> ## Documentation Index
> Fetch the complete documentation index at: https://upstash.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Serverless Golang API with Redis

This tutorial shows how to build a serverless API with Golang and Redis. The API
will simply count the page views and show it in JSON format.

### The Stack

* Serverless compute: AWS Lambda (Golang)
* Serverless data store: Redis via Upstash
* Deployment tool: AWS SAM

### Prerequisites:

* An AWS account for AWS Lambda functions.
* Install AWS SAM CLI tool as described here to create and deploy the project.
* An Upstash account for serverless Redis.

### Step 1: Init the Project

Run the sam init and then

* Select AWS Quick Start Templates
* Select 4 - go1.x
* Enter your project name: go-redis-example
* Select 1 - Hello World Example SAM will generate your project in a new folder.

### Step 2: Install a Redis Client

Our only dependency is redis client. Install go-redis via
`go get github.com/go-redis/redis/v8`

### Step 3: Create a Redis Database

Create a Redis database from Upstash console. Free tier should be enough. It is
pretty straight forward but if you need help, check
[getting started](../overall/getstarted) guide. In the database details page,
click the Connect button. You will need the endpoint and password in the next
step.

### Step 4: The function Code

Edit the hello-world>main.go as below:

```go theme={"system"}
package main
import (
    "context"
    "encoding/json"
    "github.com/aws/aws-lambda-go/events"
    "github.com/aws/aws-lambda-go/lambda"
    "github.com/go-redis/redis/v8"
    "strconv"
)
var ctx = context.Background()

type MyResponse struct {
    Count string `json:"count:"`
}

var rdb = redis.NewClient(&redis.Options{
    Addr: "YOUR_REDIS_ENDPOINT",
    Password: "YOUR_REDIS_PASSWORD",
    DB: 0,
})

func handler(request events.APIGatewayProxyRequest) (events.APIGatewayProxyResponse, error) {
    count, err := rdb.Incr(ctx, "count").Result()
    if err != nil {
        panic(err)
    }
    response := &MyResponse{
        Count: strconv.FormatInt(count, 10),
    }
    body, err := json.Marshal(response)
    return events.APIGatewayProxyResponse{
        Headers: map[string]string{"Content-Type": "application/json"},
        Body: string(body),
        StatusCode: 200,
        }, nil
}

func main() {
    lambda.Start(handler)
}
```

Replace the "YOUR\_REDIS\_ENDPOINT" and "YOUR\_REDIS\_PASSWORD" with your database's
endpoint and password which you created in the Step 3. The code simply
increments a counter in Redis database and returns its value in json format.

### Step 5: Deployment

Now we are ready to deploy our API. First build it via `sam build`. Then run the
command `sam local start-api`. You can check your API locally on
[http://127.0.0.1:3000/hello](http://127.0.0.1:3000/hello)

<br />

<br /> If it is working, you can deploy your app to AWS by running `sam deploy --guided`.
Enter a stack name and pick your region. After confirming changes, the deployment
should begin. The command will output API Gateway endpoint URL, check the API in
your browser. You can also check your deployment on your AWS console. You will see
your function has been created.

<br />

<br /> Click on your function, you will see the code is uploaded and API Gateway
is configured.

### Notes

* Check the template.yaml file. You can add new functions and APIGateway
  endpoints editing this file.
* It is a good practice to keep your Redis endpoint and password as environment
  variable.
* You can use [serverless framework](https://www.serverless.com/) instead of AWS
  SAM to deploy your function.