Red Hat 7 or Atomic Host for containers ?

Latest response

Hi all,

which solution, Red Hat 7 or Atomic Host would you use for working with containers ?
From the documentation I can see that both servers can do that but ... what is the difference ?
What can do one and not the other ?
Any practical examples ?

Best regards
Przemek

Responses

Both will host containers but if you are creating/testing containers you should be using RHEL 7 as you will have the packages available to you to develop container offerings, you can then deploy these offerings to Atomic Host.

The benefit to using atomic host is that it uses rpm-ostree to provide an immutable base OS that is upgraded using 'atomic' updates which provides a fully managed base OS. This is a very worthwhile feature and something you will be wanting if you plan to have a lot of Atomic Hosts (makes patching far less laborious!).

The downsides I have come across with Atomic Host are that it is a separate license, so if you are hosting on virtual infrastructure you will need to license twice if you also host RHEL on that infrastructure. Atomic patching also isn't currently supported on Satellite 6 (apparently coming in future), so patching Atomic Host in enterprise is a little more tedious.

I have decided to build a container host specific RHEL7 image (minimal packages installed) that I will use in place of Atomic Host until the above issues are resolved.

Hi PixelDrift.NET,

thanks for your comments. From your description it looks like RH 7 is definitely way to go. Thanks again :-)

Hi Przemyslaw,

The Getting Started Guide for Atomic Host contains an Overview of the differences between RHEL 7 and RHEL Atomic:

In general, RHEL would be a good choice for testing where you designate a part of it for the containers and the rest you use as you normally do, and then use Atomic for production. Atomic is leaner and its idea is that you only need to "worry" about managing the containers while the host system is immutable, read-only (most of it) and can be upgraded with one command: "atomic host upgrade".

However, a few recent changes made it easier to use Atomic itself as a testing environment:

  • The "ostree admin unlock" command, run directly in the terminal will grant you more flexibility with the ostree but the changes won't persist after a reboot.

  • The "rpm-ostree pkg-add " command will install the package you want layered on the ostree. This is the recommended method for production, too.

  • The "developer mode" boot option, available in the cloud images of Atomic which lets you try out Atomic without some of the setup usually requited.

Have a look at sections 1.5.3. Developer Mode and 1.5.4. Package layering of the Installation and Configuration Guide.

PixelDrift.NET,

Just to update your response. Atomic Host is included with RHEL Server subscriptions, as well as, the RHEL Virtual Data Center (VDC) SKUs. It's a deployment option of RHEL and does not require an extra subscription/license to use. Also, Satellite 6.2 fully supports patching & deploying Atomic Host. So if you're on the latest version of Satellite you should be good to go!

Ben,

When did this change? I have a customer with a number of VDC licenses that does not have access to Atomic host. I have in writing from Red Hat that if they want access to Atomic host they need to convert their VDC SKUs into RHEL physical or virtual SKUs. I checked their account this morning and they still don't have access to the Atomic isos using VDC SKUs.

PixelDrift.NET,

The process was complete a few weeks ago. Please send me an email if you still do not have access. bbreard@redhat.com

Thanks,

Ben,

I sent an email to the address listed on Wed 19th AEST including two local Red Hat resources, still awaiting a response.

For anyone else facing this issue, Red Hat have now published a solution with clarification: https://access.redhat.com/solutions/2690261

PixelDrift.NET,

For some reason I can't find your email. It may be caught in one of my filters, anyway sorry about that. We looked into this and found a mistake with the VDC SKU. We hope to get that fixes today, and have this working for you very soon. Apologies for the inconvenience.

Ben,

After referencing this thread, the customer's issue has now been resolved and they now have access to Atomic Host through their VDC SKU.

Thanks for your assistance.