External group definition script for ClusterShell. Reads group definitions from a YAML file and outputs hostnames. This is created so we can store additional metadata with the hosts

get_nodes_from_yaml.sh

#!/bin/bash
# External group definition script for ClusterShell
# Reads group definitions from a YAML file and outputs hostnames

# Default YAML file path
YAML_FILE="/etc/clustershell/groups.yaml"

# Parse command-line options
while getopts "f:" opt; do
    case $opt in
        f)
            YAML_FILE=$OPTARG
            ;;
        *)
            print_usage
            exit 1
            ;;
    esac

done
shift $((OPTIND - 1))

function print_usage() {
    echo "Usage: $0 [-f yaml_file] {map|list} <source> <group>"
}

case $1 in
    map)
        # Ensure source and group are provided
        if [[ -z $2 || -z $3 ]]; then
            echo "Error: Source and group must be specified"
            print_usage
            exit 1
        fi
        # Output resolved hosts for the specified source and group, including anchor resolution
        yq -o=json ".${2}.${3}.hosts" "$YAML_FILE" | jq -r 'flatten | .[]'
        ;;
    list)
        # If no specific source is provided, list all top-level keys
        if [[ -z $2 ]]; then
            yq "keys[]" "$YAML_FILE"
        else
            # List all group names in the specified source
            yq ".${2} | keys[]" "$YAML_FILE"
        fi
        ;;
    reverse)
        # Ensure source and node are provided
        if [[ -z $2 || -z $3 ]]; then
            echo "Error: Source and node must be specified"
            print_usage
            exit 1
        fi
        # Find groups containing the specified node
        yq -o=json ".${2}" "$YAML_FILE" | jq -r --arg NODE "$3" \
            'to_entries | map(select(.value.hosts | flatten | index($NODE) != null)) | .[].key'
        ;;
    *)
        print_usage
        exit 1
        ;;
esac

groups.conf

# ClusterShell node groups main configuration file
[Main]

# Default group source
default: roles
confdir: /etc/clustershell/groups.conf.d $CFGDIR/groups.conf.d
autodir: /etc/clustershell/groups.d $CFGDIR/groups.d

[roles]
map: /usr/local/bin/get_nodes_from_yaml.sh -f /etc/clustershell/groups.yaml map $SOURCE $GROUP
all: /usr/local/bin/get_nodes_from_yaml.sh -f /etc/clustershell/groups.yaml map $SOURCE all
list: /usr/local/bin/get_nodes_from_yaml.sh -f /etc/clustershell/groups.yaml list $SOURCE
reverse: /usr/local/bin/get_nodes_from_yaml.sh -f /etc/clustershell/groups.yaml reverse $SOURCE $NODE

groups.yaml

roles:
  adm:
    hosts: &adm_hosts
      - example0
    custom_group_value: 123
  compute:
    hosts: &compute_hosts
      - example1
      - example2
    custom_group_value: 456
  all:
    hosts:
      - *adm_hosts
      - *compute_hosts