I have a lambda function that returns a string that contains UTF-8 characters (german umlaute). However, The AWS API-Gateway response does not contain the utf-8 header. How can I add it so the client receives a readable response?
I was able to solve this problem like this in Python:
return {
'statusCode': 200,
'headers': {
"content-type":"application/json; charset=utf-8"},
'body': json.dumps(data)
}
I just needed to set the additional header "content-type".
But I'm not sure whether you need to have "HTTP-Proxy-Integration" enabled (like i did).
Related
I have the following architecture:
(1) A front-end form, which has a user input of file:
var data = new FormData();
data.append('username', 'USER123');
data.append('file', selectedFile); //selectedFile is a file which I capture form a form (user-submitted)
await fetch('myURL/test', {
method: 'post',
headers: {
"Access-Control-Allow-Origin": "*"
},
body:data
}).then(res => res.json()).then(json => console.log(json))
console.log('Done')
(2) An AWS API Gateway (which has a POST route of 'myURL/test'),
(3) An AWS Lambda Integration with the following Python Code:
def lambda_handler(event, context): #Lambda functions works and returns a response of "Hello from Lambda" during a POST request
# TODO implement
print(event['body']) //prints some base64 string
return {
'statusCode': 200,
'body': json.dumps('Hello from Lambda!')
}
What I am trying to achieve: User submits form (with .zip file) from my front-end, (2) Lambda function receives the file, (3) Lambda function checks whether file is correct size, type, (4) Lambda function uploads file to S3 Bucket. The thing is I am unable to receive the file in my lambda function. Printing of the event['body'] prints out some weird string that I'm unsure on how to process.
Any tips?
Verify that the Incoming Request at the Gateway is actually passing the POST body content (the file) to the Lambda. Likely you'll need to setup a mapping template along these lines...
{ "content": "$input.body" }
Here's a pretty good article showing the end-to-end setup to upload a file:
https://medium.com/swlh/upload-binary-files-to-s3-using-aws-api-gateway-with-aws-lambda-2b4ba8c70b8e
Requirement:
Use AWS Lambda + API Gateway
Function language: Python
Convert a text from UTF-8 to Shift_JIS (such as: 武蔵野冷蔵名古屋)
Response with csv format (application/csv)
Issue:
I'm using response = codecs.encode(inputString, 'SHIFT_JIS', errors='ignore') with inputString something like 武蔵野冷蔵名古屋: encode input string with shift_jis
And I return response to user. But facing error Invalid lambda response received: Invalid API Gateway Response Keys: {'requestId', 'errorMessage', 'stackTrace', 'errorType'} in {'errorMessage': "Unable to marshal response: 'utf-8' codec can't decode byte 0x95 in position 0: invalid start byte".
Seem that API Gateway just support UTF-8 for text.
My concern is how to response non UTF-8 text when combine Lambda + API Gateway.
I'm checking the guide setup Binary data with API Gateway but not work now
I don't want to base64.encode it and decode later at client side.
Any help for this issue? Thanks!
Thank God!
I was guided to solve this issue.
Just base64 encode the string_after_encode_to_shift_jis.
return {
'statusCode': 200,
'headers': {
'Access-Control-Allow-Origin': '*',
'Content-Type': f'application/csv; charset=shift_jis'
},
'body': base64.b64encode(data.encode(enc)).decode('utf-8'),
'isBase64Encoded': True
}
I have my API Gateway set up with application/json Content-Type mapped to
{
"param1": "$input.params('param1')"
}
and application/pdf mapped to
{
"content": "$input.body"
}
Both of these work on their own when I use postman and specify the Content-Type as one or the other.
But, I want to be able to make a request that can take both pdf binary data along with some parameters from JSON using one call and use both in lambda.
I've tried adding both of these in a content-type and setting the template as
{
"content": "$input.body",
"param1": "$input.params('param1')"
}
But this returns back an error when I call it with the params and the pdf:
"message": "Could not parse request body into json: Illegal unquoted character ((CTRL-CHAR, code 10)): has to be escaped using backslash to be included in string value\n
The "param1" is a query string parameter I have added.
I'm uploading an image to s3, through a lambda, and everything works well, with no errors, but the response from API Gateway is 500 Internal Server Error.
I configured my api-gateway following this tutorial: Binary Support for API Integrations with Amazon API Gateway.
My lambda receives the base64Image, decode it and successfully upload to s3.
This is my lambda code:
def upload_image(event, context):
s3 = boto3.client('s3')
b64_image = event['base64Image']
image = base64.b64decode(b64_image)
try:
with io.BytesIO(image) as buffer_image:
buffer_image.seek(0)
s3.upload_fileobj(buffer_image, 'MY-BUCKET', 'image')
return {'status': True}
except ClientError as e:
return {'status': False, 'error': repr(e)}
This is what i'm receiving:
{
"message": "Internal server error"
}, with a 500 status code.
Obs: I'm not using lambda proxy integration.
You need to return a header in the response, e.g. in Python:
return {
"statusCode": 200,
'headers': { 'Content-Type': 'application/json' },
"body": json.dumps(body)
}
That example looks like it falls short on mapping the responses section in favor of a pass through. In which case changing your return to: return {'status': True, 'statusCode': 200} might work.
Generally speaking there are two paths when building a response with ApiGateway-Lambda. One is the lambda-proxy (where your lambda function defines the response), the other is where ApiGateway transforms your responses and generates the appropriate headers/status based on a mapping.
The path from the example is for the latter.
Personally I would change:
return {'status': True}
to return {'status': "Success"} And create a regex that looks for the word "Success" and "Error" respectively.
I have used this blog post successfully with this technique (it also describes at length the differences between the two approaches). Once you get one mapping working you could adjust it as is more appropriate for your implementation.
EDIT: hot tip these decorators are awesome and make python & lambda even cleaner/easier but mostly for the proxy setup
I have created an API using AWS api gateway like https://api.mydomain.com/v1/download?id=1234". The download resource has GET method. And the GET method is invoking lambda function using Lambda Proxy Integration.
The Lambda function needs to act as Proxy. It needs to resolve correct backend endpoint based on header x-clientId and then forward the request to that backend endpoint and return response as it is. So it needs to be generic to handle GET request of different content-type.
My lambda function looks like ( .NET Core)
public async Task<APIGatewayProxyResponse> Route(APIGatewayProxyRequest input, ILambdaContext context)
{
var clientId = headers["x-clientId"];
var mappings = new Mappings();
var url = await mappings.GetBackendUrl(clientId, input.Resource);
var httpClient = new HttpClient();
var response = await httpClient.GetAsync(url);
response.EnsureSuccessStatusCode();
var proxyResponse = new APIGatewayProxyResponse()
{
Headers = new Dictionary<string, string>(),
StatusCode = (int)System.Net.HttpStatusCode.OK,
IsBase64Encoded = false,
Body = await response.Content.ReadAsString())
};
}
The handler above works as long as request and response's content-type is application/json or application/xml. However i am not sure how to handle response when backend returns stream.
For download API, the backend returns Content-Disposition: attachment; filename="somefilename and ContentType may be one of the following:
application/pdf
application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
application/vnd.openxmlformats-officedocument.wordprocessingml.document
application/x-zip-compressed
application/octet-stream
For these streams, How do i set APIGatewayProxyResponse.Body?
For Excel file I have tried setting body like below
var proxyResponse = new APIGatewayProxyResponse()
{
Headers = new Dictionary<string, string>(),
StatusCode = (int)System.Net.HttpStatusCode.OK,
IsBase64Encoded = true,
Body = Convert.ToBase64String(await response.Content.ReadAsByteArrayAsync())
};
proxyResponse.Headers.Add("Content-Type", "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
proxyResponse.Headers.Add("Content-Disposition", "attachment; filename=\"Report.xlsx\"");
When i access the Url from the browser and try to open the file. I get error
Excel cannot open the fileReport.xlsxbecuase the file format or file extension is not valid. Verify that the file has not been corrupted and that the extention matches the format of the file
I think the issue is how i am setting the response body
Update 1
So based on AWS doc Binary Data Now Supported by API Gateway. Now as per the documentation
you can specify if you would like API Gateway to either pass the
Integration Request and Response bodies through, convert them to text
(Base64 encoding), or convert them to binary (Base64 decoding). These
options are available for HTTP, AWS Service, and HTTP Proxy
integrations. In the case of Lambda Function and Lambda Function Proxy
Integrations, which currently only support JSON, the request body is
always converted to JSON.
I am using Lambda Function Proxy, which currently support JSON. However the example here shows how to do it with Lambda Proxy.
I think what i am missing here is Binary Media Types setting and Method Response settings. Below is my setting. Not sure if these settings are correct
Binary Media
Method Response
here how solved it
1>add Binary Media Types. API->Settings->Binary Media Types -> add
application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
2>In Method Response Add Content-Disposition and Content-Type headers for thestatus 200
3>In Integration Response map these headers to headers that are coming from the backend. And also set content handling convert to binary. (our backend api is returning file blob in body)