88 lines
4.0 KiB
Markdown
88 lines
4.0 KiB
Markdown
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### **Top-Level Job Configuration**
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#### `job`
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- **Purpose**: Defines the Nomad job.
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- **Attributes**:
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- `region`: Specifies the Nomad region where the job should run. [Reference: Nomad Regions](https://developer.hashicorp.com/nomad/docs/regions)
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- `datacenters`: Lists the datacenters in which the job is eligible to run. [Reference: Job Placement](https://developer.hashicorp.com/nomad/docs/job-specification/datacenters)
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- `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)
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---
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### **Update Block**
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#### `update`
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- **Purpose**: Specifies rolling update strategy for service jobs.
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- **Attributes**:
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- `stagger`: Time between starting updates for each allocation.
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- `max_parallel`: Number of allocations to update simultaneously.
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- `progress_deadline`: Time to wait for a deployment to progress before failing.
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- [Reference: Update Stanza](https://developer.hashicorp.com/nomad/docs/job-specification/update)
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---
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### **Group Configuration**
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#### `group`
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- **Purpose**: Defines a group of tasks that should be placed together on the same node.
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- **Attributes**:
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- `count`: Number of task groups to run.
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- [Reference: Task Group](https://developer.hashicorp.com/nomad/docs/job-specification/group)
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---
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### **Network Configuration**
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#### `network`
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- **Purpose**: Specifies networking requirements for the task group.
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- **Attributes**:
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- `port`: Defines a named port mapping for the task group.
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- `to`: Specifies the internal port the application listens to within the container.
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- [Reference: Network Stanza](https://developer.hashicorp.com/nomad/docs/job-specification/network)
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---
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### **Consul Integration**
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#### `service`
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- **Purpose**: Registers the service with Consul for discovery.
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- **Attributes**:
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- `provider`: Specifies the service discovery provider (`consul`).
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- `name`: The name of the service in Consul.
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- `port`: References the named port defined in the `network` block.
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- `tags`: Metadata tags to annotate the service (e.g., for routing in Traefik).
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- `check`: Defines health check parameters for the service.
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- `name`: Name of the health check.
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- `type`: Health check type (`tcp` in this case).
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- `interval`: Frequency of the health check.
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- `timeout`: Maximum duration for the health check.
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- [Reference: Consul Service Stanza](https://developer.hashicorp.com/nomad/docs/job-specification/service)
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---
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### **Task Configuration**
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#### `task`
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- **Purpose**: Defines a single executable unit of work.
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- **Attributes**:
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- `driver`: Specifies the driver (`docker` in this case).
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- `config`: Driver-specific configuration.
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- `image`: Docker image for the task.
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- `ports`: References the named port defined in the `network` block.
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- `env`: Sets environment variables for the task.
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- `resources`: Specifies resource requirements for the task.
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- `cpu`: CPU allocation in MHz.
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- `memory`: Memory allocation in MB.
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- [Reference: Task Stanza](https://developer.hashicorp.com/nomad/docs/job-specification/task)
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---
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### **Dynamic Port Allocation**
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#### `${NOMAD_PORT_<port-label>}`
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- **Purpose**: Refers to the dynamically allocated host port mapped to the internal container port.
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- **Usage**: This is used in the `env` and `tags` sections to dynamically configure the application and Consul registration.
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- [Reference: Port Variables](https://developer.hashicorp.com/nomad/docs/runtime/environment#ports)
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---
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### **Key Takeaways**
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1. This job defines a **service** that runs as a Docker container, listens on a dynamically assigned port, and registers itself in **Consul** for service discovery.
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2. The `network` stanza ensures that Nomad assigns a dynamic host port, while the `${NOMAD_PORT_<port-label>}` variable is used to pass this information to the container and Consul.
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3. The `update` stanza ensures smooth rolling updates for the service.
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For further details and advanced configurations, refer to the [Nomad Job Specification Documentation](https://developer.hashicorp.com/nomad/docs/job-specification). |