How to connect Amazon API Gateway with my custom API in EC2 - api

I need to create a RESTful API to expose a Windows application as a service. My first step is to create a simple REST API that returns a string, and then connect it to Amazon API Gateway.
I already launched a Windows Server instance, installed Node.js and created a simple API like this:
var express = require('express');
var app = express();
app.get('/test', function (req, res) {
console.log( "response" );
res.end( "response" );
});
var server = app.listen(8080, function () {
var host = server.address().address;
var port = server.address().port;
console.log("Example app listening at http://%s:%s", host, port);
});
I'd tested it opening http://localhost:8080/test and it works perfect.
The thing is, now I have to connect it with Amazon API Gateway but I haven't found clear documentation of how to do that. I have to use the "HTTP Proxy" option (see image below) but how do I get an "Endpoint URL"? All the tutorials take for granted that I already have that URL, but I don't.

Go to the ec2 console
Look for your instance
In the description of the instance find its public ip
Make sure its security group has the right permissions other wise you will no be able to connect with it
Use the instance public ip in API Gateway
In production use a more robust configuration, but for testing purposes you should be good.

Related

ASP.NET Core WEB API self-connection through external URL "No connection could be made because the target machine actively refused it"

I have multitenant Web API application with Hangfire scheduler that calls a task which trying to connect to self endpoint through external server DNS name with tenant name in it. Doing it this way, because Hangfire doesn't have HttpContext to resolve on which tenant task must shoot. On my staging server or if I send this request from Postman it works nice, but on my local machine and on production server it raises the error from title.
The code looks like nothing special:
var url = $"{tenant.Url}/notifications/client/send-appointment-sms";
var jwtToken = await _authService.GetTokenByUsername("admin");
using var requestMessage = new HttpRequestMessage(HttpMethod.Get, url);
requestMessage.Headers.Authorization = new AuthenticationHeaderValue("Bearer", jwtToken.AccessToken);
var response = await _httpClient.SendAsync(requestMessage);
Where tenant.Url is for example https://api.tenant1.example.com/api2 which is available from browser on production server where application is running.
If I understanding clearly, my application can not connect to itself for some reason.
I have tried common solutions like firewall settings or disable proxy, still nothing on this point. What can I check next?
UPD I must add that NodeJS server on production is able to call this service too, so I think issue is not in server but maybe more about ASP.NET configuration settings.

UrlHelper returning http links on Azure App Service

I have a service that when deployed on Azure App Services returns http links instead of https links when using UrlHelper. When testing on my development machine it returns https links as expected, and the service is available and accessed through https requests.
An example of the type of route from my startup I'm trying to use is:
routes.MapRoute(
"FooBar",
"api/Foo/{Id}/Bar");
The link is then constructed using:
IUrlHelper _urlHelper = // Injected into class via service registration
int id = 42; // Arbitrary value for example
_urlHelper.Link("FooBar", new {Id = id});
When running on my local machine using Docker on Windows from Visual Studio I get a link of https://localhost:1234/api/Foo/42/Bar, but on my deployed Linux Container App Service on Azure I get http://my-app-name.azurewebsites.net/api/Foo/42/Bar.
I don't know what I'm doing wrong to get an http link instead of an https link, and would appreciate any advice/pointing in the right direction.
So I found the solution was with the configuration of the ASP.Net Core app itself. I performed the following modifications and then everything worked correctly:
Added app.UseForwardedHeaders(); to the request pipeline.
Added the following snippet to service container registration:
services.Configure<ForwardedHeadersOptions>(options =>
{
options.ForwardedHeaders = ForwardedHeaders.All;
options.KnownNetworks.Clear();
options.KnownProxies.Clear();
});
The KnownNetworks and KnownProxies need to be cleared as they default to assuming an IIS hosting environment. For extra security you can add the known proxy/network IPs instead of clearing them here.

Azure AD Redirect URL Using Application Gateway

We have an ASP Core 2.0 App working nicely with Azure AD on the private network. However, we've been playing around with the Azure Application Gateway, investigating the possibility of allowing access to the app from outside for remote workers etc.
We have registered the app on the Gateway, and, once logged in with Azure AD, the anonymous front page is accessible via ourapp.msappproxy.net. However, when signing in (again?) in the app, the client is redirected back to intervalServer/signin-oidc which fails as it is not accessible externally.
While I doubt this is any part of the solution, I have tried overriding the redirect "CallbackPath": "/signin-oidc", to absolute path ourapp.msappproxy.net/signin-oidc but I can't seem to work out how. Changing the reply URL in Azure Portal doesn't help either (although I doubted it would, this is just for verification right?).
I can't seem to find any guidance on this on this particular scenario, so that would be welcome. Otherwise, I'm left pondering the following:
1, If I could change the redirect to ourapp.msappproxy.net/signin-oidc, would that solve the sign in issue?
2, Do I even need an additional sign in step, or should I be changing the app to accept AzureAppProxyUserSessionCookie or AzureAppProxyAccessCookie? (If that's even an option?)
Thanks to rfcdejong in the comments for putting me on track. In our case I was able use Azure AD with the Azure Application Gateway by overriding OnRedirectToIdentityProvider event and supplying the proxy url in ConfigureServices
services.AddAuthentication(...)
.AddOpenIdConnect(options =>
{
options.ClientId = Configuration["Authentication:AzureAD:ClientId"];
options.Authority = Configuration["Authentication:AzureAd:Authority"];
options.CallbackPath = Configuration["Authentication:AzureAd:CallbackPath"];
if (IsProduction) // So that I can use the original redirect to localhost in development
{
Task RedirectToIdentityProvider(RedirectContext ctx)
{
ctx.ProtocolMessage.RedirectUri = "https://ourapp.msappproxy.net/signin-oidc";
return Task.FromResult(0);
}
options.Events = new OpenIdConnectEvents
{
OnRedirectToIdentityProvider = RedirectToIdentityProvider
};
}
})
The return URI needs to be configured to match for the app in Azure Portal.
Users also need to be assigned, but the internal app is now available anywhere without requiring direct access to the server.

AWS API Gateway as proxy for HTTP AUTH

I am dealing with some legacy applications and want to use Amazon AWS API Gateway to mitigate some of the drawbacks.
Application A, is able to call URLs with parameters, but does not support HTTP basic AUTH. Like this:
https://example.com/api?param1=xxx&param2=yyy
Application B is able to handle these calls and respond. BUT application B needs HTTP basic authentication.
The question is now, can I use Amazon AWS API Gateway to mitigate this?
The idea is to create an API of this style:
http://amazon-aws-api.example.com/api?authcode=aaaa&param1=xxx&param2=yyy
Then Amazon should check if the authcode is correct and then call the API from Application A with all remaining parameters while using some stored username+password. The result should just be passed along back to Application B.
I could also give username + password as a parameter, but I guess using a long authcode and storing the rather short password at Amazon is more secure. One could also use a changing authcode like the ones used in 2-factor authentications.
Path to a solution:
I created the following AWS Lambda function based on the HTTPS template:
'use strict';
const https = require('https');
exports.handler = (event, context, callback) => {
const req = https.get(event, (res) => {
let body = '';
res.setEncoding('utf8');
res.on('data', (chunk) => body += chunk);
res.on('end', () => callback(null, body));
});
req.on('error', callback);
req.end();
};
If I use the Test function and provide it with this event it works as expected:
{
"hostname": "example.com",
"path": "/api?param1=xxx&param2=yyy",
"auth": "user:password"
}
I suppose the best way from here is to use the API gateway to provide an interface like:
https://amazon-aws-api.example.com/api?user=user&pass=pass&param1=xxx&param2=yyy
Since the params of an HTTPs request are encrypted and they are not stored in Lambda, this method should be pretty secure.
The question is now, how to connect the API gateway to the Lambda.
You can achieve the scenario mentioned with AWS API Gateway. However it won't be just a proxy integration, rather you need to have a Lambda function which will forward the request by doing the transformation.
If the credentials are fixed credentials to invoke the API, then you can use the environmental variables in Lambda to store them, encrypted by using AWS KMS Keys.
However if the credentials are sent for each user (e.g logged into the application from a web browser) the drawbacks of this approach is that you need to store username and password while also retrieving it. Its not encourage to store passwords even encrypted. If this is the case, its better to passthrough (Also doing the transformations) rather storing and retrieving in between.

Running a cloud function from express route

Using the new parse server is there a way to call a function in the main.js file from the index.js?
Example is to allow an endpoint for a third party so they can post a set of data without needed the application_id or any keys.
Old hosted parse.com allowed like this;
app.post('/test', function(req, res) {
Parse.Cloud.run('functionname' data);
}
But I cannot get the routing to work in parse-server.
Maybe later but can help!
Just write your cloud code cloud/main.js, or include your own packages there. and call Parse.Cloud.run(for js) on the client side. You have to write secure code on cloud/main.js to protect your server and datas.