» Encryption Overview

The Nomad agent supports encrypting all of its network traffic. There are two separate encryption systems, one for gossip traffic, and one for HTTP and RPC.

» Gossip

Enabling gossip encryption only requires that you set an encryption key when starting the Nomad server. The key can be set via the encrypt parameter: the value of this setting is a server configuration file containing the encryption key.

The key must be 16 bytes, base64 encoded. As a convenience, Nomad provides the nomad operator keygen command to generate a cryptographically suitable key:

$ nomad operator keygen
cg8StVXbQJ0gPvMd9o7yrg==

With that key, you can enable gossip encryption on the agent.

» HTTP, RPC, and Raft Encryption with TLS

Nomad supports using TLS to verify the authenticity of servers and clients. To enable this, Nomad requires that all clients and servers have key pairs that are generated and signed by a private Certificate Authority (CA).

TLS can be used to verify the authenticity of the servers and clients. The configuration option verify_server_hostname causes Nomad to verify that a certificate is provided that is signed by the Certificate Authority from the ca_file for TLS connections.

If verify_server_hostname is set, then outgoing connections perform hostname verification. Unlike traditional HTTPS browser validation, all servers must have a certificate valid for server.<region>.nomad or the client will reject the handshake. It is also recommended for the certificate to sign localhost such that the CLI can validate the server name.

TLS is used to secure the RPC calls between agents, but gossip between nodes is done over UDP and is secured using a symmetric key. See above for enabling gossip encryption.

» Configuring the command line tool

If you have HTTPS enabled for your Nomad agent, you must export environment variables for the command line tool to also use HTTPS:

# NOMAD_ADDR defaults to http://, so set it to https
# Alternatively you can use the -address flag
export NOMAD_ADDR=https://127.0.0.1:4646

# Set the location of your CA certificate
# Alternatively you can use the -ca-cert flag
export NOMAD_CACERT=/path/to/ca.pem

Run any command except agent with -h to see all environment variables and flags. For example: nomad status -h

By default HTTPS does not validate client certificates, so you do not need to give the command line tool access to any private keys.

» Network Isolation with TLS

If you want to isolate Nomad agents on a network with TLS you need to enable both verify_https_client and verify_server_hostname. This will cause agents to require client certificates for all incoming HTTPS connections as well as verify proper names on all other certificates.

Consul will not attempt to health check agents with verify_https_client set as it is unable to use client certificates.

» Configuring Nomad with TLS

Read the Securing Nomad with TLS Guide for details on how to configure encryption for Nomad.