go.etcd.io/etcd@v3.3.27+incompatible/Documentation/dev-internal/logging.md (about)

     1  ---
     2  title: Logging conventions
     3  ---
     4  
     5  etcd uses the [capnslog][capnslog] library for logging application output categorized into *levels*. A log message's level is determined according to these conventions:
     6  
     7  * Error: Data has been lost, a request has failed for a bad reason, or a required resource has been lost
     8    * Examples:
     9      * A failure to allocate disk space for WAL
    10  
    11  * Warning: (Hopefully) Temporary conditions that may cause errors, but may work fine. A replica disappearing (that may reconnect) is a warning.
    12    * Examples:
    13      * Failure to send raft message to a remote peer
    14      * Failure to receive heartbeat message within the configured election timeout
    15  
    16  * Notice: Normal, but important (uncommon) log information.
    17    * Examples:
    18      * Add a new node into the cluster
    19      * Add a new user into auth subsystem
    20  
    21  * Info: Normal, working log information, everything is fine, but helpful notices for auditing or common operations.
    22    * Examples:
    23      * Startup configuration
    24      * Start to do snapshot
    25  
    26  * Debug: Everything is still fine, but even common operations may be logged, and less helpful but more quantity of notices.
    27    * Examples:
    28      * Send a normal message to a remote peer
    29      * Write a log entry to disk
    30  
    31  [capnslog]: https://github.com/coreos/pkg/tree/master/capnslog