> ## Documentation Index > Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt > Use this file to discover all available pages before exploring further. # Demo Starting the Consul Process Using Dev Mode > This article covers starting a Consul server in dev mode and bootstrapping AWS EC2 instances into a Consul cluster. 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 Running Consul in **dev mode** is intended for local testing only. Data is ephemeral and not suitable for production. ### Start the Dev Agent Open PowerShell (or your preferred shell) and launch the Consul agent: ```bash theme={null} consul agent -dev ``` You should see output similar to: ```text theme={null} 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: ```bash theme={null} consul members ``` You’ll see a single-node entry. Then open your browser to explore the Consul UI: [http://127.0.0.1:8500](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.](https://kodekloud.com/kk-media/image/upload/v1752877809/notes-assets/images/HashiCorp-Certified-Consul-Associate-Certification-Demo-Starting-the-Consul-Process-Using-Dev-Mode/consul-web-interface-services-list.jpg) 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: ```bash theme={null} # Check Consul version consul version ``` ```text theme={null} Consul v1.9.3+ent Revision bd0dc9e5d Protocol 2 spoken by default, understands 2 to 3 ``` ```bash theme={null} # Confirm the binary in PATH ls /usr/local/bin ``` ```text theme={null} consul ``` ```bash theme={null} # List systemd service files ls /etc/systemd/system ``` ```text theme={null} 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: ```ini theme={null} [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`): ```json theme={null} { "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: | Parameter | Description | | ----------- | -------------------------------------------- | | server | Enables server mode | | ui | Activates the built-in web UI | | retry\_join | List of peer addresses for automatic joining | | data\_dir | Location for Raft logs and state | | bind\_addr | Network interface for cluster communication | *** ## 5. Starting Consul on Both Nodes Open required ports (8300–8302, 8500, 8600) in your security groups before proceeding. ### Node A ```bash theme={null} 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`: ```json theme={null} { "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: ```bash theme={null} sudo systemctl start consul ``` ### Verify Cluster Membership Run on either node: ```bash theme={null} consul members ``` ```text theme={null} 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 consul-node-b 10.0.101.248:8301 alive server 1.9.3+ent 2 us-east-1 ``` | Node | Address | Status | Type | | ------------- | ----------------- | ------ | ------ | | consul-node-a | 10.0.101.110:8301 | alive | server | | consul-node-b | 10.0.101.248:8301 | alive | server | 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](https://www.consul.io/docs) * [Consul Agent Overview](https://www.consul.io/docs/agent) * [Consul Web UI](https://www.consul.io/docs/ui) * [AWS EC2 Documentation](https://docs.aws.amazon.com/ec2/) * [Packer by HashiCorp](https://www.packer.io/) * [Systemd Service Files Best Practices](https://www.consul.io/docs/platforms/systemd)