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Have a probe only check for an available TCP connection without sending a request.
This is done adding .tcponly = 1 to a probe’s definition. Defaults to 0. This can be used to probe non HTTP services.
When using a tcponly probe, the following properties apply:
.interval - Time between polls (default: 5.0s).threshold - Number of successful polls in .window needed to mark backend as healthy (default: 3).window - Number of recent polls to consider (default: 8).timeout - Timeout for the TCP connection (default: 2s).initial - Number of successful polls in .window needed before Varnish starts (default: 2)The following properties are not relevant for tcponly probes since no HTTP request is sent:
.url.request.expected_response