Author: masnun

NodeJS

Deploying a NodeJS 5 app with nginx on Ubuntu

Post author By masnun
Post date January 1, 2016

In this blog post, we would follow the steps to deploy a NodeJS app using the latest version of Node with nginx on Ubuntu.

Installing Node.js 5

The official repository on Ubuntu doesn’t ship the latest version of NodeJS yet. So we will use a third party source to install it from:

curl -sL https://deb.nodesource.com/setup_5.x | sudo -E bash -
sudo apt-get install -y nodejs

1 2	curl -sL https://deb.nodesource.com/setup_5.x \| sudo -E bash - sudo apt-get install -y nodejs

Using PM2

I love PM2 for keeping my node apps alive. If you didn’t know, PM2 is an awesome tool that launches Node processes and monitors them. If it crashes, it can restart them. PM2 is very easy to setup and use. It’s also quite feature packed.

We would setup PM2, launch our app with it and then generate a launch script so PM2 itself is started on system reboot.

npm install -g pm2 # Install PM2
pm2 start index.js # Start an app
pm2 startup ubuntu # Create a launch script for PM2

npm install -g pm2 # Install PM2

pm2 start index.js # Start an app

pm2 startup ubuntu # Create a launch script for PM2

Nginx Configuration

Now that the app is running, it’s time to setup nginx as our reverse proxy. Here’s the default configurations I use:

server {
    listen 80;


    location / {
        proxy_pass http://localhost:3000;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        proxy_set_header Host $host;
        proxy_cache_bypass $http_upgrade;
    }
}

server {

listen 80;

location / {

proxy_pass http://localhost:3000;

proxy_http_version 1.1;

proxy_set_header Upgrade $http_upgrade;

proxy_set_header Connection 'upgrade';

proxy_set_header Host $host;

proxy_cache_bypass $http_upgrade;

}

Javascript NodeJS

Live Debugging Webhooks with Ngrok

Post author By masnun
Post date January 1, 2016

ngrok is an awesome service – it creates secure tunnels to localhost. With ngrok, you get a url like http://459387bb.ngrok.com which is actually tunnel to a port to your local machine. So any request you make to that url is served by the app that you run on that port.

I know there are many cool services to debug webhooks like Requestbin – but the main benefit of ngrok is the app keeps running on your app, serving live traffic. So you can debug it in real time.

In this blog post, we would use a Node.js server with ngrok to serve Mandrill webhook requests.

Installing ngrok

Downloading and installing ngrok is pretty easy as you can find here — https://ngrok.com/download. However, if you’re on OS X and use Homebrew, you can install it with just one command:

brew install ngrok

1	brew install ngrok

Creating a Node.js App

Here’s a sample Node app that listens on port 3000 and parses the mandrill payload using body-parser package.

"use strict";

//----> Require
var bodyParser = require("body-parser");
var express = require("express");

//----> Bootstrap
var app = express();

//----> Middlewares
app.use(bodyParser.urlencoded({
    extended: false
}));

//----> Routes

// Just a hello world
app.get("/", (req, res) => {
    res.send("Hello world!");
});

// Mandrill webhook
app.post("/webhooks/mandrill", (req, res) => {
    var payload = req.body['mandrill_events'];
    var events = JSON.parse(payload);

    events.forEach((item) => {
        var event = item['event'];
        var email = item['msg']['email'];
        var doc = {
            "event": event,
            "email": email
        };

        var json = JSON.stringify(doc);
        // Do some more processing

    });

    res.send("OK");
});


//----> Run the server
var server = app.listen(3000, function () {
    var host = server.address().address;
    var port = server.address().port;

    console.log('App listening at http://%s:%s', host, port);
});

"use strict";

//----> Require

var bodyParser = require("body-parser");

var express = require("express");

//----> Bootstrap

var app = express();

//----> Middlewares

app.use(bodyParser.urlencoded({

extended: false

}));

//----> Routes

// Just a hello world

app.get("/", (req, res) => {

res.send("Hello world!");

});

// Mandrill webhook

app.post("/webhooks/mandrill", (req, res) => {

var payload = req.body['mandrill_events'];

var events = JSON.parse(payload);

events.forEach((item) => {

var event = item['event'];

var email = item['msg']['email'];

var doc = {

"event": event,

"email": email

};

var json = JSON.stringify(doc);

// Do some more processing

});

res.send("OK");

});

//----> Run the server

var server = app.listen(3000, function () {

var host = server.address().address;

var port = server.address().port;

console.log('App listening at http://%s:%s', host, port);

});

Tunneling Traffic

Once we have the app running on port 3K, we can ask ngrok to create a tunnel for us. For this we just need to pass the port number to the ngrok command:

ngrok 3000

1	ngrok 3000

We would get an url soon afterwards. We can use this url to POST requests. In our case, go to your Mandrill account and create a webhook. Mandrill will send events to this url and it will be served by your app, running locally on your machine. You can make changes to the codes and restart anytime.

Awesome, no?

Python

Homebrew & Pyenv: Installing PyQT5 with Python3 on OSX

Post author By masnun
Post date December 26, 2015
3 Comments on Homebrew & Pyenv: Installing PyQT5 with Python3 on OSX

There was a time back in 2014 and earlier when PyQT5 installation was not straightforward and needed manual compilation. When searching on Google, still those posts come up on top results. But nothing to worry about, things have changed – it’s now quite simple.

Installation

If you are not already using Homebrew, you should start using it. Once Homebrew is installed, let’s install PyQT5 with this single command:

brew install pyqt5

1	brew install pyqt5

Verifying Installation

Let’s take a sample PyQT5 code as example and run it. For examples, I usually pick one up from the excellent PyQT tutorials on zetcode.com. Here’s one:

#!/usr/bin/python3
# -*- coding: utf-8 -*-

"""
ZetCode PyQt5 tutorial

In this example, we create a simple
window in PyQt5.

author: Jan Bodnar
website: zetcode.com
last edited: January 2015
"""

import sys
from PyQt5.QtWidgets import QApplication, QWidget


if __name__ == '__main__':

    app = QApplication(sys.argv)

    w = QWidget()
    w.resize(250, 150)
    w.move(300, 300)
    w.setWindowTitle('Simple')
    w.show()

    sys.exit(app.exec_())

#!/usr/bin/python3

# -*- coding: utf-8 -*-

"""

ZetCode PyQt5 tutorial

In this example, we create a simple

window in PyQt5.

author: Jan Bodnar

website: zetcode.com

last edited: January 2015

"""

import sys

from PyQt5.QtWidgets import QApplication, QWidget

if __name__ == '__main__':

app = QApplication(sys.argv)

w = QWidget()

w.resize(250, 150)

w.move(300, 300)

w.setWindowTitle('Simple')

w.show()

sys.exit(app.exec_())

Run it using:

python3 filename.py

1	python3 filename.py

If you get a nice looking small window – it worked!

Integrating with Pyenv

I am a big fan of pyenv and use it for running different versions and flavours of Python. If you use pyenv too, chances are you have your own version of Python installed through it. However, the brew formula that installs PyQT5 depends on another formula python3 – homebrew’s own Python 3 installation. When we install PyQT5, this formula is used to install the bindings, so the bindings are only available to this particular Python 3 installation and unavailable to our pyenv versions.

We will discuss two potential solutions to this issue.

Switching to `system`

One simple work around is to use the Python 3 version installed by Homebrew. We can ask pyenv to switch to the system version whenever we’re doing PyQT5 development.

pyenv global system
python3 filename.py

1 2	pyenv global system python3 filename.py

We can create an alias to quickly switch between Python versions. I have this in my .zshrc:

alias py2="pyenv global 2.7.8"
alias py3="pyenv global 3.5.0"
alias pysys="pyenv global system"

alias py2="pyenv global 2.7.8"

alias py3="pyenv global 3.5.0"

alias pysys="pyenv global system"

This way is very quick and simple but we miss the benefits of using pyenv.

Adding Site Packages

Alternatively, we can add the site-packages for this homebrew installed python 3 to our pyenv installation of python 3. Since both installations were built on the same machine and OS, the bindings should work correctly. We would be using .pth files to do this.

Let’s first find out the site-packages for the homebrew installation:

brew info python3

1	brew info python3

We would notice a message like:

They will install into the site-package directory
  /usr/local/lib/python3.5/site-packages

1 2	They will install into the site-package directory /usr/local/lib/python3.5/site-packages

That is the site-packages for this version.

Now let’s find our pyenv python3’s local site directory:

# Switch to pyenv python first
python -m site --user-site

1 2	# Switch to pyenv python first python -m site --user-site

Now create a homebrew.pth file in that directory and put the previously found site packages path there.

Let’s create the file:

# In my local site directory for pyenv

vim /Users/masnun/.local/lib/python3.5/site-packages/homebrew.pth

# In my local site directory for pyenv

vim /Users/masnun/.local/lib/python3.5/site-packages/homebrew.pth

And put these contents:

/usr/local/lib/python3.5/site-packages

1	/usr/local/lib/python3.5/site-packages

Save and exit. Now you should be able to just use:

python filename.py

1	python filename.py

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