.gl

You can also specify a proxy username and password for basic proxy authentication:

$ rlgl login --proxy=https://myproxy.example.com:8080 \
             --proxy-auth=USERNAME:PASSWORD \
             --key=MY_PERSONAL_KEY https://rl.gl

Generate an OpenSCAP report, or grab one from here:

$ curl https://raw.githubusercontent.com/atgreen/red-light-green-light/master/test/report.html > report.html

Evaluate the report against a sample policy:

$ rlgl evaluate --label id=sample-test --policy=https://github.com/atgreen/test-policy report.html

The --label id=sample-test option adds the id=sample-test key/value pair to the report. This is helpful when you want to query the report archive later. You can add any number of labels to a report.

To use a private repository, generate a personal access token at github.com with appropriate private repo access, and reference your policy repo like so:

$ rlgl evaluate -l id=sample-test --policy=https://${TOKEN}@github.com/atgreen/test-policy report.html

Be sure to click on the resulting URL and explore. You'll find the evaluation report, complete with links to git-hosted policy for specific results, as well as a link to the full, original report.

Produce a log of reports for this player ID:

$ rlgl log -l id=sample-test

The report is signed by both the server and your client. The server's signature is recorded in the pubic rekor transparency log managed by the sigstore project. You can verify these signatures and the log entry like so:

$ rlgl verify RLGL-[report ID] | sh

The verification script is provided in source form for transparency reasons.

Problem Statement

Modern DevOps pipelines require Quality Gating mechanisms in order to fully automate the promotion of software artifacts from dev all the way through to prod. These Quality Gates are responsible for deciding whether a deployable artifact (config files, software builds, container images, VM images, etc) should proceed to the next stage of a CI/CD pipeline.

Many tools are available to evaluate the quality of deployable artifacts, including container image scanners, unit test harnesses, config file linters, etc. But dealing with multiple quality testing tools introduces problems:

• bespoke gating mechanisms must be created to evaluate test results
• different tools require different exception processes and policy management
• no centralized, auditable policy management
• policies are locked within proprietary tools

Policy Driven Quality Gates

The main idea behind Red Light Green Light is to decouple the process of evaluating test results away from the underlying testing tools themselves, in a way that is:

• centrally managed
• version controlled
• auditable
• customizeable
• protected with authentication/authorization mechanisms

The goal of all of this is to enable auditors to easily answer the following questions as they relate to any artifact promoted through a CI/CD pipeline:

• who presented test results for evaluation?
• what were those test results?
• what policies were they evaluated against?
• who defined the policies and when?

The Red Light Green Light service is invoked via the rlgl command-line tool, typically within some other pipeline automation framework, such as a jenkins pipeline. Here's an example workflow:

• First, we must log into our Red Light Green Light server with rlgl cli tool like so:

$ rlgl login --key MY_API_KEY http://rlgl-server.example.com

• As the pipeline proceeds, test results are generated (scans, unit tests, etc). For each test report generated, rlgl evaluates the report against the stated git-hosted policy, resulting in a Red Light, meaning stop the pipeline, or Green Light, meaning proceed with the pipeline. It also produces a URL that links to a report showing annotated evaluation results. Annotations, include, for example, the git logs for policies defining exceptions resulting in green lights.

$ rlgl evaluate --policy https://git.example.com/policy/dev.git --id $ID my-test-report.html
GREEN: http://rlgl-server.example.com/doc?id=RLGL-BC7DB3F (sha3/256: 35da0de414ec6eaaa5c758e1b6b364ab7cad20b39bdfce5b15b44570e0f62ef8)

$ rlgl evaluate --policy https://git.example.com/policy/prod.git --id $ID oval-scan.xml
RED: http://rlgl-server.example.com/doc?id=RLGL-1CF5B3A (sha3/256: eb7cad20b64ec6f8758ea4a62e15b439bdfce5b35da0de41aa5c4570e0f1b6b3)

$ rlgl evaluate --policy https://git.example.com/policy/rel.git --id $ID gcc.log
GREEN: http://rlgl-server.example.com/doc?id=RLGL-AFC7DB2 (sha3/256: f8758e1b6b364ab7cad20b39bdfce5b35da0de414ec6eaaa5c4570e0f62e15b4)

Standard exit codes make it easy to integrate rlgl into your CI/CD pipeline scripts. GREEN lights have an exit code of 0. RED lights have an exit code of 1. Any other exit code is an error. The output also includes the sha3/256 checksum of the report for future reference. You can validate the report with openssl like so...

$ curl -s https://rlgl-server.example.com/doc?id=RLGL-AFC7DB2 | openssl dgst -sha3-256
(stdin)= f8758e1b6b364ab7cad20b39bdfce5b35da0de414ec6eaaa5c4570e0f62e15b4

The report also includes a link to the original document, which is archived, along with its sha3/256 checksum.

In addition to recording the report for future reference, the Red Light Green Light server signs the sha3/256 checksum with a private signing key. The base64-encoded signature is always available via curl by appending .sig to the report URL like so:

$ curl -s https://rlgl-server.example.com/doc?id=RLGL-AFC7DB2.sig
MGQCMBM/nx+jEdu2RVEwSPCYTqWF/bP/3FlX2FPFRGrRZjOgq/tQj0Eg5XDBO0vC1KLnFwIwVFtMPxsrv3DljSrD422qeA4zqz5JDA/PT3NpM91hI/sehmqJgmkAMQjJB/mkn0xl

You can validate this signature against the public signing key like so:

$ curl -s https://rlgl-server.example.com/doc?id=RLGL-AFC7DB2 | openssl dgst -sha3-256 - | awk '{ printf $2 }' > digest
$ curl -s https://rlgl-server.example.com/doc?id=RLGL-AFC7DB2.sig | base64 -d > digest.sig
$ openssl dgst -sha256 -verify rlgl-public.pem -signature digest.sig digest
Verified OK

The rlgl client also signs the report, and uploads the signature to the server. You can retrieve the base64-encoded client signature via curl by appending .csig to the report URL as above.

Each rlgl login produces a new private/public keypair. More commonly, however, you would generate your own keypair and provide the private key at login time like so:

$ rlgl login --key MY_API_KEY --signing-key MY_PRIVATE_KEY_FILE.pem http://rlgl-server.example.com

The Red Light Green Light server also uploads the signed digest to sigstore for non-repudiation of the results.

The rlgl tool can generate a simple shell script to verify signatures and search for the sigstore log entry. View the shell script like so:

$ rlgl verify RLGL-AFC7DB2

You can execute the verification script simply by feeding the output to a shell program:

$ rlgl verify RLGL-AFC7DB2 | sh
Checking document signature: Verified OK
Checking client signature  : Verified OK

Searching for sigstore record:
LogID: c0d23d6ad406973f9559f3ba2d1ca01f84147d8ffc5b8445c224f98b9591801d
Index: 5740
IntegratedTime: 2021-07-13T22:06:51Z
UUID: d5cb372f2067cbf2f9eb9edace960ad9ca51994a26d6450d044ed24ceffc204c
Body: {
  "RekordObj": {
    "data": {
      "hash": {
        "algorithm": "sha256",
        "value": "c9693cfbd2c371e30a012e42140e6127171cb25d435d0646c941f190b4a21f7c"
      }
    },
    "signature": {
      "content": "MGQCMBVJyQi5HseSBqyXa8dXQFb6P2h1FHjFesQRPBqDhMik+NfplFG7bt41K5rE8ywyKAIwLtIvwn/DGJSzBTvD7evBMnUzGOHopXtqxUTZhPo2skKaohV69nOPBy+y5YuJzpJb",
      "format": "x509",
      "publicKey": {
        "content": "LS0tLS1CRUdJTiBQVUJMSUMgS0VZLS0tLS0KTUhZd0VBWUhLb1pJemowQ0FRWUZLNEVFQUNJRFlnQUU4ZG8rQVFwbm5tanBwK1J1Y05tTy8zN04xVWpGNzZNZwpXd01Jcm1odlZvTjExajZXL0krSitQdk5NbDZiWHdvQnh0dk53V3dLbzFSdEZ3dGFXMWpWZnNCNEV6SkErb05PCkdEUDlNTmdCQW5uN3JiKzgrTm1XUW1IUllQeEJtbmFJCi0tLS0tRU5EIFBVQkxJQyBLRVktLS0tLQo="
      }
    }
  }
}

In order to verify client signatures, you must set the RLGL_CLIENT_PUBKEY environment variable to tell the script where to find your client's public key. Normally this is found in ~/.config/rlgl/public_key.pem, and so:

$ rlgl verify RLGL-AFC7DB2 | RLGL_CLIENT_PUBKEY=~/.config/rlgl/public_key.pem sh

Verification gives auditors confidence that the server owning the private key associated with the given public key was responsible for generating the given report. It also tells us that the evaluation was initiated by the client associated with the client public key. The rekor record provides a timestamp telling us what time this happened at. Since the report references the original test report, as well as the sha3/256 digest of that original report, we also can be certain that it is the actual report that was used for the policy evaluation. And since the report includes the git commit hash of the policy used to evaluate the report, we can be certain that it is in fact the version of the policy that was used to generate the report.

Your API key is tied to your personal account. It is personal and secret, and you should treat it accordingly. You may, however, be in a situation where you want to share an API key with others. For instance, if you are using public CI testing infrastructure for an open source project, it may not be practical or even possible to secure the API key. In situations like these, you can create what is called a 'policy bound API key'. This is an API key that is not associated with any user. Rather, it is bound to a specific policy URL.

$ rlgl new-policy-bound-api-key https://github.com/libffi/rlgl-policy
78GN98B-QUCN87V-09UN45X-AAQ89BB

You can now share this API key with others, but it will only work with the policy found at https://github.com/libffi/rlgl-policy.

That's it! The client side is very easy.

The server side, where policy is evaluated, is where the magic is.

The first step is to identify the type of report we're evaluating and convert it into a normalized form. The normalized form is defined simply as this: a sequence of JSON objects, one for each testcase result. This object has two required fields:

• result: whose value is either PASS or FAIL.
• id: a descriptive ID for the testcase (e.g. CVE number).

One optional field is:

• url: a URL linking to contextual info for that id.

All labels passed on the rlgl evaluate command appear as fields in the normalized output form. The report parser may also add report type-specific extra fields to the normalized output as they see fit. This is useful for pattern matching, as described below.

Policies are maintained in git repos, and consist of three plain text files: XFAIL, FAIL, and PASS. Each of these files contains a list of JSON matchmaking expressions to match against the canonical test results. They are evaluated this order: XFAIL, FAIL, PASS.

XFAIL contains matchmakers for test results we are expecting to fail, but allowing to pass anyway. These are your exceptions. Any matching JSON objects are reported as green, and filtered out from the list of test results to be processed by FAIL.

FAIL contains matchmakers for tests results that are definitely failures. They are reported as red, and filtered out from the test results before processing with PASS.

PASS contains matchers for known test passes and reported as green.

Any remaining entries in the test results are recorded as UNKNOWN. rlgl interprets these as red, but they are reported as UNKNOWN in order aim for 100% coverage of the PASS/FAIL scans.

The XFAIL, FAIL, PASS files are maintained in a git repo. Changing policy requires modifying the policy in git, which is logged and auditable.

In addition to this simple test evaluation service, the server can report reports based on user-provided labels. Reports submitted to and generated by Red Light Green Light are currently archived forever.

$ rlgl log --label id=test-report
Tue, 29 Jan 2019 13:15:29 -0500 Green: 00430cf0324532aab032423 http://rlgl-server.example.com/doc?id=RLGL-AFC7DB2
Tue, 29 Jan 2019 13:16:31 -0500 Green: 10430cf0324532aab032423 http://rlgl-server.example.com/doc?id=RLGL-CFB5DB3
Tue, 29 Jan 2019 13:16:50 -0500 Green: 20430cf0324532aab032423 http://rlgl-server.example.com/doc?id=RLGL-DFC55B6
Tue, 29 Jan 2019 13:16:55 -0500   Red: 30430cf0324532aab032423 http://rlgl-server.example.com/doc?id=RLGL-8FB75B4

The format of this log is:

TIMESTAMP RED-OR-GREEN: GIT-POLICY-HASH REPORT-URL

Red Light Green Light also has the ability to generate baseline XFAIL policy in cases where you want to track regressions from an already imperfect test run.

$ rlgl baseline RLGL-01234567

This command will generate XFAIL policy output to the console for every FAIL in the report RLGL-01234567 (the "RLGL-" prefix is optional).

Policy in Detail

An rlgl policy consists of three separate files in a git repo: XFAIL, FAIL and PASS. Each file contains JSON matchmaking expressions, comments and blank lines. Comments are lines starting with the characters # or ;. The matchmaking expressions are single-line JSON objects.

For example, to mark a CVE failure as an exception, we add the following to our XFAIL file:

# Ignore this failure in our container images
{ "result": "FAIL", "id": "CVE-2014-4043" }

Each JSON field string must match the corresponding string in the test result object exactly. There are two special forms of string values. Strings starting with "^" are interpreted as regular expressions, and strings of the form "NUMBER..NUMBER" are interpreted as a numeric range.

So, for example, to ignore all CVE vulnerabilities from 2013 with a score of less than 7 we add the following to our XFAIL file:

# Ignore everything but the most critical CVEs from 2013.
{ "result": "FAIL", "id": "^CVE-2013.*", "score": "0..6" }

Every element of the matchmaking expression must match the test result in order to qualify as a match.

A matchmaking expression may be followed by an expiration date, a time after which the matchmaker no longer applies.

# Whitelist this failure until April 1, 2019 and 9am
{ "result": "FAIL", "id": "CVE-2014-4043" } 2019-04-01 9:00

The date expiration time can be in any of the following formats: RFC822 (RFC1123, RFC2822, RFC5322), asctime, RFC850 (RFC1036), ISO8601 (1988, 2000, 2004, except for no-year format), W3CDTF (subset of ISO 8601), RFC3339. Examples of these include:

• Thu, 23 Jul 2013 19:42:23 GMT (RFC1123),
• Thu Jul 23 19:42:23 2013 (asctime),
• Thursday, 23-Jul-13 19:42:23 GMT (RFC1036),
• 2013-07-23T19:42:23Z (RFC3339),
• 20130723T194223Z (ISO8601:2004), etc.

Red Light Green Light will also do it's best to interpret variations of said standards, as in the example above (2019-04-01 9:00).

If a date is provided but no time, then it is interpreted as just after midnight at the start of the day.

JSON matchmaking expressions cannot span more than one line of text. This is required in order to attribute policy changes to individuals via git blame. These changelogs are available through the rlgl reports generated at evaluation time.

Report Parsers

Currently supported report parsers include:

• Anchore container vulnerability json reports
• AquaSec container microscanner reports
• Clair container scanner json reports
• DejaGnu testing framework
• JUnit XML results report
• OpenSCAP OVAL scan reports
• OpenSCAP XCCDF scan reports
• Popeye Popeye k8s sanitizer HTML reports
• Tripwire host scan reports in PDF format
• Comma separated values (CSV) for generic policy enforcement on arbitrary metrics (file size, performance results, etc).

Note that for the CSV parser, the first line of the CSV file defines the field strings used in the resulting JSON results objects. For example, this CSV file...

filename, filesize
a.out, 1234567
b.out, 87908

..produces the following JSON results objects...

{ "filename": "a.out", "filesize": "1234567" }
{ "filename": "b.out", "filesize": "87908" }

..for you to write policy against...

{ "filesize": "0..1000000" }

While the rlgl command-line tool is written in Go, the server side is written in Common Lisp, and adding additional report types requires modifying the rlgl-server lisp code. External parser support is planned, allowing you to invoke report parsers through a simple API.

Monitoring & Observability

The Red Light Green Light server exports Prometheus metrics on port 9101.

Red Light Green Light can optionally transmit usage info to a Matomo instance.

Configuration

The Red Light Green Light server is customized through a number of configuration settings. Every configuration item is settable through either environment variables or a TOML formatted configuration file, /etc/rlgl/config.ini. Environment variables override settings found in the config file.

Environment Variable	Config File Setting	Description
RLGL_SERVER_URI	server-uri	URI for the rlgl server
	db	Either sqlite or postgresql
	sqlite-db-filename	File name for sqlite DB
POSTGRESQL_PASSWORD	postgresql-password	Database password
	postgresql-host	Host for postgresql server
	postgresql-port	Port for postgresql server
	storage-driver	Either local or s3
	local-dir	Local directory for local storage driver
	s3-endpoint	API endpoint for s3 storage
	s3-bucket	s3 bucket name for s3 storage
	policy-dir	Local directory for storing policy git repos
PUBLIC_KEY_FILE	public-key-file	Public signing key for sigstore records
PRIVATE_KEY_FILE	private-key-file	Private signing key for sigstore records
MATOMO_URI	matomo-uri	URI for a Matomo sever (optional)
MATOMO_IDSITE	matomo-idsite	Site ID for Matomo tracking (optional)
MATOMO_TOKEN_AUTH	matomo-token-auth	Auth token for Matomo tracking (optional)
KEYCLOAK_OIDC_CLIENT_ID	keycloak-oidc-client-id	Keycloak client ID (optional)
KEYCLOAK_OIDC_CLIENT_SECRET	keycloak-oidc-client-secret	Keycloak client secret (optional)
KEYCLOAK_OIDC_REALM_REDIRECT_URI	keycloak-oidc-realm-redirect-uri	Keycloak realm redirect URI (optional)
KEYCLOAK_OIDC_REALM_URI	keycloak-oidc-realm-uri	Keycloak realm URI (optional)
	test-api-key	Used for testing
REKOR_SERVER	rekor-server	Defaults to https://rekor.sigstore.dev
AWS_ACCESS_KEY		Required when using s3 storage
AWS_SECRET_KEY		Required when using s3 storage

Author and License

Red Light Green Light was written by Anthony Green, and is distributed under the terms of the GNU Affero General Public License, Version 3. See COPYING for details.