Built-in Servers

Cloudprober comes with some custom servers that can be enabled through configuration. These servers can act as targets for the other probes – for example, you can run two Cloudprober instances on two different machines and have one instance’s servers act as targets and other instance probe those targets.

These servers can come in handy when the goal is to monitor the underlying infrastructure: e.g. network or load balancers.

Cloudprober (probes) ===(Network)===> Cloudprober (servers)

HTTP Server #

server {
  type: HTTP
  http_server {
    port: 8080
  }
}

This creates an HTTP server that responds on the port 8080. This HTTP server supports the following two endpoints by default:

• /healthcheck - returns ‘OK’ if instance is not in the lameduck mode.
• /lameduck - returns the lameduck status (true/false).

Lameduck mode is a mode in which a server is still running but is signaling that it is about to go down for maintenance so new requests should not be sent to it. This is typically used with load balancers to take out a backend for maintenance without returning any actual errors.

TODO(manugarg): Document how a Cloudprober can be put in the lameduck mode.

Data Handlers #

You can also add custom data handlers to the above HTTP server:

server {
  type: HTTP
  http_server {
    port: 8080
    pattern_data_handler {
      response_size: 1024
    }

    pattern_data_handler {
      response_size: 4
      pattern: "four"
    }
  }
}

Above configuration adds the following two URLs to the HTTP server:

• /data_1024 which responds with 1024 bytes of cloudprobercloudprober...(repeated).
• /data_4 which responds with four.

These endpoints are useful to monitor other aspects of the underlying network like MTU, and consistency (make sure data is not getting corrupted), etc.

See this for all HTTP server configuration options.

UDP #

UDP server can either echo packets back or completely ignore them. In echo mode, you can use it along with the UDP probe type.

server {
  type: UDP
  udp_server {
    port: 85
    type: ECHO
  }
}

server {
  type: UDP
  udp_server {
    port: 90
    type: DISCARD
  }
}

See ServerConf for all UDP server configuration options.

GRPC #

See ServerConf for all GRPC server configuration options.