88 lines
2.3 KiB
Go
88 lines
2.3 KiB
Go
package main
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import (
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"context"
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"encoding/json"
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"fmt"
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"log"
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"net/http"
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"os"
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"github.com/aws/aws-lambda-go/events"
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"github.com/aws/aws-lambda-go/lambda"
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"github.com/aws/aws-sdk-go-v2/config"
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"github.com/aws/aws-sdk-go-v2/feature/dynamodb/attributevalue"
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"github.com/aws/aws-sdk-go-v2/service/dynamodb"
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)
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// Reading represents a single IoT measurement item returned to clients
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type Reading struct {
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DeviceID string `json:"deviceId" dynamodbav:"deviceId"`
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Timestamp string `json:"timestamp" dynamodbav:"timestamp"`
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Temperature float64 `json:"temperature" dynamodbav:"temperature"`
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Humidity float64 `json:"humidity" dynamodbav:"humidity"`
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}
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type ResponseBody struct {
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Data []Reading `json:"data"`
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}
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func handler(ctx context.Context, req events.APIGatewayV2HTTPRequest) (events.APIGatewayV2HTTPResponse, error) {
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tableName := os.Getenv("TABLE_NAME")
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if tableName == "" {
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log.Print("TABLE_NAME environment variable not set")
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return events.APIGatewayV2HTTPResponse{StatusCode: http.StatusInternalServerError}, nil
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}
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cfg, err := config.LoadDefaultConfig(ctx)
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if err != nil {
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log.Printf("failed to load AWS config: %v", err)
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return events.APIGatewayV2HTTPResponse{StatusCode: http.StatusInternalServerError}, nil
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}
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db := dynamodb.NewFromConfig(cfg)
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// Simple Scan as requested for the initial version
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scanInput := &dynamodb.ScanInput{
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TableName: &tableName,
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}
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scanOutput, err := db.Scan(ctx, scanInput)
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if err != nil {
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log.Printf("dynamodb scan error: %v", err)
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return events.APIGatewayV2HTTPResponse{StatusCode: http.StatusInternalServerError}, nil
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}
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readings := make([]Reading, 0, len(scanOutput.Items))
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for _, item := range scanOutput.Items {
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var r Reading
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err := attributevalue.UnmarshalMap(item, &r)
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if err != nil {
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// skip items that fail to unmarshal but log them
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log.Printf("failed to unmarshal item: %v", err)
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continue
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}
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readings = append(readings, r)
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}
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body := ResponseBody{Data: readings}
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b, err := json.Marshal(body)
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if err != nil {
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log.Printf("failed to marshal response: %v", err)
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return events.APIGatewayV2HTTPResponse{StatusCode: http.StatusInternalServerError}, nil
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}
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return events.APIGatewayV2HTTPResponse{
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StatusCode: http.StatusOK,
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Headers: map[string]string{
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"Content-Type": "application/json",
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},
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Body: string(b),
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}, nil
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}
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func main() {
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lambda.Start(handler)
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}
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