In commit 8d27e1b, we added tracing (see docs/tracing.md) support to
Alternator requests. However, we never had a functional test that
verifies this feature actually works as expected, and we recently
noticed that for the GetItem and BatchGetItem requestd, the trace
doesn't really work (it returns an empty list of events).
So this patch adds a test, test/alternator/test_tracing.py, which verifies
that the tracing feature works for the PutItem, GetItem, DeleteItem,
UpdateItem, BatchGetItem, BatchWriteItem, Query and Scan operations.
This test is very peculiar. It needs to use out-of-band REST API
requests to enable and disable tracing (of course, the test is skipped
when running against AWS - this is a Scylla-only feature). It also needs
to read CQL-only system tables and does this using Alternator's
".scylla.alternator" interface for system tables - which came through
for us here beautifully and demonstrated their usefulness.
I paid a lot of attention for this test to remain reasonably fast -
this entire test now runs in a little less than one second. Achieving
this while testing eight different requests was a bit of a challenge,
because traces take time until they are visible in the trace table.
This is the main reason why in this patch the test for all eight
request types are done in one test, instead of eight separate tests.
Fixes#6891
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20200727115401.1199024-1-nyh@scylladb.com>
a7df8486b1