R14 – Memory Quota Exceeded

We, like many other organisations, are using heroku as the deployment server for our project open event organizer server. Things are pretty simple and awesome when your project is in its beginning phase and things run pretty smoothly. But as your project grows, there comes some server problem. And one of the biggest problems as your project grows is memory. Now since various packages have a different amount of memory assigned to you in case of hosting in generic servers such as heroku, so it might result in memory quota exceeded. Recently, we faced such a problem. R14 – Memory Quota Exceeded. Took us quite some time to understand what and why and how this occurred. So let me share a few things I found about this error.

Continue reading R14 – Memory Quota Exceeded

GET and POST requests

If you wonder how to get or update page resource, you have to read this article.

It’s trivial if you have basic knowledge about HTTP protocol. I’d like to get you little involved to this subject.

So GET and POST are most useful methods in HTTP protocol.

What is HTTP?

Hypertext transfer protocol – allow us to communicate between client and server side. In Open Event project we use web browser as client and for now we use Heroku for server side.

Difference between GET and POST methods

GET – it allows to get data from specified resources

POST – it allows to submit new data to specified resources for example by html form.

GET samples:

For example we use it to get details about event

curl http://open-event-dev.herokuapp.com/api/v2/events/95

Response from server:

Of course you can use this for another needs, If you are a poker player I suppose that you’d like to know how many percentage you have on hand.

curl http://www.propokertools.com/simulations/show?g=he&s=generic&b&d&h1=AA&h2=KK&h3&h4&h5&h6&_

POST samples:

curl -X POST https://example.com/resource.cgi

You can often find this action in a contact page or in a login page.

How does request look in python?

We use Requests library to communication between client and server side. It’s very readable for developers. You can find great documentation  and a lot of code samples on their website. It’s very important to see how it works.

>>> r = requests.get('https://api.github.com/user', auth=('user', 'pass'))
>>> r.status_code
200

I know that samples are very important, but take a look how Requests library fulfils our requirements in 100%. We have decided to use it because we would like to communicate between android app generator and orga server application. We have needed to send request with params(email, app_name, and api of event url) by post method to android generator resource. It executes the process of sending an email – a package of android application to a provided email address.

data = {
    "email": login.current_user.email,
    "app_name": self.app_name,
    "endpoint": request.url_root + "api/v2/events/" + str(self.event.id)
}
r = requests.post(self.app_link, json=data)

 

Using Heroku pipelines to set up a dev and master configuration

The open-event-webapp project, which is a generator for event websites, is hosted on heroku. While it was easy and smooth sailing to host it on heroku for a single branch setup, we moved to a 2-branch policy later on. We make all changes to the development branch, and every week once or twice, when the codebase is stable, we merge it to master branch.

So we had to create a setup where  –

master branch –> hosted on –> heroku master

development branch –> hosted on –> heroku dev

Fortunately, for such a setup, Heroku provides a functionality called pipelines and a well documented article on how to implement git-flow

 

First and foremost, we created two separate heroku apps, called opev-webgen and opev-webgen-dev

To break it down, let’s take a look at our configuration. First step is to set up separate apps in the travis deploy config, so that when development branch is build, it pushed to open-webgen-dev and when master is built, it pushes to opev-webgen app. The required lines as you can see are –

https://github.com/fossasia/open-event-webapp/blob/master/.travis.yml#L25

https://github.com/fossasia/open-event-webapp/blob/development/.travis.yml#L25

Now, we made a new pipeline on heroku dashboard, and set opev-webgen-dev and opev-webgen in the staging and production stages respectively.

Screenshot from 2016-07-31 04-33-30 Screenshot from 2016-07-31 04-34-41

Then, using the “Manage Github Connection” option, connect this app to your github repo.

Screenshot from 2016-07-31 04-36-17

Once you’ve done that, in the review stage of your heroku pipeline, you can see all the existing PRs of your repo. Now you can set up temporary test apps for each PR as well using the Create Review App option.

Screenshot from 2016-07-31 04-37-38

So now we can test each PR out on a separate heroku app, and then merge them. And we can always test the latest state of development and master branches.

Deploying PHP and Mysql Apps on Heroku

This tutorial will help you deploying a PHP and Mysql app.

Prerequisites

  1. a free Heroku account.
  2. PHP installed locally.
  3. Composer installed locally.

Set up

In this step you will install the Heroku Toolbelt. This provides you access to the Heroku Command Line Interface (CLI), which can be used for managing and scaling your applications and add-ons.

To install the Toolbelt for ubuntu/Debian

 wget -O- https://toolbelt.heroku.com/install-ubuntu.sh | sh

After installing Toolbelt you can use the heroku command from your command shell.

$ heroku login
Enter your Heroku credentials.
Email: [email protected]
Password:
...

Authenticating is required to allow both the heroku and git commands to operate.

Prepare the app

In this step, you will prepare a fossasia/engelsystem application that can be deployed.

To clone the sample application so that you have a local version of the code that you can then deploy to Heroku, execute the following commands in your local command shell or terminal:

$ git clone --recursive https://github.com/fossasia/engelsystem.git
$ cd engelsystem/

If it is not a git repository you follow these steps

$ cd engelsystem/
$ git init

You now have a functioning git repository that contains a simple application now we need to add a composer.json file. Make sure you’ve installed Composer.

The Heroku PHP Support will be applied to applications only when the application has a file named composer.json in the root directory. Even if an application has no Composer dependencies, it must include at least an empty ({}) composer.json in order to be recognized as a PHP application.

When Heroku recognizes a PHP application, it will respond accordingly during a push:

$ git push heroku master
-----> PHP app detected

Define a Procfile

A Procfile is a text file in the root directory of your application that defines process types and explicitly declares what command should be executed to start your app. Your Procfile will look something like this for engelsystem:

web: vendor/bin/heroku-php-apache2 public/

Since our folder named public that contains your JavaScript, CSS, images and index.php file, your Procfile would define the Apache web server with that directory used as document root.

Create the app

In this step you will create the app to Heroku.

Create an app on Heroku, which prepares Heroku to receive your source code:

$ heroku create
Creating sharp-rain-871... done, stack is cedar-14
http://sharp-rain-871.herokuapp.com/ | https://git.heroku.com/sharp-rain-871.git
Git remote heroku added

When you create an app, a git remote (called heroku) is also created and associated with your local git repository.

Heroku generates a random name (in this case sharp-rain-871) for your app, or you can pass a parameter to specify your own app name.

But Once you open http://sharp-rain-871.herokuapp.com/ we will not be able to view the site if there are database connections. We need to migrate the database using Cleardb

ClearDB MySQL

Migrating database

Creating your ClearDB database

To create your ClearDB database, simply type the following Heroku command:

$ heroku addons:create cleardb:ignite
-----> Adding cleardb to sharp-mountain-4005... done, v18 (free)

This will automatically provision your new ClearDB database for you and will return the database URL to access it.

You can retrieve your new ClearDB database URL by issuing the following command:

$ heroku config | grep CLEARDB_DATABASE_URL
CLEARDB_DATABASE_URL: mysql://bda37eff166954:[email protected]/heroku_3c94174e0cc6cd8?reconnect=true

After getting the cleardb database url we can import the tables by following command:

$mysql -u bda37eff166954 -h us-cdbr-iron-east-04.cleardb.net -p heroku_3c94174e0cc6cd8

than you well get a mysql prompt with connection to the database. Than you can import the tables using the following commands

mysql> source [path to engelsystem]/engelsystem/db/install.sql;
mysql> source [path to engelsystem]/engelsystem/db/update.sql;
mysql> exit;

Now the tables are migrated successfully.

Declare app dependencies

Since we have added the mysql database we need to add the dependencies also.

{
  "require": {
    "ext-mysql": "*"
  },
   "require": {
      "ext-gettext": "*"
    },
   "require-dev": {
      "heroku/heroku-buildpack-php": "*"
   }
}

The composer.json file specifies the dependencies that should be installed with your application. When an app is deployed, Heroku reads this file and installs the appropriate dependencies into the vendor directory.

Run the following command to install the dependencies, preparing your system for running the app locally:

$ composer update
Loading composer repositories with package information
Updating dependencies (including require-dev)
  - Installing psr/log (1.0.0)
    Loading from cache
...
Writing lock file
Generating autoload files

You should always check composer.json and composer.lock into your git repo. The vendor directory should be included in your .gitignore file.

Using ClearDB with PHP

Connecting to ClearDB from PHP merely requires the parsing of the CLEARDB_DATABASE_URL environment variable and passing the extracted connection information to your MySQL library of choice, e.g. MySQLi:

we need to modify it in the config/config.php file

$url = parse_url(getenv("CLEARDB_DATABASE_URL"));
$server = $url["host"];
$username = $url["user"];
$password = $url["pass"];
$db = substr($url["path"], 1);

$config = array(
    'host' => $server ,
    'user' => $username ,
    'pw' => $password,
    'db' => $db 
);

Deploy the app

All the steps are completed now we need to deploy it. Push the code to Heroku. For pushing pushing development branch we need to follow these commands.

$ git add -A
$ git commit -m "heroku deploy"
$ git push heroku development:master
Initializing repository, done.
Counting objects: 7, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (4/4), done.
Writing objects: 100% (7/7), 1.66 KiB | 0 bytes/s, done.
Total 7 (delta 0), reused 0 (delta 0)

-----> PHP app detected
-----> Setting up runtime environment...
       - PHP 5.5.12
       - Apache 2.4.9
       - Nginx 1.4.6
-----> Installing PHP extensions:
       - opcache (automatic; bundled, using 'ext-opcache.ini')
-----> Installing dependencies...
       Composer version 64ac32fca9e64eb38e50abfadc6eb6f2d0470039 2014-05-24 20:57:50
       Loading composer repositories with package information
       Installing dependencies from lock file
...
         - Installing monolog/monolog (1.9.1)
       Generating optimized autoload files
-----> Building runtime environment...
-----> Discovering process types
       Procfile declares types -> web
-----> Compressing... done, 57.4MB
-----> Launching... done, v3
       http://sharp-rain-871.herokuapp.com/ deployed to Heroku

To [email protected]:sharp-rain-871.git
 * [new branch]      development -> master

Now your app is successfully deployed you can view it here http://sharp-rain-871.herokuapp.com/

Englesystem

Development: https://github.com/fossasia/engelsystem

Issues/Bugs: Issues

 

 

Why should you use Heroku?

Last week I’ve dedicated most time to implement new heroku features to Open Event. Due to the fact that wasn’t easy tasks I can share my experience.

What is heroku?

Heroku is a cloud Platform-as-a-Service (PaaS) supporting several programming languages like Java, Node.js, Scala, Clojure, Python, PHP, and Go

Easy to deploy

what you need to do:

  1. Create account on heroku
  2. Download a heroku toolbelt to your enviroment.
  3. Go to your project directory(/open-event-orga-server)
  4. Sign in to heroku in your command line using your credentials
    $ heroku login
  5. Create app with name $
    heroku apps:create your_app_name

    after execution above command you will recive a link to your application

    http://your_app_name.herokuapp.com/
  6. Push latest changes to heroku
    $ git push heroku master
  7. If everythings is ok you can check results http://your_app_name.herokuapp.com/ (sometimes it does not work like we want 🙁 )

Easy to configure

To list/set/get config variables use:

$ heroku config
$ heroku config:set YOUR_VARIABLE=token123
$ heroku config:get YOUR_VARIABLE

or you can go to you application dashboard and make above operations

How you can get access to this variables using python langauges?

$ python

Python 2.7.10 (default, Oct 23 2015, 19:19:21) 

[GCC 4.2.1 Compatible Apple LLVM 7.0.0 (clang-700.0.59.5)] on darwin

Type "help", "copyright", "credits" or "license" for more information.

>>> import os

>>> your_variable  = os.environ.get('YOUR_VARIABLE', None)

>>> print your_variable
token123

I’ve used this to display current release in my python application(You need to generate a special API token and add it to config variables)

os.popen('curl -n https://api.heroku.com/apps/open-event/releases -H 
"Authorization: Bearer ' + token + '" -H 
"Accept: application/vnd.heroku+json; version=3"').read()

Easy to monitor

If something is wrong with your APP you need to use this command

$ heroku logs

it shows all logs

To see 10 latest releases use:

$ heroku releases

How you can set up Open Event to deploy to heroku?

  1. Clone https://github.com/fossasia/open-event-orga-server
  2. Go to directory of open event orga server(/open-event-orga-server)
  3. Add git remote
     heroku git:remote -a open-event
  4. You can check if open event is added to git remote
    $ git remote -v
    heroku https://git.heroku.com/open-event.git (fetch)
    heroku https://git.heroku.com/open-event.git (push)
    origin https://github.com/fossasia/open-event-orga-server.git (fetch)
    origin https://github.com/fossasia/open-event-orga-server.git (push)
  5. Now you can deploy changes to open-event application(You need a permissions 🙂 )

Why should you use a Heroku?

It’s great to deploy apps because you are able to share content in short time what I’ve done. Besides it’s very well documented so you can find there answers for most of your questions. Finally most of things you can configure using Heroku dashboard so it’s the best advantages of this tool.