Debugging
Logging
Cargo uses the env_logger
crate to display debug log messages. The
CARGO_LOG
environment variable can be set to enable debug logging, with a
value such as trace
, debug
, or warn
. It also supports filtering for
specific modules. Feel free to use the standard log
macros to help with
diagnosing problems.
# 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=cargo::ops::registry=debug cargo fetch
# This is an important command for diagnosing fingerprint issues.
CARGO_LOG=cargo::core::compiler::fingerprint=trace cargo build