Unable to connect docker nginx with docker ubuntu - nginx

Question

I have noticed an issue with docker nginx which is not the case when nginx is running on the host machine (apt-get install). Here is how to reproduce my issue:
solution A: 'nc' on container 1, 'nginx' on container 2, 'curl' on host
docker stop $(docker ps -aq)
docker rm $(docker ps -aq)
'nc' on container 1
docker run -ti --name agitated_stallman ubuntu:14.04 bash
nc -l 4545
'nginx' on container 2
LOLPATH=$HOME/testdocker
echo $LOLPATH
mkdir -p $LOLPATH
cd $LOLPATH
subl mple.conf
.
server {
listen 80;
root /var/www/html;
location /roz {
proxy_pass http://neocontainer:4545;
proxy_set_header Host $host;
}
}
.
docker run --link agitated_stallman:neocontainer -v $LOLPATH/mple.conf:/etc/nginx/sites-available/default -p 12345:80 nginx:1.9
'curl' on host
sudo apt-get install curl
curl http://localhost:12345/roz
ERROR response from 'nginx':
2016/03/04 19:59:18 [error] 8#8: *3 open() "/usr/share/nginx/html/roz" failed (2: No such file or directory), client: 172.17.0.1, server: localhost, request: "GET /roz HTTP/1.1", host: "localhost:12345"
172.17.0.1 - - [04/Mar/2016:19:59:18 +0000] "GET /roz HTTP/1.1" 404 169 "-" "curl/7.45.0" "-"
solution B: 'nginx' on host, 'nc' on host, 'curl' on host
'nginx' on host
sudo apt-get install nginx
sudo subl /etc/nginx/sites-available/default
.
server {
listen 80;
root /var/www/html;
location /roz {
proxy_pass http://localhost:4646;
proxy_set_header Host $host;
}
}
.
sudo service nginx restart
'nc' on host
nc -l 4646
'curl' on host
sudo apt-get install curl
curl http://localhost:80/roz
SUCCESS response from 'nc':
GET /roz HTTP/1.0
Host: localhost
Connection: close
User-Agent: curl/7.45.0
Accept: */*

Answer 1

In short: run nginx container with -v $LOLPATH/mple.conf:/etc/nginx/conf.d/default.conf
nginx:1.9 docker image currently uses nginx package from nginx's own repository, not from official debian repository. If you examine that package, you'll find that /etc/nginx/nginx.conf does include only from /etc/nginx/conf.d/*.conf, and that package ships with pre-included /etc/nginx/conf.d/default.conf:
server {
listen 80;
server_name localhost;
location / {
root /usr/share/nginx/html;
index index.html index.htm;
}
# other not important stuff
# ...
}
So your config is not used at all, which explains the open() "/usr/share/nginx/html/roz" failed error.
When you install nginx directly on host, you probably use official debian repository, which has different main config file, which in turn does include /etc/nginx/sites-available/*, and your config is actually used.