Sensu Client

Portable / Embeddable lighweight version of the sensu client

Usage

You can use this project by two different ways.

• The first is use the project as a standalone program and use external checks/metrics.

• The second is to use the project as an external golang package and write a project with another main method and add some checks / metrics inside.

Standalone project

The easiest way to get started is to download the binary from your command line:

• Linux

$ curl -sL https://github.com/upfluence/sensu-client-go/releases/download/v0.0.1/sensu-client-go-linux-amd64-0.0.1 \
  > sensu-client

$ chmod +x sensu-client

• OSX

$ curl -sL
https://github.com/upfluence/sensu-client-go/releases/download/v0.0.1/sensu-client-go-darwin-amd64-0.0.1 \
  > sensu-client

$ chmod +x sensu-client

Then you just have to run the program as ./sensu-client -c /etc/sensu/config.json. EASY!

Subpackage

Barebone check

If you want to write a simple check you just have to write a function with zero argument and which returns a check.ExtensionCheckResult. Wrap this function pointer into an check.ExtensionCheck and add it into the check.Store map with check name as key, such as:

package main

package main

import (
	"net/http"

	"github.com/upfluence/goutils/log"
	"github.com/upfluence/sensu-go/sensu/transport/rabbitmq"
	"github.com/upfluence/sensu-client-go/sensu"
	"github.com/upfluence/sensu-client-go/sensu/check"
	"github.com/upfluence/sensu-client-go/sensu/handler"
)

func HTTPCheck() check.ExtensionCheckResult {
	resp, err := http.Get("http://example.com/")

	if err != nil {
		return handler.Error(err.Error())
	}

	if resp.StatusCode >= 200 && resp.StatusCode < 300 {
		return handler.Ok("Example.com is alive!")
	} else if resp.StatusCode >= 500 {
		return handler.Error("Example.com return an 5XX status code")
	} else {
		return handler.Warning("Example.com is not responding as expected")
	}
}

func main() {
	cfg, err := sensu.NewConfigFromFlagSet(sensu.ExtractFlags())

	if err != nil {
		log.Fatal(err.Error())
	}

	t, err := rabbitmq.NewRabbitMQTransport(cfg.RabbitMQURI())

  if err != nil {
		log.Fatal(err.Error())
	}

  client := sensu.NewClient(t, cfg)

	check.Store["http_check"] = &check.ExtensionCheck{HTTPCheck}

	client.Start()
}

Standard check

If you want to write a check and a metric which inspect the same value you can use the StandardCheck struct from the github.com/upfluence/sensu-client-go/sensu/handler package. Such as:

package main

import (
	"fmt"
	"net/http"
	"time"

	"github.com/upfluence/goutils/log"
	"github.com/upfluence/sensu-go/sensu/transport/rabbitmq"
	"github.com/upfluence/sensu-client-go/sensu"
	"github.com/upfluence/sensu-client-go/sensu/check"
	"github.com/upfluence/sensu-client-go/sensu/utils"
)

func HTTPCallDuration() (float64, error) {
	t0 := time.Now().Unix()
	_, err := http.Get("http://example.com/")

	return float64(time.Now().Unix() - t0), err
}

func main() {
	c := &utils.StandardCheck{
		ErrorThreshold:   20.0,
		WarningThreshold: 10.0,
		MetricName:       "http_call.duration",
		Value:            HTTPCallDuration,
		CheckMessage: func(v float64) string {
			return fmt.Sprintf("Duration: %.2fs", v)
		},
		Comp: func(x, y float64) bool { return x > y },
	}

	cfg, err := sensu.NewConfigFromFlagSet(sensu.ExtractFlags())

	if err != nil {
		log.Fatal(err.Error())
	}

	t, err := rabbitmq.NewRabbitMQTransport(cfg.RabbitMQURI())

  if err != nil {
		log.Fatal(err.Error())
	}

	client := sensu.NewClient(t, cfg)

	check.Store["http_duration_check"] = &check.ExtensionCheck{c.Check}
	check.Store["http_duration_metric"] = &check.ExtensionCheck{c.Metric}

	client.Start()
}

If the duration exceed 20s the http_duration_check will return an Error, if the duration exceed 10s the check will return a warning otherwise it will returns an "OK" code.

The http_duration_metric will return http_call_duration 5.000000 1438125085

with 5.0 as the duration of the HTTP call and 1438125085 the timestamp

Running

You just have to compile it and execute it, such as:

$ ls

my_awesome_main.go sensu-config.json

$ go build -o sensu-client .

$ ./sensu-client -c sensu-config.json

Options

In the both cases, you can use the -c flag to use a specific configuration file, the configuration is pretty similar to the ruby client check out the doc. The difference is about the configuration of the RabbitMQ client. You have to provide an RabbitMQ URI through the RABBITMQ_URI environment variable or by adding the rabbit_uri key into the root of the JSON configuration file.

By the way you can also specify some options through environment variables:

variable	explanation	example
SENSU_CLIENT_SUBSCRIPTIONS	Comma separated subscriptions	email,slack
SENSU_CLIENT_NAME	The name of the client	node-01
SENSU_CLIENT_ADDRESS	The ip addres of the client	127.0.0.1
RABBITMQ_URI	RabbitMQ URI	amqp://guest:guest@localhost:5672/%2f

Roadmap

• Implement the keep-alives specific configurations (thresholds and hanlder)