Prefetching package manager dependencies for hermetic builds

In Konflux, you can run a hermetic build by restricting network access to the build, but without network a build can’t fetch component dependencies from a repository and might fail. To avoid that, Konflux can prefetch dependencies for your hermetic builds using Cachi2.

For every build, Cachi2 generates a software bill of materials (SBOM) where all dependencies are properly declared and pinned to specific versions. Also, Cachi2 ensures that arbitrary code is never executed during the prefetch, meaning, for example, that the build doesn’t pull any undeclared dependencies. Such measures result in very accurate SBOMs and improve the build reproducibility. For more information about SBOMs, see Inspecting SBOMs.

Table 1. Supported languages

Language

Package manager

Go

gomod

Python

pip

Node.js

npm
To use Yarn as the package manager, see the Cachi2 Usage guide.

Enabling prefetch builds for gomod

Prerequisites

  • You have a go.mod file in your repository that lists all the dependencies.

Procedure

To prefetch dependencies for a component build, complete the following steps:

  1. Go to the .tekton directory in your component repository and find the .yaml files related to both the pull request and push processes.

  2. To configure the hermetic pipeline in both .yaml files, add the following hermetic pipeline prefetch-input parameters to the spec.params sections:

    spec:
    params:
        -   ...
        -   name: prefetch-input
            value: '{"type": "gomod", "path": "."}' (1)
    1 The prefetch-input parameter specifies the path to the directory that has the lockfile and the package metadata files. In this example, the . indicates that the package manager lockfile is in the repository root. Additionally, if you have multiple directories, you can provide the path to those directories in the JSON array format. For example, [{"path": ".", "type": "gomod"}, {"path": "subpath/to/the/other/directory", "type": "gomod"}].

  3. Create a pull request by committing your changes to the repository of the component.

  4. Review and merge the pull request.

Verification

  • From the Konflux Applications view, go to Activity > Pipeline runs.

    • Go to the pipeline run with Build in the Type column and confirm that the prefetch-dependencies 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.

Enabling prefetch builds for pip

Cachi2 supports pip by parsing of pip requirements files, including but not limited to, requirements.txt files placed in the root of your repository. By generically parsing pip requirements files, Cachi2 downloads the specified dependencies.

The requirements file can have a different name because you can use multiple files to provide the dependencies. These requirements files function as lockfiles, encompassing all transitive dependencies. You must actively pin each transitive dependency listed in the requirements file to a specific version.
Prerequisites

  • You have an environment that closely matches the environment in the container build, meaning it has the same operating system and the same python $major.$minor version.

  • You have installed the pip-tools package.

Procedure

To prefetch dependencies for a component build, complete the following steps:

  1. Download the pip_find_builddeps.py script directly from GitHub.

    This script has no runtime dependency other than pip.

  2. Add the script that you downloaded in a directory that is already included in your $PATH. For example, you can use the ~/bin directory in your home folder. Ensure that it exists or create it if needed. To add it to the $PATH permanently, you can modify the shell configuration file (for example, .bashrc, .bash_profile, or .zshrc) and restart the terminal after appending the following line:

    export PATH="$HOME/bin:$PATH"

  3. Open the terminal and go to the directory where you placed the pip_find_builddeps.py script and run the following command to make it executable:

    chmod +x pip_find_builddeps.py

  4. Go to your component’s source code.

  5. Review the root of your repository for a metadata file, for example, pyproject.toml, setup.py, or setup.cfg. If there is no metadata file, create one, because Cachi2 looks for the name and version of your project in the metadata files.

    [metadata]
name = "my_package"
version = "0.1.0"
    Instead of a pyproject.toml file, you can also create a setup.py or setup.cfg file. For information about the metadata of these files, see Project metadata.

  6. Generate a fully resolved requirements.txt file that contains all the transitive dependencies and pins them to a specific version and hash by using the following command:

    $ pip-compile pyproject.toml --generate-hashes

    • To successfully run the previous command, your environment must be as close as possible to the environment in the container build. That is, the environment should have the same operating system and the same Python $major.$minor version.

    • The previous command assumes that you have defined project dependencies in pyproject.toml. However, if you have defined the project dependencies in either the setup.py, requirements.txt, or requirements.in files, make sure you update the command accordingly.

  7. Add the requirements.txt file to the root of your component source code.

  8. In the root of your repository create a requirements-build.in file.

  9. Copy the build system requirements from the pyproject.toml file to the requirements-build.in file.

  1. Run the pip_find_builddeps.py script and pip-compile the outputs by using the following command:

    $ pip_find_builddeps.py requirements.txt \
--append \
--only-write-on-update \
-o requirements-build.in

  2. Use the pip-compile command to convert the requirements-build.in file in to the requirements-build.txt file by using the following command:

    $ pip-compile requirements-build.in --allow-unsafe --generate-hashes

  3. Add the requirement-build.txt file to your project. It does not require any changes to your build process.

    pip automatically installs the build dependencies when needed for explicit installation. The purpose of the requirement-build.txt file is to enable Cachi2 to fetch the build dependencies and provide them to pip for offline installation in a network-isolated environment.

  4. Go to the .tekton directory and locate the .yaml files related to the pull request and push processes.

  5. Configure the hermetic pipeline.

    1. Add the following hermetic pipeline prefetch-input parameters in both the .yaml files:

      spec:
    params:
        -   ...
        -   name: prefetch-input
            value: '{"type": "pip", "path": "."}' (1)
      1 The prefetch-input parameter specifies the path to the directory that has the lockfile and the package metadata files. In the previous example, the . indicates that the package manager lockfile is located in the root of the repository. Additionally, if you have multiple directories, you can provide the path to those directories in the JSON array format. For example, [{"path": ".", "type": "pip"}, {"path": "subpath/to/the/other/directory", "type": "pip"}].

      • By default, Cachi2 processes requirements.txt and requirements-build.txt at a specified path.

      • When adding these parameters, you can safely ignore the default values for the pipelineSpec.params in the .yaml files.

    2. Optional: For requirements files without default names and path, add the following hermetic pipeline prefetch-input parameters in both the .yaml files:

      spec:
    params:
        -   ...
        -   name: prefetch-input
            value: '{"type": "pip", "path": ".", "requirements_files": ["requirements.txt", "requirements-extras.txt", "tests/requirements.txt"]}' (1)
      1 The prefetch-input parameter specifies the path to the directory that has the lockfile and the package metadata files. In the previous example, the . indicates that the package manager lockfile is located in the root of the repository. Additionally, if you have multiple directories, you can provide the path to those directories in the JSON array format. For example, [{"path": ".", "type": "pip", , "requirements_files": ["requirements.txt", "requirements-extras.txt", "tests/requirements.txt"]}, {"path": "subpath/to/the/other/directory", "type": "pip", "requirements_files": ["requirements.txt", "requirements-extras.txt", "tests/requirements.txt"]}].

  6. Create a pull request by committing your changes to the repository of the component.

  7. Review and merge the pull request.

Verification

  • From the Konflux Applications view, go to Activity > Pipeline runs.

    • Go to the pipeline run with Build in the Type column and confirm that the prefetch-dependencies 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.

Prefetching pip dependencies from custom index servers

Cachi2 supports the --index-url option. You can add this option to your requirements.txt file(s), instructing Cachi2 to download packages from the specified index server. For example:

--index-url=https://example.pypi.org/simple/
requests==2.32.2 \
    --hash=sha256:dd951ff5ecf3e3b3aa26b40703ba77495dab41da839ae72ef3c8e5d8e2433289 \
    --hash=sha256:fc06670dd0ed212426dfeb94fc1b983d917c4f9847c863f313c9dfaaffb7c23c

# ...other packages
Do not include credentials in the index url. If needed, provide authentication through a .netrc file (as described below).

To provide .netrc authentication for the index server:

  1. Create a key/value secret (see creating secrets for your builds). Set .netrc as the key. Upload the content of your .netrc file as the value. For more details on netrc files, review the pip documentation for netrc support.

  2. In your .tekton/ PipelineRun files, add the newly created secret to the .spec.workspaces section:

    spec:
  # ...
  workspaces:
    # ...
    - name: netrc
      secret:
        secretName: my-netrc  # the name you assigned to the secret in step 1

  3. In the .spec.pipelineSpec.tasks section, find the entry with name: prefetch-dependencies. Add the netrc workspace to the list of workspaces (if not present):

        tasks:
      # ...
      - name: prefetch-dependencies
        # ...
        workspaces:
          # ...
          - name: netrc
            workspace: netrc

Enabling prefetch builds for npm

Cachi2 supports npm by fetching any dependencies you declare in your package.json and package-lock.json project files. The npm CLI manages the package-lock.json file automatically, and Cachi2 fetches any dependencies and enables your build to install them without network access.

Prerequisites

  • You have an up-to-date package-lock.json file, newer than version 1, in your source repository. To make sure that you have the latest package-lock.json file, or to create a lockfile, run the npm-install command. You can also look at the lockfileVersion attribute in your package-lock.json file to make sure its value is a number greater than 1.

Procedure

To prefetch dependencies for a component build, complete the following steps:

  1. Go to the .tekton directory and find the .yaml files related to the pull request and push processes.

  2. Configure the hermetic pipeline by adding the following parameters in both .yaml files:

    spec:
    params:
        -   ...
        -   name: prefetch-input
            value: '{"type": "npm", "path": "."}' (1)
    1 The prefetch-input parameter specifies the path to the directory that has the lockfile and the package metadata files. In this example, the . indicates that the package manager lockfile is in the repository root. Additionally, if you have multiple directories, you can provide the path to those directories in the JSON array format. For example, [{"path": ".", "type": "npm"}, {"path": "subpath/to/the/other/directory", "type": "npm"}].

  3. Create a pull request by committing your changes to the repository of the component.

  4. Review and merge the pull request.

Verification

  • From the Konflux Applications view, go to Activity > Pipeline runs.

    • Go to the pipeline run with Build in the Type column and confirm that the prefetch-dependencies 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

  • To troubleshoot any issues you might experience when you enable prefetch builds for pip or pip with source dependencies, see Troubleshooting.

  • For more information about Cachi2, see Cachi2.