Nginx HTTP not redirecting to HTTPS 400 Bad Request "The plain HTTP request was sent to HTTPS port"

Question

I'm running nginx in docker. HTTPS works fine but when I explicitly make HTTP request I get the following error

400 Bad Request The plain HTTP request was sent to HTTPS port

nginx.conf is as follows

worker_processes auto ;          
events {}

http {

include /etc/nginx/mime.types;

access_log /var/log/nginx/main.access.log;                                           

server {    
listen 80;                                                                                                       
location / {
    return 301 https://localhost:3000$request_uri; 
}

}

server {   
listen 443 ssl;                                                      
server_name  localhost:3000;                  
 root    /var/www/html; 

ssl_certificate         /etc/nginx/ssl/cert.pem; 
ssl_certificate_key     /etc/nginx/ssl/key.pem;

ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
ssl_prefer_server_ciphers on;
ssl_ciphers ECDH+AESGCM:ECDH+AES256:ECDH+AES128:DH+3DES:!ADH:!AECDH:!MD5;

location / {
try_files  $uri /index.html;        
}

}

}

I run this container using

docker run -p 3000:443 -it -d --name nginxtest nginx-test

and get the following error

docker file is as follows

FROM nginx:latest
COPY ./build /var/www/html
COPY ./nginx.conf /etc/nginx/nginx.conf
COPY ./ssl /etc/nginx/ssl
EXPOSE 443
CMD [ "nginx","-g","daemon off;" ]

Weird thing is that sometimes it works perfectly fine, and all of a sudden it stops working and won't even work if I recreate the containers.

Even tried doing the following. Still no luck

 server {    
    listen 80;                                                                                                       
     server_name localhost:3000
        return 301 https://localhost:3000$request_uri; 
    }

Another odd thing when I run the following docker command

docker run -p 3000:443 -p 3001:80 -it -d --name nginxtest nginx-test

and go to localhost:3001 it redirects me to https just fine but other things do break. Sorry for the long question

Solution

Put the following directive to the server block where you listen for port 443.

error_page 497 https://$host:$server_port$request_uri;

This directive implies that when "The plain HTTP request was sent to HTTPS port" happens, redirect it to https version of current hostname, port and URI.

Kinda hacky but works.

Comments

[Omair Nabiel]

Man this did work though! Thanks alot. But can you please elaborate a bit as to why it's happening? Am I doing something wrong in the configuration which causes this behaviour. Any proper way of doing it? Hack does work like charm. Day saved. A little more insight would help

[Yarimadam]

It happens because you are using non-standart port for https protocol. (which is totally fine.) In a typical https setup you serve https over port 443. And when accessing that setup with https:// prefix you don't put :443 to address bar, browser adds it automatically placing request. (for http:// it adds 80). However, when you are serving https content from non standart port you can try to access like http:// example.com:3000, where nginx expects https requests. And it means "The plain HTTP request was sent to HTTPS port" :).

[Omair Nabiel]

That makes complete sense. Thanks a alot. Saved my day. Cheers :D

[Nimesh Kumar]

Worked for me ! Thanks