Metadata Signing


Content Signing is in tech-preview and may change in backwards incompatible ways in future releases.

Administrators can add signing services to Pulp using the command line tools. Users may then associate the signing services with repositories that support content signing. The example below demonstrates how a signing service can be created using gpg:

  1. Make sure the service user pulp has access to gpg and that the keypair is installed in its keyrings. The private key might alternatively be provided by a hardware cryptographic device.

  2. Create a signing script that accepts a file name as the only argument. The script needs to generate an ascii-armored detached GPG signature for that file, using the key specified via the PULP_SIGNING_KEY_FINGERPRINT environment variable. The script should then print out a JSON structure with the following format. All the file names are relative paths inside the current working directory:

    {"file": "filename", "signature": "filename.asc"}

    The filename must remain the same for the detached signature, as shown.


    Plugins may provide other signing service classes that may need their JSON output to contain different information.

    Below is an example of a signing script:

    #!/usr/bin/env bash
    # Create a detached signature
    gpg --quiet --batch --pinentry-mode loopback --yes --passphrase \
       $PASSWORD --homedir ~/.gnupg/ --detach-sign --default-key $ADMIN_ID \
       --armor --output $SIGNATURE_PATH $FILE_PATH
    # Check the exit status
    if [ $STATUS -eq 0 ]; then
       echo {\"file\": \"$FILE_PATH\", \"signature\": \"$SIGNATURE_PATH\"}
       exit $STATUS


    Make sure the script contains a proper shebang and Pulp has got valid permissions to execute it.

  3. Create a signing service consisting of an absolute path to the script and a meaningful name describing the script’s purpose. It is possible to insert the signing service in to a database by using the pulpcore-manager shell_plus interactive Python shell. Here is an example showing how to create one instance pointing to a script:

    from import AsciiArmoredDetachedSigningService
    # read an already exported public key
    with open("public.key") as key:


    While creating a signing service, the model AsciiArmoredDetachedSigningService runs additional checks in order to prevent saving invalid scripts to the database. This feature enables administrators to validate their signing scripts in advance.


    You can use pulpcore-manager add-signing-service to add a SigningService. This command is however still in tech-preview.

  4. Retrieve and check the saved signing service via REST API:

    $ http :24817/pulp/api/v3/signing-services/
        "count": 1,
        "next": null,
        "previous": null,
        "results": [
                "name": "sign-metadata",
                "pubkey_fingerprint": "19CD52BD1CA9A00DF10A842D74B14E3590C2231F",
                "public_key": "-----BEGIN PGP PUBLIC KEY BLOCK-----\n\n [...] \n-----END PGP PUBLIC KEY BLOCK-----\n",
                "pulp_created": "2020-11-06T15:42:20.645197Z",
                "pulp_href": "/pulp/api/v3/signing-services/ffb9e987-952f-47e3-a274-ffe69a80ded7/",
                "script": "/var/lib/pulp/"

Plugin writers are then able to sign selected content by the provided script. To learn more about the signing from a plugin’s perspective, see the section Metadata Signing.