Backend Logging

The backend uses env_logger together with log as a logging framework.

env_logger allows to configure logging via the environment variable RUST_LOG.

Changing the Logging Level

To change the log level you can do one of the following:

Run the backend with e.g. RUST_LOG='backend=debug,actix_web=info' cargo run to change the log level of our code to debug
Change the variable RUST_LOG in the .env file

Use detailed logging messages for easy troubleshooting. It must be clear what should have happened and what actually happened.
Include relevant context, parameters, error codes etc.
Log only if actually needed. Exceptions: all calls of endpoints and SQL queries should be completely logged (level: debug).
Always use the lowest applicable logging level.

Available logging levels are:

error
Use for events disrupting normal operations.
warn
Apply for potentially harmful situations or undesirable yet operational states.
info
Use to monitor the essential flow of the application, capturing important operations like successful user authentications.
debug
Reserved for development or debugging; includes detailed updates, states of critical application points, or SQL queries.
trace
Use for granular logging, such as step-by-step function execution, to aid in complex issue diagnosis.

To log you can simply call the macros in the log crate.

For example to log using the debug level:

log::debug!("This is my variable: {}", some_variable);

As you can see, it can be used in the same way as for example println!().

SQL queries can be converted to something that can be logged using debug_query.

let query = diesel::delete(seeds::table.find(id));
debug!("{}", debug_query::<Pg, _>(&query));
query.execute(conn).await