It is very common in the Salt codebase to see opts referred to in a number of contexts.
For example, it can be seen as __opts__ in certain cases, or simply as opts as an argument to a function in others.
Simply put, this data structure is a dictionary of Salt's runtime configuration information that's passed around in order for functions to know how Salt is configured.
When writing Python code to use specific parts of Salt, it may become necessary to initialize a copy of opts from scratch in order to have it available for a given function.
To do so, use the utility functions available in salt.config.
As an example, here is how one might generate and print an options dictionary for a minion instance:
opts = salt.config.minion_config('/etc/salt/minion')
To generate and display opts for a master, the process is similar:
opts = salt.config.master_config('/etc/salt/master')