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Generate SLSA with Harness GitLab CI/CD

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Software artifacts move through multiple stages of the software development lifecycle before deployment. Without verifiable provenance, it can be difficult to determine how an artifact was built, where it originated, and whether the build process has been tampered with. This lack of traceability increases the risk of software supply chain attacks and makes it challenging to establish trust in released artifacts.

Harness Supply Chain Security (SCS) integrates with GitLab CI/CD to automate SLSA provenance generation as part of your GitLab workflow. It enables you to generate SLSA provenance for container images or local artifacts during pipeline execution. You can also optionally attest the generated provenance using Cosign, helping you establish artifact integrity and improve software supply chain trust throughout the software development lifecycle.

What will you learn in this topic?​

By the end of this topic, you will be able to:

  • Set up Harness GitLab CI/CD integration from your SCS project.
  • Configure SLSA provenance generation in your GitLab workflow using the SLSA Generation component.
  • Configure optional SLSA provenance attestation using keyless, key-based, or Secret Manager signing methods.
  • Generate and upload SLSA provenance to the SCS module.

Before you begin​

Make a note of the following before you proceed with generating SLSA provenance using GitLab CI/CD:

  • Understand how to create Harness API keys using Personal API Keys or Service Account API Keys. For more information, go to Manage API Keys and Service Account API Keys, respectively.
  • If you're using key-based or Secret Manager signing or verification, create or configure a Cosign key pair before configuring the pipeline. For step-by-step instructions, see Quickstart Signing and Verifying with Cosign, which explains how to generate a local key pair or create one using a supported KMS provider. The key should be generated using Cosign of type ecdsa-P256. You don't need to install Cosign on your GitLab runner. The harness/ssca-plugin container image used by the Harness GitLab CI/CD components includes Cosign, so no additional installation is required.
  • If you plan to use Secret Manager attestation, store your signing key in a supported secret manager. Currently, Harness supports HashiCorp Vault. For GitLab CI/CD, you point the component at the key through pipeline variables such as KMS_KEY (and VAULT_ADDR when the key is stored in HashiCorp Vault), so you don't need to configure a Harness Secret Manager connector. For setup steps specific to HashiCorp Vault, see the Add a HashiCorp Vault secret manager.
  • Ensure that your GitLab runners support Docker-in-Docker (DinD). The component runs using the docker:24-dind service. For more information, go to Use Docker-in-Docker.

Understand SLSA generation with Harness GitLab CI/CD​

Harness SCS integrates with GitLab CI/CD through reusable GitLab CI/CD components. These components enable you to automate software supply chain security tasks in your GitLab pipelines, helping you build, verify, and govern software artifacts without adding custom implementation to your CI/CD workflow.

The SLSA Generation capability enables you to generate SLSA provenance for container images or local artifacts during pipeline execution. The generated provenance captures details about the build process, including the artifact, build environment, and source information. You can also optionally attest the generated provenance using Cosign before uploading it to the SCS module.

Once the provenance is generated, you can use it to establish artifact integrity, improve traceability across your software supply chain, and support provenance verification before software artifacts are promoted or deployed.

Why use it?When to use it?How can you leverage it?
Generate verifiable provenance for software artifacts.When you want to establish the origin and build history of software artifacts.Use generated provenance to improve software supply chain traceability, verify artifact integrity, and support SLSA compliance initiatives.

Set up Harness GitLab CI/CD​

Before configuring SLSA generation in your GitLab pipeline, set up Harness GitLab CI/CD from your SCS project. The setup guides you through creating or selecting a Harness API key and generates a project-specific YAML configuration with your Harness account ID, organization ID, project ID, and account URL already populated. You can copy this configuration into your GitLab workflow and update the remaining inputs as needed.

Complete the following steps to set up Harness GitLab CI/CD:

  1. Navigate to the Integrations page under the Manage section from the sidebar navigation of your SCS account.
  2. Click the Add Integration button to go to the Configure Integration page.
    Alternatively, you can access this page by clicking Get Started > Get Started from the sidebar navigation of your SCS account.
  3. Scroll down to the GitLab collapsible and click it to expand.
  4. Click the Configure button under Configure GitLab CI/CD in your pipeline to generate SBOM and SLSA, and sign artifacts to open the Configure Integration page, where the Artifact Security feature cards are displayed.
  5. Click the Generate SLSA card to open the SLSA Generation sidepanel.
  6. Click the Go to Key Generation button to create the Harness API key required to configure Harness GitLab CI/CD.
    • Select Using Service Account from the dropdown to create the API key using a service account. For more information, see Service Account API Keys.
    • Select Using Personal Account from the dropdown to create a personal API key. Personal API keys are created at the account level and inherit the permissions assigned to your user account. For more information, see Manage API Keys.
  7. Click Copy in the upper-right corner of the code block to copy the generated GitLab CI/CD configuration, and then paste it into your GitLab workflow file.

Configure SLSA generation in GitLab CI/CD​

After setting up Harness GitLab CI/CD, configure the SLSA Generation component in your GitLab workflow file. Add the required GitLab CI/CD variables to your GitLab project, configure the component inputs, configure the attestation settings if required, and run the pipeline. During pipeline execution, the component generates SLSA provenance for the specified artifact and uploads it to the SCS module. For the authoritative list of component inputs and defaults, see the CI/CD Catalog at SCS GitLab Plugins.

Complete the following steps to configure SLSA generation:

  1. Add the required GitLab CI/CD variables
  2. Include the SLSA Generation component
  3. (Optional) Configure SLSA provenance attestation in the workflow
  4. Review the workflow
  5. Run the pipeline

Step 1 - Add the required GitLab CI/CD variables​

Before configuring the SLSA Generation component, add the following variables to your GitLab project. For step-by-step instructions, see Define a CI/CD Variable for a project.

VariableDescriptionRequiredExampleMasked?
HARNESS_API_KEYHarness Personal API Key or Service Account API Key used to authenticate with Harness.Yespat.xxxxxxxxxYes
HARNESS_ACCOUNT_IDHarness account identifier.YesAbCdEf123456No
HARNESS_ORG_IDHarness organization identifier.YesSCS_OrgNo
HARNESS_PROJECT_IDHarness project identifier.YesSCSNo
HARNESS_ACCOUNT_URLHarness account URL.Yeshttps://example.harness.ioNo
note

Masked GitLab CI/CD variables cannot be passed through component inputs. For this reason, the Harness scope variables (HARNESS_ACCOUNT_ID, HARNESS_ORG_ID, HARNESS_PROJECT_ID, and HARNESS_ACCOUNT_URL) must remain unmasked so that they can be wired through the component inputs. HARNESS_API_KEY remains masked and is consumed directly from the job environment, not passed as a component input. These values are included in the generated YAML provided during the Set up Harness GitLab CI/CD workflow.

Step 2 - Include the SLSA Generation component​

Add an scs stage to your GitLab workflow file, or set the stage input on the component to an existing stage. Then, include the Harness SLSA Generation component in your GitLab workflow file.

The following code snippet demonstrates how to add the scs stage and include the SLSA Generation component in your GitLab workflow file. The snippet includes the minimum required component inputs because the component requires the Harness scope variables and the target artifact to run.

stages: [scs]

include:
  - component: gitlab.com/harness-scs/gitlab-plugins/slsa-generation@1.0.0
    inputs:
      HARNESS_ACCOUNT_ID: $HARNESS_ACCOUNT_ID
      HARNESS_ORG_ID: $HARNESS_ORG_ID
      HARNESS_PROJECT_ID: $HARNESS_PROJECT_ID
      HARNESS_ACCOUNT_URL: $HARNESS_ACCOUNT_URL
      TARGET: $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA

Configure the component using the GitLab CI/CD variables created in the previous step and the following component inputs.

InputDescriptionRequiredDefaultExample
HARNESS_ACCOUNT_IDHarness account ID. Pass a non-masked CI/CD variable reference.YesN/A$HARNESS_ACCOUNT_ID
HARNESS_ORG_IDHarness organization ID. Pass a non-masked CI/CD variable reference.YesN/A$HARNESS_ORG_ID
HARNESS_PROJECT_IDHarness project ID. Pass a non-masked CI/CD variable reference.YesN/A$HARNESS_PROJECT_ID
HARNESS_ACCOUNT_URLHarness base URL with scheme. Pass a non-masked CI/CD variable reference.YesN/A$HARNESS_ACCOUNT_URL
TARGETContainer image reference when SOURCE is container, or artifact file path when SOURCE is local.YesN/A$CI_REGISTRY_IMAGE:$CI_COMMIT_SHA
ATTESTGenerates and attests SLSA provenance.Nofalsetrue
SOURCEArtifact source. Supported values are container and local.Nocontainerlocal
ARTIFACT_NAMEDisplay name for a local artifact. Applicable when SOURCE=local.NoFile name from TARGETpayment-service
ARTIFACT_VERSIONArtifact version. Applicable when SOURCE=local.NoN/A$CI_COMMIT_SHORT_SHA
stageGitLab pipeline stage in which the component runs.Noscssecurity
job-nameName of the GitLab job created by the component.Noscs-slsa-generationgenerate-slsa
note

By default, the component generates provenance for a container image. To generate provenance for a local artifact, set SOURCE to local. When using a local artifact, specify the artifact path in TARGET and provide an ARTIFACT_VERSION.

To attest the generated provenance, configure the attestation inputs (ATTEST_WITH, OIDC_PROVIDER, FULCIO_URL, KMS_KEY, and VAULT_ADDR) as described in (Optional) Step 3 - Configure provenance attestation.

Override the generated job​

Standard GitLab job keywords, such as needs, before_script, script, after_script, allow_failure, and tags, are not component inputs. To set them, redeclare the generated job (default name scs-slsa-generation, or the value of job-name) in your workflow file. GitLab merges your keys into the generated job.

scs-slsa-generation:
  needs: [build-image]
  tags: [docker, linux]
  before_script:
    - echo "Starting provenance generation"
  after_script:
    - echo "Provenance generation complete"
note

If you are generating provenance for an image in a private registry that is not the GitLab container registry, provide the registry credentials as masked GitLab CI/CD variables so that the component can access the image.

(Optional) Step 3 - Configure provenance attestation​

Harness supports the following attestation methods:

  • Keyless attestation – Uses OpenID Connect (OIDC) identities to sign the generated SLSA provenance without managing long-lived signing keys.
  • Key-based attestation – Uses a cryptographic key managed through your organization's key management solution.
  • Secret Manager – Uses signing keys stored in a supported secret manager.
note

SLSA provenance attestation is disabled by default (ATTEST: false). The component generates and uploads the provenance without signing it. If you plan to verify the provenance attestation during SLSA Verification, set ATTEST: true to generate a signed attestation.

Configure the appropriate attestation inputs based on the attestation method you want to use.

If you enable SLSA attestation, you can configure keyless attestation to sign the generated SLSA provenance using an OpenID Connect (OIDC) identity. For GitLab CI/CD, set OIDC_PROVIDER to non-harness. The harness OIDC provider is not supported as of now. Keyless attestation requires GitLab 15.7 or later, because it depends on GitLab id_tokens. Configure the following inputs.

InputDescriptionRequired
ATTEST_WITHSpecifies the attestation method. Set the value to keyless.Yes
OIDC_PROVIDEROIDC provider used to obtain the signing identity. For GitLab CI/CD, set the value to non-harness.Yes
FULCIO_URLFulcio certificate authority endpoint. Used when OIDC_PROVIDER is non-harness. Defaults to https://fulcio.sigstore.dev.No

Provide the OIDC token to the generated job using id_tokens. The component reads the token from PLUGIN_NON_HARNESS_OIDC_TOKEN.

stages: [scs]
 
include:
  - component: gitlab.com/harness-scs/gitlab-plugins/slsa-generation@1.0.0
    inputs:
      HARNESS_ACCOUNT_ID: $HARNESS_ACCOUNT_ID
      HARNESS_ORG_ID: $HARNESS_ORG_ID
      HARNESS_PROJECT_ID: $HARNESS_PROJECT_ID
      HARNESS_ACCOUNT_URL: $HARNESS_ACCOUNT_URL
      TARGET: $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA
      ATTEST: true
      ATTEST_WITH: keyless
      OIDC_PROVIDER: non-harness
 
scs-slsa-generation:
  id_tokens:
    PLUGIN_NON_HARNESS_OIDC_TOKEN:
      aud: sigstore

Step 4 - Review the workflow​

After configuring the required GitLab CI/CD variables and component inputs, your GitLab workflow file should resemble the following example. This example generates SLSA provenance for a container image in Harness SCS and attests the generated provenance using Cosign with a key stored in HashiCorp Vault. The Harness scope variables are wired through inputs, HARNESS_API_KEY remains a masked GitLab CI/CD variable, and the Vault variables (KMS_KEY and VAULT_ADDR) are provided because attestation is enabled.

include:
  - component: gitlab.com/harness-scs/gitlab-plugins/slsa-generation@1.0.0
    inputs:
      HARNESS_ACCOUNT_ID: $HARNESS_ACCOUNT_ID
      HARNESS_ORG_ID: $HARNESS_ORG_ID
      HARNESS_PROJECT_ID: $HARNESS_PROJECT_ID
      HARNESS_ACCOUNT_URL: $HARNESS_ACCOUNT_URL
      TARGET: $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA
      ATTEST: true
      ATTEST_WITH: secret-manager
      KMS_KEY: hashivault://cosign
      VAULT_ADDR: $VAULT_ADDR

Step 5 - Run the pipeline​

Commit and push your changes to trigger the GitLab pipeline. During pipeline execution, the SLSA Generation component generates provenance for the specified artifact and uploads it to the SCS module. If provenance attestation is enabled, the component also generates and signs a provenance attestation using the configured attestation method. For more information on running a GitLab pipeline, see Tutorial: Create and run your first GitLab CI/CD pipeline.

After the pipeline completes, open the job execution logs and click the Harness Artifact Details link to view the generated artifact in SCS. For more information on viewing the status of a job and details of the pipeline, see View the status of your pipeline and jobs.

The Artifact Details page displays the generated SLSA provenance and its associated security results. The provenance is also automatically recorded in the Chain of Custody, providing an immutable audit trail of the artifact lifecycle and the associated GitLab CI/CD pipeline execution. For more information on navigating through artifacts, see Artifact Overview.

Example SLSA generation workflow​

Example SLSA generation workflow for a container image

The following example demonstrates how to configure the SLSA Generation component in a GitLab workflow to generate provenance for a container image. The example also shows how to optionally attest the generated provenance using Cosign with a key stored in HashiCorp Vault.

stages:
  - build
  - scs
 
build-image:
  stage: build
  image: docker:24.0.5
  services:
    - docker:24.0.5-dind
  script:
    - docker build -t $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA .
    - docker push $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA
 
include:
  - component: gitlab.com/harness-scs/gitlab-plugins/slsa-generation@1.0.0
    inputs:
      stage: scs
      job-name: generate-slsa
      HARNESS_ACCOUNT_ID: $HARNESS_ACCOUNT_ID
      HARNESS_ORG_ID: $HARNESS_ORG_ID
      HARNESS_PROJECT_ID: $HARNESS_PROJECT_ID
      HARNESS_ACCOUNT_URL: $HARNESS_ACCOUNT_URL
 
      TARGET: $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA
 
      ATTEST: true
      ATTEST_WITH: secret-manager
      KMS_KEY: hashivault://cosign
      VAULT_ADDR: $VAULT_ADDR
Example SLSA generation workflow for a local artifact

The following example generates provenance for a local artifact. It builds the artifact in an earlier job, passes it forward with artifacts, and uses needs so the SLSA job runs after the artifact is available. When SOURCE is local, TARGET is the artifact file path and ARTIFACT_VERSION is required.

stages:
  - build
  - scs
 
build-artifact:
  stage: build
  script:
    - ./build.sh -o $CI_PROJECT_DIR/target/myapp.jar
  artifacts:
    paths:
      - target/myapp.jar
 
scs-slsa-generation:
  needs: [build-artifact]
 
include:
  - component: gitlab.com/harness-scs/gitlab-plugins/slsa-generation@1.0.0
    inputs:
      HARNESS_ACCOUNT_ID: $HARNESS_ACCOUNT_ID
      HARNESS_ORG_ID: $HARNESS_ORG_ID
      HARNESS_PROJECT_ID: $HARNESS_PROJECT_ID
      HARNESS_ACCOUNT_URL: $HARNESS_ACCOUNT_URL
 
      SOURCE: local
      TARGET: $CI_PROJECT_DIR/target/myapp.jar
      ARTIFACT_VERSION: $CI_COMMIT_SHORT_SHA

Next steps​