AWS Lambda Go Handler

aws-lambda-handler.go

import (
    "context"
    "encoding/json"
    "fmt"
    "log"
    "time"

    "github.com/aws/aws-lambda-go/lambda"
    "github.com/go-viper/mapstructure/v2"
    
    vault "github.com/hashicorp/vault/api"
)

type Secrets struct {
    Hello string `mapstructure:"hello"`
    Foo   string `mapstructure:"foo"`
    Fizz  string `mapstructure:"fizz"`
    Ping  string `mapstructure:"ping"`
}

var client *vault.Client

func init() {
    var err error

    config := vault.DefaultConfig()
    config.Address = "http://127.0.0.1:8200"

    client, err = vault.NewClient(config)
    if err != nil {
        log.Fatal("Failed to create Vault client: " + err.Error())
    }
}

func getSecrets(ctx context.Context, mount, path string) (*Secrets, error) {
    ctx, cancel := context.WithTimeout(ctx, 5*time.Second)
    defer cancel()

    resp, err := client.KVv2(mount).Get(ctx, path)
    if err != nil {
        return nil, err
    }

    s := &Secrets{}
    if err := mapstructure.Decode(resp.Data, s); err != nil {
        return nil, err
    }

    return s, nil
}

func handler(ctx context.Context, event json.RawMessage) error {
    secrets, err := getSecrets(ctx, "kv", "path/to/secret")
    if err != nil { 
        return fmt.Errorf("Failed to fetch secrets from vault: %w", err) 
    }

    // do something with secrets (secrets.Hello, secrets.Foo, etc)
    // core business logic

    return nil
}

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