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Documentation Index

Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt

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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.

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1. Running Consul in Dev Mode

Running Consul in dev mode is intended for local testing only. Data is ephemeral and not suitable for production.

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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

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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
The image shows a web interface for Consul, displaying a list of services with one instance labeled "consul." The interface includes options for searching and filtering by health status and service type.
To stop the agent, press Ctrl+C in the shell where it’s running.

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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.

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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.

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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:
ParameterDescription
serverEnables server mode
uiActivates the built-in web UI
retry_joinList of peer addresses for automatic joining
data_dirLocation for Raft logs and state
bind_addrNetwork interface for cluster communication

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5. Starting Consul on Both Nodes

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

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Node A

sudo systemctl start consul

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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

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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>
NodeAddressStatusType
consul-node-a10.0.101.110:8301aliveserver
consul-node-b10.0.101.248:8301aliveserver
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

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