Guide

Logging

Ze uses hierarchical, structured logging with runtime-configurable levels per subsystem.

Log Levels

Level	Description
`disabled`	✕
`debug`	Detailed diagnostics (FSM transitions, wire events, plugin IPC)
`info`	Informational messages (peer up/down, config reload)
`warn`	Warnings and errors (default)
`err`	Errors only

Configuration

Config File

environment {
    log {
        level warn              # base level for all subsystems
        backend stderr          # output destination
        bgp.reactor debug      # subsystem-specific override
        bgp.routes info        # another override
        plugin.relay warn      # plugin stderr relay level
    }
}

Environment Variables

Environment variables take precedence over the config file:

# Set base level
export ZE_LOG=debug

# Set per-subsystem level
export ZE_LOG_BGP_FSM=debug
export ZE_LOG_PLUGIN=info

# All notation forms are equivalent:
ze.log.bgp.fsm    ZE_LOG_BGP_FSM    ze_log_bgp_fsm

CLI Flag

ze -d example.conf             # shorthand for ze.log=debug + ze.log.relay=debug

Runtime Change

Change log levels on a running daemon without restart:

ze cli -c "bgp log set bgp.fsm debug"
ze cli -c "bgp log set bgp.reactor info"
ze cli -c "bgp log levels"         # show current levels

Priority Order

Most specific wins, environment beats config:

Environment variable ZE_LOG_BGP_FSM (most specific)
Environment variable ZE_LOG_BGP (parent)
Environment variable ZE_LOG (base)
Config file bgp.fsm debug (most specific)
Config file level warn (base)
Default: warn

Backends

Backend	Config	Description
`stderr`	`backend stderr`	Standard error (default). Color auto-detected on TTY.
`stdout`	`backend stdout`	Standard output. Color auto-detected on TTY.
`syslog`	`backend syslog`	Remote syslog. Set address with `destination`.

Syslog example:

environment {
    log {
        level info
        backend syslog
        destination 10.0.0.100:514
    }
}

Plugin Stderr Relay

External plugins (forked processes) write to stderr. Ze captures this output and relays it through the logging system tagged with subsystem plugin.relay.

export ZE_LOG_PLUGIN_RELAY=debug      # see all plugin stderr
export ZE_LOG_PLUGIN_RELAY=disabled   # silence plugin output

Default relay level: warn.

Naming Convention

Subsystem names follow <domain>.<component>[.<concern>]:

Domain	Covers
`bgp`	BGP protocol (config, filter, reactor, routes, server)
`chaos`	Chaos fault injection
`cli`	CLI and editor
`hub`	Hub process management
`plugin`	Plugin infrastructure
`web`	Web UI

Setting a parent level applies to all children. ze.log.bgp=debug enables debug for every bgp.* subsystem. ze.log.plugin=info enables info for every plugin.* subsystem.

Subsystems

Run ze env to see the full list with descriptions. Below is the complete inventory:

Subsystem	Description
`bgp.config`	Configuration parsing and loading
`bgp.filter`	Route filtering (AS loop, originator-ID)
`bgp.filter.community`	Community-based route filtering plugin
`bgp.gr`	Graceful restart marker handling
`bgp.reactor`	Reactor event loop and peer management
`bgp.reactor.cache`	UPDATE cache gap-based eviction
`bgp.reactor.forward`	Per-peer forward worker pool
`bgp.reactor.peer`	Peer lifecycle and FSM transitions
`bgp.reactor.session`	Session wire protocol handling
`bgp.routes`	Route processing and announcements
`bgp.server`	TCP server and connection handling
`bgp.watchdog`	Watchdog timer plugin
`chaos`	Chaos fault injection orchestration
`chaos.peer`	Chaos testing simulated peers
`cli.editor.draft`	Config editor draft persistence
`hub.managed`	Managed mode client connection
`hub.reload`	Configuration reload handling
`plugin`	Plugin process lifecycle and event delivery
`plugin.coordinator`	Plugin startup stage coordination
`plugin.manager`	Multi-plugin coordination and respawn
`plugin.relay`	Plugin stderr relay to engine log
`plugin.server`	Plugin RPC server and stage protocol
`web.auth`	Web UI authentication
`web.server`	Web UI HTTP server

Inspecting Current Configuration

ze env list -v                 # show all env vars with current values
ze env get ze.log              # show specific var details
ze cli -c "bgp log levels"  # show runtime log levels