The server app was running quite fine on Heroku but after migrating to Azure the server would not just start.
Here is the code..
const PORT = process.env.PORT || 2498;
const INDEX = '/index.html';
const server = express()
.use((req, res) => res.sendFile(INDEX, { root: __dirname }))
.listen(PORT, () => console.log(`We\'re live on channel : ${PORT}`));
const wss = new Server({ server });
wss.on('connection', (ws) => {
console.log('Client connected');
ws.on('close', () => console.log('Client disconnected'));
ws.on('message', (message) =>{
// this stays within the server
console.log('[SERVER]: Received a message => %s', message );
})
})```
.........
Clients connected are returning not establish an handshake ....
Azure web app only supports the exposure of port 80 and 443 for website access.
My previous requirements and test results:
I think your problem is a typical problem. I also had related requirements before, and the test failed in the webapp. All documents of Azure app service, talking about websocket, all use SignalR. I also tested the signalr service and it was successful, but this service is free and currently only supports 20 client connections.
What I thought before was to create a console program and put it in webjob to let webjob provide websocket service, but it all failed in the end.
Because azure webapp runs in a sandbox environment, and only open ports 80 and 443, we can't do more configuration. Obviously, the port that your websocket service starts is 2498, so it is not supported.
Suggestion
If you must use websocket, regardless of programming language, you must support custom port opening, such as using Virtual Machine.
You can compare the charges of azure cloud service and virtaul machine. Which one is right for you and which one to use.
Another suggestion is that you can buy a third-party intranet penetration tool and use a fixed IP or URL, such as ngrok, so that you can put the websocket service on your company's internal server. (The test is valid).
Of these three options, intranet penetration may be the most cost-effective choice. You can choose according to your needs.
I am attempting to use a Google Cloud provided VM to host a React.js front-end that contacts Spring Boot services (that are running in a Docker container). I was able to successfully contact the Spring Boot services, both running locally and remotely, while my React app was on my development machine. Now, however, I am attempting to move the React portion to the cloud as well. However, when I issue a request using the axios.js library:
componentDidMount() {
axios.get(this.props.baseEndpoint + "/inventory")
.then((res) => {
const inv : any = res.data;
console.log(res);
this.setState( {inventory: inv});
});
axios.get(this.props.baseEndpoint + "/category")
.then((res) => {
const cats : any = res.data;
console.log(res);
this.setState( {categories: cats});
});
}
where "baseEndpoint" is sourced from a config file:
export const BASE_URL : string = "http://localhost";
export const SEARCH_BASE : string = BASE_URL + ":8081/find";
export const INVENTORY_BASE : string = BASE_URL + ":8082";
the request fails.
With Firefox Developer's tools, a "Network Error" is logged to the console. However, whenever I switch over to the "Network" tab itself, it is as if the "Get" request is still pending or something. There is no response status (such as 500, 404, 200, etc), and both the "transferred" and "size" fields say 0. The response payload is empty.
The React app is served using a very simplistic Nginx configuration.
server { listen 80;
root /home/kelly/workspace/front-end/distr;
index index.html
location / {}
}
However, I can use curl to successfully GET the same endpoint (http://localhost:8082/category, for example) just fine. What might the issue be? I have also tried 127.0.0.0.
Thanks.
EDIT:
Request headers from Firefox Developer tools:
Accept
application/json, text/plain, */*
Accept-Encoding
gzip, deflate
Accept-Language
en-US,en;q=0.5
Connection
keep-alive
Host
localhost:8082
Origin
http://mysite
Referer
http://mysite/index.html
User-Agent
Mozilla/5.0 (X11; Linux x86_64…) Gecko/20100101 Firefox/58.0
Sample output from curl:
[{"id":1,"skuCode":"PS1","displayName":"PlayStation"},{"id":2,"skuCode":"PS2","displayName":"PlayStation 2"},{"id":3,"skuCode":"WII","displayName":"WII"},{"id":4,"skuCode":"GBC","displayName":"Gameboy Color"},{"id":5,"skuCode":"GBA","displayName":"Gameboy Advance"},{"id":6,"skuCode":"NDS","displayName":"Nintendo DS"},{"id":7,"skuCode":"N64","displayName":"Nintendo 64"},{"id":8,"skuCode":"GC","displayName":"Gamecube"},{"id":9,"skuCode":"SEG","displayName":"Sega Genesis"}]
EDIT TWO:
Networking is not my area of expertise, however, I tried running tcptrack -i eth0 while contacting my application. I see two requests to port 80 (presumably one for my HTML page and one for my .js file) from my local machine/browser. I also see multiple connections from my VM's IP to 169.254.169.254 (which based on this question, is simply a link-local address associated with cloud providers) and my SSH connection. However, I do not see any requests to port 8081, 8082, or anywhere else for that matter. Not sure if that might help provide some insight.
Thanks again.
I'm making an API call using Axios in a React Web app. However, I'm getting this error in Chrome:
XMLHttpRequest cannot load
https://example.restdb.io/rest/mock-data. No
'Access-Control-Allow-Origin' header is present on the requested
resource. Origin 'http://localhost:8080' is therefore not allowed
access.
{
axios
.get("https://example.restdb.io/rest/mock-data", {
headers: {
"x-apikey": "API_KEY",
},
responseType: "json",
})
.then((response) => {
this.setState({ tableData: response.data });
});
}
I have also read several answers on Stack Overflow about the same issue, titled Access-Control-Allow-Origin but still couldn't figure out how to solve this. I don't want to use an extension in Chrome or use a temporary hack to solve this. Please suggest the standard way of solving the above issue.
After trying out few answers I have tried with this,
headers: {
'x-apikey': '59a7ad19f5a9fa0808f11931',
'Access-Control-Allow-Origin' : '*',
'Access-Control-Allow-Methods':'GET,PUT,POST,DELETE,PATCH,OPTIONS',
},
Now I get the error as,
Request header field Access-Control-Allow-Origin is not
allowed by Access-Control-Allow-Headers in preflight response
I'll have a go at this complicated subject.
What is origin?
The origin itself is the name of a host (scheme, hostname, and port) i.g. https://www.google.com or could be a locally opened file file:// etc.. It is where something (i.g. a web page) originated from. When you open your web browser and go to https://www.google.com, the origin of the web page that is displayed to you is https://www.google.com. You can see this in Chrome Dev Tools under Security:
The same applies for if you open a local HTML file via your file explorer (which is not served via a server):
What has this got to do with CORS issues?
When you open your browser and go to https://website.example, that website will have the origin of https://website.example. This website will most likely only fetch images, icons, js files and do API calls towards https://website.example, basically it is calling the same server as it was served from. It is doing calls to the same origin.
If you open your web browser and open a local HTML file and in that HTML file there is JavaScript which wants to do a request to Google for example, you get the following error:
The same-origin policy tells the browser to block cross-origin requests. In this instance origin null is trying to do a request to https://www.google.com (a cross-origin request). The browser will not allow this because of the CORS Policy which is set and that policy is that cross-origin requests is not allowed.
Same applies for if my page was served from a server on localhost:
Localhost server example
If we host our own localhost API server running on localhost:3000 with the following code:
const express = require('express')
const app = express()
app.use(express.static('public'))
app.get('/hello', function (req, res) {
// res.header("Access-Control-Allow-Origin", "*");
res.send('Hello World');
})
app.listen(3000, () => {
console.log('alive');
})
And open a HTML file (that does a request to the localhost:3000 server) directory from the file explorer the following error will happen:
Since the web page was not served from the localhost server on localhost:3000 and via the file explorer the origin is not the same as the server API origin, hence a cross-origin request is being attempted. The browser is stopping this attempt due to CORS Policy.
But if we uncomment the commented line:
const express = require('express')
const app = express()
app.use(express.static('public'))
app.get('/hello', function (req, res) {
res.header("Access-Control-Allow-Origin", "*");
res.send('Hello World');
})
app.listen(3000, () => {
console.log('alive');
})
And now try again:
It works, because the server which sends the HTTP response included now a header stating that it is OK for cross-origin requests to happen to the server, this means the browser will let it happen, hence no error.
Just to be clear, CORS policies are security features of modern day browsers, to protect people from harmful and malicious code.
How to fix things (One of the following)
Serve the page from the same origin as where the requests you are making reside (same host).
Allow the server to receive cross-origin requests by explicitly stating it in the response headers.
If using a reverse proxy such as Nginx, configure Nginx to send response headers that allow CORS.
Don't use a browser. Use cURL for example, it doesn't care about CORS Policies like browsers do and will get you what you want.
Example flow
Following is taken from: Cross-Origin Resource Sharing (CORS)
Remember, the same-origin policy tells the browser to block
cross-origin requests. When you want to get a public resource from a
different origin, the resource-providing server needs to tell the
browser "This origin where the request is coming from can access my
resource". The browser remembers that and allows cross-origin resource
sharing.
Step 1: client (browser) request When the browser is making a cross-origin request, the browser adds an Origin header with the
current origin (scheme, host, and port).
Step 2: server response On the server side, when a server sees this header, and wants to allow access, it needs to add an
Access-Control-Allow-Origin header to the response specifying the
requesting origin (or * to allow any origin.)
Step 3: browser receives response When the browser sees this response with an appropriate Access-Control-Allow-Origin header, the
browser allows the response data to be shared with the client site.
More links
Here is another good answer, more detailed as to what is happening: https://stackoverflow.com/a/10636765/1137669
If your backend support CORS, you probably need to add to your request this header:
headers: {"Access-Control-Allow-Origin": "*"}
[Update] Access-Control-Allow-Origin is a response header - so in order to enable CORS - you need to add this header to the response from your server.
But for the most cases better solution would be configuring the reverse proxy, so that your server would be able to redirect requests from the frontend to backend, without enabling CORS.
You can find documentation about CORS mechanism here:
https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS
I had a similar problem and I found that in my case the withCredentials: true in the request was activating the CORS check while issuing the same in the header would avoid the check:
Reason: expected ‘true’ in CORS header ‘Access-Control-Allow-Credentials’
Do not use
withCredentials: true
but set
'Access-Control-Allow-Credentials':true
in the headers.
For Spring Boot - React js apps I added #CrossOrigin annotation on the controller and it works:
#CrossOrigin(origins = {"http://localhost:3000"})
#RestController
#RequestMapping("/api")
But take care to add localhost correct => 'http://localhost:3000', not with '/' at the end => 'http://localhost:3000/', this was my problem.
I had the same error. I solved it by installing CORS in my backend using npm i cors. You'll then need to add this to your code:
const cors = require('cors');
app.use(cors());
This fixed it for me; now I can post my forms using AJAX and without needing to add any customized headers.
For any one who used cors package change
const cors = require('cors');
app.use(cors());
to
const cors = require('cors');
app.use(cors({credentials: true, origin: 'http://localhost:5003'}));
change http://localhost:5003 to your client domain
Using the Access-Control-Allow-Origin header to the request won't help you in that case while this header can only be used on the response...
To make it work you should probably add this header to your response.You can also try to add the header crossorigin:true to your request.
First of all, CORS is definitely a server-side problem and not client-side but I was more than sure that server code was correct in my case since other apps were working using the same server on different domains. The solution for this described in more details in other answers.
My problem started when I started using axios with my custom instance. In my case, it was a very specific problem when we use a baseURL in axios instance and then try to make GET or POST calls from anywhere, axios adds a slash / between baseURL and request URL. This makes sense too, but it was the hidden problem. My Laravel server was redirecting to remove the trailing slash which was causing this problem.
In general, the pre-flight OPTIONS request doesn't like redirects. If your server is redirecting with 301 status code, it might be cached at different levels. So, definitely check for that and avoid it.
After a long time of trying to figure out how CORS works. I tried many way to fix it in my FE and BE code. Some ways CORS errors appearance, some ways the server didn't receive body from client, and other errors...
And finally got this way. I'm hoping this can help someone:
BE code (NodeJS + Express)
var express = require("express");
const cors = require("cors");
var app = express();
app.use(
cors({
origin: "*",
})
);
app.use(function (req, res, next) {
res.header("Access-Control-Allow-Origin", "*");
next();
});
// your routers and codes
My FE code (JS):
fetch(url, {
method: 'POST',
headers: {
'Content-Type': 'application/json',
Connection: 'Keep-Alive',
Authorization: `Bearer test`,
},
body: JSON.stringify(data),
});
I imagine everyone knows what cors is and what it is for.
In a simple way and for example if you use nodejs and express for the management, enable it is like this
Dependency:
https://www.npmjs.com/package/cors
app.use (
cors ({
origin: "*",
... more
})
);
And for the problem of browser requests locally, it is only to install this extension of google chrome.
Name: Allow CORS: Access-Control-Allow-Origin
https://chrome.google.com/webstore/detail/allow-cors-access-control/lhobafahddgcelffkeicbaginigeejlf?hl=es
This allows you to enable and disable cros in local, and problem solved.
npm i cors
const app = require('express')()
app.use(cors())
Above code worked for me.
You can create a new instance of axios with a custom config, and then use this new configured instance,
create a file with axios-configure.js, add this sharable exported method and use this preconfigured import, rather importing axios directly like we use traditionally,
import axios from 'axios';
import baseUrl from './data-service';
const app = axios.create({
baseURL: baseUrl,
headers: {
'Access-Control-Allow-Origin': '*',
'Content-Type': 'application/json',
},
withCredentials: true
})
export default app;
use this exported function like,
import axios from '../YOUR_DIRECTORY/axios-configure';
axios.get();// wont throw cors
dont import axios from axios;
then use axios.get() it will dont throw cors worked for us,
NOTE this solution will work for them who facing CORS at local environment as local starts at 5000 and backend at 8080, but in production, build gets deployed from java 8080 no CORS in productions (Facing CORS at only local environment)
As I understand the problem is that request is sent from localhost:3000 to localhost:8080 and browser rejects such requests as CORS. So solution was to create proxy
My solution was :
import proxy from 'http-proxy-middleware'
app.use('/api/**', proxy({ target: "http://localhost:8080" }));
$ npm install cors
After installing cors from npm add the code below to your node app file. It solved my problem.
var express = require('express')
var cors = require('cors')
var app = express()
app.use(cors())
I had a similar problem when I tried to create the React Axios instance.
I resolved it using the below approach.
const instance = axios.create({
baseURL: "https://jsonplaceholder.typicode.com/",
withCredentials: false,
headers: {
'Access-Control-Allow-Origin' : '*',
'Access-Control-Allow-Methods':'GET,PUT,POST,DELETE,PATCH,OPTIONS',
}
});
try it proxy
package.json add code:
"proxy":"https://localhost:port"
and restart npm enjoy
same code
const instance = axios.create({
baseURL: "/api/list",
});
You can use cors proxy in some specific cases - https://cors.sh
In node js(backend), Use cors npm module
$ npm install cors
Then add these lines to support Access-Control-Allow-Origin,
const express = require('express')
const app = express()
app.use(cors())
app.get('/products/:id', cors(), function (req, res, next) {
res.json({msg: 'This is CORS-enabled for a Single Route'});
});
You can achieve the same, without requiring any external module
app.use(function(req, res, next) {
res.header("Access-Control-Allow-Origin", "*");
res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
next();
});
},
"proxy": "http://localhost:8080",
"devDependencies": {
use proxy in package.json
I have a WebSocket app on heroku. I tried uploading my WebSocket app without routing http server but it doesn't work. What does mean server routing? And why can't heroku run a WebSocket server without an http server?
And why does it takes express object 'server' as argument in SocketServer
Here's my code of Websocket server.
const express = require('express');
const SocketServer = require('ws').Server;
const path = require('path');
const PORT = process.env.PORT || 3000;
const INDEX = path.join(__dirname, 'index.html');
const server = express()
.use((req, res) => res.sendFile(INDEX) )
.listen(PORT, () => console.log(`Listening on ${ PORT }`));
const wss = new SocketServer({ server });
wss.on("connection",function(ws){
ws.on("message",function(message){
if(message==='exit'){
ws.close();
}else{
wss.clients.forEach(function(client){
client.send(message);
});
console.log(message);
}
});
ws.send("welcome..");
});
There are too many questions in one. I hope my answers will address all of them.
First of all, the websocket protocol is an extension of http, it is not something different. Therefore, a websocket server is necessarily an http server, even though with extended capabilities.
Also, with socket.io, the websockets and http run on the same port. Therefore you have to open the port for http to have your websockets work.
Let's have a look at this line :
const wss = new SocketServer({ server });
It has a syntax error, it must be new SocketServer(server). Also, about the variable name, I would recommend not to use wss for a websocket over http, since wss stands for secure websockets and is related to websockets like http to https.
About routing in heroku: in heroku, you have to define which port your application is using. This can be compared to the firewall on your local machine : if you want to access it from outside, you have to open the port. On heroku, technically it is different to a firewall, but in this point it is similar.
I have a simple node script to process some data from my home automation API. Everything worked fine till last Node update. Now, with Node version 4.3.0 or 5.6.0, the http module gives me this error:
{ [Error: Parse Error] bytesParsed: 193, code: 'HPE_UNEXPECTED_CONTENT_LENGTH' }
An example of the API call causing the error, it just returns one number (a temperature):
HTTP/1.1 200 OK
Access-Control-Allow-Credentials: true
Access-Control-Allow-Origin: *
Connection: keep-alive
Content-Length: 5
Content-Type: application/json
Transfer-Encoding: chunked
21.81
And a code to reproduce an error:
const http = require("http");
const url = "http://127.0.0.1:8083/ZWaveAPI/Run/devices[11].instances[2].commandClasses[49].data[1].val.value";
http.get(url, (res) => {
// consume response body
res.resume();
}).on("error", (e) => {
console.log(e);
});
I think that error related to the CVE-2016-2216 Response Splitting Vulnerability, but I tried to run the script with mentioned there --security-revert=CVE-2016-2216 flag and it didn't help. Any ideas?
I found this commit log. The problem seems is Content-Length and Transfer-encoding: chunked headers exist together:
the server is sending
both a Content-Length header and a Transfer-Encoding: chunked
header, which is a violation of the HTTP spec.
As said in the previous answer this is node design as per HTTP standards. i got this issue when I was trying to access REST-API (a content disposition call) in my DEV server from my Angular App running in my local machine. API was not adding these headers Content-Length and Transfer Encoding.
The issue resolved when the app was also deployed to Dev server (Angular App and REST API in same server).
From what I understood, Remove one header if both are being added in API
or Try deploying app in Server.
This is a useful link on this issue - https://github.com/request/request/issues/2091