Version 3.3.12 home Download and build Libraries and tools Branch management Demo Discovery service protocol Frequently Asked Questions (FAQ) Logging conventions Metrics Production users Reporting bugs Tuning etcd release guide Benchmarks Benchmarking etcd v2.1.0 Benchmarking etcd v2.2.0 Benchmarking etcd v2.2.0-rc Benchmarking etcd v2.2.0-rc-memory Benchmarking etcd v3 Storage Memory Usage Benchmark Watch Memory Usage Benchmark Developer guide Experimental APIs and features Interacting with etcd Set up a local cluster System limits Why gRPC gateway etcd API Reference etcd concurrency API Reference gRPC naming and discovery Learning etcd client architecture Client feature matrix Data model Glossary KV API guarantees Learner etcd v3 authentication design etcd versus other key-value stores etcd3 API Operations guide Clustering Guide Configuration flags Design of runtime reconfiguration Disaster recovery Failure modes Hardware recommendations Maintenance Migrate applications from using API v2 to API v3 Monitoring etcd Performance Role-based access control Run etcd clusters inside containers Runtime reconfiguration Supported systems Transport security model Versioning etcd gateway gRPC proxy Platforms Amazon Web Services Container Linux with systemd FreeBSD Upgrading Upgrade etcd from 2.3 to 3.0 Upgrade etcd from 3.0 to 3.1 Upgrade etcd from 3.1 to 3.2 Upgrade etcd from 3.2 to 3.3 Upgrade etcd from 3.3 to 3.4 Upgrade etcd from 3.4 to 3.5 Upgrading etcd clusters and applications etcd v3 API

Logging conventions



etcd uses the capnslog library for logging application output categorized into levels. A log message’s level is determined according to these conventions:

  • Error: Data has been lost, a request has failed for a bad reason, or a required resource has been lost

    • Examples:
    • A failure to allocate disk space for WAL
  • Warning: (Hopefully) Temporary conditions that may cause errors, but may work fine. A replica disappearing (that may reconnect) is a warning.

    • Examples:
    • Failure to send raft message to a remote peer
    • Failure to receive heartbeat message within the configured election timeout
  • Notice: Normal, but important (uncommon) log information.

    • Examples:
    • Add a new node into the cluster
    • Add a new user into auth subsystem
  • Info: Normal, working log information, everything is fine, but helpful notices for auditing or common operations.

    • Examples:
    • Startup configuration
    • Start to do snapshot
  • Debug: Everything is still fine, but even common operations may be logged, and less helpful but more quantity of notices.

    • Examples:
    • Send a normal message to a remote peer
    • Write a log entry to disk