Update to follow changes; fill out configuration doc

Author: pglombardo

Configuration.md

@@ -1 +1,21 @@
-TBD
+# Configuration
+
+## Agent Communication
+
+The sensor tries to communicate with the Instana agent via IP 127.0.0.1 and as a fallback via the host's default gateway for containerized environments. Should the agent not be available under either of these IPs, e.g. due to iptables or other networking tricks, you can use environment variables to configure where the Instana host agent lives.
+
+To use these, these environment variables should be set in the environment of the running Python process.
+
+```shell
+export INSTANA_AGENT_IP = '127.0.0.1'
+export INSTANA_AGENT_PORT = '42699'
+```
+
+## Debugging & More Verbosity
+
+Setting `INSTANA_GEM_DEV` to a non nil value will enable extra logging output generally useful
+for development.
+
+```Python
+export INSTANA_DEV="true"
+```

README.md

@@ -42,7 +42,7 @@ _Note: When the Django or Flask instrumentation is used, runtime monitoring is a
 To enable runtime monitoring (without request tracing), set the following environment variable in your _application boot environment_ and then restart your application:
 
   `export AUTOWRAPT_BOOTSTRAP=runtime`
-  
+
 ## uWSGI
 
 ### Threads
@@ -57,9 +57,27 @@ If you use uWSGI in forking workers mode, you must specify `--lazy-apps` (or `la
 
 The instana package will automatically collect key metrics from your Python processes.  Just install and go.
 
-## Tracing
+## OpenTracing
+
+This Python package supports [OpenTracing](http://opentracing.io/).  When using this package, the OpenTracing tracer (`opentracing.tracer`) is automatically set to the `InstanaTracer`.
+
+```Python
+import opentracing
+
+parent_span = opentracing.tracer.start_span(operation_name="asteroid")
+# ... work
+child_span = ot.tracer.start_span(operation_name="spacedust", child_of=parent_span)
+child_span.set_tag(ext.SPAN_KIND, ext.SPAN_KIND_RPC_CLIENT)
+# ... work
+child_span.finish()
+# ... work
+parent_span.finish()
+```
+
+## Configuration
+
+See [Configuration.md](https://github.com/instana/python-sensor/blob/master/Configuration.md)
 
-This Python package supports [OpenTracing](http://opentracing.io/).
 
 ## Documentation