Files
scylladb/test/alternator
Nadav Har'El 3c0603558c alternator: add validation of numbers' magnitude and precision
DynamoDB limits the allowed magnitude and precision of numbers - valid
decimal exponents are between -130 and 125 and up to 38 significant
decimal digitst are allowed. In contrast, Scylla uses the CQL "decimal"
type which offers unlimited precision. This can cause two problems:

1. Users might get used to this "unofficial" feature and start relying
   on it, not allowing us to switch to a more efficient limited-precision
   implementation later.

2. If huge exponents are allowed, e.g., 1e-1000000, summing such a
   number with 1.0 will result in a huge number, huge allocations and
   stalls. This is highly undesirable.

After this patch, all tests in test/alternator/test_number.py now
pass. The various failing tests which verify magnitude and precision
limitations in different places (key attributes, non-key attributes,
and arithmetic expressions) now pass - so their "xfail" tags are removed.

Fixes #6794

Signed-off-by: Nadav Har'El <nyh@scylladb.com>
2023-05-02 11:04:05 +03:00
..

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.