--- title: Charmhub | Deploy Certificate Transfer Interface using Charmhub - The Open Operator Collection description: Deploy the latest version of Certificate Transfer Interface on any cloud. url: https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer --- # Certificate Transfer Interface [Canonical Telco](https://charmhub.io/publisher/telco-charmers "View all packages from Canonical Telco") * [Canonical Telco](https://charmhub.io/publisher/telco-charmers "View all packages from Canonical Telco") Platform: 22.04 edge 230 ``` juju deploy certificate-transfer-interface --channel edge ``` [Learn to deploy on juju >](https://juju.is/docs/juju/manage-applications) [Toggle side navigation](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#drawer) ## charms.certificate\_transfer\_interface.v1.certificate\_transfer * [*Docstrings*Docstrings](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer) [*Code*Source code](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer/source-code) * + Download Fetch library ``` charmcraft fetch-lib charms.certificate_transfer_interface.v1.certificate_transfer ``` [Download certificate\_transfer.py](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer/download) + *Last updated* 10 Dec 2025 + *Revision* Library version 1.15 Library for the certificate\_transfer relation. This library contains the Requires and Provides classes for handling the certificate-transfer interface. It supports both v0 and v1 of the interface. For requirers, they will set version 1 in their application databag as a hint to the provider. They will read the databag from the provider first as v1, and fallback to v0 if the format does not match. For providers, they will check the version in the requirer's application databag, and send v1 if that version is set to 1, otherwise it will default to 0 for backwards compatibility. ##### Getting Started From a charm directory, fetch the library using `charmcraft`: ``` charmcraft fetch-lib charms.certificate_transfer_interface.v1.certificate_transfer ``` ###### Provider charm The provider charm is the charm providing public certificates to another charm that requires them. Example: ``` from ops.charm import CharmBase, RelationJoinedEvent from ops.main import main from lib.charms.certificate_transfer_interface.v1.certificate_transfer import ( CertificateTransferProvides, ) class DummyCertificateTransferProviderCharm(CharmBase): def __init__(self, *args): super().__init__(*args) self.certificate_transfer = CertificateTransferProvides(self, "certificates") self.framework.observe( self.on.certificates_relation_joined, self._on_certificates_relation_joined ) def _on_certificates_relation_joined(self, event: RelationJoinedEvent): certificate = "my certificate" self.certificate_transfer.add_certificates(certificate) if __name__ == "__main__": main(DummyCertificateTransferProviderCharm) ``` ###### Requirer charm The requirer charm is the charm requiring certificates from another charm that provides them. Example: ``` import logging from ops.charm import CharmBase from ops.main import main from lib.charms.certificate_transfer_interface.v1.certificate_transfer import ( CertificatesAvailableEvent, CertificatesRemovedEvent, CertificateTransferRequires, ) class DummyCertificateTransferRequirerCharm(CharmBase): def __init__(self, *args): super().__init__(*args) self.certificate_transfer = CertificateTransferRequires(self, "certificates") self.framework.observe( self.certificate_transfer.on.certificate_set_updated, self._on_certificates_available ) self.framework.observe( self.certificate_transfer.on.certificates_removed, self._on_certificates_removed ) def _on_certificates_available(self, event: CertificatesAvailableEvent): logging.info(event.certificates) logging.info(event.relation_id) def _on_certificates_removed(self, event: CertificatesRemovedEvent): logging.info(event.relation_id) if __name__ == "__main__": main(DummyCertificateTransferRequirerCharm) ``` You can integrate both charms by running: ``` juju integrate ``` --- Index * [class TLSCertificatesError](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#tlscertificateserror) * [class DataValidationError](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#datavalidationerror) * [class DatabagModel](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#databagmodel) * + [def load( cls, databag)](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#databagmodel-load) * + [def dump( self, databag, clear)](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#databagmodel-dump) * [class ProviderApplicationData](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#providerapplicationdata) * [class ProviderUnitDataV0](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#providerunitdatav0) * [class RequirerApplicationData](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#requirerapplicationdata) * [class CertificateTransferProvides](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#certificatetransferprovides) * + [def \_\_init\_\_( self, charm, relationship\_name)](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#certificatetransferprovides-__init__) * + [def add\_certificates( self, certificates, relation\_id)](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#certificatetransferprovides-add_certificates) * + [def remove\_all\_certificates( self, relation\_id)](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#certificatetransferprovides-remove_all_certificates) * + [def remove\_certificate( self, certificate, relation\_id)](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#certificatetransferprovides-remove_certificate) * [class CertificatesAvailableEvent](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#certificatesavailableevent) * + [def \_\_init\_\_( self, handle, certificates, relation\_id)](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#certificatesavailableevent-__init__) * + [def snapshot( self)](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#certificatesavailableevent-snapshot) * + [def restore( self, snapshot)](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#certificatesavailableevent-restore) * [class CertificatesRemovedEvent](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#certificatesremovedevent) * + [def \_\_init\_\_( self, handle, relation\_id)](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#certificatesremovedevent-__init__) * + [def snapshot( self)](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#certificatesremovedevent-snapshot) * + [def restore( self, snapshot)](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#certificatesremovedevent-restore) * [class CertificateTransferRequirerCharmEvents](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#certificatetransferrequirercharmevents) * [class CertificateTransferRequires](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#certificatetransferrequires) * + [def \_\_init\_\_( self, charm, relationship\_name)](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#certificatetransferrequires-__init__) * + [def get\_all\_certificates( self, relation\_id)](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#certificatetransferrequires-get_all_certificates) * + [def get\_all\_certificates\_by\_relation( self, relation\_id)](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#certificatetransferrequires-get_all_certificates_by_relation) * + [def is\_ready( self, relation)](https://charmhub.io/certificate-transfer-interface/libraries/certificate_transfer#certificatetransferrequires-is_ready) #### class TLSCertificatesError Description Base class for custom errors raised by this library. None #### class DataValidationError Description Raised when data validation fails. None #### class DatabagModel Base databag model. Description Supports both pydantic v1 and v2. Methods DatabagModel. load( cls , databag: MutableMapping ) Description Load this model from a Juju databag. None DatabagModel. dump( *self* , databag , clear: bool ) Write the contents of this model to Juju databag. Arguments databag The databag to write to. clear Whether to clear the databag before writing. Returns MutableMapping The databag. #### class ProviderApplicationData Description Provider App databag model. None #### class ProviderUnitDataV0 Description Provider Unit databag v0 model. None #### class RequirerApplicationData Description Requirer App databag model. None #### class CertificateTransferProvides Description Certificate Transfer provider class to be instantiated by charms sending certificates. None Methods CertificateTransferProvides. \_\_init\_\_( *self* , charm: CharmBase , relationship\_name: str ) CertificateTransferProvides. add\_certificates( *self* , certificates , relation\_id ) Add certificates from a set to relation data. Arguments certificates (Set[str]) A set of certificate strings in PEM format relation\_id (int) Juju relation ID Returns None Description Adds certificate to all relations if relation\_id is not provided. CertificateTransferProvides. remove\_all\_certificates( *self* , relation\_id ) Remove all certificates from relation data. Arguments relation\_id (int) Relation ID Returns None Description Removes all certificates from all relations if relation\_id not given CertificateTransferProvides. remove\_certificate( *self* , certificate: str , relation\_id ) Remove a given certificate from relation data. Arguments certificate (str) Certificate in PEM format that's in the list relation\_id (int) Relation ID Returns None Description Removes certificate from all relations if relation\_id not given #### class CertificatesAvailableEvent Description Charm Event triggered when the set of provided certificates is updated. None Methods CertificatesAvailableEvent. \_\_init\_\_( *self* , handle: Handle , certificates , relation\_id: int ) CertificatesAvailableEvent. snapshot( *self* ) Description Return snapshot. None CertificatesAvailableEvent. restore( *self* , snapshot: dict ) Description Restores snapshot. None #### class CertificatesRemovedEvent Description Charm Event triggered when the set of provided certificates is removed. None Methods CertificatesRemovedEvent. \_\_init\_\_( *self* , handle: Handle , relation\_id: int ) CertificatesRemovedEvent. snapshot( *self* ) Description Return snapshot. None CertificatesRemovedEvent. restore( *self* , snapshot: dict ) Description Restores snapshot. None #### class CertificateTransferRequirerCharmEvents Description List of events that the Certificate Transfer requirer charm can leverage. None #### class CertificateTransferRequires Description Certificate transfer requirer class to be instantiated by charms expecting certificates. None Methods CertificateTransferRequires. \_\_init\_\_( *self* , charm: CharmBase , relationship\_name: str ) Observe events related to the relation. Arguments charm Charm object relationship\_name Juju relation name CertificateTransferRequires. get\_all\_certificates( *self* , relation\_id ) Get transferred certificates. Arguments relation\_id The id of the relation to get the certificates from. Description If no relation id is given, certificates from all relations will be provided in a concatenated list. CertificateTransferRequires. get\_all\_certificates\_by\_relation( *self* , relation\_id ) Get a deterministic list of certificates grouped by relation. Arguments relation\_id If provided, only certificates for this relation are returned. Returns Dict where keys are relation IDs and values are ordered lists of PEMs. Description * Grouped by relation\_id. * The list order is sorted lexicographically by PEM content. CertificateTransferRequires. is\_ready( *self* , relation: Relation ) Description Check if the relation is ready by checking that it has valid relation data. None