Version 1.12. This version is no longer supported. For information about how to upgrade to version 1.13, see Upgrading Anthos on bare metal in the 1.13 documentation. For more information about supported and unsupported versions, see the Version history page in the latest documentation.

Configure RHEL

You must configure the base operating system of your node machines to use Google Distributed Cloud. This page contains the steps you need to take to complete the needed configuration. For more information about troubleshooting Google Distributed Cloud, see the troubleshooting guides.

Before you begin

Ensure you are using a supported version of your operating system. Google Distributed Cloud supports the following versions of RHEL:

RHEL 8.1
RHEL 8.2
RHEL 8.3
RHEL 8.4
RHEL 8.5

Ensure that you have your RedHat username and password, and that you have root access to the machines you're configuring. Validate Package manager with the following steps:

If you haven't registered your operating system, register with RedHat using your RedHat username and password to download updates:
```
sudo subscription-manager register
sudo subscription-manager refresh
sudo subscription-manager attach --auto
```

Check for updates:

sudo dnf check-update

Ensure the output has no errors and includes the last metadata expiration check. For example:

Updating Subscription Management repositories.
...
# Last metadata expiration check: ...
...

Configure or disable firewalld

Firewalld can be configured for use with Google Distributed Cloud or disabled. For information on configuring firewalld, see Configure firewalld ports on the Network requirements page.

The following instructions disable firewalld.

Disable firewalld:

sudo systemctl stop firewalld
sudo systemctl disable firewalld

Check the status of firewalld to ensure it is disabled:

sudo systemctl status firewalld | grep "Active"
# Output
# Active: inactive (dead)

Configure Docker 19.03+ on your workstation

Follow these steps to manually install Docker:

Remove any previous Docker version:

sudo dnf remove docker \
    docker-client \
    docker-client-latest \
    docker-common \
    docker-latest \
    docker-latest-logrotate \
    docker-logrotate \
    docker-engine

Remove podman-manpages:
```
sudo dnf remove podman-manpages
```

Install Docker 19.03+:

sudo dnf install -y yum-utils
sudo yum-config-manager \
    --add-repo \
    https://download.docker.com/linux/centos/docker-ce.repo
sudo dnf install -y --allowerasing docker-ce docker-ce-cli containerd.io
sudo systemctl start docker

Verify that you are now running version 19.03+:
```
sudo docker version
```

Compare your output with the following example to ensure the Client and Server versions are 19.03+:

 Client: Docker Engine - Community
 Version:           19.03.13
 ...
 Server: Docker Engine - Community
  Engine:
  Version:          19.03.13

Verify Docker runs:
```
docker run hello-world
```
You should see something similar to this:
```
Hello from Docker!
```
This message shows that your installation appears to be working correctly.

Set up time synchronization

Time synchronization consists of setting the clocks on your node machines, using a designated external time reference. Time synchronization is important for time-sentive cluster activities, such as event logging and metrics collection. The kernel of your node machine controls the clock in containers that run on the node. To ensure proper time synchronization, install a network time protocol (NTP) service on your machines, using any of the available services: chrony, systemd-timesyncd, ntp, or ntpdate. Run timedatectl to verify the system clock is synchronized. The output of timedatectl should contain the following status:

System clock synchronized: yes

Best Practices

To simplify installation, we recommend that you configure RHEL using a minimal installation with headless management. Also, be sure to enable your network connection and either use the default DHCP or provide a valid, static IP address and network information. Ensure that the machine can connect to the required external resources, such as cloud.google.com.

If Docker fails to run, check that the Docker daemon is running with the following command:

sudo systemctl start docker