» Nomad Deployment Guide

This deployment guide covers the steps required to install and configure a single HashiCorp Nomad cluster as defined in the Nomad Reference Architecture.

These instructions are for installing and configuring Nomad on Linux hosts running the systemd system and service manager.

» Reference Material

This deployment guide is designed to work in combination with the Nomad Reference Architecture and Consul Deployment Guide. Although it is not a strict requirement to follow the Nomad Reference Architecture, please ensure you are familiar with the overall architecture design. For example, installing Nomad server agents on multiple physical or virtual (with correct anti-affinity) hosts for high-availability.

» Overview

To provide a highly-available single cluster architecture, we recommend Nomad server agents be deployed to more than one host, as shown in the Nomad Reference Architecture.

Reference diagram

These setup steps should be completed on all Nomad hosts:

» Download Nomad

Precompiled Nomad binaries are available for download at https://releases.hashicorp.com/nomad/ and Nomad Enterprise binaries are available for download by following the instructions made available to HashiCorp Enterprise customers.

You should perform checksum verification of the zip packages using the SHA256SUMS and SHA256SUMS.sig files available for the specific release version. HashiCorp provides a guide on checksum verification for precompiled binaries.

NOMAD_VERSION="0.8.4"
curl --silent --remote-name https://releases.hashicorp.com/nomad/${NOMAD_VERSION}/nomad_${NOMAD_VERSION}_linux_amd64.zip
curl --silent --remote-name https://releases.hashicorp.com/nomad/${NOMAD_VERSION}/nomad_${NOMAD_VERSION}_SHA256SUMS
curl --silent --remote-name https://releases.hashicorp.com/nomad/${NOMAD_VERSION}/nomad_${NOMAD_VERSION}_SHA256SUMS.sig

» Install Nomad

Unzip the downloaded package and move the nomad binary to /usr/local/bin/. Check nomad is available on the system path.

unzip nomad_${NOMAD_VERSION}_linux_amd64.zip
sudo chown root:root nomad
sudo mv nomad /usr/local/bin/
nomad --version

The nomad command features opt-in autocompletion for flags, subcommands, and arguments (where supported). Enable autocompletion.

nomad -autocomplete-install
complete -C /usr/local/bin/nomad nomad

Create a unique, non-privileged system user to run Nomad and create its data directory.

sudo useradd --system --home /etc/nomad.d --shell /bin/false nomad
sudo mkdir --parents /opt/nomad
sudo chown --recursive nomad:nomad /opt/nomad

» Configure systemd

Systemd uses documented sane defaults so only non-default values must be set in the configuration file.

Create a Nomad service file at /etc/systemd/system/nomad.service.

sudo touch /etc/systemd/system/nomad.service

Add this configuration to the Nomad service file:

[Unit]
Description="HashiCorp Nomad - An application and service scheduler"
Documentation=https://www.nomad.io/docs/
Requires=network-online.target
After=network-online.target
ConditionFileNotEmpty=/etc/nomad.d/nomad.hcl

[Service]
User=nomad
Group=nomad
ExecStart=/usr/local/bin/nomad agent -config=/etc/nomad.d/
ExecReload=/bin/kill --signal HUP $MAINPID
KillMode=process
Restart=on-failure
RestartSec=2
StartLimitBurst=3
StartLimitIntervalSec=10
LimitNOFILE=65536

[Install]
WantedBy=multi-user.target

The following parameters are set for the [Unit] stanza:

  • Description - Free-form string describing the nomad service
  • Documentation - Link to the nomad documentation
  • Requires - Configure a requirement dependency on the network service
  • After - Configure an ordering dependency on the network service being started before the nomad service
  • ConditionFileNotEmpty - Check for a non-zero sized configuration file before nomad is started

The following parameters are set for the [Service] stanza:

  • User, Group - Run nomad as the nomad user
  • ExecStart - Start nomad with the agent argument and path to the configuration file
  • ExecReload - Send nomad a SIGHUP signal to trigger a configuration reload in nomad
  • KillMode - Treat nomad as a single process
  • Restart - Restart nomad unless it returned a clean exit code
  • RestartSec - Restart nomad after 2 seconds of it being considered 'failed'
  • StartLimitBurst, StartLimitIntervalSec - Configure unit start rate limiting
  • LimitNOFILE - Set an increased Limit for File Descriptors

The following parameters are set for the [Install] stanza:

  • WantedBy - Creates a weak dependency on nomad being started by the multi-user run level

» Configure Nomad

Nomad uses documented sane defaults so only non-default values must be set in the configuration file. Configuration can be read from multiple files and is loaded in lexical order. See the full description for more information about configuration loading and merge semantics.

Some configuration settings are common to both server and client Nomad agents, while some configuration settings must only exist on one or the other. Follow the common configuration guidance on all hosts and then the specific guidance depending on whether you are configuring a Nomad server or client.

» Common configuration

Create a configuration file at /etc/nomad.d/nomad.hcl:

sudo mkdir --parents /etc/nomad.d
sudo touch /etc/nomad.d/nomad.hcl
sudo chown --recursive nomad:nomad /etc/nomad.d
sudo chmod 640 /etc/nomad.d/nomad.hcl

Add this configuration to the nomad.hcl configuration file:

datacenter = "dc1"
data_dir = "/opt/nomad"
  • datacenter - The datacenter in which the agent is running.
  • data_dir - The data directory for the agent to store state.

» Server configuration

Create a configuration file at /etc/nomad.d/server.hcl:

sudo mkdir --parents /etc/nomad.d
sudo touch /etc/nomad.d/server.hcl
sudo chown --recursive nomad:nomad /etc/nomad.d
sudo chmod 640 /etc/nomad.d/server.hcl

Add this configuration to the server.hcl configuration file:

server {
  enabled = true
  bootstrap_expect = 3
}
  • server - Specifies if this agent should run in server mode. All other server options depend on this value being set.
  • bootstrap-expect - This flag provides the number of expected servers in the datacenter. Either this value should not be provided or the value must agree with other servers in the cluster.

» Client configuration

Create a configuration file at /etc/nomad.d/client.hcl:

sudo mkdir --parents /etc/nomad.d
sudo touch /etc/nomad.d/client.hcl
sudo chown --recursive nomad:nomad /etc/nomad.d
sudo chmod 640 /etc/nomad.d/client.hcl

Add this configuration to the client.hcl configuration file:

client {
  enabled = true
}
  • client - Specifies if this agent should run in client mode. All other client options depend on this value being set.

» ACL configuration

The Access Control guide provides instructions on configuring and enabling ACLs.

» TLS configuration

Securing Nomad's cluster communication with mutual TLS (mTLS) is recommended for production deployments and can even ease operations by preventing mistakes and misconfigurations. Nomad clients and servers should not be publicly accessible without mTLS enabled.

The Securing Nomad with TLS guide provides instructions on configuring and enabling TLS.

» Start Nomad

Enable and start Nomad using the systemctl command responsible for controlling systemd managed services. Check the status of the nomad service using systemctl.

sudo systemctl enable nomad
sudo systemctl start nomad
sudo systemctl status nomad

» Next Steps

  • Read Outage Recovery to learn the steps required to recover from a Nomad cluster outage.
  • Read Autopilot to learn about features in Nomad 0.8 to allow for automatic operator-friendly management of Nomad servers.