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Introduction​

Elemental uses the Rancher System Agent, renamed to Elemental System Agent, to initially bootstrap the node with a simple plan.

The plan will apply the following configurations:

  • Set some labels for the node
  • Set the proper hostname according to the MachineInventory value
  • Install the default Rancher System Agent from Rancher Server, and install the proper Kubernetes components

The bootstrap service also accepts local plans stored under /var/lib/elemental/agent/plans. Any plan written in there will also be applied during the initial node start after the installation is completed.

tip

The local plans run only during the initial Elemental bootstrap before Kubernetes is installed on the node.

Types of Plans​

The type of plans that Elemental can use are:

  • One time instructions: Only run once
  • Periodic instructions: They run periodically
  • Files: Creates files
  • Probes: http probes
tip

Both one time instructions and periodic instructions can run either a direct command or a docker image.

Adding local plans on Elemental​

You can add local plans to Elemental as part of the MachineRegistration CRD, in the cloud-config section as follows:

apiVersion: elemental.cattle.io/v1beta1kind: MachineRegistrationmetadata:  name: my-nodes  namespace: fleet-defaultspec:  config:    cloud-config:      users:        - name: root          passwd: root      write_files:        - path: /var/lib/elemental/agent/plans/mycustomplan.plan          permissions: "0600"          content: |            {"instructions":                [                  {                    "name":"set hostname",                    "command":"hostnamectl",                    "args": ["set-hostname", "myHostname"]                  },                  {                    "name":"stop sshd service",                    "command":"systemctl",                    "args": ["stop", "sshd"]                  }                ]            }    elemental:      install:        reboot: true        device: /dev/sda        debug: true  machineName: my-machine  machineInventoryLabels:    location: "europe"

Plan examples​

The following plans are provided as a quick reference and are not guaranteed to work in your environment. To learn more about plans please check Rancher System Agent.

{"instructions":    [        {            "name":"set hostname",            "command":"hostnamectl",            "args": ["set-hostname", "myHostname"]        },        {            "name":"stop sshd service",            "command":"systemctl",            "args": ["stop", "sshd"]        }    ]}