Infrastructure at your Service

Joël Cattin

Red Hat Enterprise Linux 8 – Application Streams

You may have heard that : Red Hat Enterprise Linux 8 is available for downloading in beta version since few weeks…
You want to download it ? Click here.
RH_EnterpriseLinux8beta_stacked_RGB_BlueA significant change coming with this new version is the way the applications packages are provided. As you know, up to RHEL7 packages were downloaded via repositories listed in .repo files located by default under /etc/yum.repos.d/. This is still the same with RHEL8, but two new major repositories are available in the default redhat.repo files.

In order to get access to them we must of course register the server to a Red Hat Subscription…
[root@rhel8beta1 ~]# subscription-manager register --username xxx.yyy@zzz.com
Registering to: subscription.rhsm.redhat.com:443/subscription
Password:
The system has been registered with ID: e42829a5-8a8e-42d3-a69a-07a1499e9b0e
The registered system name is: rhel8beta1
[root@rhel8beta1 ~]#

…and attach it to a Pool (here the Pool will be chosen automatically) :
[root@rhel8beta1 ~]# subscription-manager attach --auto
Installed Product Current Status:
Product Name: Red Hat Enterprise Linux for x86_64 Beta
Status: Subscribed
[root@rhel8beta1 ~]#

As the /etc/yum.repos.d/redhat.repo is now available, let’s check which repository does it contain :
[root@rhel8beta1 ~]# grep -B1 name /etc/yum.repos.d/redhat.repo
[rhel-8-for-x86_64-rt-beta-debug-rpms] name = Red Hat Enterprise Linux 8 for x86_64 - Real Time Beta (Debug RPMs)
--
[rhel-8-for-x86_64-rt-beta-source-rpms] name = Red Hat Enterprise Linux 8 for x86_64 - Real Time Beta (Source RPMs)
--
[rhel-8-for-x86_64-supplementary-beta-rpms] name = Red Hat Enterprise Linux 8 for x86_64 - Supplementary Beta (RPMs)
--
[rhel-8-for-x86_64-resilientstorage-beta-debug-rpms] name = Red Hat Enterprise Linux 8 for x86_64 - Resilient Storage Beta (Debug RPMs)
--
[fast-datapath-beta-for-rhel-8-x86_64-source-rpms] name = Fast Datapath Beta for RHEL 8 x86_64 (Source RPMs)
--
[codeready-builder-beta-for-rhel-8-x86_64-debug-rpms] name = Red Hat CodeReady Linux Builder Beta for RHEL 8 x86_64 (Debug RPMs)
--
[codeready-builder-beta-for-rhel-8-x86_64-source-rpms] name = Red Hat CodeReady Linux Builder Beta for RHEL 8 x86_64 (Source RPMs)
--
[rhel-8-for-x86_64-appstream-beta-source-rpms] name = Red Hat Enterprise Linux 8 for x86_64 - AppStream Beta (Source RPMs)
--
[rhel-8-for-x86_64-nfv-beta-source-rpms] name = Red Hat Enterprise Linux 8 for x86_64 - Real Time for NFV Beta (Source RPMs)
--
[rhel-8-for-x86_64-nfv-beta-rpms] name = Red Hat Enterprise Linux 8 for x86_64 - Real Time for NFV Beta (RPMs)
--
[rhel-8-for-x86_64-resilientstorage-beta-source-rpms] name = Red Hat Enterprise Linux 8 for x86_64 - Resilient Storage Beta (Source RPMs)
--
[codeready-builder-beta-for-rhel-8-x86_64-rpms] name = Red Hat CodeReady Linux Builder Beta for RHEL 8 x86_64 (RPMs)
--
[rhel-8-for-x86_64-supplementary-beta-debug-rpms] name = Red Hat Enterprise Linux 8 for x86_64 - Supplementary Beta (Debug RPMs)
--
[rhel-8-for-x86_64-highavailability-beta-source-rpms] name = Red Hat Enterprise Linux 8 for x86_64 - High Availability Beta (Source RPMs)
--
[rhel-8-for-x86_64-supplementary-beta-source-rpms] name = Red Hat Enterprise Linux 8 for x86_64 - Supplementary Beta (Source RPMs)
--
[rhel-8-for-x86_64-appstream-beta-rpms] name = Red Hat Enterprise Linux 8 for x86_64 - AppStream Beta (RPMs)
--
[rhel-8-for-x86_64-rt-beta-rpms] name = Red Hat Enterprise Linux 8 for x86_64 - Real Time Beta (RPMs)
--
[rhel-8-for-x86_64-appstream-beta-debug-rpms] name = Red Hat Enterprise Linux 8 for x86_64 - AppStream Beta (Debug RPMs)
--
[fast-datapath-beta-for-rhel-8-x86_64-debug-rpms] name = Fast Datapath Beta for RHEL 8 x86_64 (Debug RPMs)
--
[rhel-8-for-x86_64-resilientstorage-beta-rpms] name = Red Hat Enterprise Linux 8 for x86_64 - Resilient Storage Beta (RPMs)
--
[rhel-8-for-x86_64-baseos-beta-rpms] name = Red Hat Enterprise Linux 8 for x86_64 - BaseOS Beta (RPMs)
--
[rhel-8-for-x86_64-nfv-beta-debug-rpms] name = Red Hat Enterprise Linux 8 for x86_64 - Real Time for NFV Beta (Debug RPMs)
--
[fast-datapath-beta-for-rhel-8-x86_64-rpms] name = Fast Datapath Beta for RHEL 8 x86_64 (RPMs)
--
[rhel-8-for-x86_64-baseos-beta-debug-rpms] name = Red Hat Enterprise Linux 8 for x86_64 - BaseOS Beta (Debug RPMs)
--
[rhel-8-for-x86_64-highavailability-beta-debug-rpms] name = Red Hat Enterprise Linux 8 for x86_64 - High Availability Beta (Debug RPMs)
--
[rhel-8-for-x86_64-highavailability-beta-rpms] name = Red Hat Enterprise Linux 8 for x86_64 - High Availability Beta (RPMs)
--
[rhel-8-for-x86_64-baseos-beta-source-rpms] name = Red Hat Enterprise Linux 8 for x86_64 - BaseOS Beta (Source RPMs)
[root@rhel8beta1 ~]#

AppStream ? BaseOS ? What’s that… This is what we will discover in this blog.

First of all we can see that both are enabled by default :
[root@rhel8beta1 ~]# subscription-manager repos --list-enabled
+----------------------------------------------------------+
Available Repositories in /etc/yum.repos.d/redhat.repo
+----------------------------------------------------------+
Repo ID: rhel-8-for-x86_64-baseos-beta-rpms
Repo Name: Red Hat Enterprise Linux 8 for x86_64 - BaseOS Beta (RPMs)
Repo URL: https://cdn.redhat.com/content/beta/rhel8/8/x86_64/baseos/os
Enabled: 1


Repo ID: rhel-8-for-x86_64-appstream-beta-rpms
Repo Name: Red Hat Enterprise Linux 8 for x86_64 - AppStream Beta (RPMs)
Repo URL: https://cdn.redhat.com/content/beta/rhel8/8/x86_64/appstream/os
Enabled: 1
[root@rhel8beta1 ~]#

BaseOS

Content in BaseOS is intended to provide the core set of the underlying OS functionality that provides the foundation for all installations“.
This is how Red Hat define it. Over a thousand of packages are available from the BaseOS repository :
[root@rhel8beta1 ~]# yum --disablerepo "*" --enablerepo "rhel-8-for-x86_64-baseos-beta-rpms" list available | wc -l
1145
[root@rhel8beta1 ~]#

You can get the full list here.
Basically, those packages are system-related and are mainly used to manage and configure the OS and services (such as NetworkManager, Chrony, Dracut, aso…). In other words most of them are intended for use by system administrators. So nothing very new here except for the fact that they are all grouped in a unique dedicated repository.

AppStream

The second repository contains much more packages (full list here) :
[root@rhel8beta1 /]# yum --disablerepo "*" --enablerepo "rhel-8-for-x86_64-appstream-beta-rpms" list available | wc -l
4318
[root@rhel8beta1 /]#

Application Stream provides additional user space applications, runtime languages and databases. It replaces the “extra” Repos and the Software Collection. All the content in AppStream is available in two formats : the well known RPM format and a brand new one called “module” which an extension to the RPM format.
A module is a set of RPM packages that are linked together. For exemple, if you want to check which packages are concerned by the Postgresql module, you must use the new “yum module” command :
[root@rhel8beta1 /]# yum module list postgresql
Updating Subscription Management repositories.
Updating Subscription Management repositories.
Last metadata expiration check: 0:47:42 ago on Mon Nov 26 15:13:03 2018.
Red Hat Enterprise Linux 8 for x86_64 - AppStream Beta (RPMs)
Name Stream Profiles Summary
postgresql 10 [d] client, default [d] postgresql module
postgresql 9.6 client, default [d] postgresql module


Hint: [d]efault, [e]nabled, [x]disabled, [i]nstalled
[root@rhel8beta1 /]#

By the way, YUM is no longer the default Packages Manager with RHEL8. The command is still available but it’s actually an alias of the DNF tool (coming from Fedora) :
[root@rhel8beta1 ~]# which yum
/usr/bin/yum
[root@rhel8beta1 ~]# ll /usr/bin/yum
lrwxrwxrwx. 1 root root 5 Oct 15 10:25 /usr/bin/yum -> dnf-3
[root@rhel8beta1 ~]#

If you want to have a look to the main usage differences between YUM and DNF, check that :
[root@rhel8beta1 /]# man yum2dnf
YUM2DNF(8)


NAME
yum2dnf - Changes in DNF compared to YUM
[...] [...]

Let’s go back to our modules. Here is how you can check the packages contained in a module :
[root@rhel8beta1 /]# yum module info postgresql
Updating Subscription Management repositories.
Updating Subscription Management repositories.
Red Hat Enterprise Linux 8 for x86_64 - AppStream Beta (RPMs) 2.9 kB/s | 4.1 kB 00:01
Red Hat Enterprise Linux 8 for x86_64 - BaseOS Beta (RPMs) 2.9 kB/s | 4.1 kB 00:01
Name : postgresql
Stream : 10 [d] Version : 20180813131250
Context : 9edba152
Profiles : client, default [d] Default profiles : default
Repo : rhel-8-for-x86_64-appstream-beta-rpms
Summary : postgresql module
Description : This postgresql module has been generated.
Artifacts : postgresql-0:10.5-1.el8+1546+27ad5f8e.x86_64
: postgresql-contrib-0:10.5-1.el8+1546+27ad5f8e.x86_64
: postgresql-docs-0:10.5-1.el8+1546+27ad5f8e.x86_64
: postgresql-plperl-0:10.5-1.el8+1546+27ad5f8e.x86_64
: postgresql-plpython3-0:10.5-1.el8+1546+27ad5f8e.x86_64
: postgresql-pltcl-0:10.5-1.el8+1546+27ad5f8e.x86_64
: postgresql-server-0:10.5-1.el8+1546+27ad5f8e.x86_64
: postgresql-server-devel-0:10.5-1.el8+1546+27ad5f8e.x86_64
: postgresql-static-0:10.5-1.el8+1546+27ad5f8e.x86_64
: postgresql-test-0:10.5-1.el8+1546+27ad5f8e.x86_64
: postgresql-test-rpm-macros-0:10.5-1.el8+1546+27ad5f8e.x86_64
: postgresql-upgrade-0:10.5-1.el8+1546+27ad5f8e.x86_64
: postgresql-upgrade-devel-0:10.5-1.el8+1546+27ad5f8e.x86_64


Name : postgresql
Stream : 9.6
Version : 20180813131400
Context : 9edba152
Profiles : client, default [d] Default profiles : default
Repo : rhel-8-for-x86_64-appstream-beta-rpms
Summary : postgresql module
Description : This postgresql module has been generated.
Artifacts : postgresql-0:9.6.10-1.el8+1547+210b7007.x86_64
: postgresql-contrib-0:9.6.10-1.el8+1547+210b7007.x86_64
: postgresql-docs-0:9.6.10-1.el8+1547+210b7007.x86_64
: postgresql-plperl-0:9.6.10-1.el8+1547+210b7007.x86_64
: postgresql-plpython3-0:9.6.10-1.el8+1547+210b7007.x86_64
: postgresql-pltcl-0:9.6.10-1.el8+1547+210b7007.x86_64
: postgresql-server-0:9.6.10-1.el8+1547+210b7007.x86_64
: postgresql-server-devel-0:9.6.10-1.el8+1547+210b7007.x86_64
: postgresql-static-0:9.6.10-1.el8+1547+210b7007.x86_64
: postgresql-test-0:9.6.10-1.el8+1547+210b7007.x86_64
: postgresql-test-rpm-macros-0:9.6.10-1.el8+1547+210b7007.x86_64


Hint: [d]efault, [e]nabled, [x]disabled, [i]nstalled
[root@rhel8beta1 /]#

The above output shows that a module can contain several streams. Each stream represent a different version of the application.
Moreover, a module can have couple of profiles. A profile is a set of certain RPM packages selected to be installed together for a particular use-case (server, client, development, minimal install, aso…).

To install an application from the default stream and with the default profile, add the ‘@’ character before the application name :
[root@rhel8beta1 /]# yum install @postgresql
Updating Subscription Management repositories.
Updating Subscription Management repositories.
Last metadata expiration check: 0:25:55 ago on Mon Nov 26 16:27:13 2018.
Dependencies resolved.
=======================================================================================================================================================================================
Package Arch Version Repository Size
=======================================================================================================================================================================================
Installing group/module packages:
postgresql-server x86_64 10.5-1.el8+1546+27ad5f8e rhel-8-for-x86_64-appstream-beta-rpms 5.1 M
Installing dependencies:
libpq x86_64 10.5-1.el8 rhel-8-for-x86_64-appstream-beta-rpms 188 k
postgresql x86_64 10.5-1.el8+1546+27ad5f8e rhel-8-for-x86_64-appstream-beta-rpms 1.5 M
Installing module profiles:
postgresql/default
Enabling module streams:
postgresql 10


Transaction Summary
=======================================================================================================================================================================================
Install 3 Packages


Total download size: 6.7 M
Installed size: 27 M
Is this ok [y/N]: y
[...] [...] [root@rhel8beta1 /]#

You can also use the “yum module install postgresql” command.

Quick check :
[root@rhel8beta1 ~]# which postgres
/usr/bin/postgres
[root@rhel8beta1 ~]# /usr/bin/postgres --version
postgres (PostgreSQL) 10.5
[root@rhel8beta1 ~]#

And if you want to install Postgres from an oldest stream and with another profile (here Postgres 9.6 client only) :
[root@rhel8beta1 /]# yum install @postgresql:9.6/client
Updating Subscription Management repositories.
Updating Subscription Management repositories.
Last metadata expiration check: 0:33:45 ago on Mon Nov 26 16:27:13 2018.
Dependencies resolved.
=======================================================================================================================================================================================
Package Arch Version Repository Size
=======================================================================================================================================================================================
Installing group/module packages:
postgresql x86_64 9.6.10-1.el8+1547+210b7007 rhel-8-for-x86_64-appstream-beta-rpms 1.4 M
Installing dependencies:
libpq x86_64 10.5-1.el8 rhel-8-for-x86_64-appstream-beta-rpms 188 k
Installing module profiles:
postgresql/client
Enabling module streams:
postgresql 9.6


Transaction Summary
=======================================================================================================================================================================================
Install 2 Packages


Total download size: 1.6 M
Installed size: 5.8 M
Is this ok [y/N]: y
[...] [...] [root@rhel8beta1 /]#

Check :
[root@rhel8beta1 ~]# which postgres
/usr/bin/postgres
[root@rhel8beta1 ~]# /usr/bin/postgres --version
postgres (PostgreSQL) 9.6.10
[root@rhel8beta1 ~]#


[root@rhel8beta1 ~]# yum module list --enabled
Updating Subscription Management repositories.
Updating Subscription Management repositories.
Last metadata expiration check: 0:04:43 ago on Thu Dec 13 08:34:05 2018.
Red Hat Enterprise Linux 8 for x86_64 - AppStream Beta (RPMs)
Name Stream Profiles Summary
container-tools 1.0 [d][e] default [d] Common tools and dependencies for container runtimes
postgresql 9.6 [e] client [i], default [d] [i] postgresql module
satellite-5-client 1.0 [d][e] gui, default [d] Red Hat Satellite 5 client packages
virt rhel [d][e] default [d] Virtualization module


Hint: [d]efault, [e]nabled, [x]disabled, [i]nstalled
[root@rhel8beta1 ~]#

Hummm… Only the module 9.6 is enabled ? Let’s try to enable the version 10 :
[root@rhel8beta1 ~]# yum module enable postgresql:10
Updating Subscription Management repositories.
Updating Subscription Management repositories.
Last metadata expiration check: 0:08:06 ago on Thu Dec 13 07:52:30 2018.
Dependencies resolved.
======================================================================================================================================
Package Arch Version Repository Size
======================================================================================================================================
Switching module streams:
postgresql 9.6 -> 10


Transaction Summary
======================================================================================================================================


Is this ok [y/N]: y
Complete!


Switching module streams does not alter installed packages (see 'module enable' in dnf(8) for details)
[root@rhel8beta1 ~]#

It’s better now :
[root@rhel8beta1 ~]# yum module list --enabled
Failed to set locale, defaulting to C
Updating Subscription Management repositories.
Updating Subscription Management repositories.
Last metadata expiration check: 0:13:22 ago on Thu Dec 13 08:34:05 2018.
Red Hat Enterprise Linux 8 for x86_64 - AppStream Beta (RPMs)
Name Stream Profiles Summary
container-tools 1.0 [d][e] default [d] Common tools and dependencies for container runtimes
postgresql 10 [d][e] client [i], default [d] [i] postgresql module
satellite-5-client 1.0 [d][e] gui, default [d] Red Hat Satellite 5 client packages
virt rhel [d][e] default [d] Virtualization module


Hint: [d]efault, [e]nabled, [x]disabled, [i]nstalled
[root@rhel8beta1 ~]#

But…
[root@rhel8beta1 ~]# which postgres
/usr/bin/postgres
[root@rhel8beta1 ~]# /usr/bin/postgres --version
postgres (PostgreSQL) 9.6.10
[root@rhel8beta1 ~]#

…still using 9.6 :-(
After switching from one module to another, we must upgrade the corresponding packages :
[root@rhel8beta1 ~]# yum distro-sync
Updating Subscription Management repositories.
Updating Subscription Management repositories.
Last metadata expiration check: 0:18:40 ago on Thu Dec 13 08:34:05 2018.
Dependencies resolved.
=========================================================§=====================================================================================
Package Arch Version Repository Size
==============================================================================================================================================
Upgrading:
postgresql x86_64 10.5-1.el8+1546+27ad5f8e rhel-8-for-x86_64-appstream-beta-rpms 1.5 M
postgresql-server x86_64 10.5-1.el8+1546+27ad5f8e rhel-8-for-x86_64-appstream-beta-rpms 5.1 M


Transaction Summary
==============================================================================================================================================
Upgrade 2 Packages


Total download size: 6.5 M
Is this ok [y/N]: y
Downloading Packages:
(1/2): postgresql-server-10.5-1.el8+1546+27ad5f8e.x86_64.rpm 1.3 MB/s | 5.1 MB 00:03
(2/2): postgresql-10.5-1.el8+1546+27ad5f8e.x86_64.rpm 371 kB/s | 1.5 MB 00:04
--------------------------------------------------------------------------------------------------------------- --------------------------------
Total 1.6 MB/s | 6.5 MB 00:04
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
Preparing : 1/1
Running scriptlet: postgresql-10.5-1.el8+1546+27ad5f8e.x86_64 1/1
Upgrade: postgresql-10.5-1.el8+1546+27ad5f8e.x86_64
Upgrading : postgresql-10.5-1.el8+1546+27ad5f8e.x86_64 1/4
Upgrade: postgresql-10.5-1.el8+1546+27ad5f8e.x86_64
Upgrade: postgresql-server-10.5-1.el8+1546+27ad5f8e.x86_64
Running scriptlet: postgresql-server-10.5-1.el8+1546+27ad5f8e.x86_64 2/4
Upgrading : postgresql-server-10.5-1.el8+1546+27ad5f8e.x86_64 2/4
Running scriptlet: postgresql-server-10.5-1.el8+1546+27ad5f8e.x86_64 2/4
Upgrade: postgresql-server-10.5-1.el8+1546+27ad5f8e.x86_64
Upgraded: postgresql-server-9.6.10-1.el8+1547+210b7007.x86_64
Running scriptlet: postgresql-server-9.6.10-1.el8+1547+210b7007.x86_64 3/4
Cleanup : postgresql-server-9.6.10-1.el8+1547+210b7007.x86_64 3/4
Upgraded: postgresql-server-9.6.10-1.el8+1547+210b7007.x86_64
Running scriptlet: postgresql-server-9.6.10-1.el8+1547+210b7007.x86_64 3/4
Upgraded: postgresql-9.6.10-1.el8+1547+210b7007.x86_64
Cleanup : postgresql-9.6.10-1.el8+1547+210b7007.x86_64 4/4
Upgraded: postgresql-9.6.10-1.el8+1547+210b7007.x86_64
Running scriptlet: postgresql-9.6.10-1.el8+1547+210b7007.x86_64 4/4
Verifying : postgresql-10.5-1.el8+1546+27ad5f8e.x86_64 1/4
Verifying : postgresql-9.6.10-1.el8+1547+210b7007.x86_64 2/4
Verifying : postgresql-server-10.5-1.el8+1546+27ad5f8e.x86_64 3/4
Verifying : postgresql-server-9.6.10-1.el8+1547+210b7007.x86_64 4/4


Upgraded:
postgresql-10.5-1.el8+1546+27ad5f8e.x86_64 postgresql-server-10.5-1.el8+1546+27ad5f8e.x86_64


Complete!
[root@rhel8beta1 ~]#

And now it’s fine :
[root@rhel8beta1 ~]# which postgres
/usr/bin/postgres
[root@rhel8beta1 ~]# /usr/bin/postgres --version
postgres (PostgreSQL) 10.5
[root@rhel8beta1 ~]#

So what ?

That was only a first quick try with the AppStream fonctionality. What we can remember here is that with this new way to manage packages we can benefit from parallel availability of multiple versions of software. This is due to the disassociation from the kernel space (BaseOS) – which is still managed in a traditional way, and the user space (AppStream) – which is now deployed in the form of “containerized” applications.
Up to now, when we wanted to upgrade an application to a given version, we had to think about the inter-dependency between this application and the other one that we didn’t want to update. With RHEL8, we can now upgrade one while keeping the other in its current version.

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Joël Cattin
Joël Cattin

Consultant