Python Microservices Development

Adding extra fields

Graypy adds some metadata fields to each log such as the following:

• The remote address
• The PID, process, and thread names
• The name of the function from which the call was made

Graylog itself will add the hostname from which each log is received, as the source field, and a few other fields.

For a distributed system, we need to add more contextual information to be able to search efficiently in our logs. For example, knowing the username is useful to search for a sequence of calls that was made in the stack in the same user session.

This information is usually stored inside app.session in our microservices, and we can use a logging.Filter class to add it in each logging record sent to Graylog:

 from flask import session ...