» RHEL Requirements for Terraform Enterprise
When installing Terraform Enterprise on RedHat Enterprise Linux (RHEL), ensure your OS and Docker configuration meet the following requirements.
» Install Requirements
- RedHat Enterprise Linux version 7.3 or later.
- Docker 1.13.1 (available in RHEL extras), or Docker EE version 17.06 or later. The later versions are not available in the standard RHEL yum repositories.
- For Docker EE, there are explicit RHEL instructions to follow: https://docs.docker.com/install/linux/docker-ee/rhel/
- For Docker from RHEL extras, the following should enable the RHEL extras repository:
yum-config-manager --enable rhel-7-server-extras-rpms
- on AWS:
yum-config-manager --enable rhui-REGION-rhel-server-extras
- A properly configured docker storage backend, either:
- Devicemapper configured for production usage, according to the Docker documentation: https://docs.docker.com/storage/storagedriver/device-mapper-driver/#configure-direct-lvm-mode-for-production. This configuration requires a second block device available to the system to be used as a thin-pool for Docker. You may need to configure this block device before the host system is booted, depending on the hosting platform.
- A system capable of using overlay2. The requires at least kernel version 3.10.0-693 and, if XFS is being used, the flag ftype=1. The full documentation on this configuration is at: https://docs.docker.com/storage/storagedriver/overlayfs-driver/
- If using Docker from RHEL Extras, storage can be configured using the
docker-1.13.1-84.git07f3374.el7.x86_64 will result in an RPC error as well as 502 errors and inability to use the application.
» Pinning the Docker Version
To pin the version of Docker and prevent an inadvertent upgrade, follow this guide from RedHat.
» Downgrading the Docker Version
yum downgrade command can be used to downgrade the version of Docker that is installed.
For example, to downgrade from
docker-1.13.1-72.git6f36bd4el8.x86_64 stop the Docker service and execute the following.
sudo yum downgrade docker-1.13.1-72.git6f36bd4el7.x86_64 docker-client-1.13.1-72.git6f36bd4el7.x86_64 docker-common-1.13.1-72.git6f36bd4el7.x86_64 docker-rhel-push-plugin-1.13.1-72.git6f36bd4el7.x86_64
Afterwards, restart the Docker service and verify the newly installed version using
» Mandatory Configuration
If you opt to use Docker from RHEL extras, then you must make a change to its default configuration to avoid hitting an out of memory bug.
- Remove the line that contains
systemctl daemon-reload && systemctl restart docker
docker info 2> /dev/null | grep Authorizationto verify that there are no authorization plugins active. If nothing is printed, your installation is properly configured. If anything is printed, please contact support for further assistance.
» Can I use the Docker version in rpm-extras?
Sure! Just be sure to have at least 1.13.1 and authorization plugins disabled.
» When I run the installer, it allows me to download and install Docker CE on RedHat. Can I use that?
Yes, Docker CE is compatible with the current installer. However, it is not directly supported by RedHat. You still need to be sure that the storage backend is configured properly as by default, Docker will be using devicemapper in loopback, an entirely unsupported mode.
Can an installation where
docker info says that I’m using devicemapper with a loopback file work?
No. This is an installation that docker provides as sample and is not supported by Terraform Enterprise due to the significant instability in it. Docker themselves do not suggest using this mode: https://docs.docker.com/storage/storagedriver/device-mapper-driver/#configure-loop-lvm-mode-for-testing
» How do I know if an installation is in devicemapper loopback mode?
Run the command
sudo docker info | grep dev/loop. If there is any output, you’re in devicemapper loopback mode. Docker may also print warning about loopback mode when you run the above command, which is another indicator.