Set up the cluster with Consul and Nomad

In this tutorial, you will create the required infrastructure and set up access to the CLI and UI of Consul and Nomad.

Infrastructure overview

The cluster consists of three server nodes, three private client nodes, and one publicly accessible client node. Each node runs the Consul agent and Nomad agent. The agents run in either server or client mode depending on the role of the node.

Nomad server nodes are responsible for accepting jobs, managing client nodes, and scheduling workloads. Consul server nodes are responsible for storing state information like service address, the results of health checks, and other service-specific configurations.

Nomad client nodes are the nodes where Nomad schedules workloads to run. The Nomad client registers with the Nomad servers, communicates health status to the servers, accepts task allocations, and updates the status of allocations. Consul client nodes report node and service health statuses to Consul servers.

Prerequisites

Running this tutorial locally requires the following software and credentials:

• Nomad CLI installed locally
• Consul CLI installed locally
• Packer CLI installed locally
• Terraform CLI installed locally
• AWS account with credentials environment variables set locally
• openssl and hey CLI tools installed locally

Create the cluster

The cluster creation process includes steps to build the machine images with Packer and then deploy the infrastructure with Terraform.

Make sure that you have cloned the tutorial's code repository locally and changed into the directory.

Build the machine image

Change into the aws directory.

$ cd aws

Rename the example variables file.

$ cp variables.hcl.example variables.hcl

Open variables.hcl in your text editor. Update the region variable to your preferred AWS region. In this example, the region is us-east-1. The remaining variables are for Terraform and you will update them after building the AMI. Save the file.

# Packer variables (all are required)
region          = "us-east-1"

# ...

Initialize Packer to download the required plugins. This command returns no output when it finishes successfully.

$ packer init image.pkr.hcl

Build the image and provide the variables file with the -var-file flag.

$ packer build -var-file=variables.hcl image.pkr.hcl

# ...

Build 'amazon-ebs' finished after 14 minutes 32 seconds.

==> Wait completed after 14 minutes 32 seconds

==> Builds finished. The artifacts of successful builds are:
--> amazon-ebs: AMIs were created:
us-east-1: ami-0445eeea5e1406960

The terminal outputs the value of the AMI.

Deploy the infrastructure

Open variables.hcl in your text editor and update the ami variable with the value output from the Packer build. In this example, the value is ami-0445eeea5e1406960. Save the file.

# Packer variables (all are required)
region                    = "us-east-1"

# Terraform variables (all are required)
ami                       = "ami-0b2d23848882ae42d"

# ...

The variables.hcl file includes options for values used to configure Consul.

Consul is configured with TLS encryption and to trust the certificate provided by the Consul servers. The Consul Terraform provider requires the CONSUL_TLS_SERVER_NAME environment variable to be set.

The Terraform code defaults the datacenter and domain variables in variables.hcl to dc1 and global so CONSUL_TLS_SERVER_NAME will be consul.dc1.global.

# ...
# These variables will default to the values shown
# and do not need to be updated unless you want to
# change them
# domain                  = "global"
# datacenter              = "dc1"

You can update these variables with other values. If you do, be sure to also update the CONSUL_TLS_SERVER_NAME variable.

Export the CONSUL_TLS_SERVER_NAME environment variable.

$ export CONSUL_TLS_SERVER_NAME="consul.dc1.global"

Initialize the Terraform configuration to download the necessary providers and modules.

$ terraform init
Initializing the backend...
Initializing modules...
Downloading registry.terraform.io/terraform-aws-modules/vpc/aws 5.13.0 for vpc...
- vpc in .terraform/modules/vpc

Initializing provider plugins...
- Finding hashicorp/tls versions matching "4.0.5"...
- Finding hashicorp/local versions matching "2.5.1"...
- Finding hashicorp/consul versions matching "2.21.0"...
- Finding hashicorp/nomad versions matching "2.3.1"...
- Finding hashicorp/aws versions matching ">= 5.46.0, ~> 5.46.0"...
- Finding hashicorp/random versions matching ">= 2.0.0"...

# ...

Terraform has been successfully initialized!

Provision the resources and provide the variables file with the -var-file flag. Respond yes to the prompt to confirm the operation. Terraform will output addresses for the Consul and Nomad UIs when it completes the process.

$ terraform apply -var-file=variables.hcl

# ...

Plan: 88 to add, 0 to change, 0 to destroy.

Changes to Outputs:
  + Configure-local-environment = "source ./datacenter.env"
  + Consul_UI                   = (known after apply)
  + Consul_UI_token             = (sensitive value)
  + Nomad_UI                    = (known after apply)
  + Nomad_UI_token              = (sensitive value)

Do you want to perform these actions?
  Terraform will perform the actions described above.
  Only 'yes' will be accepted to approve.

# ...

Apply complete! Resources: 85 added, 0 changed, 0 destroyed.

Outputs:

Configure-local-environment = "source ./datacenter.env"
Consul_UI = "https://18.116.52.247:8443"
Consul_UI_token = <sensitive>
Nomad_UI = "https://18.116.52.247:4646"
Nomad_UI_token = <sensitive>

Set up Consul and Nomad access

Set up access to Consul and Nomad from your local terminal using the output values from Terraform.

The Terraform code generates a datacenter.env environment file that contains all the necessary variables to connect to your Consul and Nomad instances using the CLI.

Source the datacenter.env file to set the Consul and Nomad environment variables. This command returns no output when it runs successfully.

$ source ./datacenter.env

$ consul members
Node                    Address          Status  Type    Build   Protocol  DC   Partition  Segment
consul-server-0         10.0.4.203:8301  alive   server  1.19.0  2         dc1  default    <all>
consul-server-1         10.0.4.213:8301  alive   server  1.19.0  2         dc1  default    <all>
consul-server-2         10.0.4.70:8301   alive   server  1.19.0  2         dc1  default    <all>
consul-client-0         10.0.4.4:8301    alive   client  1.19.0  2         dc1  default    <default>
consul-client-1         10.0.4.82:8301   alive   client  1.19.0  2         dc1  default    <default>
consul-client-2         10.0.4.19:8301   alive   client  1.19.0  2         dc1  default    <default>
consul-public-client-0  10.0.4.22:8301   alive   client  1.19.0  2         dc1  default    <default>

$ nomad server members
Name                   Address     Port  Status  Leader  Raft Version  Build  Datacenter  Region
nomad-server-0.global  10.0.4.231  4648  alive   false   3             1.8.3  dc1         global
nomad-server-1.global  10.0.4.19   4648  alive   true    3             1.8.3  dc1         global
nomad-server-2.global  10.0.4.156  4648  alive   false   3             1.8.3  dc1         global

$ nomad ui -authenticate
Opening URL "https://18.116.52.247:4646" with one-time token

Next steps

In this tutorial, you created a cluster running Consul and Nomad and set up CLI and UI access to Consul and Nomad.

In the next tutorial, you will deploy the initial containerized version of the HashiCups application.