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Day 1: Deploy Your First Datacenter

Deployment Guide

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

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

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

Reference Diagram

These setup steps should be completed on all Consul hosts.

  1. Download Consul
  2. Install Consul
  3. Configure systemd
  4. Configure Consul (server) or (client)
  5. Start Consul
  6. Apply Enterprise license
  7. Configure Consul ACLs

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

»Download Consul

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

$ export CONSUL_VERSION="1.7.0"
curl --silent --remote-name https://releases.hashicorp.com/consul/${CONSUL_VERSION}/consul_${CONSUL_VERSION}_linux_amd64.zip
curl --silent --remote-name https://releases.hashicorp.com/consul/${CONSUL_VERSION}/consul_${CONSUL_VERSION}_SHA256SUMS
curl --silent --remote-name https://releases.hashicorp.com/consul/${CONSUL_VERSION}/consul_${CONSUL_VERSION}_SHA256SUMS.sig

»Install Consul

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

$ unzip consul_${CONSUL_VERSION}_linux_amd64.zip
$ sudo chown root:root consul
$ sudo mv consul /usr/local/bin/
$ consul --version

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

$ consul -autocomplete-install
$ complete -C /usr/local/bin/consul consul

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

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

»Configure systemd

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

Create a Consul service file at /etc/systemd/system/consul.service.

$ sudo touch /etc/systemd/system/consul.service

Add this configuration to the Consul service file:

[Unit]
Description="HashiCorp Consul - A service mesh solution"
Documentation=https://www.consul.io/
Requires=network-online.target
After=network-online.target
ConditionFileNotEmpty=/etc/consul.d/consul.hcl

[Service]
Type=notify
User=consul
Group=consul
ExecStart=/usr/local/bin/consul agent -config-dir=/etc/consul.d/
ExecReload=/usr/local/bin/consul reload
ExecStop=/usr/local/bin/consul leave
KillMode=process
Restart=on-failure
LimitNOFILE=65536

[Install]
WantedBy=multi-user.target

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

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

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

  • Type - Set to notify so systemd will not attempt to start any dependent services until after Consul sends the notify signal
  • User, Group - Run Consul as the consul user
  • ExecStart - Start Consul with the agent argument and path to the configuration file
  • ExecReload - Send Consul a reload signal to trigger a configuration reload in Consul
  • ExecStop - Stop Consul with the leave argument to allow for a graceful leave from the datacenter
  • KillMode - Treat consul as a single process
  • Restart - Restart consul unless it returned a clean exit code
  • LimitNOFILE - Set an increased limit for file descriptors

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

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

»Configure Consul (server)

Consul 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.

Consul server agents typically require a superset of configuration required by Consul client agents. We will specify common configuration used by all Consul agents in consul.hcl and server specific configuration in server.hcl.

»General configuration

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

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

Add this configuration to the consul.hcl configuration file:

datacenter = "dc1"
data_dir = "/opt/consul"
encrypt = "Luj2FZWwlt8475wD1WtwUQ=="
  • datacenter - The datacenter in which the agent is running.
  • data_dir - The data directory for the agent to store state.
  • encrypt - Specifies the secret key to use for encryption of Consul network traffic.

»Cluster auto-join

The retry_join parameter allows you to configure all Consul agents to automatically form a cluster using a common Consul server accessed via DNS address, IP address or using Cloud Auto-join. This removes the need to manually join the Consul datacenter nodes together.

Add the retry_join parameter to the consul.hcl configuration file:

retry_join = ["172.16.0.11"]
  • retry_join - Address of another agent to join upon starting up.

»Performance stanza

The performance stanza allows tuning the performance of different subsystems in Consul.

Add the performance configuration to the consul.hcl configuration file:

performance {
  raft_multiplier = 1
}
  • raft_multiplier - An integer multiplier used by Consul servers to scale key Raft timing parameters. Setting this to a value of 1 will configure Raft to its highest-performance mode, equivalent to the default timing of Consul prior to 0.7, and is recommended for production Consul servers.

For more information on Raft tuning and the raft_multiplier setting, see the server performance documentation.

»Telemetry stanza

The telemetry stanza specifies various configurations for Consul to publish metrics to upstream systems.

If you decide to configure Consul to publish telemetry data, you should complete the Monitoring and Metrics guide at the end of the Day 1 learning path.

»Server configuration

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

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

Add this configuration to the server.hcl configuration file:

server = true
bootstrap_expect = 3
  • server - This flag is used to control if an agent is in server or client mode.
  • bootstrap-expect - This flag provides the number of expected servers in the datacenter. Either this value should not be provided or the value should be consistent across all servers in the datacenter.

»Consul UI

Consul features a web-based user interface, allowing you to easily view all services, nodes, intentions and more using a graphical user interface, rather than the CLI or API.

Optionally, add the UI configuration to the server.hcl configuration file to enable the Consul UI:

ui = true

»Configure Consul (client)

Consul client agents typically require a subset of configuration required by Consul server agents. All Consul clients can use the consul.hcl file created when configuring the Consul servers. If you have added host-specific configuration such as identifiers, you will need to set these individually.

»Start Consul

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

sudo systemctl enable consul
sudo systemctl start consul
sudo systemctl status consul

»Apply Enterprise license

When using the Enterprise version of Consul binaries, there is a time limit Consul will function without applying a license. For Enterprise customers that have purchased a license, work with your TAM to get the appropriate license. To apply the license you'll need to follow the below steps:

  1. Ensure you are using an Enterprise binary.

    The license commands are only available in enterprise versions of the binaries. Make sure enterprise versions of the binaries have been installed and are running on the servers.

    consul version
    

    Consul Enterprise version will end with +ent.

    Consul v1.7.2+ent
    Protocol 2 spoken by default, understands 2 to 3 (agent will automatically use protocol >2 when speaking to compatible agents)
    
  2. Run the following command on the Consul leader.

    $ consul license put "<paste license text here>"
    

    Once the command runs successfully, the output should indicate that the license is valid.

    License is valid
    License ID: a763ad9f-ecfa-948c-7355-5a502aeac721
    Customer ID: 7e6ac3e0-f44b-23c3-c486-3264eabc4326
    Expires At: 2018-06-30 06:59:59.999 +0000 UTC
    Datacenter: *
    Package: cHJlbWl1bQ==
    Licensed Features:
        Automated Backups
        Automated Upgrades
        Enhanced Read Scalability
        Network Segments
        Redundancy Zone
        Advanced Network Federation
    

    The license will be replicated to other the Consul servers from the leader.

»Configure Consul ACLs

The Securing Consul with ACLs guide provides instructions on configuring and enabling ACLs on new agents. The below guidance assumes Consul has already been started without ACLs configured.

»Configure ACLs on Consul >= 1.4.x

  1. Create a Consul configuration file (/etc/consul.d/acl.hcl) on all servers and clients to use ACLs and choose a default policy of "allow" (like a soft limit or blacklist) or "deny" (like a hard limit or whitelist).

    acl {
      enabled = true
      default_policy = "deny"
      enable_token_persistence = true
    }
    
  2. Initiate a rolling restart of all Consul agents, starting with the servers.

    $ sudo systemctl restart consul
    
  3. Working from one agent generate the Consul bootstrap token, which has unrestricted privileges.

    $ consul acl bootstrap
    

    This will return the Consul bootstrap token. You will need the SecretID for all subsequent Consul API requests (including CLI and UI). Ensure that you save the SecretID.

  4. Set CONSUL_MGMT_TOKEN env variable.

    $ export CONSUL_MGMT_TOKEN="<Token SecretID from previous step>"
    
  5. Create a node policy file (node-policy.hcl) with write access for nodes related actions and read access for service related actions.

    agent_prefix "" {
      policy = "write"
    }
    node_prefix "" {
      policy = "write"
    }
    service_prefix "" {
      policy = "read"
    }
    session_prefix "" {
      policy = "read"
    }
    
  6. Generate the Consul node ACL policy with the newly created policy file.

    $ consul acl policy create \
      -token=${CONSUL_MGMT_TOKEN} \
      -name node-policy \
      -rules @node-policy.hcl
    
  7. Create the node token with the newly created policy.

    $ consul acl token create \
      -token=${CONSUL_MGMT_TOKEN} \
      -description "node token" \
      -policy-name node-policy
    
  8. On all Consul Servers add the node token.

    $ consul acl set-agent-token \
      -token="<Management Token SecretID>" \
      agent "<Node Token SecretID>"
    

»Summary

In this guide you configured servers and clients in accordance to the reference architecture. This is the first step in deploying your first datacenter. In the next guide, you will learn how to configure backups to ensure the cluster state is protected against possible failures.

To increase security for your datacenter, we recommend completing the Securing Consul with ACLs, agent encryption guide, and certificates guide. All three guides are in the Day 1 learning path.

Finally, we also recommend reviewing the Windows agent guide for a mixed workload environment.