Could not able to access flask application deployed in GCP compute engine - flask

I deployed flask application in GCP compute engine. It is exposed at 5000 port. When I tried to do curl from vm, curl "localhost:5000/health", I am getting response "service up". But when I tried accessing through public IP, I am not able to access. I have created network firewall rule allowing both http & https traffic and for all the ports and for all IP (0.0.0.0/0).
Please let me know, if I am missing anything here.

Posting this answer based on the solution that was provided by #Rakesh.
Issue got resolved by changing the local host in the flask code to 0.0.0.0.
So the final configuration looks as follows:
app.run(host='0.0.0.0',debug=True,port=5000)

Related

Unable to open Public IPv4 DNS in AWS EC2 - Linux instance

I have a Spring boot project which I want to host on an AWS-EC2 instance. I was able to create its image using Git-hub, Jenkin and docker. I was also able to successfully pull and run this image in the Linux console of my AWS-EC2 instance.
According the tutorial I was following I should have been able to open the project now using the public IPv4 DNS but the response I got was that it refuse to connect.
I know that this usually has to do with Inbound rules so I added a rule to allow all traffic but it didn't help.
For anyone who wants to know:
Git-hub repository: https://github.com/SalahuddinShayan/telecom
Docker-Hub repository: https://hub.docker.com/repository/docker/salahuddinshayan/telecom
Command I used to run the image in AWS:
docker run -p8081:8081 --name final-app --link docker-mysql:mysql salahuddinshayan/telecom
Security Groups:
Networking Details:
Here is the Error:
I am completely stumped by it. Does anyone an idea on what to do to fix this?
Please check if your client is calling the right protocol, e.g. http vs https.
You are transmitting on port 8081. http://3.110.29.193:8081/ works fine from the EC2 side. 404 status is raised, so this is a client side error, not a server side error.
It means that no firewall is blocking traffic and a process (your app) was found that listens on IP:Port that you require. The problem is that the process it encountered (your app) is sending only a WhiteLabel Error Page, which is a generic Spring Boot error page that is displayed when no custom error page is present. So the issue is with the Spring app itself and not with EC2 or with connection. In other words: the traffic can reach your Spring app, but your Spring app has nothing to say in response.
As a side note, after deploying your app I would advise to refine the inbound traffic rules to allow only the traffic you want. There is no need of allowing all traffic on all ports.

Connection refused error with AWS + Hashicorp Vault

I have configured a Hashicorp Vault server on a EC2 instance. When trying to use postman to test transit secret engine API I keep getting a error connection refused on postman, I went full ape mode and opened all ports on the security group inbound rule and it didn't work, I attached an elastic IP to the instance and didnt work either, im just trying with a simple GET and I just keep getting the same connectionrefused error.
When I use cUrl on the ssh connected session i have no issues though. The specified hosted adress is 127.0.0.1:8200, in postman I replaced that localhost with the public adress of the instance that i obviously censored in the screencap, in the headers theres the token needed to access vault, for simplicity I was just using the root token.
Postman screecap if it helps
#Emilio Marchant
I have faced similar issue (not with postman, but with telnet), Let's try to understand problem here.
The issue is with 127.0.0.1 IP. This is loopback IP and When you (or your computer) call an IP address, you are usually trying to contact another computer on the internet. However, if you call the IP address 127.0.0.1 then you are communicating with the localhost – in principle, with your own computer.
Reference link : https://www.ionos.com/digitalguide/server/know-how/localhost/
What you can try is below.
Start vault dev server with --dev-listen-address parameter.
Eg:
vault server -dev -dev-listen-address="123.456.789.1:8200"
in above command replace '123.456.789.1:8200' with '<your ec2 instance private IP : 8200'>
Next set VAULT_ADDR and VAULT_TOKEN parameter as below
export VAULT_ADDR='http://123.456.789.1:8200'
export VAULT_TOKEN='*****************'
Again replace 'http://123.456.789.1:8200' with 'http://[Your ec2 instance private IP]:8200'
For Vault_token : you should get a root token in console, when you start vault server , use that token
Now try to connect from postman or using curl command. It should work.
Reference question and solution :
How to connect to remote hashicorp vault server
The notable thing here is that the response is "connection refused". This error means that the connection is getting established and it found that there are no processes running on that port. This error means that there is no issue with firewall. A firewall will cause the connection to either drop (reject) or timeout (ignore), but won't give "Econnrefused".
The most likely issue is that the vault server process is not bound to the correct network interface. There must be a configuration in hashicorp-vault to setup the IP on which to bind. Most servers, by default, bind only on loopback address which is accessible only from 127.0.0.1. You need to bind it to "all" network interfaces by changing that to 0.0.0.0. I am not aware of the specific configuration option of hashicorp vault, but there has to be something to this effect.
Possible security issue:
Note that some servers expect you to run it behind a reverse proxy so that you can setup SSL (https) and other authentication if needed. Applications like vault servers should not be publicly accessible on http without SSL.

Deploying a Go app in AWS ec2 got connection refused

I have a compiled Go project that I want to deploy to an AWS EC2 instance. I just simply upload the application and run ./application on the remote server.
In the terminal, the application is running and says he's listening to localhost:3000.
I've already added the 3000 port to the security group.
However, when I tried to access it in my browser using <public-ip>:3000, it always shows connection refused, whether I've run the application or not.
I tried to run the app locally, it does work.
So is it because I deploy it incorrectly?
It is a bit difficult to help you because of no code being shared.
Some reasons why you got connection refused:
Your application is listening only localhost:3000
EC2 security group does not expose port 3000
How to fix:
Most applications are defining the host address on a config file or env variables. If you have access to change it, change it from localhost:3000 to 0.0.0.0:3000 to accepts connection from all IP or to your_ec2_public_ip:3000
If host address is hardcoded and you have access to code, change the code per above
If you don't have access to config or code to change the host address, then add a reverse proxy to route the incoming call to localhost:3000. This is a good link about using Nginx as reverse proxy https://docs.nginx.com/nginx/admin-guide/web-server/reverse-proxy/
Ensure EC2 Security Group allowing inbound connection for the designated port, in this case, is 3000 if you manage to route the incoming to your_ip:3000

Flask app cannot open server to Google Cloud Compute instance external IP

I can't get my Flask API to respond to API calls using my instance external IP.
I've setup an instance using the Google Cloud Compute running Ubuntu 18.04, already opened up HTTP / HTTPS traffic in the firewall and set a static external IP to my instance, but I can not get my Flask app to listen to any incoming HTTP requests.
Running ifconfig does not show the instance's external IP, only the local IP, but I can ping the external IP.
I've already tried using app.run(host="0.0.0.0", port=8888) but it doesn't matter which port I choose to run the server on, the problem persists.
I can access my intance via internet running python -m SimpleHTTPServer 80, so I don't really know what is going on here anymore.
I'm clueless as to why this is happening, I would greatly appreciate any help :)
SOLVED: Turns out I'm actually dumb. Like I said, my Flask server was running on the 8888 port, so all I had to do was create a firewall rule that used the same port. Now everything's working like it's supposed to! :)

How do you host Django's dev server on an external IP?

Basically, my internal IP is masked by an external IP of my internet service provider. So, my internal IP can only be accessed inside my intranet. I want to let users outside the intranet to access my Dev server as well which is hosted on 0.0.0.0:8000 on my system. How do I do that?
Check out localtunnel on github, it does exactly what you're asking.
https://github.com/progrium/localtunnel
If you are willing to go that far you can use Reverse SSH Tunnel:
open a free micro linux instance on Amazon's AWS and create a reverse SSH tunnel to redirect port 80 on the server to your machine.
This is a cool solution for testing purposes and low traffic usage...
You can read more about it here:
http://www.techrepublic.com/article/setting-up-a-reverse-ssh-tunnel/5779944