cmdoptesc · December 11, 2019 18:46 · Dec 11, 2019 · Dec 11, 2019
diff --git a/listing_boto3_exceptions.md b/listing_boto3_exceptions.md
@@ -7,7 +7,8 @@ An ugly, but workable solution to find out what exceptions are available on each
 ```python
 import boto3
 client = boto3.client('sns')  # or whatever client you're using
-client.exceptions.__dict__
+# client.exceptions.__dict__
+client.exceptions.__dict__['_code_to_exception'].keys()
 ```
 
 should print something like this:

diff --git a/listing_boto3_exceptions.md b/listing_boto3_exceptions.md
@@ -0,0 +1,167 @@
+## Listing Available AWS Boto3 Exceptions
+
+[alexpareto](https://github.com/alexpareto) commented on [Jul 22, 2019](https://github.com/boto/boto3/issues/1262#issuecomment-406882706)
+
+An ugly, but workable solution to find out what exceptions are available on each client from the command line:
+
+```python
+import boto3
+client = boto3.client('sns')  # or whatever client you're using
+client.exceptions.__dict__
+```
+
+should print something like this:
+
+```
+{'_code_to_exception': {'AuthorizationError': <class 'botocore.errorfactory.AuthorizationErrorException'>, 'EndpointDisabled': <class 'botocore.errorfactory.EndpointDisabledException'>, 'InternalError': <class 'botocore.errorfactory.InternalErrorException'>, 'InvalidParameter': <class 'botocore.errorfactory.InvalidParameterException'>, 'ParameterValueInvalid': <class 'botocore.errorfactory.InvalidParameterValueException'>, 'NotFound': <class 'botocore.errorfactory.NotFoundException'>, 'PlatformApplicationDisabled': <class 'botocore.errorfactory.PlatformApplicationDisabledException'>, 'SubscriptionLimitExceeded': <class 'botocore.errorfactory.SubscriptionLimitExceededException'>, 'Throttled': <class 'botocore.errorfactory.ThrottledException'>, 'TopicLimitExceeded': <class 'botocore.errorfactory.TopicLimitExceededException'>}}```
+```
+
+---
+
+[dacut](https://github.com/dacut) commented on [May 7, 2019](https://github.com/boto/boto3/issues/1262#issuecomment-489986337)
+
+There are currently (as of version 1.12.142) three base exceptions and two warnings:
+
+* BotoCoreError
+* ClientError
+* UndefinedModelAttributeError
+* ImminentRemovalWarning
+* UnsupportedTLSVersionWarning
+
+The `ClientError` exception appears to be raised when a remote call is made but the service returns an error. The `BotoCoreError` hierarchy appears to reflect issues in creating or handling the call itself. (Why `UndefinedModelAttributeError` is not a subclass of `BotoCoreError` is a mystery to me.)
+
+## Structure of a ClientError
+Within `ClientError` (but _not_ `BotoCoreError`), there will be an `operation_name` attribute (should be a str) and a `response` attribute (should be a dict). The `response` attribute should have the following form (example from a malformed ec2.DescribeImages call):
+
+```js
+{
+    "Error": {
+        "Code": "InvalidParameterValue",
+        "Message": "The filter 'asdfasdf' is invalid"
+    },
+    "ResponseMetadata": {
+        "RequestId": "aaaabbbb-cccc-dddd-eeee-ffff00001111",
+        "HTTPStatusCode": 400,
+        "HTTPHeaders": {
+            "transfer-encoding": "chunked",
+            "date": "Fri, 01 Jan 2100 00:00:00 GMT",
+            "connection": "close",
+            "server": "AmazonEC2"
+        },
+        "RetryAttempts": 0
+    }
+}
+```
+
+## Error handling
+Typically, you want to handle specific error codes. Because this is largely only quasi-documented, this is what I typically do for error handling (in this case, handling the `InvalidParameterValue` from my ec2.DescribeImages call):
+
+```python
+except ClientError as e:
+    error_code = e.response.get("Error", {}).get("Code")
+    if error_code == "InvalidParameterValue":
+        # Do something
+        pass
+    else:
+        raise
+```
+
+Or, if I need to intermingle it with other exception handling code (much rarer) and am feeling lazy about it:
+
+```python
+except Exception as e:
+    error_code = getattr(e, "response", {}).get("Error", {}).get("Code")
+    ...
+```
+
+## Exception hierarchy (May 7, 2019)
+Here's the full hierarchy of **statically defined** exceptions/warnings I found programmatically. Note that some exception classes use multiple inheritance.
+
+```
+AliasConflictParameterError < ValidationError < BotoCoreError < Exception
+ApiVersionNotFoundError < BotoCoreError < Exception
+BaseEndpointResolverError < BotoCoreError < Exception
+BotoCoreError < Exception
+ChecksumError < BotoCoreError < Exception
+ClientError < Exception
+ConfigNotFound < BotoCoreError < Exception
+ConfigParseError < BotoCoreError < Exception
+ConnectTimeoutError < [ConnectionError < BotoCoreError < Exception, ConnectTimeout < [ConnectionError < RequestException < OSError < Exception, Timeout < RequestException < OSError < Exception]]
+ConnectionClosedError < HTTPClientError < BotoCoreError < Exception
+ConnectionError < BotoCoreError < Exception
+CredentialRetrievalError < BotoCoreError < Exception
+DataNotFoundError < BotoCoreError < Exception
+EndpointConnectionError < ConnectionError < BotoCoreError < Exception
+EventStreamError < ClientError < Exception
+HTTPClientError < BotoCoreError < Exception
+ImminentRemovalWarning < Warning < Exception
+IncompleteReadError < BotoCoreError < Exception
+InfiniteLoopConfigError < InvalidConfigError < BotoCoreError < Exception
+InvalidConfigError < BotoCoreError < Exception
+InvalidDNSNameError < BotoCoreError < Exception
+InvalidExpressionError < BotoCoreError < Exception
+InvalidMaxRetryAttemptsError < InvalidRetryConfigurationError < BotoCoreError < Exception
+InvalidRetryConfigurationError < BotoCoreError < Exception
+InvalidS3AddressingStyleError < BotoCoreError < Exception
+MD5UnavailableError < BotoCoreError < Exception
+MetadataRetrievalError < BotoCoreError < Exception
+MissingParametersError < BotoCoreError < Exception
+MissingServiceIdError < UndefinedModelAttributeError < Exception
+NoCredentialsError < BotoCoreError < Exception
+NoRegionError < BaseEndpointResolverError < BotoCoreError < Exception
+OperationNotPageableError < BotoCoreError < Exception
+PaginationError < BotoCoreError < Exception
+ParamValidationError < BotoCoreError < Exception
+PartialCredentialsError < BotoCoreError < Exception
+ProfileNotFound < BotoCoreError < Exception
+ProxyConnectionError < [ConnectionError < BotoCoreError < Exception, ProxyError < ConnectionError < RequestException < OSError < Exception]
+RangeError < ValidationError < BotoCoreError < Exception
+ReadTimeoutError < [HTTPClientError < BotoCoreError < Exception, ReadTimeout < Timeout < RequestException < OSError < Exception, ReadTimeoutError < [TimeoutError < HTTPError < Exception, RequestError < PoolError < HTTPError < Exception]]
+RefreshWithMFAUnsupportedError < BotoCoreError < Exception
+SSLError < [ConnectionError < BotoCoreError < Exception, SSLError < ConnectionError < RequestException < OSError < Exception]
+ServiceNotInRegionError < BotoCoreError < Exception
+StubAssertionError < [StubResponseError < BotoCoreError < Exception, AssertionError < Exception]
+StubResponseError < BotoCoreError < Exception
+UnStubbedResponseError < StubResponseError < BotoCoreError < Exception
+UndefinedModelAttributeError < Exception
+UnknownClientMethodError < BotoCoreError < Exception
+UnknownCredentialError < BotoCoreError < Exception
+UnknownEndpointError < [BaseEndpointResolverError < BotoCoreError < Exception, ValueError < Exception]
+UnknownKeyError < ValidationError < BotoCoreError < Exception
+UnknownParameterError < ValidationError < BotoCoreError < Exception
+UnknownServiceError < DataNotFoundError < BotoCoreError < Exception
+UnknownServiceStyle < BotoCoreError < Exception
+UnknownSignatureVersionError < BotoCoreError < Exception
+UnseekableStreamError < BotoCoreError < Exception
+UnsupportedSignatureVersionError < BotoCoreError < Exception
+UnsupportedTLSVersionWarning < Warning < Exception
+ValidationError < BotoCoreError < Exception
+WaiterConfigError < BotoCoreError < Exception
+WaiterError < BotoCoreError < Exception
+```
+
+## Appendix
+Code for how I generated the above (Python 3.7):
+
+```python
+def hierarchy(t):
+    if t is Exception or t is object:
+        return t.__name__
+
+    result = t.__name__ + " < "
+    if len(t.__bases__) == 1:
+        result += hierarchy(t.__bases__[0])
+    else:
+        result += "[" + ", ".join([hierarchy(base) for base in t.__bases__]) + "]"
+    return result
+
+# Getting the list of base exceptions/warnings
+for key, value in sorted(botocore.exceptions.__dict__.items()):
+    if isinstance(value, type) and (value.__bases__ == (Exception,) or value.__bases__ == (Warning,)):
+        print(key)
+
+# Printing the hierarchy
+for key, value in sorted(botocore.exceptions.__dict__.items()):
+     if isinstance(value, type):
+        print(hierarchy(value))
+```