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Install Docker on Linux Mint 17.2

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This post provides practical steps to setting up docker to run on Linux Mint 17.2, which is what I’m using on my development machine at the moment.

Before beginning, make sure you have remove any existing version(s) of Docker from your system.

First, add the Docker repository key

sudo apt-key adv --keyserver hkp://pgp.mit.edu:80 --recv-keys 58118E89F3A912897C070ADBF76221572C52609

Then create a new file for apt to find the Docker repository

sudo nano /etc/apt/sources.list.d/docker.list

Inside the docker.list file enter the following

# Ubuntu Trusty/Mint 17.2
deb https://apt.dockerproject.org/repo ubuntu-trusty main

Save and close the file. Now we want to get the latest updates from the new repository

sudo apt-get update

Once this finishes, you should now be able to install the latest Docker version

sudo apt-get install docker-engine

Once this has run, you can test the hello world docker image, which is tiny and quick to download

sudo docker run hello-world

 

Repairing a ThinkPad style rubberised finish

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Lenovo ThinkPads traditionally have a rubberised finish on the outer casing of the screen. My T500 is pushing 5 years old now, and the corners are warn away to the plastic beneath, so I have started looking into rapairing or replacing the rubberised finish on the laptop. After doing some googling I found people reccomending plasti-dip, which is a spray on finish that appears rubberised but can be peeled off as a thin film of plastic. Plasti-dip is available in the UK, but quite expensive and I’m not sure how well a “peelable” finish would work on a laptop.

Plasti-dip is intended for use on cars, which got me thinking about things like truck bed liner so I took a trip to Halfords (for those not in the UK, Halfords is a big chain of car and bike stores generally thought of as expensive but quick-and-easy). I ended up picking up black underseal and on a recommendation from a friend underseal for cars.

Lenovo ThinkPads rubberised finish is a matt black and quite resistant – the texture generates friction – while appearing quite smooth. I pulled out a scrap laptop from the collection that hasn’t made it to the computer graveyard yet and sprayed it in half; one side underseal the other bedliner.

Truck bedliner paint

Truck bedliner paint

The bedliner was much harder to get an even coat on, and even after several hours it wasn’t completely dry. It has a much coarser texture to it, making it a little unpleasant to handle the laptop but it does feel far more substantial in terms of the amount of protection it provides and the strenght of it.

The underseal came out a dark grey, not black, but was far easier to coat consistently. It’s actually a pretty close match to the Lenovo ThinkPad rubberised texture – so much so I had to get my ThinkPad out and put them side to side in order to spot the difference.

Car Underseal

Car Underseal

I’m now wondering about doing something with both paints using a stencil – but probably not something for my precious T500. For it, I’m looking at either using a light abrasive like oven cleaner to take off all of the rubberised finish, taping off the display lights, hinges and logo before respraying the whole thing in underseal or trying to touch up the areas that are affected.

 

side by side comparison

side by side comparison of underseal and truck bed liner on an old laptop

Linux Mint Docker “Error loading docker apparmor profile”

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I’ve recently been experimenting with Docker containers, but found there’s an error with installing it on Linux Mint:

2015/07/30 14:00:53 WARNING: Your kernel does not support cgroup swap limit.
Error loading docker apparmor profile: exec: "/sbin/apparmor_parser": stat /sbin/apparmor_parser: no such file or directory ()

It’s quite easy to solve, you just have to install app-armour:

sudo apt-get install apparmor

Then start the docker demon from the terminal to make sure it’s loading okay:

sudo docker -d

You should see something similar to the following:

2015/07/30 14:07:14 docker daemon: 1.0.1 990021a; execdriver: native; graphdriver: 
[67068605] +job serveapi(unix:///var/run/docker.sock)
[67068605] +job initserver()
[67068605.initserver()] Creating server
2015/07/30 14:07:14 Listening for HTTP on unix (/var/run/docker.sock)
[67068605] +job init_networkdriver()
[67068605] -job init_networkdriver() = OK (0)
2015/07/30 14:07:14 WARNING: Your kernel does not support cgroup swap limit.
2015/07/30 14:07:14 Local (127.0.0.1) DNS resolver found in resolv.conf and containers can't use it. Using default external servers : [8.8.8.8 8.8.4.4]
Loading containers: : done.
[67068605.initserver()] Creating pidfile
[67068605.initserver()] Setting up signal traps
[67068605] -job initserver() = OK (0)
[67068605] +job acceptconnections()
[67068605] -job acceptconnections() = OK (0)

 

Once it loads this far, you can use ctrl + c to exit and start the service. If you have any further errors you’ll need to investigate further. Then start the service using:

sudo service docker.io start

Setting up a Buildroot Environment on Ubuntu or Mint

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I’ve got a project that requires really fast boot times, so I’ve been looking into buildroot, which is a tool for building embedded Linux systems. When I started playing with the tutotials I noticed that I was getting errors with the make menuconfig command:

make menuconfig

...

/development/rpi_buildroot/buildroot/output/build/buildroot-config/conf.o
 *** Unable to find the ncurses libraries or the
 *** required header files.
 *** 'make menuconfig' requires the ncurses libraries.
 *** 
 *** Install ncurses (ncurses-devel) and try again.
 ***

In order to use buildroot on Ubuntu or Linux Mint the following packages need to be installed:

sudo apt-get install build-essential ncurses-base ncurses-bin libncurses5-dev dialog

After which you should be able to run make menuconfig without errors.

 

Fixing Raspberry Pi Arch ‘pacman-db-upgrade’ Permissions Error

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I’ve installed Arch Linux on the Raspberry Pi for the first time, and after getting the package manager pacman to update all of the software to the latest versions I’ve been getting the following error:

error: try running pacman-db-upgrade

When running the upgrade command this permissions error was returned:

ERROR: You must have correct permissions to upgrade the database.

After looking at several forum posts I discovered that the upgrade made my filesystem read-only. To fix this edit /boot/cmdline.txt and add the rw flag

nano /boot/cmdline.txt

selinux=0 plymouth.enable=0 smsc95xx.turbo_mode=N dwc_otg.lpm_enable=0 console=ttyAMA0,115200 kgdboc=ttyAMA0,115200 console=tty1 root=/dev/mmcblk0p6 rootfstype=ext4 elevator=noop rw rootwait

Your installation my have a different cmdline.txt file, but the important bit is the rw flag, usually placed after the root filesystem is declared.

For more information see this forum post: https://www.raspberrypi.org/forums/viewtopic.php?f=53&t=97657