The Matt-Cloud Way

#!/bin/bash

# Dynamic inventory generation script ansible

# Function to display usage
usage() {
    echo "Usage: $0 -i IP_LIST -u JENKINS_USER -g JENKINS_GROUP [-a SERVER_SUBNET_GROUP] [-s] [-v] [-e]"
    echo "Options:"
    echo "  -i IP_LIST                  Comma-separated list of IPs. Will not fail if blank, but why 0_o"
    echo "  -u JENKINS_USER             Jenkins user"
    echo "  -g JENKINS_GROUP            Jenkins primary group"
    echo "  -a SERVER_SUBNET_GROUP      Jenkins group for SSH access, need to pass something when called"
    echo "  -q                          Be quieter"
    echo "  -s                          Set variable to true if more than one IP is passed"
    echo "  -v                          Display Ansible Version"
    exit 1
}

# Initialize variables with default values
skip=false
more_than_one=false
display_version=false
allsubnet_group=missing
be_quiet=false

# Parse command line options
while getopts ":i:u:g:a:svq" opt; do
  case ${opt} in
    i ) # process option i
        IP_LIST=$OPTARG
        ;;
    u ) # process option u
        JENKINS_USER=$OPTARG
        ;;
    g ) # process option g
        JENKINS_GROUP=$OPTARG
        ;;
    s ) # process option s
        skip=true
        ;;
    v ) # process option v
        display_version=true
        ;;
    q ) # process option q
        be_quiet=true
        ;;
    a ) # process option a
        allsubnet_group=$OPTARG
        ;;
    \? ) usage
        ;;
  esac
done
shift $((OPTIND -1))
# Check if all required options are provided
if [ -z "$JENKINS_USER" ] || [ -z "$JENKINS_GROUP" ]; then
    usage
fi

if $display_version; then
    if ! $be_quiet; then
        echo "Showing ansible version"
        ansible --version   
    fi
fi

# Generate an 8-character hash from the IP list
hash=$(echo -n "$IP_LIST" | md5sum | cut -c 1-8)

if ! $be_quiet; then
    echo "IP List:"
    echo $IP_LIST
    echo $hash
fi


# Define the inventory file path with the hash
inventory_file="/var/jenkins_home/ansible/.inv/inventory-$hash.yml"

if $skip; then
    IFS=',' read -ra IPS <<< "$IP_LIST"
    if [ ${#IPS[@]} -gt 1 ]; then
        more_than_one=true
    fi
fi

if $skip; then
    if ! $be_quiet; then
        echo "Single host option set"
    fi
    if $more_than_one; then
        if ! $be_quiet; then
            echo "IP list provided, inventory will be emptied"
        fi
        IP_LIST=""
    fi
fi

# Initialize the YAML inventory content
inventory_content="---
all:
  hosts:
"

# Loop through each IP in the comma-separated list
IFS=',' read -ra IPS <<< "$IP_LIST"
for IP in "${IPS[@]}"; do
    ip_check=$(curl -s http://172.25.100.15:15010/ip_check?ip=${IP} | jq .in_subnets)
    # if this is a restricted subnet, then check the group
    if $ip_check; then
        if ! $be_quiet; then
            echo "Subnet restricted, checking group membership"
        fi
        if [ "$allsubnet_group" == "$SERVER_SUBNET_GROUP" ]; then
            if ! $be_quiet; then
                echo "IP Check Passed, adding endpoint ${IP} to inventory"
            fi
            inventory_content+="    ${IP}:
      ansible_host: ${IP}
        
"
        else
            if ! $be_quiet; then
                echo "Warning: User ${JENKINS_USER} not member of ${SERVER_SUBNET_GROUP}!"
                echo "Auth Check Failed for endpoint ${IP}, not adding to inventory"
            fi
        fi
    # if the subnet is not restricted, just add the endpoint to the inventory
    else
        if ! $be_quiet; then
            echo "Unrestricted subnet, adding endpoint ${IP} to inventory"
        fi
        inventory_content+="    ${IP}:
      ansible_host: ${IP}
"
    fi
done

inventory_content+="  vars:
    ansible_connection: ssh
    ansible_ssh_private_key_file: /var/jenkins_home/jenkins_key
    ansible_python_interpreter: /usr/bin/python3
    jenkins_user: '${JENKINS_USER}'
    jenkins_group: '${JENKINS_GROUP}'
    subnet_group_check: '${allsubnet_group}'
    SERVER_SUBNET_GROUP: '${SERVER_SUBNET_GROUP}'
"

# Write the inventory content to the file
echo "$inventory_content" > $inventory_file

# echo inventory
if ! $be_quiet; then
    echo "Inventory file created at $inventory_file with the following content:"
    cat $inventory_file
fi

This script outputs something like this depending on the flags that are set. This screenshot is also from an older version of the inventory script.