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Sdnotify Extension

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Overview

• Send READY=1 once all pipelines have started.
• Send STOPPING=1 when the process is shutting down after receiving SIGINT or SIGTERM, so systemd knows the shutdown is intentional.
• (only for Type=notify-reload) On SIGHUP send RELOADING=1 (paired with MONOTONIC_USEC as required by sd_notify(3)) so systemd’s state machine correctly reflects that a reload is in progress. The extension doesn’t itself drive a reload or cycle the process on SIGHUP. The OpenTelemetry Collector has its own SIGHUP handler that performs an in-process reload.
• When systemd has set WATCHDOG_USEC for the collector’s PID, send WATCHDOG=1 keep-alive notifications every WATCHDOG_USEC / 2 as recommended by sd_watchdog_enabled(3), for as long as the collector is running, so systemd can restart the process if it hangs.

It is recommended that a daemon sends a keep-alive notification message to the service manager every half of the time returned here.

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Configuration

extensions:
  sd_notify: {}

service:
  extensions: [sd_notify]

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Example systemd unit

[Unit]
Description=OpenTelemetry Collector
After=network-online.target

[Service]
Type=notify-reload
ExecStart=/usr/local/bin/otelcol --config=/etc/otelcol/config.yaml
WatchdogSec=30s
Restart=always
RestartSec=2s

[Install]
WantedBy=multi-user.target

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Development

make test mod-integration-test