create-tfbackend

#!/bin/bash
# -----------------------------------------------------------------------------
# This script creates a terraform backend config file for a terraform module.
# It is not meant to be used directly. Instead, it is called by other scripts
# that set up and configure the infra/accounts module and the infra/app/ modules
# such as infra/app/build-repository and infra/app/service
#
# Positional parameters:
#   module_dir (required) - the directory of the root module that will be configured
#   backend_config_name (required) - the name of the backend that will be created.
#     For environment specific configs, the backend_config_name will be the same
#     as environment. For shared configs, the backend_config_name will be "shared".
#   tf_state_key (optional) - the S3 object key of the tfstate file in the S3 bucket
#     Defaults to [module_dir]/[backend_config_name].tfstate
# -----------------------------------------------------------------------------
set -euo pipefail

module_dir="$1"
backend_config_name="$2"
tf_state_key="${3:-${module_dir}/${backend_config_name}.tfstate}"

# The local tfbackend config file that will store the terraform backend config
backend_config_file="${module_dir}/${backend_config_name}.s3.tfbackend"

# Get the name of the S3 bucket that was created to store the tf state
# and the name of the DynamoDB table that was created for tf state locks.
# This will be used to configure the S3 backends in all the application
# modules
tf_state_bucket_name=$(terraform -chdir="infra/accounts" output --raw tf_state_bucket_name)
tf_locks_table_name=$(terraform -chdir="infra/accounts" output --raw tf_locks_table_name)
region=$(terraform -chdir="infra/accounts" output --raw region)

echo "===================================="
echo "Create terraform backend config file"
echo "===================================="
echo "Input parameters"
echo "  module_dir=${module_dir}"
echo "  backend_config_name=${backend_config_name}"
echo

# Create output file from example file
cp infra/example.s3.tfbackend "${backend_config_file}"

# Replace the placeholder values
sed -i.bak "s/<TF_STATE_BUCKET_NAME>/${tf_state_bucket_name}/g" "${backend_config_file}"
sed -i.bak "s|<TF_STATE_KEY>|${tf_state_key}|g" "${backend_config_file}"
sed -i.bak "s/<TF_LOCKS_TABLE_NAME>/${tf_locks_table_name}/g" "${backend_config_file}"
sed -i.bak "s/<REGION>/${region}/g" "${backend_config_file}"

# Remove the backup file created by sed
rm "${backend_config_file}.bak"

echo "Created file: ${backend_config_file}"
echo "------------------ file contents ------------------"
cat "${backend_config_file}"
echo "----------------------- end -----------------------"