python-cassandra-jaeger 0.4

Description:

pythoncassandrajaeger 0.4

python-cassandra-jaeger



When do I use it?
When I'm using the following technologies:

cassandra-driver
cassandra-jaeger-tracing

And you want to attach your traces to Cassandra's requests.
Note: so far only Jaeger tracing and MockTracer are supported. I mean,
theoretically every opentracing-compatible framework
is supported, but only Jaeger's tracing enables to select
which query to trace or not.
In case that you're not using Jaeger or MockTracer, every single query will be
sent with a tracing request, which may negatively impact your
performance, Cassandra-wise.
If you have an issue with that, please file an
issue
with a description of what it is that you're using for tracing.
A relevant warning will be shown as well.
Usage
Just do the following:
from python_cassandra_jaeger import SessionTracer
from cassandra.cluster import Cluster

from .tracing import tracer

c = Cluster(['127.0.0.1'])
s = c.connect('keyspace')
st = SessionTracer(s, tracer)

st.execute('SELECT * FROM table')

And you keep on utilizing st instead of s.
This will automatically execute tracing when your span is being traced.
Just remember to match your tracing key with
Cassandra's JAEGER_TRACE_KEY.
What does it do?
It hijacks session.execute, grabs the current span,
determines if sampling is active for this span (currently
works only with Jaeger) and if it is so, starts a new
child span, attaches it's ID to custom_payload and enables
tracing for the request.
Additionally metricizing your queries
Added in v0.4:
You can also metrify how long did your queries take to execute, say:
from satella.instrumentation.metrics import getMetric

met_sum = getMetric('cassandra.query.time.summary', 'summary')
s = c.connect('keyspace')
st = SessionTracer(s, tracer, metric=met_sum)

History
v0.4

added an option to metricize the queries
added support for MockTracker

v0.3

a warning will be shown with unsupported tracing mechanism

v0.2

improved reporting when arguments is a dict