Cargo uses the
tracing crate to display debug log messages.
CARGO_LOG environment variable can be set to enable debug logging, with a value such as
It also supports filtering for specific modules with comma-separated [directives].
Feel free to use shorthand macros to help with diagnosing problems.
We’re looking forward to making Cargo logging mechanism more structural!
# Outputs all logs with levels debug and higher
CARGO_LOG=debug cargo generate-lockfile
# Don't forget that you can filter by module as well
CARGO_LOG=cargo::core::resolver=trace cargo generate-lockfile
# This will print lots of info about the download process. `trace` prints even more.
CARGO_HTTP_DEBUG=true CARGO_LOG=network=debug cargo fetch
# This is an important command for diagnosing fingerprint issues.
CARGO_LOG=cargo::core::compiler::fingerprint=trace cargo build