Demo Starting the Consul Process Using Dev Mode

Welcome to the first lab of this course. In this lesson, we’ll cover two main tasks:

1. Starting a Consul server in dev mode on your local machine
2. Bootstrapping two AWS EC2 instances into a Consul cluster

Throughout the course, we’ll reuse these servers so you can follow along and observe how the cluster evolves.

1. Running Consul in Dev Mode

Start the Dev Agent

Open PowerShell (or your preferred shell) and launch the Consul agent:

consul agent -dev

You should see output similar to:

2021-02-10T16:03:43.762-0500 [INFO]  agent.leader: started routine: routine="federation state anti-entropy"
2021-02-10T16:03:43.763-0500 [DEBUG] agent.server: successfully established leadership: duration=19.001ms
2021-02-10T16:03:43.817-0500 [INFO]  agent: Synced node info
2021-02-10T16:03:45.177-0500 [DEBUG] agent: Node info in sync

Verify the Local Agent

In a new shell, confirm the agent is running:

consul members

You’ll see a single-node entry. Then open your browser to explore the Consul UI:

http://127.0.0.1:8500

To stop the agent, press Ctrl+C in the shell where it’s running.

2. Preparing AWS EC2 Instances

I’ve provisioned two EC2 instances and used Packer to install Consul under /usr/local/bin. Let’s verify everything:

# Check Consul version
consul version

Consul v1.9.3+ent
Revision bd0dc9e5d
Protocol 2 spoken by default, understands 2 to 3

# Confirm the binary in PATH
ls /usr/local/bin

consul

# List systemd service files
ls /etc/systemd/system

consul.service  consul-snapshot.service  basic.target.wants  ...  

You should see both consul.service and consul-snapshot.service.

3. Reviewing the Systemd Service File

Open /etc/systemd/system/consul.service to inspect how Consul is managed:

[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/config.hcl

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

[Install]
WantedBy=multi-user.target

This unit ensures Consul starts after networking is available and points to our main configuration file.

4. Reviewing the Consul Configuration (Node A)

Below is the JSON-based configuration at /etc/consul.d/config.hcl for node A (10.0.101.110):

{
  "log_level": "INFO",
  "node_name": "consul-node-a",
  "server": true,
  "ui": true,
  "leave_on_terminate": true,
  "data_dir": "/etc/consul.d/data",
  "datacenter": "us-east-1",
  "client_addr": "0.0.0.0",
  "bind_addr": "10.0.101.110",
  "advertise_addr": "10.0.101.110",
  "retry_join": ["10.0.101.248"],
  "enable_syslog": true,
  "performance": {
    "raft_multiplier": 1
  }
}

Key configuration parameters:

5. Starting Consul on Both Nodes

Open required ports (8300–8302, 8500, 8600) in your security groups before proceeding.

Node A

sudo systemctl start consul

Node B

On the second instance (10.0.101.248), the /etc/consul.d/config.hcl is identical except for IP addresses and node_name:

{
  "node_name": "consul-node-b",
  "bind_addr": "10.0.101.248",
  "advertise_addr": "10.0.101.248",
  "retry_join": ["10.0.101.110"],
  ...
}

Start the service:

sudo systemctl start consul

Verify Cluster Membership

Run on either node:

consul members

Node           Address             Status  Type    Build       Protocol  DC          Segment
consul-node-a  10.0.101.110:8301   alive   server  1.9.3+ent   2         us-east-1   <all>
consul-node-b  10.0.101.248:8301   alive   server  1.9.3+ent   2         us-east-1   <all>

Because of the retry_join settings, both servers automatically discover each other and form a cluster.

That concludes this lab. You’ve learned how to:

• Run Consul in dev mode locally
• Prepare EC2 instances and verify Consul installation
• Inspect systemd service and configuration files
• Bootstrap a two-node Consul server cluster on AWS

Links and References

• Consul Documentation
• Consul Agent Overview
• Consul Web UI
• AWS EC2 Documentation
• Packer by HashiCorp
• Systemd Service Files Best Practices