Questions[amazon-ami](server)

What is the current way of installing Docker on an AWS EC2 instance running the AMI? There has been an announcement of Docker Enterprise Edition and now I want to know if anything has changed. Until now, I have been using yum install docker and do get a Docker versioned at 1.12.6, build 7392c3b/1.12.6 right now (3/3/2017). However, the Docker repository on GitHub tells me that there are already newer releases.

I remember the official Docker (package) repository having a package named docker-engine replacing docker some time ago and now they seem to split the package up into docker-ce and docker-ee, where e.g. "Docker Community Edition (Docker CE) is not supported on Red Hat Enterprise Linux." [Source]

So is or will it still be correct to use the above to get the latest stable Docker version on EC2 instances running the AMI or do I need to pull the package from somewhere else (and if so which one, CE or EE)?

I just attached another ebs volume to running instance. But how do I access the volume? I can't find the /dev/sda directory anywhere. Where should I look?

After Amazon's Aug 8 outage, all (EBS based) AMIs stopped working for many users. This is due to corruption of some sectors in snapshots that the AMIs are based on.

However, Amazon created recovery snapshots where the disk problems should be fixed. Those are named along the lines of "Recovery snapshot for vol-xxxxxxxx".

I created a new AMI from recovery snapshot which worked fine, but instances launched from this new AMI do not work: their state is "Running", but I cannot ssh into the machine nor access any of the web services that should be running there. It boils down to this (from System Log, accessible through AWS management console):

EXT3-fs: sda1: couldn't mount because of unsupported optional features (240).

EXT2-fs: sda1: couldn't mount because of unsupported optional features (244).

Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(8,1)

I've mounted a volume created from that recovery snapshot in a another server on AWS, and everything looks quite normal though. For example, fsck says:

$ sudo fsck -a /dev/xvdg
fsck from util-linux-ng 2.17.2
uec-rootfs: clean, 53781/524288 files, 546065/2097152 blocks

In one of the AWS forum discussions, I found this advice from someone with similar problems:

A work around will be to make a volume from the snapshot and attach it to a running instance, use fsck --force to force the checking of the filesystem and once cleared, you can make a snapshot and use it for the AMI.

But I don't know how to force fsck on Ubuntu (11.04):

$ sudo fsck --force /dev/xvdg
fsck from util-linux-ng 2.17.2
fsck.ext3: invalid option -- 'o'

Anyone know how to force file system check on the volume on Ubuntu? Any other ideas on how to launch working instances that are based on the recovery snapshot?

Right now it looks like it might be quicker to just start over from a clean Ubuntu AMI and re-setup all our services. :-( But of course I would prefer not to do that if there's any way to get the recovery snapshot to actually work.

I have been poking around Amazon EC2, and am a little confused on some of the terminology. Specifically with regard to AMI, snapshots and volumes, and an EBS

Please correct me if I am wrong, or fill in any serious gaps in my following statements:

• An AMI (Amazon Machine Image) is a full 'disk' capture of an operating system and configuration. When you launch an instance, you launch it from an AMI

• An EBS (Elastic Block Storage) is a way to persist the state of any modifications you made once booting from a given AMI. In my mind, this is sort of like a diff on the final state of your instance vs the AMI.

• A snapshot is ... well, I'm not sure. I can only assume it is a snapshot of a specific instance, but it is not clear to me how this differs from the state stored in an EBS. How is a snapshot different from creating an EBS AMI from an existing instance?

• A volume is ... it would seem mounted disk space into which an AMI/EBS pair is loaded? I'm not sure on this one either. I can see (from the AWS Console) that you can create a volume from a snapshot, and that you can attach/detach volumes, but it isn't clear to me why or when you would do that.

I've downloaded the Amazon Ubuntu EC2 AMI images (from http://uec-images.ubuntu.com/releases/10.04/release/) and I am trying to run it locally on my linux desktop. Is it possible to run the AMI using VirtualBox? Is some other virtualization software required?