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Generate SLSA with Harness GitLab CI/CD

Use Harness GitLab CI/CD to Generate SLSA Provenance

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. Go to Manage API Keys and Service Account API Keys to create them.

  • If you are using key-based or Secret Manager signing or verification, create or configure a Cosign key pair before configuring the pipeline. Go tos Quickstart Signing and Verifying with Cosign 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 do not 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 do not need to configure a Harness Secret Manager connector. For setup steps specific to HashiCorp Vault, go to 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. Go to Use Docker-in-Docker to configure DinD support.

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. Go to Service Account API Keys to create one.

    • 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. Go to Manage API Keys to manage them.

  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.

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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.

If you are using GitLab Self-Managed, mirror the required Harness GitLab CI/CD components to your GitLab instance before configuring your pipeline. After mirroring the components, update the component reference in your workflow file to use the mirrored component. Go to Use a GitLab.com component on GitLab Self-Managed to mirror components.

Complete the following steps to configure SLSA generation:

  1. Add the required GitLab CI/CD variables

  2. Include the SLSA Generation component

  3. Configure SLSA provenance attestation in the workflow (optional)

  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. Go to Define a CI/CD Variable for a project to add them.

Variable
Description
Required
Example
Masked?

HARNESS_API_KEY

Harness Personal API Key or Service Account API Key used to authenticate with Harness.

Yes

pat.xxxxxxxxx

Yes

HARNESS_ACCOUNT_ID

Harness account identifier.

Yes

AbCdEf123456

No

HARNESS_ORG_ID

Harness organization identifier.

Yes

SCS_Org

No

HARNESS_PROJECT_ID

Harness project identifier.

Yes

SCS

No

HARNESS_ACCOUNT_URL

Harness account URL.

Yes

https://example.harness.io

No

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.

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

Input

Description

Required

Default

Example

HARNESS_ACCOUNT_ID

Harness account ID. Pass a non-masked CI/CD variable reference.

Yes

N/A

$HARNESS_ACCOUNT_ID

HARNESS_ORG_ID

Harness organization ID. Pass a non-masked CI/CD variable reference.

Yes

N/A

$HARNESS_ORG_ID

HARNESS_PROJECT_ID

Harness project ID. Pass a non-masked CI/CD variable reference.

Yes

N/A

$HARNESS_PROJECT_ID

HARNESS_ACCOUNT_URL

Harness base URL with scheme. Pass a non-masked CI/CD variable reference.

Yes

N/A

$HARNESS_ACCOUNT_URL

TARGET

Container image reference when SOURCE is container, or artifact file path when SOURCE is local.

Yes

N/A

$CI_REGISTRY_IMAGE:$CI_COMMIT_SHA

ATTEST

Generates and attests SLSA provenance.

No

false

true

SOURCE

Artifact source. Supported values are container and local.

No

container

local

ARTIFACT_NAME

Display name for a local artifact. Applicable when SOURCE=local.

No

File name from TARGET

payment-service

ARTIFACT_VERSION

Artifact version. Applicable when SOURCE=local.

No

N/A

$CI_COMMIT_SHORT_SHA

stage

GitLab pipeline stage in which the component runs.

No

scs

security

job-name

Name of the GitLab job created by the component.

No

scs-slsa-generation

generate-slsa

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 Step 3: Configure provenance attestation (optional).

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.

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.

Step 3: Configure provenance attestation (optional)

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.

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.

Input
Description
Required

ATTEST_WITH

Specifies the attestation method. Set the value to keyless.

Yes

OIDC_PROVIDER

OIDC provider used to obtain the signing identity. For GitLab CI/CD, set the value to non-harness.

Yes

FULCIO_URL

Fulcio 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.

To sign the generated SLSA provenance using a cryptographic key, set ATTEST_WITH to keybased and provide the Cosign key material as masked GitLab CI/CD variables on the job. KMS_KEY is not used for key-based attestation. It applies only to Secret Manager attestation.

Input
Description
Required

ATTEST_WITH

Specifies the attestation method. Set the value to keybased.

Yes

Provide the following masked GitLab CI/CD variables on the job:

Variable
Description
Required

SSCA_SLSA_GENERATION_COSIGN_PRIVATE_KEY

Cosign private key used to sign the SLSA provenance attestation.

Yes

SSCA_SLSA_GENERATION_COSIGN_PASSWORD

Password for the Cosign private key.

Yes

To use a signing key stored in a supported secret manager, configure the following inputs.

Input
Description
Required

ATTEST_WITH

Specifies the attestation method. Set the value to secret-manager.

Yes

KMS_KEY

KMS or Vault key URI for the signing key stored in the secret manager.

Yes

VAULT_ADDR

HashiCorp Vault address. Required when KMS_KEY uses a Vault URI.

Conditional

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.

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. Go to Tutorial: Create and run your first GitLab CI/CD pipeline to run a GitLab pipeline.

After the pipeline completes, open the job execution logs and click the Harness Artifact Details link to view the generated artifact in SCS. Go to View the status of your pipeline and jobs to check job status and pipeline details.

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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. Go to Artifact Overview to navigate through artifacts.

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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.

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.

Next steps

PreviousSLSA using GitLab CI/CD
NextVerify SLSA with Harness GitLab CI/CD

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