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Deploying Consul on Azure (Single and Multi-Region)

This objective of this project is to provide an examples of a single and multi-region Consul cluster deployment in Azure using Terraform. This is a high-level overview of the environment(s) that is created:

• Creates a Resource Group to contain all resources created by this guide
• [Single-Region] Creates a virtual network, one public subnet, and three private subnets in the West US Azure region
• [Multi-Region] Creates a virtual network, one public subnet, and three private subnets in the West US and East US Azure regions
• Creates a publically-accessible jumphost for SSH access in each public subnet
• Creates one Consul cluster in each region (3 server nodes in each) using an install script for on-the-fly Consul installation and configuration
• Uses Consul's cloud auto-join to connect the Consul nodes within in each region to each other (LAN gossip pool)
• Additionally, for the Multi-Region deployment, we connect the Consul clusters in each region to each other (WAN gossip pool)
  • You can read more about Consul's Gossip protocol here.
  • You can read more about Consul's Basic Federation approach here.

Deployment Prerequisites

1. In order to perform the steps in this guide, you will need to have an Azure subscription for which you can create Service Principals as well as network and compute resources. You can create a free Azure account here.

2. Certain steps will require entering commands through the Azure CLI. You can find out more about installing it here.

3. Create Azure API Credentials - set up the main Service Principal that will be used by Terraform:

   • https://www.terraform.io/docs/providers/azurerm/index.html
   • The above steps will create a Service Principal with the Contributor role in your Azure subscription

4. export environment variables for the main Terraform Service Principal. For example, create a env.sh file with the following values (obtained from step 1 above):

   export ARM_SUBSCRIPTION_ID="xxxxxxxx-yyyy-zzzz-xxxx-yyyyyyyyyyyy"
   export ARM_CLIENT_ID="xxxxxxxx-yyyy-zzzz-xxxx-yyyyyyyyyyyy"
   export ARM_CLIENT_SECRET="xxxxxxxx-yyyy-zzzz-xxxx-yyyyyyyyyyyy"
   export ARM_TENANT_ID="xxxxxxxx-yyyy-zzzz-xxxx-yyyyyyyyyyyy"
   

   You can then source these environment variables as such:

   $ source env.sh
   

5. Create a read-only Azure Service Principal (using the Azure CLI) that will be used to perform the Consul auto-join (make note of these values as you will use them later in this guide):

   $ az ad sp create-for-rbac --role="Reader" --scopes="/subscriptions/[YOUR_SUBSCRIPTION_ID]"
   

Deploy the Consul Cluster

1. git clone the hashicorp-guides/azure-consul repository

2. cd into the desired Terraform subdirectory: azure-consul/terraform/[single-region | multi-region]

3. At this point, you will need to create a terraform.tfvars file, which contains the Azure read-only credentials for Consul auto-join.

   • NOTE: We explicitly add this file to our .gitignore file to avoid inadvertantly committing sensitive information. There's a terraform.tfvars.example file provided that you can copy and update with your specific values:

   • auto_join_subscription_id, auto_join_client_id, auto_join_client_secret, auto_join_tenant_id will use the values obtained from creating the read-only auto-join Service Principal created in step #5 of the Deployment Prerequisites earlier.

4. Run terraform init to initialize the working directory and download appropriate providers

5. Run terraform plan to verify deployment steps and validate all modules

6. Finally, run terraform apply to deploy the Consul cluster

Verify Deployment

• SSH into a jumphost, then SSH into Consul servers:

jumphost_ssh_connection_strings = [
    ssh-add private_key.pem && ssh -A -i private_key.pem azure-user@13.64.0.0
]
consul_private_ips = [
    ssh azure-user@172.31.48.4,
    ssh azure-user@172.31.64.4,
    ssh azure-user@172.31.80.4
]

• Since we are installing and configuring Consul at runtime, you will need to wait several minutes for everything to complete. You can view the progress of the installation with tail -f /var/log/user-data.log.

• Once you see the message "Completed Configuration of Consul Node. Run 'consul members' to view cluster information." you can perform the following:

• Run consul members to view the status of the local cluster:

$ consul members

Node             Address         Status  Type    Build  Protocol  DC   Segment
consul-eastus-0  10.1.48.4:8301  alive   server  1.0.0  2         dc1  <all>
consul-eastus-1  10.1.64.4:8301  alive   server  1.0.0  2         dc1  <all>
consul-eastus-2  10.1.80.4:8301  alive   server  1.0.0  2         dc1  <all>

• [Multi-Region] To view the status of your WAN-connected clusters, run consul members -wan:

$ consul members -wan

Node                 Address         Status  Type    Build  Protocol  DC   Segment
consul-eastus-0.dc1  10.1.48.4:8302  alive   server  1.0.0  2         dc1  <all>
consul-eastus-1.dc1  10.1.64.4:8302  alive   server  1.0.0  2         dc1  <all>
consul-eastus-2.dc1  10.1.80.4:8302  alive   server  1.0.0  2         dc1  <all>
consul-westus-0.dc1  10.0.48.4:8302  alive   server  1.0.0  2         dc1  <all>
consul-westus-1.dc1  10.0.64.4:8302  alive   server  1.0.0  2         dc1  <all>
consul-westus-2.dc1  10.0.80.4:8302  alive   server  1.0.0  2         dc1  <all>