Enabling hermetic builds

A hermetic build is a secure, self-contained build process that doesn’t depend on anything outside of the build environment. This means that it does not have network access, is not vulnerable to external influences, and cannot fetch dependencies at run time. Instead, you must declare all required resources and dependencies in your build definition.

In Konflux, you can block network access to the build process and run a hermetic build by setting the hermetic parameter in your pipeline definition file to true. This means that you must fetch all dependencies before the build can start. The following is an example code snippet:

kind: PipelineRun
spec:
  params:
    ...
  - name: hermetic
    value: "true"
    ...

Hermetic builds disable network access, so a build with dependencies outside of its Git repository—including supported languages—might fail. To prevent this, or to pull in dependencies from a package manager for one of the supported languages, follow the instructions in Prefetching the package manager dependencies for the hermetic build.

Similarly, with a Buildah task for a non-Java application, when you set the hermetic parameter to true, you’re isolating the build from the network, which restricts it to building only from dependencies listed in your Git repository.
Do not add these parameters to the pipelineSpec.params section, as it should always display the default values for hermetic builds.

Procedure

To create a hermetic build for a component, complete the following steps:

Go to the .tekton directory in your component’s repository and find the .yaml files related to your pull request and push processes.
To configure the hermetic pipeline in both the .yaml files, add the following hermetic pipeline parameters to the spec.params section:
```
spec:
    params:
        -   ...
        -   name: hermetic
            value: "true"
```
Commit your changes to the component repository and create a pull request.
Verify that your build was successful, then merge your pull request.

Verification

From the Konflux Applications view, go to Activity > Pipeline runs.
- Look at the pipeline run with Build in the Type column and confirm that the build-container stage displays a green checkmark. This indicates that the build process successfully fetched all dependencies.
From the Konflux Applications view, go to Activity > Latest commits.

Troubleshooting

If your build fails, be sure to look at your logs:

In Konflux, from the Applications view, select the application build you want to troubleshoot, then from the resulting Overview page, select the Activity tab. From there, under Activity By, select Pipeline runs. From the Name column, select the build whose logs you want to check, then from the resulting Pipeline run details view, do one of the following:

Select the Logs tab.
Alternatively, you can click build-container. When the right panel opens, select the Logs tab to see a partial view of the log for that build.

Additional resources

For more information about the importance of provenance, see Supply chain security through SLSA conformity.