I have a Nifi cluster with a flow which starts with listenHTTP processor. Basically flow receives POST calls with JSON payload. It works fine with postman request or a curl call. But when a request comes from a web browser, the OPTION request fails with following error:
Access to fetch at 'https://{server_endpoint}/process' from
origin 'https://{client_endpoint}:3443' has been blocked by CORS
policy: Response to preflight request doesn't pass access control
check: No 'Access-Control-Allow-Origin' header is present on the
requested resource. If an opaque response serves your needs,
set the request's mode to 'no-cors' to fetch the resource
with CORS disabled.
How should we configure cors in ListenHTTP processor.
The ListenHTTP does not support CORS. Your only option is to use a proxy server that will be the one to send your browser requests to the NiFi cluster.
Related
I'm having problem with CORS.
My Node.js Server with apollo-server-express(version 3.7)
My problem is CORS is not constant.
My React Project request api server and works well.
But sometimes api server response this error
Access to fetch at 'https://api.example.com/' from origin 'https://example.com' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.
Why same client request sometime response cors error?
Please Help.
I have receive the following response when trying to access an API via an ajax request in Chrome:
"Failed to load http://localhost:1880/api_resource: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin http://localhost:3000 is therefore not allowed access."
As you can see from the message, both client and API are running locally.
I understand that this situation relates to a CORS cross origin request. I see that there are similar questions about this on stack overflow, but from those answers I do not understand what the message is telling me and where it comes from.
Specifically I understand that the response header "Access-Control-Allow-Origin" must be set (typically to '*') to allow access to the API from a different domain to the one on which the API is being served. But the message seems to relate to the request and not the response, and as far as I am aware, no request ever reaches the API.
What is a preflight request and how is it failing?
As I now understand it, modern browsers will issue a 'preflight' request before the actual cross origin request. This preflight request uses the 'OPTIONS' HTTP verb along with the CORS headers Access-Control-Request-Method and Access-Control-Request-Headers to which it expects to see a response with valid Access-Control-Allow-Origin in the header that indicates that the server understands the CORS protocol and will allow the actual (GET/POST/PUT) request.
The message "Response to preflight request doesn't pass access control check" means that the browser did not see a valid "Access-Control-Allow-Origin" header in the Options response.
In my case this was because the server (implementing a REST API) was set up to respond correctly to PUT and POST requests but not setup to respond to OPTIONS requests with the CORS headers.
in my case the problem was for my website address, i'm calling all apis from the same server but i got this error.
my website address is sateh.ir
so im my ajax request i set the url: http://sateh.ir/api/...
after getting this error and working on it for some hours, i got that i had to set ajax url to: http://www.sateh.ir/api/...
i dont know why my website cant understand that i'm calling api from the same server if i dont put 'www', but that was my problem at all.
I am trying to access NIFI rest api of another server from my machine using ajax like below,
url:"https://serverip:port/nifi-api/",
{Authorization : 'Bearer ' + 'access token here'}
Getting Response to preflight request doesn't pass access control
check: No 'Access-Control-Allow-Origin' header is present on the
requested resource error.
Apache NiFi's API is designed to be invoked by a variety of clients, but in this case I think you are encountering a security precaution put in place by CORS (Cross-Origin Resource Sharing).
If a piece of code on server A (your non-NiFi machine) makes an AJAX request to a different origin (your NiFi instance), and the HTTP method is not GET (and some other minor restrictions), server A will first send a "preflight" request, which is HTTP OPTIONS, to the remote instance to determine what requests are valid. A server can reply to this with the header Access-Control-Allow-Origin: *, which is a wildcard value denoting it accepts requests from any origin. However, if you want to send credentials along with the request, the originating hostname must be explicitly listed in the response (Access-Control-Allow-Origin: https://serverA.com).
Because NiFi uses an embedded Jetty server to host the API, you may have to explicitly add a CrossOriginFilter as described here.
I have implemented a restful service. I have tested it using an ajax request within the application and also with postman client and both worked. But when i try to send an ajax request from a different application i get the below error in browser console.
http://localhost:8080/AusIncomeCalculator/AUSTax/post. Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:8089' is therefore not allowed access.
I don't understand how the postman client get a successful response while the other applications cannot.
RESTful service is hosted in JBOSS-eap 7.0 with rest easy
What happen is for security reasons, browsers restrict cross-origin HTTP requests initiated from within scripts.Postman is a REST Client that runs as an application inside the Chrome browser. It is specifically designed for testing rest APIs, and therefore it doesn't restrict cross origin resource request.
I'm working on an Ajax application that pulls data from a oData Rest service.
The oData service needs me to send an additional header:
Prefer : odata.maxpagesize = 20
I've updated my Cors filter to allow it like so, (by the way this is running off a Tomcat server).
<param-name>cors.allowed.headers</param-name>
<param-value>Perfer,odata-maxversion,content-type,cache-control,postman-token,authorization,Content-Type,X-Requested-With,accept,Origin,Access-Control-Request-Method,Access-Control-Request-Headers</param-value>
</init-param>
But it's not working and I keep getting the dreaded:
XMLHttpRequest cannot load http://127.0.0.1:8080/pfs/odata/BEER/?.
Response to preflight request doesn't pass access control check: No
'Access-Control-Allow-Origin' header is present on the requested
resource. Origin 'http://localhost:3000' is therefore not allowed
access. The response had HTTP status code 403.
All other calls work perfectly and if don't pass the additional "Perfer" header it works as well.
Thanks so much in advance.
Sorry, it turns out I just had a typo in the Cors filter.