Lambda S3
Upload, Download, or Delete files from AWS S3 with one function through AWS Lambda and AWS APIGateway.
How to Build locally
make build
How to Test locally
cp .env.example .env
copy the example .env
file to use as a base
nano .env
insert real values for each environment variable
make test
How to Use
go get github.com/seantcanavan/lambda_s3@latest
import github.com/seantcanavan/lambda_s3
- Get the file headers uploaded via AWS Lambda / API Gateway:
headers, err := lambda_s3.GetHeaders()
- Make sure to check the value of APIGatewayProxyRequest.IsBase64Encoded and make sure it matches the form body contents
- Upload the uploaded file contents via the file headers:
lambda_s3.UploadHeader(header[0], region, bucket, name)
- Download the file contents via the file's bucket/key combination:
lambda_s3.Download()
- Use
errors.Is
to check for different error cases returned from GetHeaders
, UploadHeader
, Download
, and Delete
- Check below for sample code on how to implement the functions and use
errors.Is
- Delete the uploaded file via the values returned from Upload:
lambda_s3.Delete(region, bucket,name)
Sample Upload Lambda Handler Example
func UploadLambda(ctx context.Context, lambdaReq events.APIGatewayProxyRequest) (events.APIGatewayProxyResponse, error) {
// get the file header and multipart form data from Lambda
files, err := lambda_s3.GetFileHeadersFromLambdaReq(lambdaReq, MaxFileSizeBytes)
if err != nil {
switch {
case
errors.Is(err, lambda_s3.ErrContentTypeHeaderMissing),
errors.Is(err, lambda_s3.ErrParsingMediaType),
errors.Is(err, lambda_s3.ErrBoundaryValueMissing):
return ERROR - bad request
default:
return ERROR - internal server
}
}
fileName := uuid.New().String() // generate a UUID for filename to guarantee uniqueness
// take the first file uploaded via HTTP and upload it to S3
// you can also loop through all the files in files to upload each individually:
// for _, currentFile := range files { Upload... }
uploadResult, err := lambda_s3.UploadFileHeaderToS3(files[0], os.Getenv("REGION_AWS"), os.Getenv("FILE_BUCKET"), fileName)
if err != nil {
switch {
case
errors.Is(err, lambda_s3.ErrParameterRegionEmpty),
errors.Is(err, lambda_s3.ErrParameterBucketEmpty),
errors.Is(err, lambda_s3.ErrParameterNameEmpty):
return ERROR - bad request
default:
return ERROR - internal server
}
}
return events.APIGatewayProxyResponse{
StatusCode: http.StatusOK,
Body: "",
}, nil
}
Sample Download Lambda Handler Example
func DownloadLambda(ctx context.Context, lambdaReq events.APIGatewayProxyRequest) (events.APIGatewayProxyResponse, error) {
fileID := lambdaReq.PathParameters["id"]
if fileID == "" {
return ERROR - bad request
}
file, err := GetFileByID(ctx, fileID) // get the file object from your database to retrieve its unique name
if err != nil {
return ERROR - not found
}
fileBytes, err := lambda_s3.DownloadFileFromS3(os.Getenv("REGION_AWS"), os.Getenv("FILE_BUCKET"), file.Name)
if err != nil {
switch {
case
errors.Is(err, lambda_s3.ErrParameterRegionEmpty),
errors.Is(err, lambda_s3.ErrParameterBucketEmpty),
errors.Is(err, lambda_s3.ErrParameterNameEmpty),
errors.Is(err, lambda_s3.ErrEmptyFileDownloaded):
return ERROR - bad request
default:
return ERROR - internal server
}
}
return events.APIGatewayProxyResponse{
StatusCode: http.StatusOK,
Headers: map[string]string{
"Content-Type": file.ContentType,
},
Body: base64.StdEncoding.EncodeToString(fileBytes),
IsBase64Encoded: true,
}, nil
}
All tests are passing
=== RUN TestDelete
--- PASS: TestDelete (0.43s)
=== RUN TestDownloadFileFromS3
=== RUN TestDownloadFileFromS3/verify_err_when_region_is_empty
=== RUN TestDownloadFileFromS3/verify_err_when_bucket_is_empty
=== RUN TestDownloadFileFromS3/verify_err_when_name_is_empty
=== RUN TestDownloadFileFromS3/verify_err_when_region_is_invalid
=== RUN TestDownloadFileFromS3/verify_err_when_target_file_is_empty
=== RUN TestDownloadFileFromS3/verify_download_works_with_correct_inputs
--- PASS: TestDownloadFileFromS3 (0.62s)
--- PASS: TestDownloadFileFromS3/verify_err_when_region_is_empty (0.00s)
--- PASS: TestDownloadFileFromS3/verify_err_when_bucket_is_empty (0.00s)
--- PASS: TestDownloadFileFromS3/verify_err_when_name_is_empty (0.00s)
--- PASS: TestDownloadFileFromS3/verify_err_when_region_is_invalid (0.48s)
--- PASS: TestDownloadFileFromS3/verify_err_when_target_file_is_empty (0.10s)
--- PASS: TestDownloadFileFromS3/verify_download_works_with_correct_inputs (0.05s)
=== RUN TestGetFileHeadersFromLambdaReq
=== RUN TestGetFileHeadersFromLambdaReq/verify_err_when_Content-Type_header_not_set
=== RUN TestGetFileHeadersFromLambdaReq/verify_err_when_content_type_is_invalid
=== RUN TestGetFileHeadersFromLambdaReq/verify_err_when_content_type_has_no_boundary_value
=== RUN TestGetFileHeadersFromLambdaReq/verify_get_headers_works_with_correct_inputs
--- PASS: TestGetFileHeadersFromLambdaReq (0.00s)
--- PASS: TestGetFileHeadersFromLambdaReq/verify_err_when_Content-Type_header_not_set (0.00s)
--- PASS: TestGetFileHeadersFromLambdaReq/verify_err_when_content_type_is_invalid (0.00s)
--- PASS: TestGetFileHeadersFromLambdaReq/verify_err_when_content_type_has_no_boundary_value (0.00s)
--- PASS: TestGetFileHeadersFromLambdaReq/verify_get_headers_works_with_correct_inputs (0.00s)
=== RUN TestUploadFileHeaderToS3
=== RUN TestUploadFileHeaderToS3/verify_err_when_region_is_empty
=== RUN TestUploadFileHeaderToS3/verify_err_when_bucket_is_empty
=== RUN TestUploadFileHeaderToS3/verify_err_when_name_is_empty
=== RUN TestUploadFileHeaderToS3/verify_err_when_*multipart.FileHeader_is_empty
=== RUN TestUploadFileHeaderToS3/verify_err_when_region_is_invalid_and_upload_fails
=== RUN TestUploadFileHeaderToS3/verify_upload_works_with_correct_inputs
--- PASS: TestUploadFileHeaderToS3 (0.78s)
--- PASS: TestUploadFileHeaderToS3/verify_err_when_region_is_empty (0.00s)
--- PASS: TestUploadFileHeaderToS3/verify_err_when_bucket_is_empty (0.00s)
--- PASS: TestUploadFileHeaderToS3/verify_err_when_name_is_empty (0.00s)
--- PASS: TestUploadFileHeaderToS3/verify_err_when_*multipart.FileHeader_is_empty (0.00s)
--- PASS: TestUploadFileHeaderToS3/verify_err_when_region_is_invalid_and_upload_fails (0.71s)
--- PASS: TestUploadFileHeaderToS3/verify_upload_works_with_correct_inputs (0.07s)
PASS
ok github.com/seantcanavan/lambda_s3 1.838s