Text Logs (syslog style)

In full-service and fog, the mc-common crate contains "logger" implementations based on the rust slog crate.

The mc-sgx-slog crate provides an slog::Logger appropriate for the enclave. It is recommended to refer to mc_common::logger::Logger in the portable enclave-impl crates, and put the calls to mc-sgx-slog in the enclave-trusted crates.

Most servers use the mc_common::logger::create_app_logger function at their entrypoint to create a logger for the server. This logger uses an in-memory buffer and a background thread to eventually write the log messages to where they are supposed to go.

The create_root_logger function sets up several possible log destinations:

• STDOUT (or STDERR if an environment variable is set)

• UDP-JSON logging (if enabled)

• Sentry logging (forwarding error and critical messages directly to Sentry servers)

The background thread is enabling the main thread to make progress asynchronously while these network calls are in progress.

(Note that this is very different from the "12 factor app" guidance: https://12factor.net/logs.)