Prometheus datasource patching fails with single HA Front-end

[sk4zuzu]

Description
The patch_datasources.rb tool fails when OpenNebula runs on single FE in HA mode (leader w/o followers).

To Reproduce
Deploy the prometheus feature on single FE in HA mode.

Expected behavior
Prometheus datasources should be patched (no error).

Details

• Affected Component: Prometheus
• Hypervisor: KVM
• Version: 6.6

Additional context
This problem is most likely caused by (SERVER is not a list in this case):

{
  "ZONE": {
    "ID": "0",
    "NAME": "OpenNebula",
    "STATE": "0",
    "TEMPLATE": {
      "ENDPOINT": "http://localhost:2633/RPC2"
    },
    "SERVER_POOL": {
      "SERVER": {
        "ENDPOINT": "http://n1a1:2633/RPC2",
        "ID": "0",
        "NAME": "n1a1",
        "STATE": "3",
        "TERM": "1",
        "VOTEDFOR": "0",
        "COMMIT": "21",
        "LOG_INDEX": "21",
        "FEDLOG_INDEX": "-1"
      }
    }
  }
}

Progress Status

• Code committed
• Testing - QA
• Documentation (Release notes - resolved issues, compatibility, known issues)