IOpipe Agent for Go (beta)

This package provides analytics and distributed tracing for event-driven applications running on AWS Lambda.

Installation
Usage
Running Tests
Contributing
License

Installation

Using go get:

go get github.com/iopipe/iopipe-go

Using dep:

dep ensure -add github.com/iopipe/iopipe-go

Usage

Set the IOPIPE_TOKEN environment variable to your project token,

import this library, instantiate an agent, and wrap your handler that you expose to AWS:

import (
	"github.com/aws/aws-lambda-go/lambda"
	"github.com/iopipe/iopipe-go"
)

var agent = iopipe.NewAgent(iopipe.Config{})

func hello() (string, error) {
	return "Hello ƛ!", nil
}

func main() {
	lambda.Start(agent.WrapHandler(hello))
}

The iopipe.Config struct offers further options for configuring how your function interacts with IOpipe, please refer to the godocfor more information.

Configuration

The following may be set via the iopipe.Config{} struct passed to the iopipe.NewAgent() initializer:

`Token` (*string: required)

Your IOpipe project token. If not supplied, the environment variable IOPIPE_TOKEN will be used if present. Find your project token

`Debug` (*bool: optional = false)

Debug mode will log all data sent to IOpipe servers. This is also a good way to evaluate the sort of data that IOpipe is receiving from your application. If not supplied, the environment variable IOPIPE_DEBUG will be used if present.

`TimeoutWindow` (*time.Duration: optional = 150)

By default, IOpipe will capture timeouts by exiting your function 150 milliseconds early from the AWS configured timeout, to allow time for reporting. You can disable this feature by setting timeout_window to 0 in your configuration. If not supplied, the environment variable IOPIPE_TIMEOUT_WINDOW will be used if present.

`Enabled` (*bool: optional = true)

Conditionally enable/disable the agent. The environment variable IOPIPE_ENABLED will also be checked.

Contexts

The IOpipe agent wraps the lambdacontext.LambdaContext. So instead of doing this:

import (
	"context"
	"fmt"

	"github.com/aws/aws-lambda-go/lambda"
)

func hello(ctx context.Context) (string, error) {
	context, _ := lambdacontext.FromContext(ctx)

	return fmt.Sprintf("My requestId is %s", context.AwsRequestID), nil
}

func main() {
	lambda.Start(agent.WrapHandler(hello))
}

You can do this:

import (
	"context"
	"fmt"

	"github.com/aws/aws-lambda-go/lambda"
	"github.com/iopipe/iopipe-go"
)

var agent = iopipe.NewAgent(iopipe.Config{})

func hello(ctx context.Context) (string, error) {
	context, _ := iopipe.FromContext(ctx)

	return fmt.Sprintf("My requestId is %s", context.AwsRequestID), nil
}

func main() {
	lambda.Start(agent.WrapHandler(hello))
}

And the lambdacontext.LambdaContext will be embedded in context. In addition to this, iopipe.FromContext() also attaches context.IOpipe which exposes methods to instrument your functions. See the sections below for examples.

Custom Metrics

You can log custom values in the data sent upstream to IOpipe using the following syntax:

import (
	"context"

	"github.com/aws/aws-lambda-go/lambda"
	"github.com/iopipe/iopipe-go"
)

var agent = iopipe.NewAgent(iopipe.Config{})

func hello(ctx context.Context) (string, error) {
	context, _ := iopipe.FromContext(ctx)

	// numerical (int, float) and string types supported for values
	context.IOpipe.Metric("my_metric", 42)

	return "Hello ƛ!", nil
}

func main() {
	lambda.Start(agent.WrapHandler(hello))
}

Metric key names are limited to 128 characters, and string values are limited to 1024 characters.

Labels

Invocation labels can be sent to IOpipe by calling the Label method with a string (limit of 128 characters):

import (
	"context"

	"github.com/aws/aws-lambda-go/lambda"
	"github.com/iopipe/iopipe-go"
)

var agent = iopipe.NewAgent(iopipe.Config{})

func hello(ctx context.Context) (string, error) {
	context, _ := iopipe.FromContext(ctx)

	// the name of the label must be a string
	context.IOpipe.Label("this-invocation-is-special")

	return "Hello ƛ!", nil
}

func main() {
	lambda.Start(agent.WrapHandler(hello))
}

Reporting Errors

The IOpipe agent will automatically recover, trace and re-panic any unhandled panics in your function. If you want to trace errors in your case, you can use the .Error(err) method. This will add the error to the current report.

import (
	"context"

	"github.com/aws/aws-lambda-go/lambda"
	"github.com/iopipe/iopipe-go"
)

var agent = iopipe.NewAgent(iopipe.Config{})

func hello(ctx context.Context) (string, error) {
	context, _ := iopipe.FromContext(ctx)

	thing, err := doSomething()

	if err != nil {
	  context.IOpipe.Error(err)
	}

	return "Hello ƛ!", nil
}

func main() {
	lambda.Start(agent.WrapHandler(hello))
}

It is important to note that a report is sent to IOpipe when Error() is called. So you should only record exceptions this way for failure states. For caught exceptions that are not a failure state, it is recommended to use custom metrics.

You also don't need to use Error() if the error is being returned as the second return value of the function. IOpipe will add that error to the report for you automatically.

Running Tests

The tests use Convey, so make sure that is installed:

go get github.com/smartystreets/goconvey

We use dep for package dependencies, to installed them:

dep ensure

To run the tests:

go test -v

Contributing

Please refer to our code of conduct. Please follow it in all your interactions with the project.

License

Apache 2.0

ariasf/iopipe-go