System Requirements

System Requirements

Hardware Prerequisites

You must have a single bootstrap node, an odd number of Mesos master nodes, and any number Mesos of agent nodes.

Bootstrap node

1 node with 2 Cores, 16 GB RAM, 60 GB HDD. This is the node where DC/OS installation is run. This bootstrap node must also have:

  • A High-availability (HA) TCP/Layer 3 load balancer, such as HAProxy, to balance the following TCP ports to all master nodes: 80, 443, 8080, 8181, 2181, 5050.
  • An unencrypted SSH key that can be used to authenticate with the cluster nodes over SSH. Encrypted SSH keys are not supported.

Important: The bootstrap node must be separate from your cluster nodes.

Cluster nodes

The cluster nodes are designated Mesos masters and agents during installation.

Master nodes

You must have an odd number of master nodes.

Here are the master node hardware requirements.

Minimum Recommended
Nodes: 1
OS: RHEL/CentOS 7.2
Processor: 4 cores
Memory: 32 GB RAM
Hard disk space: 120 GB
Nodes: 3
OS: RHEL/CentOS 7.2
Processor: 4 cores
Memory: 32 GB RAM
Hard disk space: 120 GB

There are many mixed workloads on the masters, for example Mesos replicated log and ZooKeeper. Some of these require fsync()ing every so often, and this can generate a lot of very expensive random I/O. We recommend the following:

  • Solid-state drive (SSD)
  • RAID controllers with a BBU
  • RAID controller cache configured in writeback mode

Agent nodes

Here are the agent node hardware requirements.

Minimum Recommended
Nodes: 1
OS: RHEL/CentOS 7.2
Processor: 2 cores
Memory: 16 GB RAM
Hard disk space: 60 GB
Nodes: 6 or more
OS: RHEL/CentOS 7.2
Processor: 2 cores
Memory: 16 GB RAM
Hard disk space: 60 GB
The agent nodes must also have:
  • A /var directory with 10 GB or more of free space. This directory is used by the sandbox for both Docker and Mesos Containerizer.
  • Network Access to a public Docker repository or to an internal Docker registry.
  • On RHEL 7 and CentOS 7, firewalld must be stopped and disabled. It is a known Docker issue that firewalld interacts poorly with Docker. For more information, see the Docker CentOS firewalld documentation.

    sudo systemctl stop firewalld && sudo systemctl disable firewalld
    
  • DC/OS is installed to /opt/mesosphere. Make sure that /opt/mesosphere exists on a partition that is not on an LVM Logical Volume or shared storage.
  • The Mesos master and agent persistent information of the cluster is stored in the /var/lib/mesos directory.

    Important: Do not remotely mount /var/lib/mesos or the Docker storage directory (by default /var/lib/docker).

  • Do not mount /tmp with noexec. This will prevent Exhibitor and ZooKeeper from running.

Port and Protocol Configuration

  • Secure Shell (SSH) must be enabled on all nodes.
  • Internet Control Message Protocol (ICMP) must be enabled on all nodes.
  • Each node is network accessible from the bootstrap node.
  • Each node has unfettered IP-to-IP connectivity from itself to all nodes in the DC/OS cluster.
  • UDP must be open for ingress to port 53 on the masters. To attach to a cluster, the Mesos agent node service (dcos-mesos-slave) uses this port to find leader.mesos.

High Speed Internet Access

High speed internet access is recommended for DC/OS installation. A minimum 10 MBit per second is required for DC/OS services. The installation of some DC/OS services will fail if the artifact download time exceeds the value of MESOS_EXECUTOR_REGISTRATION_TIMEOUT within the file /opt/mesosphere/etc/mesos-slave-common. The default value for MESOS_EXECUTOR_REGISTRATION_TIMEOUT is 10 minutes.

Software Prerequisites

Tip: Refer to this shell script for an example of how to install the software requirements for DC/OS masters and agents on a CentOS 7 host.

All Nodes

Docker

Docker must be installed on all bootstrap and cluster nodes. The supported versions of Docker are:

  • 1.7.x
  • 1.8.x
  • 1.9.x
  • 1.10.x
  • 1.11.x

Important: Version 1.12.x is not supported.

Recommendations

Distribution-Specific Installation

Each Linux distribution requires Docker to be installed in a specific way:

For more more information, see Docker’s distribution-specific installation instructions.

Disable sudo password prompts

To use the GUI or CLI installation methods, you must disable password prompts for sudo.

Add the following line to your /etc/sudoers file. This disables the sudo password prompt.

%wheel ALL=(ALL) NOPASSWD: ALL

Alternatively, you can SSH as the root user.

Enable NTP

Network Time Protocol (NTP) must be enabled on all nodes for clock synchronization. By default, during DC/OS startup you will receive an error if this is not enabled. You can check if NTP is enabled by running one of these commands, depending on your OS and configuration:

ntptime
adjtimex -p
timedatectl

Bootstrap node

Before installing DC/OS, you must ensure that your bootstrap node has the following prerequisites.

Important:

  • If you specify exhibitor_storage_backend: zookeeper, the bootstrap node is a permanent part of your cluster. With exhibitor_storage_backend: zookeeper the leader state and leader election of your Mesos masters is maintained in Exhibitor ZooKeeper on the bootstrap node. For more information, see the configuration parameter documentation.
  • The bootstrap node must be separate from your cluster nodes.

DC/OS setup file

Download and save the DC/OS setup file to your bootstrap node. This file is used to create your customized DC/OS build file.

Docker Nginx (advanced installer)

For advanced install only, install the Docker Nginx image with this command:

sudo docker pull nginx

Cluster nodes

For advanced install only, your cluster nodes must have the following prerequisites. The cluster nodes are designated as Mesos masters and agents during installation.

Data compression (advanced installer)

You must have the UnZip, GNU tar, and XZ Utils data compression utilities installed on your cluster nodes.

To install these utilities on CentOS7 and RHEL7:

sudo yum install -y tar xz unzip curl ipset

Cluster permissions (advanced installer)

On each of your cluster nodes, use the following command to:

  • Disable SELinux or set it to permissive mode.
  • Add nogroup to each of your Mesos masters and agents.
  • Reboot your cluster for the changes to take effect.

    sudo sed -i s/SELINUX=enforcing/SELINUX=permissive/g /etc/selinux/config &&
    sudo groupadd nogroup &&
    sudo reboot
    

    Tip: It may take a few minutes for your node to come back online after reboot.

Locale requirements

You must set the LC_ALL and LANG environment variables to en_US.utf-8.

Next steps


Install Docker on CentOS

Docker’s CentOS-specific installation instructions are always going to be the most up to date for the latest version of Docker. However, the following recommendations and instructions should make it easier to manage the Docker installation over time and mitigate several known issues with various other configurations.