Installing native Docker on AlmaLinux

 

Today, I had to reinstall a Docker host, which was previously running on my beloved CentOS 8. As that is quickly approaching it's end, I decided to give AlmaLinux a try. To use it as a Docker host, I had to install native Docker. (I prefer to use native Docker over the one, that is part of the distribution.) So, according to https://get.docker.com/, this is supposed to work as follows:

    curl -fsSL https://get.docker.com -o get-docker.sh

    sudo sh get-docker.sh

In the past, I did that on CentOS, quite a lot, so I expected it to work out of the box. Unfortunately, that didn't quite work, and failed with the error message below:

    sudo sh get-docker.sh

# Executing docker install script, commit: 7cae5f8b0decc17d6571f9f52eb840fbc13b2737 ERROR: Unsupported distribution 'almalinux'

In other words, the Docker installer isn't quite uptodate. Fortunately, fixing a shell script isn't that big of a problem, and I got it running by applying the following patch:

[jwi@gitjndhost ~]$ diff -ub get-docker-orig.sh get-docker.sh --- get-docker-orig.sh 2021-04-28 12:10:12.477498011 +0200 +++ get-docker.sh 2021-04-28 12:03:23.300011495 +0200 @@ -342,7 +342,7 @@ esac ;; - centos|rhel) + centos|rhel|almalinux) if [ -z "$dist_version" ] && [ -r /etc/os-release ]; then dist_version="$(. /etc/os-release && echo "$VERSION_ID")" fi @@ -427,8 +427,8 @@ echo_docker_as_nonroot exit 0 ;; - centos|fedora|rhel) - yum_repo="$DOWNLOAD_URL/linux/$lsb_dist/$REPO_FILE" + centos|fedora|rhel|almalinux) + yum_repo="$DOWNLOAD_URL/linux/centos/$REPO_FILE" if ! curl -Ifs "$yum_repo" > /dev/null; then echo "Error: Unable to curl repository file $yum_repo, is it valid?" exit 1

Note: In order to overcome minor dependency conflicts with podman, buildah, and the like, I also had to issue the command

    sudo dnf -y remove runc

        

Installing CentOS 7 Prerelease on VMWare

Hi,

if you haven't heard the news: A prerelease of CentOS 7 is out. This is important, because:

1. CentOS 7 is a major release and will be the base of the Linux Distro that people like me will be using in the next years on servers. (Yes, I do know about Ubuntu 14.04 LTS, OpenSUSE Whatever, Debian Something, etc. However, that is most likely not what I will be using. Logically, so won't do people like me. End of discussion.)
2. Quite a few things have changed since CentOS 6. In particular, much has been adopted from recent Fedora versions: 
1.  The new Anaconda Installer. (I am personally not overly happy with it. The old one worked quite well for me, but I had my share of trouble with the new one. In particular, I am less than enthusiastic about how Disk Partitioning works nowadays. OTOH, this version of Anaconda (the one distributed with the CentOS 7 Prerelease) is a step forward in that aspect. Perhaps, more people like me had similar trouble.)
2.  GNOME 3: Well, this one will definitely be the cause of a major uproar on the Red Hat Continent. I readily admit that I was one of the people who initially went with MATE as a GNOME 2 replacement, so as to avoid GNOME 3. However, in the meantime, I've learned to live with it and can even appreciate some features like the enhanced keyboard control. The one thing I am still missing is the pictures screenblanker, though. I learned to live with xscreensaver, although this still smells like a very ugly hack.) Like it, or not, people like me (c) will have to face it.
3.  This prerelease was published not even one weak after the release of RHEL 7. Compare that to the months we had with some minor versions of CentOS 6. So, we benefit from Red Hat adopting CentOS. Good news!

So, what is this posting about?

•  I won't cover generic aspects of installing CentOS, or Fedora. I'll assume that you have installed either of which before and have a rough idea of what I am talking about. In particular, I assume that you know what a network installation is, because right now this is the only installation method available through an ISO image. (Forget "Live DVD", or whatever else you have hoped for.)
• I will, hovever, concentrate on installing this very special prerelease version, because it is not quite like installing an official version. (Neither is it overly complex, though.) Hopefully, I'll also cover what has changed since version 6.

 If that is interesting for you: Read on. If not: I am sorry! Google (Planet Apache, or whatever else brought you here, did wrong and is to blame).

So, what's to do?
Download the ISO Image from http://buildlogs.centos.org/centos/7/os/x86_64-20140614/images/boot.iso and save it, for example as "centos7-netinstall.iso".

1. Create a new VM (My Parameters were "I will install the operating system later.", "Guest operating system=Linux", Version="CentOS 64-bit", Maximum disk size=30GB, Memory=3072GB. Everything else was as suggested by VMWare Player 6.0.2 build-1744117.
2. Select Virtual Machine Settings, CD/DVD (IDE). Enable "Connect at power on" and "Use ISO Image file". Select the file you downloaded in step 1.
3. Start up the created VM. From the boot menu, select "Install CentOS 7". (You may as well test the media, but you did check the MD5 Sum anyways, did you? :-) At least, you know the difference... (Remember that "won't cover generic aspects" above?)
4. Hopefully, the Anaconda graphical installer will come up. (At least, it does so on a VMWare machine. I'd never hope so on a machine with an NVIDIA or AMD graphics card. Don't expect me to help you with that crap.  I'm all with Linus on that. :-)
5. Select your language (Safe choice is, of course,"English-US").
6. Anaconda will notify that  this is prerelease, unstable software. You knew that anyways, so click on "I want to proceed."
7. The Anaconda "Installation Summary" screen will come up. This will be an unknown thing (Remember: New Anaconda) for a lot of people, so here's a screenshot:
   
   
   
   
   The important thing to keep in mind is the order of the following steps.
8.  Start with the Keyboard. (You're likely to use that in the following steps.) Click on "Keyboard" (Not the small keyboard icon, but the big icon, or the word.) Click on the "+" sign, and select your favourite keyboard layout. (In my case "German, Germany, Eliminate dead keys".) Remove any unwanted layout by clicking on it, and clicking on the "-" sign. Finish by clicking on "Done" in the upper left corner. (Who the heck came up with that? Anyways, remember the location.)
9. The next thing you're gonna need is the network. (Most likely, you are currently "Not Connected".) Click on "Network & Hostname". Click on "Off" in the upper right corner to enable networking. Enter a meaningful host name. (I choose "c7wm96.mcjwi01.eur.ad.sag". Avoid "localhost.localdomain".) Click on "Done". (Upper left corner, remember?)
10. Now we can edit "Date & Time", aka time zone. I choose "Europe/Berlin".
11. If you need that (You don't, really...), click on "Language Support" and select additional languages.
12. The most obvious trap is the "Installation Source" (Hopefully, it won't be in the official releases, which will select an URL automatically): Click on that, enable "On the network", and enter the URL buildlogs.centos.org/centos/7/os/x86_64-20140614/. If you need to use an HTTP Proxy, click on "Proxy setup". Enter your proxy host name and port (in my case "httpprox.hq.sag:8080") Click on "Add". Click on "Done". Wait a few seconds until you see "Downloading package metadata", or the like. If you do see something like "Error setting up Base Repository", changes are that the URL is wrong. Fix it, and retry. Wait a few seconds more until downloading the package data and checking for dependencies has finished.
13. Next, go to "Software Selection". The default is "Minimal Install". This is fine, if you are happy with a server that has no X11 enabled. I choose "Server with GUI" instead, to make my colleagues happy. On the right hand side, you can choose to have KDE installed addizionally. (AFAIK, no support for MATE, Cinnamon, LXDE, whatever. No idea, whether that will come.) You might wish to deselect LibreOffice, if you manage to do that. Click on "Done". Wait a few seconds until the message "Checking for software dependencies" disappears.
14. Another, somewhat difficult step is the "Installation Destination". Click on that. If you need "Custom Partitioning", enable "I will configure partitioning." below. (The default is "Automatically configure partitioning.", The presence of this option is what has changed since Fedora 20, and I consider this to be a major improvement.) Click on "Done", even if you're actually not. If the window for "Manual Partitioning" appears, select your desired partition type ("Standard Partition", "BTRFS", "LVM") and add a few partitions by clicking on the "+" button. I create the following partitions (in that order):
1. /boot with a Capacity of 500MB.
2. Swap with a Capacity of 6GB. (I need that much, because the Oracle Installer wants 8GB of physical memory, but accepts Swap as a replecement.)
3. / with a Capacity of 8 GB.
4. /home with a Capacity of 16.21GB
Click on "Done". Click on "Accept Changes". If no error messages can be seen on the "Installation Summary" screen, then you have mastered the major hurdles.

• Click on "Begin Installation".
• Regardless of the ongoing installation, click on "Root Password". Enter a meaningful, and secure, root password. Repeat it. Click on "Done". (You never even considered to enter a weak password, did you? Well, if you did: Click on "Done" twice. :-)
• The installation is still ongoing. Click on "User Creation". Enter a real name and a login name, enable "Make this user administrator" (The option will actually add the created user to the "wheel" group, which has permissions to use "sudo"). Enter a password and repeat it. Click on "Done" twice. (Oops, your passsword is secure: Then once is sufficient.)
• Keep in mind that this is a "network installation": Anaconda will download each and every single RPM to install (In my case about 1200.), so the process will take time. OTOH, with a fast network (DSL, or something like that) it won't take much longer than installation from a DVD.
• Once the actual installation is finished, you'll be asked for a reboot. Confirm that, and the new system comes up. Almost done. One minor step to perform: Accept the GPL license, and accept another reboot. (No, this isn't Windows, but still....)

If you got this far, then you've got a system running CentOS 7 Prerelease. Congratulations. Unfortunately, one thing is still left. Your system doesn't have a valid Yum configuration. (Convince yourself by running

  sudo yum repolist all

Oops, you need a terminal window to do that. That's no problem if you are running KDE or any other desktop that you are used to. If it's GNOME 3, and you are not, here's what to do: Press, and release, the "Windows" key. (No, this is still not Windows, but anyways. If it helps, call it the "Linux" key.) Press, and release, the following keys, in that order: "t", "e", "r", "m", and Enter. At that point, a GNOME Terminal window should appear. (Or, in theory, any other desktop application containing the word "term". However, you had no chance to install "xterm" do far. :-) Using the command

  sudo yum vi /etc/yum.repos.d/centos7-prerelease.repo

create a new file with the following contents:

  [centos7-prerelease]
  name=CentOS 7 Prerelease
  url=http://buildlogs.centos.org/centos/7/os/x86_64-20140614/
  enabled=1
  priority=1
  gpgcheck=0

And now (I am not avoiding any flame wars today :-) you can do

  sudo yum install emacs emacs-nox gcc make binutils kernel-headers

A final note on the VMware tools: Anaconda did automatically install "open-vm-tools-desktop". So, mouse integration, copy and paste, etc. worked immediately for me. No need for a seprate installation.