#!/bin/bash

# turn GCP (Google Cloud Platform) metadata key/values into shell environment variables

# Function to fetch metadata and set as environment variable
fetch_and_export() {
  local path=$1
  local value=$(curl "http://metadata.google.internal/computeMetadata/v1/${path}" -H "Metadata-Flavor: Google" --silent)
  if [ $? -eq 0 ] && [ ! -z "$value" ]; then
    # Convert metadata keys to uppercase and replace invalid characters for shell variable names
    local varname=$(echo $path | tr '[:lower:]/-' '[:upper:]__')

    # Special handling for the instance zone to extract only the last part
    if [ "$path" == "instance/zone" ]; then
      value=$(basename "$value")
    fi 

    # Remove 'PROJECT__' prefix if present
    varname=$(echo $varname | sed 's/^PROJECT_PROJECT_/PROJECT_/')
    varname=$(echo $varname | sed 's/^PROJECT_NUMERIC_PROJECT_ID/PROJECT_NUMERIC_ID/')

    # Export the environment variable
    export "$varname"="$value"
    #echo "Exported $varname"
  fi
}

# Metadata paths to fetch and set as environment variables
METADATA_PATHS=(
  "instance/cpu-platform"
  "instance/disks"
  "instance/id"
  "instance/machine-type"
  "instance/name"
  "instance/scheduling/automatic-restart"
  "instance/scheduling/on-host-maintenance"
  "instance/scheduling/preemptible"
  "instance/service-accounts/default/aliases"
  "instance/service-accounts/default/email"
  "instance/service-accounts/default/scopes"
  "instance/tags"
  "instance/zone"
  "project/numeric-project-id"
  "project/project-id"
)

# Loop through the metadata paths and set environment variables
for path in "${METADATA_PATHS[@]}"; do
  fetch_and_export $path
done

# Now, print all environment variables that were set
printenv | grep '^INSTANCE_' || echo "No instance-specific environment variables were set."
printenv | grep '^PROJECT_' || echo "No project-specific environment variables were set."