"""
Context information passed to each CLI command
"""
import logging
import uuid
import boto3
import botocore
import botocore.session
from botocore import credentials
import click
from samcli.commands.exceptions import CredentialsError
class Context:
"""
Top level context object for the CLI. Exposes common functionality required by a CLI, including logging,
environment config parsing, debug logging etc.
This object is passed by Click to every command that adds the proper annotation.
Read this for more details on Click Context - http://click.pocoo.org/5/commands/#nested-handling-and-contexts
Each command gets its own context object, but linked to both parent and child command's context, like a Linked List.
This class itself does not rely on how Click works. It is just a plain old Python class that holds common
properties used by every CLI command.
"""
def __init__(self):
"""
Initialize the context with default values
"""
self._debug = False
self._aws_region = None
self._aws_profile = None
self._session_id = str(uuid.uuid4())
@property
def debug(self):
return self._debug
@debug.setter
def debug(self, value):
"""
Turn on debug logging if necessary.
:param value: Value of debug flag
"""
self._debug = value
if self._debug:
# Turn on debug logging
logging.getLogger("samcli").setLevel(logging.DEBUG)
logging.getLogger("aws_lambda_builders").setLevel(logging.DEBUG)
@property
def region(self):
return self._aws_region
@region.setter
def region(self, value):
"""
Set AWS region
"""
self._aws_region = value
self._refresh_session()
@property
def profile(self):
return self._aws_profile
@profile.setter
def profile(self, value):
"""
Set AWS profile for credential resolution
"""
self._aws_profile = value
self._refresh_session()
@property
def session_id(self):
"""
Returns the ID of this command session. This is a randomly generated UUIDv4 which will not change until the
command terminates.
"""
return self._session_id
@property
def command_path(self):
"""
Returns the full path of the command as invoked ex: "sam local generate-event s3 put". Wrapper to
https://click.palletsprojects.com/en/7.x/api/#click.Context.command_path
Returns
-------
str
Full path of the command invoked
"""
# Uses Click's Core Context. Note, this is different from this class, also confusingly named `Context`.
# Click's Core Context object is the one that contains command path information.
click_core_ctx = click.get_current_context()
if click_core_ctx:
return click_core_ctx.command_path
return None
@staticmethod
def get_current_context():
"""
Get the current Context object from Click's context stacks. This method is safe to run within the
actual command's handler that has a ``@pass_context`` annotation. Outside of the handler, you run
the risk of creating a new Context object which is entirely different from the Context object used by your
command.
.. code:
@pass_context
def my_command_handler(ctx):
# You will get the right context from within the command handler. This will also work from any
# downstream method invoked as part of the handler.
this_context = Context.get_current_context()
assert ctx == this_context
Returns
-------
samcli.cli.context.Context
Instance of this object, if we are running in a Click command. None otherwise.
"""
# Click has the concept of Context stacks. Think of them as linked list containing custom objects that are
# automatically accessible at different levels. We start from the Core Click context and discover the
# SAM CLI command-specific Context object which contains values for global options used by all commands.
#
# https://click.palletsprojects.com/en/7.x/complex/#ensuring-object-creation
#
click_core_ctx = click.get_current_context()
if click_core_ctx:
return click_core_ctx.find_object(Context) or click_core_ctx.ensure_object(Context)
return None
def _refresh_session(self):
"""
Update boto3's default session by creating a new session based on values set in the context. Some properties of
the Boto3's session object are read-only. Therefore when Click parses new AWS session related properties (like
region & profile), it will call this method to create a new session with latest values for these properties.
"""
try:
botocore_session = botocore.session.get_session()
boto3.setup_default_session(
botocore_session=botocore_session, region_name=self._aws_region, profile_name=self._aws_profile
)
# get botocore session and setup caching for MFA based credentials
botocore_session.get_component("credential_provider").get_provider(
"assume-role"
).cache = credentials.JSONFileCache()
except botocore.exceptions.ProfileNotFound as ex:
raise CredentialsError(str(ex))
def get_cmd_names(cmd_name, ctx):
"""
Given the click core context, return a list representing all the subcommands passed to the CLI
Parameters
----------
cmd_name : name of current command
ctx : click.Context
Returns
-------
list(str)
List containing subcommand names. Ex: ["local", "start-api"]
"""
if not ctx:
return []
if ctx and not getattr(ctx, "parent", None):
return [ctx.info_name]
# Find parent of current context
_parent = ctx.parent
_cmd_names = []
# Need to find the total set of commands that current command is part of.
if cmd_name != ctx.info_name:
_cmd_names = [cmd_name]
_cmd_names.append(ctx.info_name)
# Go through all parents till a parent of a context exists.
while _parent.parent:
info_name = _parent.info_name
_cmd_names.append(info_name)
_parent = _parent.parent
# Make sure the output reads natural. Ex: ["local", "start-api"]
_cmd_names.reverse()
return _cmd_names