Deploy Fano web application with Nginx load balancer module

Nginx provides reverse proxy load balancer to distribute load to one or more application instances. When one application is unable to handle request, load balancer distributes load to other application instance thus improving performance, availability and scalability.

Requirement

Deploy Fano Application with load balancer with Fano CLI

This is mostly similar to deploy Fano web application with Apache load balancer module with Fano CLI.

The difference is that you need to pass --web-server=nginx parameter when deploying, for example

$ sudo fanocli --deploy-lb-scgi=myapp.fano --web-server=nginx

Replace with --deploy-lb-fcgi, --deploy-lb-uwsgi or --deploy-lb-http for setting up FastCGI, uwsgi or http web application respectively.

Skip adding domain name entry in /etc/hosts

By default --deploy-* parameter will cause domain name entry is added in /etc/hosts file. You may want to setup domain name with DNS server manually or you do not want to mess up with /etc/hosts file. You can avoid it by adding --skip-etc-hosts parameter.

$ sudo fanocli --deploy-lb-scgi=myapp.fano --skip-etc-hosts

Generate virtual host config to standard output

If you want to generate virtual host configuration without actually modifying web server configuration, you can use --stdout command line option. This option will generate virtual host configuration and print it to standard output. It is useful if you want to deploy configuration manually.

Because it will not change any web server configuration, you do not need to run it with root privilege. So following code is suffice.

$ fanocli --deploy-lb-fcgi=myapp.fano --web-server=nginx --stdout

Deploy Fano Application with load balancer manually

Skip this section if you use Fano CLI to deploy application.

If you prefer setting up virtual host manually, create new file in /etc/nginx/conf.d or /usr/local/etc/nginx/conf.d directory for Linux or FreeBSD respectively and add, for example, following code,

upstream my-app-load-balancer {
    server 127.0.0.1:20477;
    server 127.0.0.1:20478;
}

server {
    listen 80;
    root /path/to/my/app/doc/root;
    server_name myapp.fano;

    error_log /var/nginx/log/myapp.fano-error.log;
    access_log /var/nginx/log/myapp.fano-access.log;

    location / {
        try_files $uri @myapp.fano;
    }

    location @myapp.fano {
        scgi_pass my-app-load-balancer;
        include scgi_params;
    }
}

Replace scgi_pass and scgi_params with fastcgi_pass and fastcgi_params for FastCGI or uwsgi_pass and uwsgi_params for uwsgi web application.

For http web application, configuration is similar except that you need to replace location with

    location @myapp.fano {
        proxy_pass http://my-app-load-balancer;
    }

Reload Nginx

$ sudo systemctl reload nginx

Add entry to /etc/hosts file so you can access application during development,

127.0.0.1 myapp.fano

Running multiple applications with load balancer

Build the application and then run two applications at once with consecutive listening ports.

$ ./build.sh
$ ./bin/app.cgi --port=20477 & ./bin/app.cgi --port=20478 &

& is required to make sure that both applications are running in parallel.

To stop all applications,

$ pkill app.cgi

Access application from browser

Open http://myapp.fano you should see main controller is invoked.

Set balancer member

By default, if parameter --members not set, it is assumed that you will use two application instances, running on 127.0.0.1:20477 and 127.0.0.1:20478 respectively.

--members parameter allows set multiple balancer members separated by coma.

$ sudo fanocli --deploy-lb-scgi=myapp.fano --web-server=nginx --members=127.0.0.1:20000,localhost:20001

Run applications at once with consecutive listening ports.

$ ./bin/app.cgi --host=127.0.0.1 --port=20000 & ./bin/app.cgi --host=localhost --port=20001 &

Developer is responsible to make sure that no other application is using those listening ports.

Change load balancing scheduler algorithm

By default, if parameter --lbmethod is not set, round-robin algorithm is assumed, which will distribute requests in round-robin fashion. Please refer to Nginx load balancer documentation for available algorithms.

For example, to use least connected load balancing, set to least_conn,

$ sudo fanocli --deploy-lb-scgi=myapp.fano --lbmethod=least_conn

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Documentation