oslo.context/doc/source/user/usage.rst

Usage

oslo.context is used in conjunction with oslo.log to provide context aware log records when specifying a ~oslo_context.context.RequestContext object.

This code example demonstrates two INFO log records with varying output format due to the use of RequestContext.

examples/usage_simple.py

Source: example_usage_simple.py

Example Logging Output:

2016-01-20 21:56:29.283 8428 INFO __main__ [-] Message without context
2016-01-20 21:56:29.284 8428 INFO __main__ [req-929d23e9-f50e-46ae-a8a7-02bc8c3fd2c8 - - - - -] Message with context

The format of these log records are defined by the logging_default_format_string and logging_context_format_string configuration options respectively. The logging_user_identity_format option also provides further context aware definition flexibility.

Context Variables

The oslo.context variables used in the logging_context_format_string and logging_user_identity_format configuration options include:

• global_request_id - A request id (e.g. req-9f2c484a-b504-4fd9-b44c-4357544cca50) which may have been sent in from another service to indicate this is part of a chain of requests.
• request_id - A request id (e.g. req-9f2c484a-b504-4fd9-b44c-4357544cca50)
• user - A user id (e.g. e5bc7033e6b7473c9fe8ee1bd4df79a3)
• tenant - A tenant/project id (e.g. 79e338475db84f7c91ee4e86b79b34c1)
• domain - A domain id
• user_domain - A user domain id
• project_domain - A project domain id

This code example demonstrates defining a context with specific attributes that are presented in the output log record.

examples/usage.py

Source: example_usage.py

Example Logging Output:

2016-01-21 17:30:50.263 12201 INFO __main__ [-] Message without context
2016-01-21 17:30:50.264 12201 INFO __main__ [req-e591e881-36c3-4627-a5d8-54df200168ef 6ce90b4d d6134462 - - a6b9360e] Message with context

A context object can also be passed as an argument to any logging level message.

examples/usage.py

Example Logging Output:

2016-01-21 22:43:55.621 17295 INFO __main__ [req-ac2d4a3a-ff3c-4c2b-97a0-2b76b33d9e72 ace90b4d b6134462 - - c6b9360e] Message with passed context

Note

To maintain consistent log messages for operators across multiple OpenStack projects it is highly recommended that logging_default_format_string and logging_context_format_string are not modified from oslo.log default values.

Project Specific Variables

Individual projects can also subclass ~oslo_context.context.RequestContext to provide additional attributes that can be using with oslo.log. The Nova RequestContext class for example provides additional variables including user_name and project_name.

This can for example enable the defining of logging_user_identity_format = %(user_name)s %(project_name)s which would produce a log record containing a context portion using names instead of ids such as [req-e4b9a194-a9b1-4829-b7d0-35226fc101fc admin demo]

This following code example shows how a modified logging_user_identity_format configuration alters the context portion of the log record.

examples/usage_user_identity.py

Source: example_usage_user_identity.py

Example Logging Output:

2016-01-21 20:56:43.964 14816 INFO __main__ [-] Message without context
2016-01-21 20:56:43.965 14816 INFO __main__ [req-abc 6ce90b4d/d6134462@a6b9360e] Message with context