Initial commit

.gitignore

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+.vscode
+Pipfile.lock
+
+.DS_Store?
+._*
+.Spotlight-V100
+.Trashes
+ehthumbs.db
+Thumbs.db
+*.swp
+
+*.egg-info
+.*project
+*.py[cxo]
+__pycache__
+.venv
+.env
+
+.aws-sam
+samconfig.toml
+
+dist
+poetry.lock

LICENSE

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README.md

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+# aws-error-utils
+**Making botocore.exceptions.ClientError easier to deal with**
+
+All AWS service exceptions are raised by `boto3` as a `ClientError`, with the contents of the exception indicating what kind of exception happened.
+This is not very pythonic, and the contents themselves are rather opaque, being held in a dict rather than as properties.
+The functions in this package help dealing with that.
+
+The package is on PyPI but I tend to prefer just copying the `aws_error_utils.py` file into my projects, often then my only dependency is on boto3, which is usually somewhere in my environment anyway (e.g., in a Lambda function). But that's just me.
+
+## `catch_aws_error()`
+This is probably the most useful function in the package. Make exception catching more natural. You use this function in an `except` statement instead of `ClientError`. The function takes as input error code(s), and optionally operation name(s), to match against the current raised exception. If the exception matches, the `except` block is executed. Usage looks like this:
+
+```python
+try:
+    s3 = boto3.client('s3')
+    s3.list_objects_v2(Bucket='bucket-1')
+    s3.get_object(Bucket='bucket-2', Key='example')
+except catch_aws_error('NoSuchBucket', operation_name='GetObject'):
+    # This will be executed if the GetObject operation raises NoSuchBucket
+    # But not if the ListObjects operation raises it
+```
+
+You can provide error codes either as positional args or as the `code` keyword argument, and there either as a single string or a list of strings.
+
+```python
+catch_aws_error('NoSuchBucket')
+catch_aws_error(code='NoSuchBucket')
+
+catch_aws_error('NoSuchBucket', 'NoSuchKey')
+catch_aws_error(code=['NoSuchBucket', 'NoSuchKey'])
+```
+
+The operation name can only be provided as the `operation_name` keyword argument, but similarly either as a single string or a list of strings.
+
+You must provide an error code. To match exclusively against operation name, use the `aws_error_utils.ALL_CODES` token. There is similarly an `ALL_OPERATIONS` token.
+
+```python
+try:
+    s3 = boto3.client('s3')
+    s3.list_objects_v2(Bucket='bucket-1')
+    s3.get_object(Bucket='bucket-1', Key='example')
+except catch_aws_error(ALL_CODES, operation_name='ListObjectsV2') as e:
+    # This will execute for all ClientError exceptions raised by the ListObjectsV2 call
+```
+
+For more complex conditions, instead of providing error codes and operation names, you can provide a callable to evaluate the exception:
+
+```python
+import re
+def matcher(e):
+    info = get_aws_error_info(e)
+    return re.search('does not exist', info.message)
+
+try:
+    s3 = boto3.client('s3')
+    s3.list_objects_v2(Bucket='bucket-1')
+except catch_aws_error(matcher) as e:
+    # This will be executed if e is a ClientError and matcher(e) returns True
+    # Note the callable can assume the exception is a ClientError
+```
+
+## `get_aws_error_info()`
+This function takes a returns an `AWSErrorInfo` object, which is a `collections.NamedTuple` with the error code, error message, HTTP status code, and operation name extracted, along with the raw response dictionary. If you're not modifying your code's exception handling, this can be useful instead of remembering exactly how the error code is stored in the response, etc.
+
+## `aws_error_matches()`
+This is the matching logic behind `catch_aws_error()`. It takes a `ClientError`, with the rest of the arguments being error codes and operation names identical to `catch_aws_error`, except that it does not support providing a callable.

aws_error_utils.py

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+# Copyright 2020 Ben Kehoe
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Helpful snippets:
+error_code = e.response.get('Error', {}).get('Code')
+error_msg = e.response.get('Error', {}).get('Message')
+status_code = e.response.get('ResponseMetadata', {}).get('HTTPStatusCode')
+operation_name = e.operation_name
+"""
+
+__version__ = '1.0.0'
+
+import collections
+import sys
+import botocore.exceptions
+
+AWSErrorInfo = collections.namedtuple('AWSErrorInfo', ['code', 'message', 'http_status_code', 'operation_name', 'response'])
+def get_aws_error_info(client_error):
+    """Returns an AWSErrorInfo namedtuple with the important details of the error extracted"""
+    if not isinstance(client_error, botocore.exceptions.ClientError):
+        raise TypeError("Error is of type {}, not ClientError".format(client_error))
+    return AWSErrorInfo(
+            client_error.response.get('Error', {}).get('Code'),
+            client_error.response.get('Error', {}).get('Message'),
+            client_error.response.get('ResponseMetadata', {}).get('HTTPStatusCode'),
+            client_error.operation_name,
+            client_error.response,
+    )
+
+ALL_CODES = "__aws_error_utils_ALL_CODES__"
+ALL_OPERATIONS = "__aws_error_utils_ALL_OPERATIONS__"
+
+def aws_error_matches(client_error, *args, **kwargs):
+    """Tests if a botocore.exceptions.ClientError matches the arguments.
+    Any positional arguments and the contents of the 'code' kwarg are matched
+    against the Error.Code response field.
+    If the 'operation_name' kwarg is provided, it is matched against the
+    operation_name property.
+    Both kwargs can either be a single string or a list of strings.
+    The tokens aws_error_utils.ALL_CODES and aws_error_utils.ALL_OPERATIONS
+    can be used to match all error codes and operation names.
+
+    try:
+        s3 = boto3.client('s3')
+        s3.list_objects_v2(Bucket='bucket-1')
+        s3.get_object(Bucket='bucket-2', Key='example')
+    except botocore.exceptions.ClientError as e:
+        if aws_error_matches(e, 'NoSuchBucket', operation_name='GetObject'):
+            pass
+        else:
+            raise
+    """
+    err_args = args + tuple((kwargs.get('code'),) if isinstance(kwargs.get('code'), str) else kwargs.get('code', tuple()))
+    op_args = (kwargs.get('operation_name'),) if isinstance(kwargs.get('operation_name'), str) else kwargs.get('operation_name', tuple())
+    if not err_args:
+        raise ValueError('No error codes provided')
+    err = client_error.response.get('Error', {}).get('Code')
+    err_matches = (err and (err in err_args)) or (ALL_CODES in err_args)
+    op_matches = (client_error.operation_name in op_args) or (not op_args) or (ALL_OPERATIONS in op_args)
+    return err_matches and op_matches
+
+def catch_aws_error(*args, **kwargs):
+    """For use in an except statement, returns the current error if it matches the arguments, otherwise a non-matching error
+    Any positional arguments and the contents of the 'code' kwarg are matched
+    against the Error.Code response field.
+    If the 'operation_name' kwarg is provided, it is matched against the
+    operation_name property.
+    Both kwargs can either be a single string or a list of strings.
+    The tokens aws_error_utils.ALL_CODES and aws_error_utils.ALL_OPERATIONS
+    can be used to match all error codes and operation names.
+    Alternatively, provide a callable that takes the error and returns true for a match.
+
+    try:
+        s3 = boto3.client('s3')
+        s3.list_objects_v2(Bucket='bucket-1')
+        s3.get_object(Bucket='bucket-2', Key='example')
+    except catch_aws_error('NoSuchBucket', operation_name='GetObject'):
+        pass
+    """
+    client_error = sys.exc_info()[1]
+    if isinstance(client_error, botocore.exceptions.ClientError):
+        if len(args) == 1 and callable(args[0]):
+            if args[0](client_error):
+                return type(client_error)
+        elif aws_error_matches(client_error, *args, **kwargs):
+            return type(client_error)
+    return type('RedHerring', (BaseException,), {})