Step by Step Guide to Building a Fastly API Integration in Go

Introduction

Hey there, fellow developer! Ready to supercharge your content delivery with Fastly? Let's dive into building a Fastly API integration using Go. Why Go, you ask? Well, it's fast, efficient, and perfect for building robust API clients. Plus, if you're already a Gopher, you'll feel right at home!

Prerequisites

Before we jump in, make sure you've got:

• Go installed on your machine (you're a pro, so I'm sure you do!)
• A Fastly account with an API key (if not, hop over to Fastly and grab one)

Setting up the project

Let's kick things off by creating a new Go module:

mkdir fastly-api-integration
cd fastly-api-integration
go mod init fastly-api-integration

Now, let's grab the Fastly Go client:

go get github.com/fastly/go-fastly/v3/fastly

Authentication

Time to authenticate! Create a new file called main.go and add this:

package main

import (
    "log"
    "os"

    "github.com/fastly/go-fastly/v3/fastly"
)

func main() {
    apiKey := os.Getenv("FASTLY_API_KEY")
    client, err := fastly.NewClient(apiKey)
    if err != nil {
        log.Fatalf("Error creating Fastly client: %v", err)
    }

    // We're in! Let's do some cool stuff...
}

Pro tip: Keep that API key safe! Using an environment variable is a solid practice.

Basic API operations

Let's flex those API muscles with some basic operations:

// List services
services, err := client.ListServices(&fastly.ListServicesInput{})
if err != nil {
    log.Fatalf("Error listing services: %v", err)
}

for _, s := range services {
    log.Printf("Service: %s (ID: %s)", s.Name, s.ID)
}

// Get service details
serviceID := "your-service-id"
service, err := client.GetService(&fastly.GetServiceInput{
    ID: serviceID,
})
if err != nil {
    log.Fatalf("Error getting service: %v", err)
}

log.Printf("Service Details: %+v", service)

Working with VCL

VCL is the secret sauce of Fastly. Let's see how to work with it:

// Fetch VCL
vcl, err := client.GetVCL(&fastly.GetVCLInput{
    Service: serviceID,
    Version: 1, // Use the appropriate version
    Name:    "main",
})
if err != nil {
    log.Fatalf("Error fetching VCL: %v", err)
}

log.Printf("VCL Content: %s", vcl.Content)

// Update VCL
_, err = client.UpdateVCL(&fastly.UpdateVCLInput{
    Service: serviceID,
    Version: 1,
    Name:    "main",
    Content: "// Your updated VCL here",
})
if err != nil {
    log.Fatalf("Error updating VCL: %v", err)
}

Purging content

Need to clear that cache? We've got you covered:

// Purge individual URL
err = client.PurgeURL(&fastly.PurgeURLInput{
    URL: "https://example.com/path/to/asset",
})
if err != nil {
    log.Fatalf("Error purging URL: %v", err)
}

// Purge entire service
err = client.PurgeAll(&fastly.PurgeAllInput{
    Service: serviceID,
})
if err != nil {
    log.Fatalf("Error purging service: %v", err)
}

Handling responses and errors

Always handle your responses and errors gracefully:

// Parsing JSON responses
var result map[string]interface{}
err = client.GetJSON(&fastly.GetJSONInput{
    URL: "https://api.fastly.com/service/" + serviceID,
}, &result)
if err != nil {
    log.Fatalf("Error fetching JSON: %v", err)
}

// Error handling
if err, ok := err.(*fastly.HTTPError); ok {
    log.Printf("HTTP Error: %v", err)
    // Handle specific HTTP errors
}

Advanced topics

For the power users out there:

// Rate limiting
client.SetRateLimit(100) // 100 requests per second

// Concurrency
var wg sync.WaitGroup
for i := 0; i < 10; i++ {
    wg.Add(1)
    go func() {
        defer wg.Done()
        // Make API calls here
    }()
}
wg.Wait()

// Logging
client.SetLogger(log.New(os.Stdout, "", log.LstdFlags))

Testing and validation

Don't forget to test your integration:

func TestListServices(t *testing.T) {
    client := fastly.NewClientForTesting(fastly.Config{
        APIKey: "test-key",
    })

    services, err := client.ListServices(&fastly.ListServicesInput{})
    assert.NoError(t, err)
    assert.NotEmpty(t, services)
}

Deployment considerations

As you gear up for deployment:

• Use environment variables or a secure secret management system for API keys
• Implement proper logging and monitoring to track API usage and errors
• Consider using a circuit breaker pattern for resilience

Conclusion

And there you have it! You're now equipped to build a robust Fastly API integration in Go. Remember, the Fastly API is powerful and flexible, so don't be afraid to explore and experiment.

For more in-depth info, check out the Fastly API Documentation and the go-fastly GitHub repo.

Now go forth and optimize that content delivery! Happy coding! 🚀