Nginx select based on HTTP header

Feb 27, 2018 procedure article

There is a service api.example with two different versions:

1.0.0: api-v1.example
2.0.0: api-v2.example

To select different virtual server pools based on client http headers, such as:

# To api-v1.example
$ curl -X GET \
     -H 'Version: 1.0.0' \
     http://api.example


# To api-v2.example
$ curl -X GET \
     -H 'Version: 2.0.0' \
     http://api.example

# To api-v2.example by default
$ curl -X GET \
     http://api.example

To accomplish this in Nginx you can use the following code in your configuration:

upstream v1 {
     server api-v1.example;
}

upstream v2 {
     server api-v2.example;
}

# map to different upstream backends based on header
map $http_api_version $pool {
    default "v2";
    1.0.0 "v1";
    2.0.0 "v2";
}

server {
     listen 80;
     server_name api.example;
     location / {
          proxy_pass http://$pool;

          #standard proxy settings
          proxy_set_header X-Real-IP $remote_addr;
          proxy_redirect off;
          proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
          proxy_set_header Host $http_host;
          proxy_redirect off;
          proxy_set_header X-Forwarded-Proto $scheme;
          proxy_set_header X-NginX-Proxy true;
          proxy_connect_timeout 600;
          proxy_send_timeout 600;
          proxy_read_timeout 600;
          send_timeout 600;
    }
}

Also looking for here.