Docker Fails to Install: Ubuntu Xenial - 16.04

 Something that impressed me from the get-go about Docker was how simple it turns out to be to install and get the engine running on most platforms.

 Then the other day I got stuck trying follow their simple instructions to install it on Ubuntu 16.04 Xenial and if you have faced this - you would have tried all manner of things with package repositories, etc as well. 

 The following is an example of the related discussions which could solve your problem: 

• https://askubuntu.com/questions/1030179/package-docker-ce-has-no-installation-candidate-in-18-04
• https://unix.stackexchange.com/questions/363048/unable-to-locate-package-docker-ce-on-a-64bit-ubuntu 
• https://www.digitalocean.com/community/tutorials/how-to-install-and-use-docker-on-ubuntu-16-04
• https://medium.com/@randima.somathilaka/docker-engine-install-fails-in-ubuntu-3e70762c2187
• https://www.liquidweb.com/kb/install-docker-ubuntu-16-04/
  

 

However - note that my problem was actually a simple but subtle one. and none of the above worked for me until I chanced upon this post: 

https://forums.docker.com/t/installation-failure-ubuntu-16-04-lts/43667

Thanks to madsivas! I had been trying to install on the i386 version - once I switched to the amd64 one, everything just worked.

Accessing files from a USB drive on non-GUI Ubuntu

Ubuntu Desktops transparently make available the files on a USB drive as a folder on the user's desktop. But with Ubuntu server and no GUI, the same can appear challenging. However, Ubuntu makes it really easy:

All you do is plug in the device as usual. Ubuntu may display some logging on the current console to indicate USB registration. Now if you want the files and folders in the drive to appear in folder called called '/test' under your home folder - simply do the following:
mount /usr/dev/sda1 /test (provided "/test" exists on your system.)

Another option is to try the following:
ls /media

If your USB hard drive had been correctly inserted and registered, you should see under media, a list of the currently inserted USB devices including the one you want to access, as folders. You can simply change directories and access files under the relevant folder

Dell Latitude C640, Ubuntu and WPA2

The Problem:
I have a Dell Latitude C640 which had Ubuntu Feisty Fawn running on it. With my older Linksys WRT54G, everything was going fine, albeit with less security since I could only manage WEP on it. Then a few weeks back the router flamed out and I had to buy a new one.

Interestingly - for those in the market for the new Linksys router you may be confused by a Linux friendly open source model and another Windows compatible one. The specs do not help you understand why they should be different and I figured out only after some Googling what the mystery behind the brand separation was...

Now the new router supports WPA2 and I had to have that running over my wireless network. But here I have an embarrassing problem. While my Windows based Dell Latitude D810 is happily running over the same network, Ubuntu is just not doing that well.


The Solutions:?
Unfortunately no solutions so far. These are some of the things I've tried:

* Removed Network Manager and replaced it with wicd. According to some posts this problem could be due to a problem with Network manager trying to drop WPA2 connections and reconnecting constantly. It did seem to help initially (I could get intermittent connectivity) but not anymore
* Upgrade to Gutsy Gibbon. This has improved a lot of things but not connectivity to a WPA2 wireless network.

More coming up on this investigation...

Ubuntu and VMWare VM Copies

The Problem:
I had created Ubuntu Server based virtual machine through VMWare Server sometime back and was in the process of creating two Ubuntu servers that would need to run simultaneously in a LAN. Each VM was using NATed networking and were getting the IP addresses through DHCP. Keeping the original as it was, I created 2 copies of the virtual machine files. As per VMWare recommendations, on startup for each new VM, I had VMWare create a new UID to prevent confusion.

I was pleasantly surprised to find that everything worked perfectly when I brought up each of the servers up separately but then when I brought both up, the one that came up second, started having network issues - specifically there seemed to be a IP / MAC address conflict between the 2 machines.

Initially I thought it was a VMWare issue. Perhaps VMWare was not creating a unique MAC address for the virtual machines when I copied them across. The vmx file which stores the VM meta information seemed to be the potential culprit and I all that was possible to do to make sure that the information in there was good. But eventually I had to admit that VMWare was handling this part of its functionality without a flaw. So where was the problem? Who or what was storing MAC addresses that was eventually leading to the conflict?

The Solution:
The answer was simple when I finally found it somewhat indirectly at the following posting. The two copies were being told by VMWare about their physical MAC addresses correctly. However, Ubuntu (V6.10) remembers the mapping between hardware ethernet addresses and the ethN name that they should get through the information in the /etc/iftab file. Since I had the exact same value for MAC address in all three iftab contents I kept getting conflict reports. Once I edited the contents in the 2 VM copies and matched them with the values configured in the vmx file everything started working fine.

Note the updates in this bug report though.

UPDATE: Its important to realize that by default in bridged networking, VMWare will select the first available interface to bridge. This may not be the interface you want to bridge over resulting in problems. Use the vmnetcfg.exe tool on Windows to select the interface to bridge over.

Edubuntu

Had a great experience with Edubuntu the other day and I felt I just had to write about it.

The Problem:
I'm volunteering at the local Hindu Mandir where they have started a montessori school. They had recently received 20 PCs from a corporate sponsor and wanted to use them for their older children. The PCs were fairly old and had Windows NT loaded on them and the teacher in charge, Sheela, could not figure out a way to use these machines to entertain her 4 year+ olds. Her requirements were as follows:

• The PCs were to be easy to start, stop, login etc - technically inexperienced teachers and children would be operating them
• They had to have some stuff loaded on them to make them into simple entertainment centers
• They had to be robust - not just from the hardware perspective but immune to children accidentally and otherwise deleting, modifying and moving things around, etc (Its amazing how quickly a child can disable a PC by simple deleting key shortcuts from a desktop)

A Solution:
When Sheela approached me, I thought first of Ubuntu. Running Windows NT meant it would be relatively hard to get the latest software to run on the machines and could also attract licensing problems. On the other hand, the desktop Ubuntu had everything already installed on it like games etc. However, Ubuntu does not make a PC immune to kids banging away on keyboards. So I started looking around for a better alternative and thats when I found the Edubuntu Live CD downloads.

With Ubuntu 7.04 (Feisty Fawn) Sheela could:

• Sheela could simply boot off the CD I created for her and have an attractive, easy to use system with all she needed for her class, and more (of course I was lucky that the PCs had BIOSes that allowed me to set the boot order and also to boot from their CDROM drives.)
• Have a whole host of educational open source applications available on this live CD apart from several popular computer games like Nibbles, Chess, etc
  
• The best part was that now, all she needed to get going was a PC with a working CDROM drive - it didn't matter even if the HDD was dead! And if the kids screwed up something, you simply rebooted to have a pristine system going again!!
• No need to create users and maintain them - the live CD just gives you a default login without a login screen to have to go through