The AWS C++ SDK has a bug (https://github.com/aws/aws-sdk-cpp/issues/2554)
where even if a user specifies a specific enpoint URL, the SDK uses
DescribeEndpoints to try to "refresh" the endpoint. The problem is that
DescribeEndpoints can't return a scheme (http or https) and the SDK
arbitrarily picks https - making it unable to communicate with Alternator
over http. As an example, the new "dynamodb shell" (written in C++)
cannot communicate with Alternator running over http.
This patch adds a configuration option, "alternator_describe_endpoints",
which can be used to override what DescribeEndpoints does:
1. Empty string (the default) leaves the current behavior -
DescribeEndpoints echos the request's "Host" header.
2. The string "disabled" disables the DescribeEndpoints (it will return
an UnknownOperationException). This is how DynamoDB Local behaves,
and the AWS C++ SDK and the Dynamodb Shell work well in this mode.
3. Any other string is a fixed string to be returned by DescribeEndpoints.
It can be useful in setups that should return a known address.
Note that this patch does not, by default, change the current behaivor
of DescribeEndpoints. But it us the future to override its behavior
in a user experiences problems in the field - without code changes.
Fixes#14410.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Closes#14432
d6aba8232b