
### **Top-Level Job Configuration**
#### `job`
- **Purpose**: Defines the Nomad job.
- **Attributes**:
  - `region`: Specifies the Nomad region where the job should run. [Reference: Nomad Regions](https://developer.hashicorp.com/nomad/docs/regions)
  - `datacenters`: Lists the datacenters in which the job is eligible to run. [Reference: Job Placement](https://developer.hashicorp.com/nomad/docs/job-specification/datacenters)
  - `type`: Defines the job type (`service` in this case). Service jobs are typically long-running. [Reference: Job Types](https://developer.hashicorp.com/nomad/docs/job-specification/job)

---

### **Update Block**
#### `update`
- **Purpose**: Specifies rolling update strategy for service jobs.
- **Attributes**:
  - `stagger`: Time between starting updates for each allocation.
  - `max_parallel`: Number of allocations to update simultaneously.
  - `progress_deadline`: Time to wait for a deployment to progress before failing.
- [Reference: Update Stanza](https://developer.hashicorp.com/nomad/docs/job-specification/update)

---

### **Group Configuration**
#### `group`
- **Purpose**: Defines a group of tasks that should be placed together on the same node.
- **Attributes**:
  - `count`: Number of task groups to run.
- [Reference: Task Group](https://developer.hashicorp.com/nomad/docs/job-specification/group)

---

### **Network Configuration**
#### `network`
- **Purpose**: Specifies networking requirements for the task group.
- **Attributes**:
  - `port`: Defines a named port mapping for the task group.
    - `to`: Specifies the internal port the application listens to within the container.
- [Reference: Network Stanza](https://developer.hashicorp.com/nomad/docs/job-specification/network)

---

### **Consul Integration**
#### `service`
- **Purpose**: Registers the service with Consul for discovery.
- **Attributes**:
  - `provider`: Specifies the service discovery provider (`consul`).
  - `name`: The name of the service in Consul.
  - `port`: References the named port defined in the `network` block.
  - `tags`: Metadata tags to annotate the service (e.g., for routing in Traefik).
  - `check`: Defines health check parameters for the service.
    - `name`: Name of the health check.
    - `type`: Health check type (`tcp` in this case).
    - `interval`: Frequency of the health check.
    - `timeout`: Maximum duration for the health check.
- [Reference: Consul Service Stanza](https://developer.hashicorp.com/nomad/docs/job-specification/service)

---

### **Task Configuration**
#### `task`
- **Purpose**: Defines a single executable unit of work.
- **Attributes**:
  - `driver`: Specifies the driver (`docker` in this case).
  - `config`: Driver-specific configuration.
    - `image`: Docker image for the task.
    - `ports`: References the named port defined in the `network` block.
  - `env`: Sets environment variables for the task.
  - `resources`: Specifies resource requirements for the task.
    - `cpu`: CPU allocation in MHz.
    - `memory`: Memory allocation in MB.
- [Reference: Task Stanza](https://developer.hashicorp.com/nomad/docs/job-specification/task)

---

### **Dynamic Port Allocation**
#### `${NOMAD_PORT_<port-label>}`
- **Purpose**: Refers to the dynamically allocated host port mapped to the internal container port.
- **Usage**: This is used in the `env` and `tags` sections to dynamically configure the application and Consul registration.
- [Reference: Port Variables](https://developer.hashicorp.com/nomad/docs/runtime/environment#ports)

---

### **Key Takeaways**
1. This job defines a **service** that runs as a Docker container, listens on a dynamically assigned port, and registers itself in **Consul** for service discovery.
2. The `network` stanza ensures that Nomad assigns a dynamic host port, while the `${NOMAD_PORT_<port-label>}` variable is used to pass this information to the container and Consul.
3. The `update` stanza ensures smooth rolling updates for the service.

For further details and advanced configurations, refer to the [Nomad Job Specification Documentation](https://developer.hashicorp.com/nomad/docs/job-specification).