| Property |
Description |
| ${attr.cpu.arch} |
CPU architecture of the client (e.g. amd64, 386) |
| ${attr.cpu.numcores} |
Number of CPU cores on the client |
| ${attr.cpu.totalcompute} |
cpu.frequency × cpu.numcores but may be overridden by client.cpu_total_compute
|
| ${attr.consul.datacenter} |
The Consul datacenter of the client (if Consul is found) |
| ${attr.driver.<property>} |
See the [task drivers](/docs/drivers/index.html) for property documentation |
| ${attr.unique.hostname} |
Hostname of the client |
| ${attr.unique.network.ip-address} |
The IP address fingerprinted by the client and from which task ports are allocated |
| ${attr.kernel.name} |
Kernel of the client (e.g. linux, darwin) |
| ${attr.kernel.version} |
Version of the client kernel (e.g. 3.19.0-25-generic, 15.0.0) |
| ${attr.platform.aws.ami-id} |
AMI ID of the client (if on AWS EC2) |
| ${attr.platform.aws.instance-type} |
Instance type of the client (if on AWS EC2) |
| ${attr.os.name} |
Operating system of the client (e.g. ubuntu, windows, darwin) |
| ${attr.os.version} |
Version of the client OS |
Here are some examples of using node attributes and properties in a job file:
```hcl
job "docs" {
# This will constrain this job to only run on 64-bit clients.
constraint {
attribute = "${attr.cpu.arch}"
value = "amd64"
}
# This will restrict the job to only run on clients with 4 or more cores.
# Note: you may also declare a resource requirement for CPU for a task.
constraint {
attribute = "${cpu.numcores}"
operator = ">="
value = "4"
}
# Only run this job on a memory-optimized AWS EC2 instance.
constraint {
attribute = "${attr.platform.aws.instance-type}"
value = "m4.xlarge"
}
}
```
## Environment Variables