Chapter 1. About Red Hat Update Infrastructure 4

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Red Hat Update Infrastructure 4 (Red Hat Update Infrastructure 4) is a highly scalable, highly redundant framework that enables you to manage repositories and content. It also enables cloud providers to deliver content and updates to Red Hat Enterprise Linux (RHEL) instances. Based on the upstream Pulp project, RHUI allows cloud providers to locally mirror Red Hat-hosted repository content, create custom repositories with their own content, and make those repositories available to a large group of end users through a load-balanced content delivery system.

As a system administrator, you can prepare your infrastructure for participation in the Red Hat Certified Cloud and Service Provider program by installing and configuring the Red Hat Update Appliance (RHUA), content delivery servers (CDS), repositories, shared storage, and load balancing.

Configuring RHUI comprises the following tasks:

  • Creating and synchronizing a Red Hat repository
  • Creating client entitlement certificates and client configuration RPMs
  • Creating client profiles for the RHUI servers

Experienced RHEL system administrators are the target audience. System administrators with limited RHEL skills should consider engaging Red Hat Consulting to provide a Red Hat Certified Cloud Provider Architecture Service.

Learn about configuring, managing, and updating RHUI with the following topics:

  • the RHUI components
  • content provider types
  • the command line interface (CLI) used to manage the components
  • utility commands
  • certificate management
  • content management

1.1. Installation options

The following table presents the various Red Hat Update Infrastructure 4 components.

Table 1.1. Red Hat Update Infrastructure components and functions

Red Hat Update Appliance


Downloads new packages from the Red Hat content delivery network and copies new packages to each CDS node


Content Delivery Server


Provides the yum repositories that clients connect to for the updated packages




Provides load balancing across CDS nodes

Existing load balancing solution

Shared storage


Provides shared storage

Existing storage solution

The following table describes how to perform installation tasks.

Table 1.2. Red Hat Update Infrastructure installation tasks
Installation TaskPerformed on

Install RHEL 8

RHUA, CDS, and HAProxy

Subscribe the system

RHUA, CDS, and HAProxy

Attach a RHUI subscription

RHUA, CDS, and HAProxy

Apply updates

RHUA, CDS and HAProxy

Install rhui-installer


Run rhui-installer


1.1.1. Option 1: Full installation

  • A RHUA
  • Two or more CDS nodes with shared storage
  • One or more HAProxy load-balancers

1.1.2. Option 2: Installation with an existing storage solution

  • A RHUA
  • Two or more CDS nodes with an existing storage solution
  • One or more HAProxy load-balancers

1.1.3. Option 3: Installation with an existing load-balancer solution

  • A RHUA
  • Two or more CDS nodes with shared storage
  • An existing load-balancer

1.1.4. Option 4: Installation with existing storage and load-balancer solutions

  • A RHUA
  • Two or more CDS nodes with existing shared storage
  • An existing load-balancer

The following figure depicts a high-level view of how the various Red Hat Update Infrastructure 4 components interact.

Figure 1.1. Red Hat Update Infrastructure 4 overview

Red Hat Update Infrastructure Overview

You need to subscribe the RHUA as --type rhui and have a Red Hat Certified Cloud and Service Provider subscription to install RHUI. You also need an appropriate content certificate.

Install the RHUA and CDS nodes on separate x86_64 servers (bare metal or virtual machines). Ensure all the servers and networks that connect to RHUI can access the Red Hat Subscription Management service.

1.2. RHUI 4 components

Understanding how each RHUI component interacts with other components will make your job as a system administrator a little easier.

1.2.1. Red Hat Update Appliance

There is one RHUA per RHUI installation, though in many cloud environments there will be one RHUI installation per region or data center, for example, Amazon’s EC2 cloud comprises several regions. In every region, there is a separate RHUI set up with its own RHUA node.

The RHUA allows you to perform the following tasks:

  • Download new packages from the Red Hat content delivery network (CDN). The RHUA is the only RHUI component that connects to Red Hat, and you can configure the synchronization schedule for the RHUA.
  • Copy new packages to the shared network storage.
  • Verify the RHUI installation’s health and write the results to a file located on the RHUA. Monitoring solutions use this file to determine the RHUI installation’s health.
  • Provide a human-readable view of the RHUI installation’s health through a CLI tool.

RHUI uses two main configuration files: /etc/rhui/rhui-tools.conf and /etc/rhui/rhui-subscription-sync.conf.

The /etc/rhui/rhui-tools.conf configuration file contains general options used by the RHUA, such as the default file locations for certificates, and default configuration parameters for the Red Hat CDN synchronization. This file normally does not require editing.

The Red Hat Update Infrastructure Management Tool generates the /etc/rhui/rhui-subscription-sync.conf configuration file based on user-inputted values. It contains all the information that drives the running of a RHUA in a particular region. An example configuration includes the destination on the RHUA to download packages.

The RHUA employs several services to synchronize, organize, and distribute content for easy delivery.

RHUA services

The service that oversees management of the supporting services, providing a user interface for users to interact with
A PostgreSQL database used to keep track of currently synchronized repositories, packages, and other crucial metadata.

1.2.2. Content delivery server

The CDS nodes provide the repositories that clients connect to for the updated content. There can be as few as one CDS. Because RHUI provides a load-balancer with failover capabilities, we recommended that you use multiple CDS nodes.

The CDS nodes host content to end-user RHEL systems. While there is no required number of systems, the CDS works in a round-robin style load-balanced fashion (A, B, C, A, B, C) to deliver content to end-user systems. The CDS uses HTTP to host content to end-user systems via httpd-based yum repositories.

During configuration, you specify the CDS directory where packages are synchronized. Similar to the RHUA, the only requirement is that you mount the directory on the CDS. It is up to the cloud provider to determine the best course of action when allocating the necessary devices. The Red Hat Update Infrastructure Management Tool configuration RPM linked the package directory with the NGINX configuration to serve it.

Currently, RHUI supports the following shared storage solutions:


If NFS is used, rhui-installer can configure an NFS share on the RHUA to store the content as well as a directory on the CDS nodes to mount the NFS share. The following rhui-installer options control these settings:

  • --remote-fs-mountpoint is the file system location where the remote file system share should be mounted (default: /var/lib/rhui/remote_share)
  • --remote-fs-server is the remote mount point for a shared file system to use, for example, (default:

If using CephFS, you must configure CephFS separately and then use it with RHUI as a mount point. The following rhui-installer options control these settings:

  • --remote-fs-server is the remote mount point for a shared file system to use, for example, (default:

This document does not provide instructions to set up or configure Ceph shared file storage. For any Ceph related tasks, consult your system administrator, or see the Ceph documentation.

If these default values are used, the /export directory on the RHUA and the /var/lib/rhui/remote_share directory on each CDS are identical.

The expected usage is that you use one shared network file system on the RHUA and all CDS nodes, for example, NFS. It is possible the cloud provider will use some form of shared storage that the RHUA writes packages to and each CDS reads from.


The storage solution must provide an NFS or CephFS endpoint for mounting on the RHUA and CDS nodes. If local storage is implemented, shared storage is needed for the cluster to work. If you want to provide local storage to the RHUA, configure the RHUA to function as the NFS server with a endpoint configured.

Do not set up Ceph shared file storage on any of the RHUI nodes. You must configure CephFS on independent dedicated machines.

The only nonstandard logic that takes place on each CDS is the entitlement certificate checking. This checking ensures that the client making requests on the yum repositories is authorized by the cloud provider to access those repositories. The check ensures the following conditions:

  • The entitlement certificate was signed by the cloud provider’s Certificate Authority (CA) Certificate. The CA Certificate is installed on the CDS as part of its configuration to facilitate this verification.
  • The requested URI matches an entitlement found in the client’s entitlement certificate.

If the CA verification fails, the client sees an SSL error. See the CDS node’s NGINX logs under /var/log/nginx/ for more information.

[root@cds01 ~]# ls -1 /var/log/nginx/

The NGINX configuration is handled through the /etc/nginx/conf.d/ssl.conf file during the CDS installation.

If multiple clients experience problems updating against a repository, this may indicate a problem with the RHUI. See Yum generates 'Errno 14 HTTP Error 401: Authorization Required' while accessing RHUI CDS for more details.

1.2.3. HAProxy load-balancer

If more than one CDS is used, a load-balancing solution must be in place to spread client HTTPS requests across all servers. RHUI ships with HAProxy, but it is up to you to choose what load-balancing solution (for example, the one from the cloud provider) to use during the installation. If HAProxy is used, you must also decide how many nodes to bring in.

Clients are not configured to go directly to a CDS; their repository files are configured to point to HAProxy, the RHUI load-balancer. HAProxy is a TCP/HTTP reverse proxy particularly suited for high-availability environments. HAProxy performs the following tasks:

  • Routes HTTP requests depending on statically assigned cookies
  • Spreads the load among several servers while assuring server persistence through the use of HTTP cookies
  • Switches to backup servers in the event a main server fails
  • Accepts connections to special ports dedicated to service monitoring
  • Stops accepting connections without breaking existing ones
  • Adds, modifies, and deletes HTTP headers in both directions
  • Blocks requests matching particular patterns
  • Persists client connections to the correct application server, depending on application cookies
  • Reports detailed status as HTML pages to authenticated users from a URI intercepted from the application

If you use an existing load-balancer, ensure port 443 is configured in the load-balancer for the cds-lb-hostname forwarded to the pool and that all CDSs in the cluster are in the load-balancer’s pool.

The exact configuration depends on the particular load-balancer software you use. See the following configuration, taken from a typical HAProxy setup, to understand how you should configure your load-balancer:

[root@rhui4proxy ~]# cat /etc/haproxy/haproxy.cfg
# This file managed by Puppet
  chroot  /var/lib/haproxy
  group  haproxy
  log local0
  maxconn  4000
  pidfile  /run/
  stats  socket /var/lib/haproxy/stats
  user  haproxy

  log  global
  maxconn  8000
  option  redispatch
  retries  3
  stats  enable
  timeout  http-request 10s
  timeout  queue 1m
  timeout  connect 10s
  timeout  client 1m
  timeout  server 1m
  timeout  check 10s

listen https00
  balance roundrobin
  option tcplog
  option tcp-check
    server check
    server check

Keep in mind that when clients fail to connect, it is important to review the nginx logs on the CDS under /var/log/nginx/ to ensure that any request reached the CDS. If requests do not reach the CDS, issues such as DNS or general network connectivity may be at fault.

1.2.4. Repositories and content

A repository is a storage location for software packages (RPMs). RHEL uses yum commands to search a repository, download, install, and configure the RPMs. The RPMs contain all the dependencies needed to run an application. RPMs also download updates for software in your repositories.

RHEL uses core technologies such as control groups (cgroups) for resource management, namespaces for process isolation, and SELinux for security, enabling secure multiple tenancy, and reducing the potential for security exploits. These technologies enable rapid application deployment, simpler testing, maintenance, and troubleshooting while improving security.

Content, as it relates to RHUI, is the software (such as RPMs) that you download from the Red Hat CDN for use on the RHUA and the CDS nodes. The RPMs provide the files necessary to run specific applications and tools. Clients are granted access by a set of SSL content certificates and keys provided by an rpm package, which also provides a set of generated yum repository files.

1.3. Content provider types

There are three types of cloud computing environments:

  • public cloud
  • private cloud
  • hybrid cloud

This guide focuses on public and private clouds. We assume the audience understands the implications of using public, private, and hybrid clouds.

1.4. Component communications

All RHUI components use the HTTPS communication protocol over port 443.

Table 1.3. Red Hat Update Infrastructure communication protocols

Red Hat Update Appliance

Red Hat Content Delivery Network


Downloads packages from Red Hat


Content Delivery Server


Forwards the client’s yum




Used by yum on the client to download packages from a CDS

Content Delivery Server

Red Hat Update Appliance


Might request information from Pulp API about content

RHUI nodes require the following network access to communicate with each other.


Make sure that the network port is open and that network access is restricted to only those nodes that you plan to use.

Table 1.4. Red Hat Update Infrastructure network access



RHUA, CDS01, CDS02, …​ CDSn



Client virtual machines

1.5. Changing the admin password

The rhui-installer sets the initial RHUI login password. It is also written in the /etc/rhui/rhui-subscription-sync.conf file. You can override the initial password with the --rhui-manager-password option.

If you want to change the initial password later, you can change it through the rhui-manager tool or through rhui-installer. Run the rhui-installer --help command to see the full list of rhui-installer options.


  1. Navigate to the Red Hat Update Infrastructure Management Tool home screen:

    [root@rhua ~]# rhui-manager
  2. Press u to select manage RHUI users.
  3. From the User Manager screen, press p to select change admin’s password (followed by logout):

    -= User Manager =-
       p   change admin's password (followed by logout)
       rhui (users) => p
       Warning: After password change you will be logged out.
       Use ctrl-c to cancel password change.
       New Password:
  4. Enter your new password; reenter it to confirm the change.

    New Password:
    Re-enter Password:
    [localhost] env PULP_SETTINGS=/etc/pulp/ /usr/bin/pulpcore-manager reset-admin-password -p ********


  1. The following message displays after you change the admin password:

    Password successfully updated. For security reasons you have been logged out.
    [root@ip-10-141-150-145 ~]#

1.6. Additional resources

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