Nginx config on Docker to serve multiple containerized apps

  proxy_cache_path /var/cache/nginx/mycache levels=1:2 keys_zone=mycache:1m inactive=10m;


  # mapping between file type and expires length for browser caching;
  map $sent_http_content_type $expires {
      default                    off;
      text/html                  epoch;
      text/css                   max;
      application/javascript     max;
      ~image/                    max;
  }

  log_format my_log ' "Request: $Request, Status: $status, Request_uri: $request_uri, Host: $host, Host: $upstream, Client_IP: $remote_addr, Proxy_IP: $proxy_add_x_forwarded_for, Proxy_Hostname: $proxy_host, Real_IP: $http_x_real_ip, Cache_Status: $upstream_cache_status  "';
  # check tail -f access.log

  server {
    server_name webapp.me*; # file /etc/hosts modified & <- if SSL
    listen 8080  default_server;

    access_log /var/log/nginx/access.log my_log; #<- to watch logs

    set $upstream $PROXY_UPSTREAM;

    proxy_set_header  Host            $upstream;  # $http_host needed for Rails ??
    proxy_set_header Connection       "";
    proxy_set_header  X-Real-IP       $remote_addr; # client IP adress
    proxy_set_header  X-Forwarded-For $proxy_add_x_forwarded_for;

    # configure a resolver for Nginx with the address of your actual DNS resolver.
    resolver 127.0.0.11:53  valid=1s; # <- Docker network DNS resolver

    expires   $expires;       # reading the mapping file/$expires

    # Proxy-caching by Nginx
    proxy_cache       mycache;
    proxy_cache_valid 60m;
    add_header        X-Proxy-Cache $upstream_cache_status;
    proxy_cache_key   $scheme$request_method$host$request_uri;

    location ~ \.(jpeg|css|png|js|webp|ico)$ {
      # since we run nginx in a separate container from the app, then we need to copy
      # the static files into the nginx container. We do this with a bind, and tthe files
      # are located in the folder below.
      root /usr/share/nginx/html;

      # return 200 http://webapp:8080$uri; # testing..

      # gzip_static on;
      access_log off;
      add_header Cache-Control public;
      add_header Last-Modified "";
      add_header ETag "";

      break;
    }

    # any other request not found by the regex and starting with '/' will be served by @app
    location / {
      # proxy_pass http://webapp;   <- if 'upstream directive as can't pass env var'
      proxy_pass http://$upstream; #$request_uri; # $request_uri; <- revers proxying

      gzip_static on;
      proxy_pass_header Authorization;
      proxy_http_version 1.1;
      proxy_ssl_server_name on;

      proxy_buffering       off;
      proxy_read_timeout    5s;
      proxy_redirect        off;
      proxy_ssl_verify      off;
      client_max_body_size  0;
    }
  }

Postgres & ORM Sequel

gem 'pg' gem 'sequel' gem 'gem 'sequel_pg', :require=>'sequel' (no require)

1. Create database >: psql createdb test

2. Create USER/PWD >: psql create ...

3. Create table Run a SQL script

4. Connect ot the database Sequel.connect($POSTGRES_URL)

5. Create model

class Owner < Sequel::Model
  one_to_many :dogs

  def validate
    super
    errors.add(:name, "must be present") if name.empty?
  end
end

6. Migration

Sequel.migration do
  change do
    create_table(:dogs) do
      primary_key :id
      String :ip, :null => false
      ...
    end
  end
end

and run: `sequel [path/to/migrate-file] postgres://[host]/[db-name]`` For example:

> sequel -m /db/migrates/ postgres://localhost/test

7. Seeding With the gem sequel-seed, we do:

Sequel.seed do
    def run
        ['123.123.123','/', 2020-11-01],
        ['127.0.0.1','/',2020-11-02]
        .each do |ip, path, requested_at|
            Request.create(ip: ip, path: path, requested_at: requested_at )
        end
    end
end

we can do in the app:

require 'sequel/extensions/seed'
Sequel.extension :seed

Sequel::Seeder.apply(DB,"db/seeds")

Useful commands

crop images and change format with Imagemagick

magick convert puma.jpeg -resize 180x180! puma.webp

Sinatra console (IRB)

bundle exec irb -I. -r app.rb

find file by name

ls / f -name puma.rb => /usr/local/bin/puma

find directory by name

ls / -type d -name bundle

find all directories in current directory

ls . -type d

create several subdir with '-p' in one go)

mkdir -p tmp/{pids,sockets}

count number of lines

• List all Docker processes with:
• docker ps -q |wc -l ('-q' is the get the process id, and '|wc' is 'Word Count)
• List all TCP connections with netstat -t

Dotenv with Sinatra (or Rack based apps)

https://github.com/bkeepers/dotenv

We pass environment variables to Sinatra via the .env file and the Dotenv gem. It shuold be loaded as early as possible in the Rakefile. It loads by default .env:

#Rakefile
require 'dotenv'
Dotenv.load('.env')

Then we can get the variables with ENV['PORT'] or better ENV.fetch('PORT') { 9292 } since this fraises an exception if not present. We also yield a default value.

Config Sinatra / Puma / Rack

We extend the class Sinatra::Base with a class App < Sinatra::Base so we need to pass the class to run App.

Since we use bundler, we need a config.ru for rackup since Rack launchs with rackup config.ru. The location of the "DefaultRackupis found withFile.expand_path(".",dir)` (try this in IRB).

Then we can start the app in the Dockerfile with bundle exec Puma -C puma.rb where 'puma.rb' is Puma's config file.

https://medium.com/@theterminalguy/using-bundler-with-sinatra-e194c3422c6a

.dockerignore

To avoid to copy files into the container such as /tmp/pids/, you exclude them by putting into the dockerignore.

Docker-compose

docker-compose up --build docker-compose down Open a container for exploration during execution: docker-compose exec webapp sh Scale up: `docker-compose up --scale webapp=2``