Module sls_tools.param_store.param_store

Classes

class ParamStore

Provides access to key/values (variables) stored locally on the OS or AWS SSM.

examples:

# Set and get a value in SSM:
ParamStore.set('MY_VAR', '123')
my_var = ParamStore.get('MY_VAR').value
>> '123'

# Set and get a value from the OS:
ParamStore.set('MY_VAR', '123', store=ParamStore.Stores.OS)
my_var = ParamStore.get('MY_VAR').value
>> '123'
# Or explicitly:
my_var = ParamStore.get('MY_VAR', store=ParamStore.Stores.OS).value
>> '123'

# Set and get a value in SSM and convert it to a list:
ParamStore.set('MY_VAR', 'one,two,three')
my_var = ParamStore.get('MY_VAR').to_list()
>> ['one', 'two', 'three']

Expand source code

class ParamStore:
    """Provides access to key/values (variables) stored locally on the OS or AWS SSM.

    examples:

        # Set and get a value in SSM:
        ParamStore.set('MY_VAR', '123')
        my_var = ParamStore.get('MY_VAR').value
        >> '123'

        # Set and get a value from the OS:
        ParamStore.set('MY_VAR', '123', store=ParamStore.Stores.OS)
        my_var = ParamStore.get('MY_VAR').value
        >> '123'
        # Or explicitly:
        my_var = ParamStore.get('MY_VAR', store=ParamStore.Stores.OS).value
        >> '123'

        # Set and get a value in SSM and convert it to a list:
        ParamStore.set('MY_VAR', 'one,two,three')
        my_var = ParamStore.get('MY_VAR').to_list()
        >> ['one', 'two', 'three']
    """

    class Stores(Enum):
        """Enum for the available Key/Value stores.

        Supported options are: OS, SSM, AUTO

        "AUTO" is a reserved keyword that can be passed to each method to delegate
        the choice to each individual method.
        """
        OS = 'os'
        SSM = 'ssm'
        AUTO = 'auto'

    @classmethod
    def set(cls, key, value, store=Stores.SSM):
        """Sets a key/value pair.

        Args:
            key: The key to set.
            value: The value to set.
            store: Where to set the value. Defaults to Stores.SSM.

        Returns:
            True if successfully set otherwise False.
        """
        result = False

        # Set the value in the local environment.
        if store in [cls.Stores.OS, cls.Stores.AUTO]:
            result = cls._set_in_os(key, value)

        # Set the value in SSM.
        if store in [cls.Stores.SSM, cls.Stores.AUTO]:
            result = cls._set_in_ssm(key, value)

        return result

    @classmethod
    def get(cls, key, default=None, store=Stores.AUTO):
        """Gets the value for a key.

        Will return the value from the OS if its set otherwise it will try to get the value from SSM.
        
        Args:
            key: The key for the value to get.
            default: The value to return if the key value is None.
            store: Where to get the value from. Defaults to Stores.AUTO.

        Returns:
            ParamStoreResult
        """
        # Try to get the value from the local environment.
        if store in [cls.Stores.OS, cls.Stores.AUTO]:
            result = cls._get_from_os(key)
            if result is not None:
                return ParamStoreResult(key, result, cls.Stores.OS)

        # Try to get the value from SSM.
        if store in [cls.Stores.SSM, cls.Stores.AUTO]:
            result = cls._get_from_ssm(key)
            if result is not None:
                return ParamStoreResult(key, result, cls.Stores.SSM)

        return ParamStoreResult(key, default, None)

    @classmethod
    def delete(cls, key, store=Stores.AUTO):
        """Deletes a key/value.

        Args:
            key: The key to delete.
            store: Where to delete from. Defaults to Stores.AUTO.

        Returns:
            True if successfully deleted otherwise False.
        """
        result = False

        # Delete the value from the local environment.
        if store in [cls.Stores.OS, cls.Stores.AUTO]:
            result = cls._delete_from_os(key)

        # Delete the value from SSM.
        if store in [cls.Stores.SSM, cls.Stores.AUTO]:
            result = cls._delete_from_ssm(key)

        return result

    @classmethod
    def contains(cls, key, store=Stores.AUTO):
        """Gets if a key is present in one of the param stores.

        Args:
            key: The key to check for.
            store: Where to look for the key. Defaults to Stores.AUTO.

        Returns:
            True if the key is contained in the store.
        """
        result = cls.get(key, default=None, store=store)
        return result.store is not None and result.value is not None

    @classmethod
    def _get_from_os(cls, key):
        """Gets a value from the OS environment variables.

        Args:
            key: The key for the value to get.

        Returns:
            The key value or None.
        """
        return os.environ.get(key)

    @classmethod
    def _set_in_os(cls, key, value):
        """Sets a key/value in the OS environment.

        Args:
            key: The key to set.
            value: The value to set.

        Returns:
            True
        """
        os.environ[key] = value
        return True

    @classmethod
    def _delete_from_os(cls, key):
        """Deletes the key from the OS environment.

        Args:
            key: The key to delete.

        Returns:
            True
        """
        if key in os.environ.keys():
            del os.environ[key]

        return True

    @classmethod
    def _get_from_ssm(cls, key):
        """Gets a value from SSM.

        Args:
            key: The key for the value to get.

        Returns:
            The key value or None, or raises
        """
        result = None
        ssm_key = cls._build_ssm_key(key)
        client = cls._get_ssm_client()
        try:
            get_response = client.get_parameter(Name=ssm_key, WithDecryption=True)
            result = get_response.get('Parameter').get('Value')
        except client.exceptions.ParameterNotFound:
            logging.exception('SSM Parameter Not Found: {0}'.format(ssm_key))
        except Exception as ex:
            logging.exception('SSM Error: {0}'.format(ex))

        return result

    @classmethod
    def _set_in_ssm(cls, key, value, type='SecureString'):
        """Sets a key/value pair in SSM.

        Args:
            key: The key to set.
            value: The value to set.
            type: The SSM parameter type. Defaults to SecureString.

        Returns:
            True if successful otherwise False.
        """
        ssm_key = cls._build_ssm_key(key)
        try:
            cls._get_ssm_client().put_parameter(Name=ssm_key, Value=value, Type=type, Overwrite=True)
            return True
        except Exception as ex:
            logging.exception('SSM Error: {0}'.format(ex))
        return False

    @classmethod
    def _delete_from_ssm(cls, key):
        """Deletes a key in SSM.

        Args:
            key: The key to delete.

        Returns:
            True if successful or the key does not exist otherwise False.
        """
        ssm_key = cls._build_ssm_key(key)
        try:
            cls._get_ssm_client().delete_parameter(Name=ssm_key)
            return True
        except cls._get_ssm_client().exceptions.ParameterNotFound as ex:
            return True
        except Exception as ex:
            logging.exception('SSM Error: {0}'.format(ex))
        return False

    @classmethod
    def _build_ssm_key(cls, key):
        """Builds an SSM key.

        The format is "service_name/service_stage/key".

        Args:
            key: The key to build a fully qualified key for.

        Returns:
            The fully qualified key string.
        """
        service_name = cls.get('SERVICE_NAME', store=cls.Stores.OS).value
        service_stage = cls.get('SERVICE_STAGE', store=cls.Stores.OS).value

        if not service_name:
            raise ValueError('Environment variable not set: SERVICE_NAME')

        if not service_stage:
            raise ValueError('Environment variable not set: SERVICE_STAGE')

        return '/{0}/{1}/{2}'.format(service_name, service_stage, key)

    # Cached instance of the SSM client.
    _ssm_client = None

    @classmethod
    def _get_ssm_client(cls):
        """Gets an SSM boto3 client.

        Returns:
            SSM client or None.
        """
        try:
            if not cls._ssm_client:
                cls._ssm_client = boto3.client('ssm')
            return cls._ssm_client
        except Exception as ex:
            logging.exception('SSM Error: {0}'.format(ex))
        return None

Class variables

var Stores

Enum for the available Key/Value stores.

Supported options are: OS, SSM, AUTO

"AUTO" is a reserved keyword that can be passed to each method to delegate the choice to each individual method.

Static methods

def contains(key, store=Stores.AUTO)

Gets if a key is present in one of the param stores.

Args

key

The key to check for.

store

Where to look for the key. Defaults to Stores.AUTO.

Returns

True if the key is contained in the store.

Expand source code

@classmethod
def contains(cls, key, store=Stores.AUTO):
    """Gets if a key is present in one of the param stores.

    Args:
        key: The key to check for.
        store: Where to look for the key. Defaults to Stores.AUTO.

    Returns:
        True if the key is contained in the store.
    """
    result = cls.get(key, default=None, store=store)
    return result.store is not None and result.value is not None

def delete(key, store=Stores.AUTO)

Deletes a key/value.

Args

key

The key to delete.

store

Where to delete from. Defaults to Stores.AUTO.

Returns

True if successfully deleted otherwise False.

Expand source code

@classmethod
def delete(cls, key, store=Stores.AUTO):
    """Deletes a key/value.

    Args:
        key: The key to delete.
        store: Where to delete from. Defaults to Stores.AUTO.

    Returns:
        True if successfully deleted otherwise False.
    """
    result = False

    # Delete the value from the local environment.
    if store in [cls.Stores.OS, cls.Stores.AUTO]:
        result = cls._delete_from_os(key)

    # Delete the value from SSM.
    if store in [cls.Stores.SSM, cls.Stores.AUTO]:
        result = cls._delete_from_ssm(key)

    return result

def get(key, default=None, store=Stores.AUTO)

Gets the value for a key.

Will return the value from the OS if its set otherwise it will try to get the value from SSM.

Args

key

The key for the value to get.

default

The value to return if the key value is None.

store

Where to get the value from. Defaults to Stores.AUTO.

Returns

ParamStoreResult

Expand source code

@classmethod
def get(cls, key, default=None, store=Stores.AUTO):
    """Gets the value for a key.

    Will return the value from the OS if its set otherwise it will try to get the value from SSM.
    
    Args:
        key: The key for the value to get.
        default: The value to return if the key value is None.
        store: Where to get the value from. Defaults to Stores.AUTO.

    Returns:
        ParamStoreResult
    """
    # Try to get the value from the local environment.
    if store in [cls.Stores.OS, cls.Stores.AUTO]:
        result = cls._get_from_os(key)
        if result is not None:
            return ParamStoreResult(key, result, cls.Stores.OS)

    # Try to get the value from SSM.
    if store in [cls.Stores.SSM, cls.Stores.AUTO]:
        result = cls._get_from_ssm(key)
        if result is not None:
            return ParamStoreResult(key, result, cls.Stores.SSM)

    return ParamStoreResult(key, default, None)

def set(key, value, store=Stores.SSM)

Sets a key/value pair.

Args

key

The key to set.

value

The value to set.

store

Where to set the value. Defaults to Stores.SSM.

Returns

True if successfully set otherwise False.

Expand source code

@classmethod
def set(cls, key, value, store=Stores.SSM):
    """Sets a key/value pair.

    Args:
        key: The key to set.
        value: The value to set.
        store: Where to set the value. Defaults to Stores.SSM.

    Returns:
        True if successfully set otherwise False.
    """
    result = False

    # Set the value in the local environment.
    if store in [cls.Stores.OS, cls.Stores.AUTO]:
        result = cls._set_in_os(key, value)

    # Set the value in SSM.
    if store in [cls.Stores.SSM, cls.Stores.AUTO]:
        result = cls._set_in_ssm(key, value)

    return result