goProbe

google group

Summary

goProbe is a probe service written in Go programming language. It has three parts to it, a core, probe modules and a metric exposition component.

It currently supports probe metric exposition in json (default) as well as prometheus compatible format.

Pobes are modules and goProbe can potentially be confgured with arbitrary number of modules. Currently the only module configured is the http module.

goProbe takes a json file as a config input which typically supplies the probe name (each should be unique), run intervals, timeouts etc. Each module can have its own json config fields. Below is an example config snippet of the built-in http probe module. It configures two probes probe1 and probe 2 of type http.

[
	{
    "probe_type": "http",
    "probe_config": {
        "probe_name": "probe1",
        "probe_url": "http://example.com",
        "probe_timeout": 20,
        "probe_interval": 30
        }
	},
	{
    "probe_type": "http",
    "probe_config": {
        "probe_name": "probe2",
        "probe_url": "http://example.com"
        }
    }
]  

Installation

Install mercuruial. On ubuntu,

$ sudo apt-get install mercurial

$ go get -u github.com/samitpal/goProbe

$ cd $GOPATH/src/github.com/samitpal/goProbe

$ go install

Running the binary

First set the environmental variable which points to the html templates, e.g

$ export GOPROBE_TMPL="templates/*"

$ $GOPATH/bin/goProbe -config <path to config file>

By default goProbe displays the probe metrics via the /metrics http handler in json format. It also displays the current configs via its /config http handler. The /status handler is yet to be implemented.

To expose the metrics in prometheus format, run it as follows,

$ $GOPATH/bin/goProbe -config <path to config file> -exposition_type prometheus

Http probe json configs

Mandatory fields

• probe_name: The name of the probe. This should be unique globally.
• probe_url: The complete url.

Other fields

• probe_http_method : The http method. Default value is http GET.
• probe_action : This configures the mechanism used to determine the success/failure of a probe. Currently it can be either of the following strings
  • check_ret_200 : It checks if the response status code is 200. This is the default.
  • check_match_string : If this is set then probe_match_string needs to be set as well. Essentially the module will match the http body with the probe_match_string string.
• probe_match_string : This needs to be set to a regexp if probe_action is set to "check_match_string".
• probe_interval : The frequency (in seconds) with which to run the probe. Default value is 60.
• probe_timeout : Time out in seconds for a given probe. Default value is 40. This value needs to be less than the probe_interval.

Developing probe module

There is a sample module called sample_probe.go which can give you a start. Essentially all you need to do is implement the Prober interface defined in prober.go. In addition to the module source it also needs a minor change in config.go to register the new module type.