Deploying a Go app in AWS ec2 got connection refused - amazon-web-services

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

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.

Container instance network

I am having troubles to connect one ECS container instance(www, python) to another container instance (redis).
I am getting an "connecting to 0.0.0.0:6379. Connection refused" error from the www container.
Both instances are running on the same host and were created using two task definitions each containing one docker image.
Both use Bridge networking mode. Each task is executed by means of a service.
I also did setup service discovery for both services.
Things I did do and try:
Assure that Redis is bound to 0.0.0.0 and not 127.0.0.1
Added port mappings for www (80) and redis container (6379)
ssh'ed into the ec2 instance to assure port mappings are ok. I can telnet to both port 80 and 6379
connected to the www instance and tested by means of the python console if 0.0.0.0:6379 was available.
It wasn't the case. I also tried with the docker(redis) IP address 172.17.0.3 without luck. I also tried using the .local service discovery name of the redis container without luck. The service discovery name did not resolve
resolving the service discovery name from the ec2 container (using dig): that did work but returned a 10.0.* address
I am a bit out of option why this is the case. Obviously things do work on a local development machine.
Update 10/5: I changed container networking to type "host" which appears to be working. Still not understanding why "bridge" won't work.

EC2 Multi App Instance - Some Ports not Reachable

I have started an AWS EC2 (UBUNTU 18 AMI) instance running three apps:
Web server on port 80
REST API on port 8786
DB on port X
I am able to
SSH into the instance
Reach the website via browser on port 80.
Reach the REST API from within the SSH session.
I am unable to
Reach the REST API via AJAX from the browser (tried postman as well).
I have
Configured the Security Group to receive inbound connections from all sources on 8786
verified that iptable is not loaded
Tried reaching the website from a mobile network - to no avail.
Swapped the ports between the Web Server and the REST API - which resulted in being able to access the API via the browser and postman.
Verified that the API is bound to 0.0.0.0 - not to localhost.
This smells like an EC2 issue, but I have no idea what to do.
Help would be much appreaciated.
As it turns out, 8786 is a reserved port, and should not be used. Issues were resolved when I changed to 8080, which I should have done in the very beginning.

Connection getting refused to socket.io server on Amazon EC2

I have set up a a micro EC2 instance on AWS. Currently, I am using the free tier in Oregon. There are two problems which I am facing.
When I try to SSH the instance using the public DNS, it says host does not exist but when I try conencting it using the public IP, it connects to it. What setting is needed to use the public DNS ?
I have opened the SSH client using the IP address. I want to set up my application which needs Node.js and MongoDB. I installed Node.js using this
Next I installed MongoDB using this
Then I connected to my instance using Filezilla and uploaded my code to it. I then start my node application which uses socket.io.
When I try to connect to socket.io server using web browser, I get a message which says connection refused "error 111". I have opened TCP port 80 in instance's security groups. In iptables, I have forwarded port 80 to 8080, but still it does not work. I have also checked that the firewall is disabled in ec2. Kindly help me to resolve this issue.
Did you check if all of the necessary ports are open on Amazon Security Policy?
What you can do is to allow all traffic on Amazon Security Policy for test and see if the connection goes well or not.
You might also check if you need access DB from outside. In that case, you also have to open the mongodb port and setup mongodb correctly as well.
Other tools that might useful to test firewall and connection issue will be tcpdump and syslog file
For the dns issue, did you try to nslookup on that name and see if the IP shown matches your server IP?
As Amazon gives a long DNS hostname for the server, I always use my own domain name. It's much easier.
example : ec2.domainname.com, which points to the Amazon IP address
Hope that help.
My problem is resolved now..
For the DNS issue, earlier I needed proxy to access internet, so I guess the DNS name was not getting resolved. When I tried using proxy free internet, I was able to ssh using public DNS.
And regarding connection to socket.io, I used port 8080 instead of 80 and used "sudo node main.js" to run my node file. Now I am able to connect to the socket.io server and MongoDB.
Another thing which I want to ask is that would running the node file with sudo rights create some security issue ?
Thanks for the answer! That also worked for me. I had the same problem trying to connect through sockets (http://myipaddress:3000) to a node.js server, i tried opening ports on the actual ec2 instance and disabling the firewall through SSH but nothing worked. Had to go to Security Groups on the ec2 console and open a new inbound tcp rule enabling that port