f41dac2a3a
Alternator request sizes can be up to 16 MB, but the current implementation had the Seastar HTTP server read the entire request as a contiguous string, and then processed it. We can't avoid reading the entire request up-front - we want to verify its integrity before doing any additional processing on it. But there is no reason why the entire request needs to be stored in one big *contiguous* allocation. This always a bad idea. We should use a non- contiguous buffer, and that's the goal of this patch. We use a new Seastar HTTPD feature where we can ask for an input stream, instead of a string, for the request's body. We then begin the request handling by reading lthe content of this stream into a vector<temporary_buffer<char>> (which we alias "chunked_content"). We then use this non-contiguous buffer to verify the request's signature and if successful - parse the request JSON and finally execute it. Beyond avoiding contiguous allocations, another benefit of this patch is that while parsing a long request composed of chunks, we free each chunk as soon as its parsing completed. This reduces the peak amount of memory used by the query - we no longer need to store both unparsed and parsed versions of the request at the same time. Although we already had tests with requests of different lengths, most of them were short enough to only have one chunk, and only a few had 2 or 3 chunks. So we also add a test which makes a much longer request (a BatchWriteItem with large items), which in my experiment had 17 chunks. The goal of this test is to verify that the new signature and JSON parsing code which needs to cross chunk boundaries work as expected. Fixes #7213. Signed-off-by: Nadav Har'El <nyh@scylladb.com> Message-Id: <20210309222525.1628234-1-nyh@scylladb.com>
Tests for Alternator that should also pass, identically, against DynamoDB.
Tests use the boto3 library for AWS API, and the pytest frameworks (both are available from Linux distributions, or with "pip install").
To run all tests against the local installation of Alternator on
http://localhost:8000, just run pytest.
Some additional pytest options:
- To run all tests in a single file, do
pytest test_table.py. - To run a single specific test, do
pytest test_table.py::test_create_table_unsupported_names. - Additional useful pytest options, especially useful for debugging tests:
- -v: show the names of each individual test running instead of just dots.
- -s: show the full output of running tests (by default, pytest captures the test's output and only displays it if a test fails)
Add the --aws option to test against AWS instead of the local installation.
For example - pytest --aws test_item.py or pytest --aws.
If you plan to run tests against AWS and not just a local Scylla installation, the files ~/.aws/credentials should be configured with your AWS key:
[default]
aws_access_key_id = XXXXXXXXXXXXXXXXXXXX
aws_secret_access_key = xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
and ~/.aws/config with the default region to use in the test:
[default]
region = us-east-1
HTTPS support
In order to run tests with HTTPS, run pytest with --https parameter. Note that the Scylla cluster needs to be provided
with alternator_https_port configuration option in order to initialize a HTTPS server.
Moreover, running an instance of a HTTPS server requires a certificate. Here's how to easily generate
a key and a self-signed certificate, which is sufficient to run --https tests:
openssl genrsa 2048 > scylla.key
openssl req -new -x509 -nodes -sha256 -days 365 -key scylla.key -out scylla.crt
If this pair is put into conf/ directory, it will be enough
to allow the alternator HTTPS server to think it's been authorized and properly certified.
Still, boto3 library issues warnings that the certificate used for communication is self-signed,
and thus should not be trusted. For the sake of running local tests this warning is explicitly ignored.
Authorization
By default, boto3 prepares a properly signed Authorization header with every request. In order to confirm the authorization, the server recomputes the signature by using user credentials (user-provided username + a secret key known by the server), and then checks if it matches the signature from the header. Early alternator code did not verify signatures at all, which is also allowed by the protocol. A partial implementation of the authorization verification can be allowed by providing a Scylla configuration parameter:
alternator_enforce_authorization: true
The implementation is currently coupled with Scylla's system_auth.roles table,
which means that an additional step needs to be performed when setting up Scylla
as the test environment. Tests will use the following credentials:
Username: alternator
Secret key: secret_pass
With CQLSH, it can be achieved by executing this snipped:
cqlsh -x "INSERT INTO system_auth.roles (role, salted_hash) VALUES ('alternator', 'secret_pass')"
Most tests expect the authorization to succeed, so they will pass even with alternator_enforce_authorization
turned off. However, test cases from test_authorization.py may require this option to be turned on,
so it's advised.