cas_wrapper/cas_wrapper.py

import json
import logging
import typing

from plumbum import local, ProcessExecutionError


class CasWrapper:
    """
    The python wrapper around binary `cas`
    from Codenotary Community Attestation Service
    """

    binary_name = 'cas'

    @classmethod
    def _is_binary_present(cls):
        if cls.binary_name not in local:
            raise FileNotFoundError(
                'Binary CAS is not found in PATH on the machine',
            )

    def __init__(
            self,
            cas_api_key: str,
            cas_signer_id: str,
            logger: logging.Logger = None,
    ):
        self._is_binary_present()
        self._cas_api_key = cas_api_key
        self._cas_signer_id = cas_signer_id
        self._cas = local['cas']
        self._logger = logger
        if self._logger is None:
            self._logger = logging.getLogger()

    @classmethod
    def get_version(cls):
        cls._is_binary_present()
        command = local['cas']['--version']
        version = command().split()[-1].split('v')[1]
        return version

    def ensure_login(self):
        with local.env(
            CAS_API_KEY=self._cas_api_key,
            SIGNER_ID=self._cas_signer_id,
        ):
            self._cas['login']()

    def notarize(
            self,
            local_path: str,
            metadata: typing.Dict = None,
    ) -> str:
        """
        Wrapper around `cas notarize`
        :param local_path: path to a local Git repo
        :param metadata: additional metadata
        :return: hash of notarized commit
        :rtype: str
        """
        command = self._cas[
            'notarize',
            local_path,
            '-o',
            'json',
        ]
        if metadata is not None:
            for key, value in metadata.items():
                command = command[
                    '-a',
                    f'{key}={value}',
                ]
        with local.env(
                CAS_API_KEY=self._cas_api_key,
                SIGNER_ID=self._cas_signer_id
        ):
            result_of_execution = command()
        return json.loads(result_of_execution)['hash']

    def notarize_no_exc(
            self,
            local_path: str,
            metadata: typing.Dict = None,
    ) -> typing.Tuple[bool, str]:
        """
        Wrapper for avoiding raising exceptions during notarization.
        Return `success` flag instead for library user to react respectively.
        :param local_path: path to a local Git repo
        :param metadata: additional metadata
        :return: boolean flag for operation success and the hash
            of the notarized artifact.
        :rtype: tuple
        """
        success = False
        try:
            cas_hash = self.notarize(local_path, metadata=metadata)
            success = True
        except Exception:
            self._logger.exception('Cannot notarize artifact: %s',
                                   local_path)
            cas_hash = ''
        return success, cas_hash

    def authenticate(
            self,
            local_path: str,
            return_json: bool = False,
            use_hash: bool = False,
            signer_id: str = None,
    ):
        """
        Wrapper around `cas authenticate`
        :param local_path: path to a local Git repo
               (should be started from `git://`)
               or to a single local file or hash
        :param return_json: flag for return json response
        :param use_hash: flag for authenticate by hash
        :return: true if a commit is trusted, vice versa - false
                 or dict with result if return_json param is True
        :rtype: bool or dict
        """
        command_args = ['authenticate', local_path]
        if use_hash:
            command_args = ['authenticate', '--hash', local_path]
        if signer_id:
            command_args.extend(('--signerID', signer_id))
        command_args.extend(('-o', 'json'))
        command = self._cas[command_args]
        try:
            with local.env(
                    CAS_API_KEY=self._cas_api_key,
                    SIGNER_ID=self._cas_signer_id
            ):
                result_of_execution = command()
        except ProcessExecutionError:
            with local.env(
                    CAS_API_KEY=self._cas_api_key,
                    SIGNER_ID=self._cas_signer_id
            ):
                # in case if commit is untrusted
                result_of_execution = command(retcode=1)
        json_result = json.loads(result_of_execution)
        if return_json:
            return json_result
        return not bool(json_result['status'])

    def authenticate_source(
        self,
        local_path: str,
        signer_id: str = None,
    ) -> typing.Tuple[bool, typing.Optional[str]]:
        """
        Authenticates source by git path.
        Returns authenticate result and source commit hash.
        """
        is_authenticated = False
        commit_cas_hash = None
        self.ensure_login()
        try:
            result_json = self.authenticate(
                local_path,
                return_json=True,
                signer_id=signer_id
            )
            is_authenticated = result_json['verified']
            commit_cas_hash = result_json['hash']
        # we can fall with ProcessExecutionError,
        # because source can be not notarized
        except ProcessExecutionError:
            self._logger.exception('Cannot authenticate: %s', local_path)
        return is_authenticated, commit_cas_hash

    def authenticate_artifact(
        self,
        local_path: str,
        use_hash: bool = False,
        signer_id: str = None,
    ) -> bool:
        """
        Authenticates artifact by artifact path or hash if `use_hash` is True.
        Returns authenticate result.
        """
        is_authenticated = False
        self.ensure_login()
        try:
            is_authenticated = self.authenticate(
                local_path,
                use_hash=use_hash,
                return_json=True,
                signer_id=signer_id
            )['verified']
        # we can fall with ProcessExecutionError,
        # because artifact can be not notarized
        except ProcessExecutionError:
            self._logger.exception('Cannot authenticate: %s', local_path)
        return is_authenticated

    def notarize_artifacts(
        self,
        artifact_paths: typing.List[str],
        metadata: typing.Dict[str, typing.Any],
    ) -> typing.Tuple[bool, typing.Dict[str, str]]:
        """
        Notarize artifacts by their paths.
        Returns `True` if all artifacts was succesful notarizated
        and dict with CAS hashes.
        """
        all_artifacts_is_notarized = True
        notarized_artifacts = {}
        self.ensure_login()

        # ALBS-576: We stopped doing this process in parallel due to the
        # problems experienced and described in this CAS issue:
        # https://github.com/codenotary/cas/issues/275
        # Hence, we decided to go sequential here until the problem is
        # resolved in CAS itself.
        for artifact_path in artifact_paths:
            try:
                cas_artifact_hash = self.notarize(artifact_path, metadata)
            except Exception:
                self._logger.exception('Cannot notarize artifact: %s',
                                       artifact_path)
                all_artifacts_is_notarized = False
                continue
            notarized_artifacts[artifact_path] = cas_artifact_hash
        return all_artifacts_is_notarized, notarized_artifacts