Webgateway

This role provides a stack of components that enables you to serve a web application via HTTP. In addition, you can do load balancing and configure failover support.

Role architecture

The role includes of two software packages:

  • the nginx web server
  • the HAProxy load balancer and proxy server

Both packages get a basic configuration, which can be found here for nginx and here for HAProxy.

In any way, you will have to add custom configuration to serve your site.

Note

Although we install nginx and HAProxy, there is no need to use them both. Since there is no connection between them w.r.t configuration, you can still use only one of them and leave the other one as is.

How we differ from what you are used to

Here is how we differ from what you already know from common Linux distributions and how you are used to configure, start, stop and maintain these packages.

  • configuration file locations:

    We do not edit files in /etc/nginx/* or /etc/haproxy/*, respectively. Since we use NixOS, files have to be edited in /etc/local/nginx and /etc/local/haproxy/, followed by a NixOS rebuild which copies them into the Nix store and activates the new configuration. To do so, run the command sudo fc-manage --build

  • service control:

    We use systemd to control processes. You can use familiar commands like sudo systemctl restart nginx.service to control services. However, remember that invoking sudo fc-manage --build is necessary to put configuration changes into effect. A simple restart is not sufficient. For further information, also see Local configuration.

Role configuration

Your custom configuration goes to /etc/local/nginx/<your_config_name>.conf for nginx and to /etc/local/haproxy/haproxy.cfg for HAProxy. Please note that all configuration has to be performed as a service user.

HAProxy

For HAProxy, you will already find a configuration file which you can change to fit your needs. For reference, please refer to the official documentation.

nginx

For nginx, you will have to add a file yourself that contains at least one server block declaration as described in the official documentation. Your files will then be integrated with nginx’ default config. Therefore, please omit the http clause. It is already set by the default config. A structure like the following is sufficient:

server {
    listen 127.0.0.1:8080;
    # The rest of server configuration
}

Note

If you configure SSL, please place your certificate files next to the config in /etc/local/nginx/ and use absolute paths to these files inside your configuration, e.g.:

ssl_certificate /etc/local/nginx/mydomain.crt;
ssl_certificate_key /etc/local/nginx/mydomain.key;

Debugging

nginx’ access logs are stored in:

$ ls /var/log/nginx/*.log

nginx’ error logs go to systemd’s journal by default. To view them, use journalctl(1) as usual, e.g.:

$ journalctl --since -1h --unit nginx.service