Setup Simple Ruby on Rails App On Ubuntu 16.04 From Scratch

Rails is one of the most popular ruby framework out there. And now, I want to try to run the simple app on Ubuntu 16.04 machine. it’s for testing purpose.

First, update the system and install essential dependencies:

$ sudo apt-get update
$ sudo apt-get build-essential curl sudo vim

Install nodejs:

$ curl -sL https://deb.nodesource.com/setup_9.x | sudo -E bash -
$ apt-get install nodejs

Create a dedicated user for the app, for example, ubuntu user. And this also make the ubuntu user with sudo privilege and run the command without password. Which is useful to run command that needs sudo privilege in the next steps.

$ useradd ubuntu -m
$ echo 'ubuntu ALL=(root) NOPASSWD: ALL' >> /etc/sudoers

swith to ubuntu user and install GPG keys for install rvm:

$ su - ubuntu
ubuntu~$ gpg --keyserver hkp://keys.gnupg.net \ --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 \ 7D2BAF1CF37B13E2069D6956105BD0E739499BDB

Download and install rvm:

ubuntu~$ \curl -sSL https://get.rvm.io | bash -s stable

Install ruby interpreter with version 2.5.1, you might wanna change it with your preferable version:

ubuntu~$ source ~/.rvm/scripts/rvm
ubuntu~$ rvm install 2.5.1
ubuntu~$ rvm use 2.5.1 --default

Install rails with gem, and create new app without writing the Gemfile. Why? because everytime I create new app, I ended up facing errors with dependencies in Gemfile. So, it safe to setup new app without the Gemfile, we’ll create it manually later.

ubuntu~$ gem install rails
ubuntu~$ rails new app --skip-gemfile

Create the Gemfile:

ubuntu~$ touch ~/app/Gemfile
ubuntu~$ vim ~/app/Gemfile

Gemfile, fill these dependencies below into the file, save and exit:

source 'https://rubygems.org'
gem 'rails', '~> 5.2.1'
gem 'bootsnap', '~> 1.3.2'
gem 'tzinfo-data', '~> 1.2018.5'
gem 'listen', '~> 3.1.5'
gem 'sqlite3'

Now, install all the gems with bundle:

ubuntu~$ cd ~/app
ubuntu app~$ bundle install

Try run the rails:

ubuntu app~$ rails server -b 0.0.0.0

 

Linux machine Failed to hibernate, “system via logind: Sleep verb not supported”

So after using fedora 28 for a while. I tried to configure my power management using xfce power management system.

Looking at these power management settings, are very simple explanation. I set my machine to hibernate or sleep mode when inactive for 16 minutes.

Saved the settings. then I closed the laptop lid, so it started to be inactive until the next 16 minutes. Supposed to be hibernated.

But it did not, instead…

I opened up my laptop, and there is this error:

System via logind: Sleep verb not supported...

It turns out that the states of the machine are not available for hibernate. You can check them out with this simple command:

$ sudo cat /sys/power/disk
[disabled]

Now, that’s a problem. The machine cannot be hibernate, nor suspend if the output is disabled.

The solution is quite simple. Reboot the machine, then enter BIOS mode. This one is requires the BIOS setting, secure boot to be disabled.

Secure boot setting in BIOS

Switch the secure boot in BIOS setting to Disabled. Then reboot the system.

After I rebooted the system with secure boot disabled, the output of /sys/power/disk now is contains more than one, including suspend/hibernate.

$ cat /sys/power/disk 
[platform] shutdown reboot suspend test_resume

The machine’s power management system now can run the machine with hibernate mode.

Setup ftp that works with local user with vsftpd on ubuntu

Install vsftpd and start the service:

$ sudo apt-get install vsftpd -y
$ sudo systemctl start vsftpd.service
$ sudo systemctl enable vsftpd.service

Open vsftpd.conf file, and make sure these lines below are enabled:

$ sudo vim /etc/vsftpd.conf
...
...
local_enable=YES
chroot_local_user=YES

Create local user:

$ sudo useradd -s /bin/bash -md /srv/ftpuser
$ sudo passwd ftpuser

Make sure your user format is looks like this:

$ cat /etc/passwd
ftpuser:x:1000:1000::/srv/ftpuser:/bin/bash

Test your ftp user out:

$ ftp example.com

 

Install pulse secure linux 9 on Fedora 28

This installation is using pulse secure linux version 9 with rpm package ps-pulse-linux-9.0r1.0-b739-centos-rhel-64-bit-installer.rpm

$ sudo dnf install compat-libicu57-57.1-2.fc28.x86_64
$ sudo dnf install libgnome-keyring
$ sudo rpm -i ps-pulse-linux-9.0r1.0-b739-centos-rhel-64-bit-installer.rpm

Create vpn shortcut (optional):

$ sudo touch /usr/bin/vpn
$ sudo vim /usr/bin/vpn

Fill with this script below:

#!/bin/bash

export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/pulse
/usr/local/pulse/pulseUi

Make it executable:

$ sudo chmod +x /usr/bin/vpn

Now, you can just open the app with command vpn

Run containerized python app in kubernetes

Run containerized python app in kubernetes

First of all we need a Docker image that will be run inside the kubernetes cluster. So I assumed that we already have a kubernetes cluster. So the next we do is to build the docker image or you can use your docker image yourself.

But in this tutorial, I will show you how to run the containerized python app with my version from the start.

What we need

These applications should be installed on your local machine before get started. In my case, I use my remote server with ubuntu 16.04 installed.

1. Docker
2. Kubernetes

Setup Kubernetes on Ubuntu 16.04

Build docker image

Let’s begin with clone of of my repo that contains Dockerfile to build the image:

$ git clone https://github.com/muffat/docker-images.git
$ cd docker-images/simple-python-app/
~/docker-images/simple-python-app$ sudo docker build -t simple .

Wait until the process successfully built. And then you’ll see a new docker image when you type this command:

$ docker images

Push docker image to repository (docker hub)

Before pushing the image to docker hub, we need to tag the successfully built image.

$ docker tag fbd064597ae4 cerpin/simple:1.0

Push the image

$ docker push cerpin/simple
The push refers to a repository [docker.io/cerpin/simple]
bc69ee44ef1a: Pushed 
7957c9ab59bb: Pushed 
2366fc011ccb: Pushed 
b18f9eea2de6: Pushed 
6213b3fcd974: Pushed 
fa767832af66: Pushed 
bcff331e13e3: Mounted from cerpin/test 
2166dba7c95b: Mounted from cerpin/test 
5e95929b2798: Mounted from cerpin/test 
c2af38e6b250: Mounted from cerpin/test 
0a42ee6ceccb: Mounted from cerpin/test

After it pushed. You will have the docker image in the repository and ready to use it:

cerpin/simple:1.0

Run the image in kubernetes

First of all, I’m not a big fan of kubectl command, so I usually make a symlink to create the shorter version of kubectl:

$ sudo ln -s /usr/bin/kubectl /usr/bin/cap

Run the docker image in kubernetes

$ cap run simple --image=cerpin/simple:1.0

Then the container will be created. Just wait a moment until the state becomes Running

$ cap get pods
simple-79d85db8b9-466kd 1/1 Running 0 26m

After it’s ready, expose the service with port 5002 to become LoadBalancer. So the service will be accessible from the outside world

$ cap expose deployment simple --type=LoadBalancer --port=5002

Check the service that has been exposed:

$ cap get services
simple LoadBalancer 10.105.115.251 <pending> 5002:31969/TCP 21m

You will see that the service will have forwarded port to 31969 from 5002.

If you open up the browser and navigate to http://external IP:31969, you’ll see the app is running.

Or, just use a curl command instead:

$ curl http://167.xxx.xxx.xxx:31969
{
"message": "welcome", 
"status": "ok"
}