Linux AUM Onboard Script

[Jessica Brown]

A while back, I was tasked to create a BASH script to onboard Linux machines to Azure Update Manager. Since multiple Business units were going to be using this, I needed it to be easy to use, with plug and play arguments and easy to follow instructions. Overall, this is the script that has been working for over 350 RHEL machines and VMs.

#!/bin/bash
# linux_aum_onboard.sh

# Version 2.1.0 [Dec. 17, 2023]
# By Jessica Brown
# Added argument parsing for all required parameters.
# Added logging and log file argument handling.
# Simplified --help for clear instructions.

# Aum Arc Onboarding
# Key Changes:
# Argument Handling: Added getopts-like case parsing for all arguments.
# Logging: Enhanced logging functions to reflect levels clearly.
# Defaults: Assigned default values for log file and logging level.
# Validation: Ensures all required arguments are supplied, else exits with --help.

# Default values
servicePrincipalClientId=""
servicePrincipalSecret=""
SUBSCRIPTION_ID=""
RESOURCE_GROUP=""
TENANT_ID=""
LOCATION=""
CORRELATION_ID=""
logging="info"
aum_log_file="aum_install_$(LC_ALL=C date +"%Y-%m-%d_%H-%M-%S")_${USER}.log"
CLOUD="AzureCloud"
tempdir="/tmp"

# Function to print help
usage() {
  cat << EOF
Usage: $0 [options]

Options:
  --help, -h                          Show this help message
  --servicePrincipalClientId, -spc    Service Principal Client ID
  --servicePrincipalSecret, -sps      Service Principal Secret
  --subscriptionId, -sid              Azure Subscription ID
  --resourceGroup, -rg                Azure Resource Group
  --tenantId, -tid                    Azure Tenant ID
  --location, -l                      Azure Location
  --correlationId, -cid               Correlation ID
  --logging                           Logging level (default: info)
                                      Options: debug, info, warning, error, critical
  --logFile                           Log file name (default: aum_install_<date>_<user>.log)
EOF
  exit 0
}

# Logging functions
log_level=5  # Default to "info"
log() {
  local level=$1; shift
  local msg="$*"
  local timestamp="$(LC_ALL=C date +"%Y-%m-%d %H:%M:%S")"
  local levels=("" "CRITICAL" "ERROR" "WARNING" "NOTICE" "INFO" "DEBUG")

  if [ ${level} -le ${log_level} ]; then
    echo "[${timestamp}]:[${levels[level]}]:${msg}" | tee -a "${aum_log_file}"
  fi
}

set_log_level() {
  case "$logging" in
    critical) log_level=1 ;;
    error)    log_level=2 ;;
    warning)  log_level=3 ;;
    info)     log_level=5 ;;
    debug)    log_level=6 ;;
    *)        log_level=5; log warning "Unknown logging level: $logging, defaulting to info." ;;
  esac
}

# Parse arguments
while [[ $# -gt 0 ]]; do
  key="$1"
  case $key in
    -h|--help)
      usage
      ;;
    -spc|--servicePrincipalClientId)
      servicePrincipalClientId="$2"; shift 2;;
    -sps|--servicePrincipalSecret)
      servicePrincipalSecret="$2"; shift 2;;
    -sid|--subscriptionId)
      SUBSCRIPTION_ID="$2"; shift 2;;
    -rg|--resourceGroup)
      RESOURCE_GROUP="$2"; shift 2;;
    -tid|--tenantId)
      TENANT_ID="$2"; shift 2;;
    -l|--location)
      LOCATION="$2"; shift 2;;
    -cid|--correlationId)
      CORRELATION_ID="$2"; shift 2;;
    --logging)
      logging="$2"; shift 2;;
    --logFile)
      aum_log_file="$2"; shift 2;;
    *)
      log 2 "Unknown argument: $1"; usage;;
  esac
done

# Validate required arguments
if [[ -z "$servicePrincipalClientId" || -z "$servicePrincipalSecret" || -z "$SUBSCRIPTION_ID" || \
      -z "$RESOURCE_GROUP" || -z "$TENANT_ID" || -z "$LOCATION" ]]; then
  log 2 "Missing required arguments."
  usage
fi

# Set logging level
set_log_level

# Start Logging
log 5 "Starting AUM Linux Onboarding Script"
log 5 "Log file: ${aum_log_file}"

# Dependencies and preparation
if ! command -v curl &>/dev/null; then
  log 2 "curl is not installed. Installing..."
  sudo -E yum -y install curl || { log 1 "Failed to install curl."; exit 1; }
fi

log 5 "Downloading install_linux_azcmagent.sh..."
curl -o install_linux_azcmagent.sh https://gbl.his.arc.azure.com/azcmagent-linux || {
  log 1 "Failed to download install_linux_azcmagent.sh."; exit 1;
}
chmod +x install_linux_azcmagent.sh

log 5 "Running installation script..."
./install_linux_azcmagent.sh || {
  log 1 "Installation failed."; exit 1;
}

log 5 "Connecting to Azure using azcmagent..."
./azcmagent connect \
  --service-principal-id "${servicePrincipalClientId}" \
  --service-principal-secret "${servicePrincipalSecret}" \
  --resource-group "${RESOURCE_GROUP}" \
  --tenant-id "${TENANT_ID}" \
  --location "${LOCATION}" \
  --subscription-id "${SUBSCRIPTION_ID}" \
  --cloud "${CLOUD}" \
  --tags "Region=Americas" \
  --correlation-id "${CORRELATION_ID}" || {
    log 1 "Failed to connect using azcmagent."; exit 1;
  }

log 5 "AUM Linux Onboarding completed successfully."