5. Requirements


Tower is a full application and the installation process installs several dependencies such as PostgreSQL, Django, NGINX, and others.

It is required that you install Tower on a standalone VM or cloud instance and do not co-locate any other applications on that machine (beyond possible monitoring or logging software). Although Tower and Ansible are written in Python, they are not just simple Python libraries. Therefore, Tower cannot be installed in a Python virtualenv or any similar subsystem; you must install it as described in the installation instructions in this guide. Also, DO NOT change the default alternative for Python 3.

For OpenShift-based deployments, refer to OpenShift Deployment and Configuration.

Ansible Tower has the following requirements:

Starting with Ansible Tower 3.8, you must have valid subscriptions attached before installing the Ansible Automation Platform. See Attaching Subscriptions for detail.

  • Supported Operating Systems:

    • Red Hat Enterprise Linux 8.2 or later 64-bit (x86)

    • Red Hat Enterprise Linux 7.7 or later 64-bit (x86)

    • CentOS 7.7 or later 64-bit (x86)


For Automation Hub, selinux-policy package version greater or equal to 3.13.1-268.el7_9.2 is required. If your setup has rhel-7-server-rpms repository enabled, the _9.2 version will be pulled automatically along with Automation Hub. Also, RHUI subscriptions cannot be used to install Automation Hub.


The next major release of Ansible Tower will not support Red Hat Enterprise Linux 7 or CentOS (any version) as an installation platform.

  • A currently supported version of Mozilla Firefox or Google Chrome

    • Other HTML5 compliant web browsers may work but are not fully tested or supported.

  • 2 CPUs minimum for Automation Platform installations. Refer to the capacity algorithm section of the Ansible Tower User Guide for determining the CPU capacity required for the number of forks in your particular configuration.

  • 4 GB RAM minimum for Automation Platform installations

    • 4 GB RAM (minimum and recommended for Vagrant trial installations)

    • 4 GB RAM (minimum for external standalone PostgreSQL databases)

    • For specific RAM needs, refer to the capacity algorithm section of the Ansible Tower User Guide for determining capacity required based on the number of forks in your particular configuration

  • 20 GB of dedicated hard disk space for Tower service nodes

    • 10 GB of the 20 GB requirement must be dedicated to /var/, where Tower stores its files and working directories

    • The storage volume should be rated for a minimum baseline of 750 IOPS.

  • 20 GB of dedicated hard disk space for nodes containing a database (150 GB+ recommended)

    • The storage volume should be rated for a high baseline IOPS (1000 or more.)

    • All Tower data is stored in the database. Database storage increases with the number of hosts managed, number of jobs run, number of facts stored in the fact cache, and number of tasks in any individual job. For example, a playbook run every hour (24 times a day) across 250, hosts, with 20 tasks will store over 800000 events in the database every week.

    • If not enough space is reserved in the database, old job runs and facts will need cleaned on a regular basis. Refer to Management Jobs in the Ansible Tower Administration Guide for more information

  • 64-bit support required (kernel and runtime)

  • PostgreSQL version 10 required to run Ansible Tower 3.7 and later. Backup and restore will only work on PostgreSQL versions supported by your current Ansible Tower version.

  • Ansible version 2.9 required to run Ansible Tower versions 3.8 and later


You cannot use versions of PostgreSQL and Ansible older than those stated above and be able to run Ansible Tower 3.7 and later. Both are installed by the install script if they aren’t already present.

  • For Automation Hub: Starting with Ansible Tower 3.8, Automation Hub will act as a content provider for Ansible Tower, which requires both an Ansible Tower deployment and an Automation Hub deployment running alongside each other. Tower and Automation Hub can run on either RHEL 7 or 8, but only Tower (not Automation Hub) is supported on an OpenShift Container Platform (OCP).

  • For Amazon EC2:

    • Instance size of m4.large or larger

    • An instance size of m4.xlarge or larger if there are more than 100 hosts

5.1. Additional Notes on Automation Platform Requirements

Actual RAM requirements vary based on how many hosts Tower will manage simultaneously (which is controlled by the forks parameter in the job template or the system ansible.cfg file). To avoid possible resource conflicts, Ansible recommends 1 GB of memory per 10 forks + 2GB reservation for Tower, see the capacity algorithm for further details. If forks is set to 400, 40 GB of memory is recommended.

For the hosts on which we install Ansible Tower, Tower checks whether or not umask is set to 0022. If not, the setup fails. Be sure to set umask=0022 to avoid encountering this error.

A larger number of hosts can of course be addressed, though if the fork number is less than the total host count, more passes across the hosts are required. These RAM limitations are avoided when using rolling updates or when using the provisioning callback system built into Tower, where each system requesting configuration enters a queue and is processed as quickly as possible; or in cases where Tower is producing or deploying images such as AMIs. All of these are great approaches to managing larger environments. For further questions, please contact Ansible via the Red Hat Customer portal at

The requirements for systems managed by Ansible Automation Platform are the same as for Ansible at:

5.1.1. Notable PostgreSQL Changes

Automation Platform uses PostgreSQL 10, which is an SCL package on RHEL 7 and an app stream on RHEL8. Some changes worth noting when upgrading to PostgreSQL 10 are:

  • PostgreSQL user passwords will now be hashed with SCRAM-SHA-256 secure hashing algorithm before storing in the database.

  • You will no longer need to provide a pg_hashed_password in your inventory file at the time of installation because PostgreSQL 10 can now store the user’s password more securely. If users supply a password in the inventory file for the installer (pg_password), that password will be SCRAM-SHA-256 hashed by PostgreSQL as part of the installation process. DO NOT use special characters in pg_password as it may cause the setup to fail.

  • Since Ansible Tower and Automation Hub are using a Software Collections version of PostgreSQL in 3.8, the rh-postgresql10 scl must be enabled in order to access the database. Administrators can use the awx-manage dbshell command, which will automatically enable the PostgreSQL SCL.

  • If you just need to determine if your Tower instance has access to the database, you can do so with the command, awx-manage check_db.

5.1.2. PostgreSQL Configurations

Optionally, you can configure the PostgreSQL database as separate nodes that are not managed by the Automation Platform installer. When the Automation Platform installer manages the database server, it configures the server with defaults that are generally recommended for most workloads. However, you can adjust these PostgreSQL settings for standalone database server node where ansible_memtotal_mb is the total memory size of the database server:

max_connections == 1024
shared_buffers == ansible_memtotal_mb*0.3
work_mem == ansible_memtotal_mb*0.03
maintenance_work_mem == ansible_memtotal_mb*0.04

Refer to PostgreSQL documentation for more detail on tuning your PostgreSQL server.

5.2. Ansible Software Requirements

While Automation Platform depends on Ansible Playbooks and requires the installation of the latest stable version of Ansible before installing Tower, manual installations of Ansible are no longer required.

Upon new installations, Tower installs the latest release package of Ansible 2.9.

If performing a bundled Automation Platform installation, the installation program attempts to install Ansible (and its dependencies) from the bundle for you (refer to Using the Bundled Ansible Automation Platform Installer for more information).

If you choose to install Ansible on your own, the Automation Platform installation program will detect that Ansible has been installed and will not attempt to reinstall it. Note that you must install Ansible using a package manager like yum and that the latest stable version must be installed for Automation Platform to work properly. Ansible version 2.9 is required for Ansible Tower versions 3.8 and later.