added logging documentation

DevReadMe.md

@@ -151,6 +151,10 @@ PORTS="5000:5000 8000:8000 1000:1000" ./scripts/run_docker start --inbound-trans
 
 Refer to [the previous section](#Running) for instructions on how to run the software.
 
+### Logging
+
+You can find more details about logging and log levels [here](Logging.md).
+
 ### Running Tests
 
 To run the ACA-Py test suite, use the following script:

Logging.md

@@ -0,0 +1,52 @@
+# Logging docs
+
+Acapy supports multiple configurations of logging.
+
+## Log level
+
+Acapy's logging is based on python's [logging lib](https://docs.python.org/3/howto/logging.html).
+Log levels `DEBUG`, `INFO` and `WARNING` are available.
+Other log levels fall back to `WARNING`.
+
+## Command Line Arguments
+
+* `--log-level` - The log level to log on std out.
+* `--log-file` - Path to a file to log to.
+
+Example:
+
+```sh
+./bin/aca-py start --log-level debug --log-file acapy.log
+```
+
+## Environment Variables
+
+The log level can be configured using the environment variable `ACAPY_LOG_LEVEL`.
+The log file can be set by `ACAPY_LOG_FILE`.
+The log config can be set by `ACAPY_LOG_CONFIG`.
+
+Example:
+
+```sh
+ACAPY_LOG_LEVEL=info ACAPY_LOG_FILE=./acapy.log ACAPY_LOG_CONFIG=./acapy_log.ini ./bin/aca-py start
+```
+
+## Acapy Config File
+
+Following parameters can be used in a configuration file like [this](demo/demo-args.yaml).
+
+```yaml
+log-level: WARNING
+debug-connections: false
+debug-presentations: false
+```
+
+Warning: debug-connections and debug-presentations must not be used in a production environment as they log also credential claims values.
+Both parameters are independent of the log level, which means:
+Also if log-level is set to WARNING, connections and presentations will be logged like in debug log level.
+
+## Log config file
+
+Find an example in [default_logging_config.ini](aries_cloudagent/config/default_logging_config.ini).
+
+You can find more detail description in the [logging documentation](https://docs.python.org/3/howto/logging.html#configuring-logging).