Rapport RES Labo HTTP

Introduction

All our work have been saved in the repository: https://github.com/SmithHeig/Teaching-HEIGVD-RES-2018-Labo-HTTPInfra

Step 1: Static HTTP server apache httpd

The template used in this step is: https://startbootstrap.com/template-overviews/resume/

Our Dockerfile is:

FROM php:5.6-apache # Php apache based image

RUN apt-get update && \
 apt-get install -y vim # Install vim in the container

COPY content/ /var/www/html/ # Copy the content of the web site in the directory where apache will load the files

Step2: Dynamic HTTP server with express.js

For the generation of the animals, we used an express server:

var Chance = require('chance');
var chance = Chance();

var express = require('express');
var app = express();

app.get('/', function(req, res) {
    res.send(generateAnimals());
});

app.listen(3000, function() {
    console.log('Accepting HTTP requests on port 3000.');
});

function generateAnimals() {
    var numberOfAnimals = chance.integer({
        min: 0,
        max: 10
    });

    console.log(numberOfAnimals);

    var animals = [];

    for(var i = 0; i < numberOfAnimals; ++i){
        animals.push({
            firstName : chance.animal(),
            lastName : chance.animal()
        });
    }

    console.log(animals);
    return animals;

}

The dockerfile for this server is:

FROM node:4.4

RUN apt-get update && \
 apt-get install -y vim # Install vim

COPY src /opt/app # copy the app express into the container

WORKDIR /opt/app

CMD ["node","index.js"] # run the server

Step 3: Reverse proxy with apache (static configuration)

The static configuration is bad because docker give dynamically ip address. So, every time we lunch the dockers containers, we need to configure the proxy.

To configure the reverse proxy, we need to write a config file called 001-reverse-proxy.conf:

<VirtualHost *:80>
  ServerName demo.res.ch

  # Not available in this container
  # ErrorLog ${APACHE_LOG_DIR}/error.log
  # CustomLog ${APACHE_LOG_DIR}/access.log combined
  
  ProxyPass "/api/student/" "http://172.17.0.3:3000/" # hardcoded addresse dynamic server
  ProxyPassReverse "/api/students/" "http://172.17.0.3:3000/"# hardcoded addresse dynamic server

  ProxyPass "/" "http://172.17.0.2:80/" # hardcoded addresse static server
  ProxyPassReverse "/" "http://172.17.0.2:80/" # hardcoded addresse static server

</VirtualHost>

We need to enable mods in apache to have the proxy working. We directly did that in the Dockerfile:

FROM php:5.6-apache

COPY conf/ /etc/apache2

RUN a2enmod proxy proxy_http # Install mods for the reverse proxy
RUN a2ensite 000-* 001-* # enable the configuration we wrote before

Step 4 : AJAX requests with JQuery

We've changed the description of our static content to have a class animals:

<span class="animals">Hello</span>

The script who will do the request to the dynamic HTTP server:

$(function() {
  console.log("loading students");
  function loadAnimals() {
    $.getJSON( "/api/students/", function (animals ) {
      console.log(animals);
      var message= "No animals is here";
      if( animals.length > 0){
        message = animals[0].firstName + " " + animals[0].lastName;
      }
      $(".animals").text(message);
    });
  };
  loadAnimals();
  setInterval(loadAnimals, 2000);
});

This script need to find a tag with the class "animals".

To add the script to our page we add this line at the end of our index.html:

<script src="js/students.js"></script>

Step 5: Dynamic reverse proxy configuration

To configure dynamically the ip address of our servers, we used the useful -e from docker to add environment variable.

We generate a .config 001-reverse-proxy with a php script:

<?php
  $dynamic_app = getenv('DYNAMIC_APP');
  $static_app = getenv('STATIC_APP');
?>

<VirtualHost *:80>
  ServerName demo.res.ch

  # Not available in this container
  # ErrorLog ${APACHE_LOG_DIR}/error.log
  # CustomLog ${APACHE_LOG_DIR}/access.log combined
  
  ProxyPass '/api/students/' 'http://<?php print "$dynamic_app"?>/'
  ProxyPassReverse '/api/students/' 'http://<?php print "$dynamic_app"?>/'

  ProxyPass "/" "http://<?php print "$static_app"?>/"
  ProxyPassReverse "/" "http://<?php print "$static_app"?>/"

</VirtualHost>

To run our setup, we coded a script:

echo "\n### Kill all containers...\n"
docker kill $(docker ps -qa)

echo "\n### Remove all container...\n"
docker rm $(docker ps -qa)

echo "\n### Build apache_static\n"
docker build -t apache_static ./apache-php-image/

echo "\n### Build express_dynamic\n"
docker build -t express_dynamic ./express-image/

echo "\n### Build apache_rp\n"
docker build -t express_dynamic ./apache-reverse-proxy/

echo "\n### Run apache_static container\n"
docker run -d --name apache_static res/apache_php

echo "\n### Run express_dynamic\n"
docker run -d --name express_dynamic res/express

echo "\n### Run apache_rp"
static_app=`docker inspect --format '{{ .NetworkSettings.IPAddress }}' apache_static`
dynamic_app=`docker inspect --format '{{ .NetworkSettings.IPAddress }}' express_dynamic`

echo "## IP of injected: static $static_app and dynamic $dynamic_app\n" 
docker run -d -p 8080:80 -e STATIC_APP=$static_app:80 -e DYNAMIC_APP=$dynamic_app:3000 --name apache_rp res/apache_rp

In the line bellow, you can the the -e :

docker run -d -p 8080:80 -e STATIC_APP=$static_app:80 -e DYNAMIC_APP=$dynamic_app:3000 --name apache_rp res/apache_rp

The Dockerfile need to be update:

FROM php:5.6-apache

RUN apt-get update && \
 apt-get install -y vim

COPY apache2-foreground /usr/local/bin/

COPY conf/ /etc/apache2/
COPY templates/ /var/apache2/templates

RUN a2enmod proxy proxy_http
RUN a2ensite 000-* 001-*

Load balancing: multiple server nodes

To do this part, we used this tutorial: https://httpd.apache.org/docs/2.4/fr/mod/mod_proxy_balancer.html

We had to add some new mods:

FROM php:5.6-apache

RUN apt-get update && \
 apt-get install -y vim

COPY apache2-foreground /usr/local/bin/

COPY conf/ /etc/apache2/
COPY templates/ /var/apache2/templates

RUN a2enmod proxy proxy_http proxy_balancer lbmethod_byrequests status
RUN a2ensite 000-* 001-*

proxy_balancer: mod to use the load balancer
lbmethod_byrequests: algorithm used to balanc the charge. (required)
status: will be useful later for the admin interface

We duplicate both server (dynamic and static). so we had to add 2 environment variable.

We modified our script:

echo "\n### Kill all containers...\n"
docker kill $(docker ps -qa)

echo "\n### Remove all container...\n"
docker rm $(docker ps -qa)

echo "\n### Build apache_static\n"
docker build -t res/apache_php ./apache-php-image/

echo "\n### Build express_dynamic\n"
docker build -t res/express ./express-image/

echo "\n### Build apache_rp\n"
docker build -t res/apache_rp ./apache-reverse-proxy/

echo "\n### Run apache_static containers\n"
docker run -d res/apache_php #useless
docker run -d res/apache_php #useless
docker run -d --name apache_static1 res/apache_php
docker run -d --name apache_static2 res/apache_php

echo "\n### Run express_dynamic containers\n"
docker run -d res/express #useless
docker run -d res/express #useless
docker run -d --name express_dynamic1 res/express
docker run -d --name express_dynamic2 res/express

echo "\n### Run apache_rp"
static_app1=`docker inspect --format '{{ .NetworkSettings.IPAddress }}' apache_static1`
static_app2=`docker inspect --format '{{ .NetworkSettings.IPAddress }}' apache_static2`
dynamic_app1=`docker inspect --format '{{ .NetworkSettings.IPAddress }}' express_dynamic1`
dynamic_app2=`docker inspect --format '{{ .NetworkSettings.IPAddress }}' express_dynamic2`

echo "## IP of injected: static $static_app1, $static_app2 and dynamic $dynamic_app1, $dynamic_app2\n" 
docker run -d -p 8080:80 -e STATIC_APP1=$static_app1:80 -e STATIC_APP2=$static_app2:80 -e DYNAMIC_APP1=$dynamic_app1:3000 -e DYNAMIC_APP2=$dynamic_app2:3000 --name apache_rp res/apache_rp

And changed the php script:

<?php
  $dynamic_app1 = getenv('DYNAMIC_APP1');
  $dynamic_app2 = getenv('DYNAMIC_APP2');
  $static_app1 = getenv('STATIC_APP1');
  $static_app2 = getenv('STATIC_APP2');
?>

<VirtualHost *:80>
  ServerName demo.res.ch

  # Not available in this container
  # ErrorLog ${APACHE_LOG_DIR}/error.log
  # CustomLog ${APACHE_LOG_DIR}/access.log combined

  <Proxy "balancer://dynamic_app">
    BalancerMember 'http://<?php print "$dynamic_app1"?>'
    BalancerMember 'http://<?php print "$dynamic_app2"?>'
  </Proxy>
  <Proxy "balancer://static_app">
    BalancerMember 'http://<?php print "$static_app1"?>/'
    BalancerMember 'http://<?php print "$static_app2"?>/'
  </Proxy>

  ProxyPass '/api/students/' 'balancer://dynamic_app/'
  ProxyPassReverse '/api/students/' 'balancer://dynamic_app/'

  ProxyPass '/' 'balancer://static_app/'
  ProxyPassReverse '/' 'balancer://static_app/'

  # Ajouter dans httpd.conf
  # <Location "/balancer-manager">
  #   SetHandler balancer-manager
  #   Require host demo.res.ch
  # </Location>

</VirtualHost>

The <Proxy> defined a cluster of servers.

We changed the ProxyPass to go to the cluster.

Tests

Run the two containers per cluster
Test if it works
Kill one of them
Look if it still works
Kill both and look that stop responding

Load balancing: round-robin vs sticky sessions

Not yet done

Management UI

For this part, we used Portainer, a very useful UI for docker containers management.

To use it, it's very simple. I wrote a small script to run it:

#Source : https://portainer.io/install.html
docker volume create portainer_data
docker run -d -p 9000:9000 -v /var/run/docker.sock:/var/run/docker.sock -v portainer_data:/data portainer/portainer

To access to this management UI, you need to connect to <ipAdressContainer>:9000.

This is a shown to test this step.

Setup

To run all this steps and us this system easerly, We wrote a script in ./docker-images/run.sh

AdamZouari/Teaching-HEIGVD-RES-2018-Labo-HTTPInfra