SignalFx Go Google Cloud Function Wrapper

SignalFx Golang Google Cloud Function Wrapper.

Usage

The SignalFx Go Google Cloud Function Wrapper is a wrapper around an Google Cloud Function Go function handler, used to instrument execution of the function and send metrics to SignalFx.

Installation

To install run the command:

$ go get https://github.com/signalfx/google-cloud-function-go

Configuring the ingest endpoint

By default, this function wrapper will send to the us0 realm. If you are not in this realm you will need to set the SIGNALFX_INGEST_ENDPOINT environment variable to the correct realm ingest endpoint (https://ingest.{REALM}.signalfx.com/v2/datapoint). To determine what realm you are in, check your profile page in the SignalFx web application (click the avatar in the upper right and click My Profile).

Environment Variable

Set the SIGNALFX_AUTH_TOKEN environment variable with the appropriate SignalFx authentication token. Change the default values of the other variables accordingly if desired.

SIGNALFX_AUTH_TOKEN=<SignalFx authentication token>

SIGNALFX_INGEST_ENDPOINT=https://ingest.{REALM}.signalfx.com/v2/datapoint

SIGNALFX_SEND_TIMEOUT_SECONDS=5

Wrapping a function

The SignalFx Go Google Cloud Function Wrapper wraps the user cloud function. Pass the cloud function to sfxgcf.NewHandlerWrapper function to create the wrapper sfxgcf.HandlerWrapper. Finally, invoked the wrapped function by calling Invoke method of the wrapper. See the example below.

import (
  ...
  "github.com/signalfx/google-cloud-function-go"
  ...
)
...

func userFunc(w http.ResponseWriter, r *http.Request) {
  ...  
}
...

func main(w http.ResponseWriter, r *http.Request) {
  ...
  wrapper := sfxgcf.NewHandlerWrapper(userFunc)
  wrapper.Invoke(w, r)
  ...
}
...

Metrics and dimensions sent by the wrapper

The Google Cloud Function wrapper sends the following metrics to SignalFx:

Metric Name	Type	Description
function.invocations	Counter	Count number of Cloud Function invocations
function.cold_starts	Counter	Count number of cold starts
function.duration	Gauge	Milliseconds in execution time of underlying Cloud Function handler

The Cloud Function wrapper adds the following dimensions to all data points sent to SignalFx:

Dimension	Description
gcf_region	Google Cloud Function Region
gcf_project_id	Google Cloud Function Project ID
gcf_function_name	Google Cloud Function Name
gcf_function_version	Google Cloud Function Version
function_wrapper_version	SignalFx function wrapper qualifier (e.g. signalfx_gcf_go-0.0.1)
metric_source	The literal value of 'gcf_wrapper'

Sending custom metric in the Google Cloud function

Use the method sfxgcf.SendDatapoint() of HandlerWrapper to send custom metric datapoints to SignalFx from within your cloud function. A sfxgcf.HandlerWrapper variable needs to be declared globally in order to be accessible from within your cloud function. See example below.

import (
  ...
  "github.com/signalfx/google-cloud-function-go"
  "github.com/signalfx/golib/datapoint"
  ...
)
...

var wrapper sfxgcf.HandlerWrapper
...

func userFunc(w http.ResponseWriter, r *http.Request) {
  ...
  // Custom counter metric.
  dp := datapoint.Datapoint {
      Metric: "db_calls",
      Value: datapoint.NewIntValue(1),
      MetricType: datapoint.Counter,
      Dimensions: map[string]string{"db_name":"mysql1",}
  }
  // Sending custom metric to SignalFx.
  wrapper.SendDatapoints([]*datapoint.Datapoint{&dp})
  ...
}
...

func main(w http.ResponseWriter, r *http.Request) {
  ...
  wrapper := sfxgcf.NewHandlerWrapper(handler)
  wrapper.Invoke(w, r)
  ...
}
...

seonsfx/serverless-go