clone_prod_db.sh

#!/usr/bin/env bash
set -e

# Function to delete an RDS instance.
#
# Arguments
#   - $1: The identifier of the RDS instance to be deleted.
#

delete_instance() {
  local instance_id=$1
  local status=$(aws rds delete-db-instance --skip-final-snapshot --db-instance-identifier $instance_id 2>&1)
  if echo $status | grep -q "DBInstanceNotFound"; then
    echo "Instance $instance_id not found."
  else
    local state=$(echo $status | jq -r '.DBInstance.DBInstanceStatus')
    echo "Deleting $instance_id..."
  fi
  wait_for_db_delete_status $instance_id
}


# Function to get the latest snapshot of an RDS instance
# 
# Arguments:
#   - $1: The identifier of the RDS instance to be deleted.
# 
# Returns:
#   - latest_snapshot: the identifier of the latest snapshot
#   - "No snapshots found for this instance." if no snapshots were found

get_latest_snapshot() {
  local instance_id=$1
  local snapshots
  local latest_snapshot
  snapshots=$(aws rds describe-db-snapshots --query 'DBSnapshots[?DBInstanceIdentifier==`'$instance_id'`].{SnapshotCreateTime:SnapshotCreateTime,DBSnapshotIdentifier:DBSnapshotIdentifier}' --output json)
  if echo "$snapshots" | jq '. | length'  | grep -q 0
  then
    echo "No snapshots found for this instance."
  else
    latest_snapshot=$(echo "$snapshots" | jq -r 'sort_by(.SnapshotCreateTime | split(".")[0] | strptime("%Y-%m-%dT%H:%M:%S") | mktime) | .[-1] | .DBSnapshotIdentifier')
    echo $latest_snapshot
  fi
}


# Function to restore an RDS instance from a snapshot.
#
# Arguments
#   - $1: The identifier of the snapshot to be restored.
#   - $2: The identifier of the RDS instance to be restored.
#

restore_db_from_snapshot() {
    local snapshot_id=$1
    local instance_name=$2
    error=$(aws rds restore-db-instance-from-db-snapshot --db-snapshot-identifier $snapshot_id --db-instance-identifier $instance_name --no-auto-minor-version-upgrade 2>&1 > /dev/null)
    if [ -n "$error" ]; then
      echo "An error occurred: $error"
    else
      echo "The command completed successfully."
    fi
    wait_for_db_status $instance_name
}

# Function to wait for an RDS instance to be available.
#
# Arguments
#   - $1: The identifier of the RDS instance to wait for.
#

wait_for_db_status() {
    local instance_name=$1
    local status=""
    while [ "$status" != "available" ]; do
        status=$(aws rds describe-db-instances --db-instance-identifier $instance_name | jq -r '.DBInstances[].DBInstanceStatus')
        if [ "$status" != "available" ]; then
            echo "Current status: $status. Waiting for availability..."
            sleep 5
        fi
    done
    echo "Instance $instance_name is now $status"
}

# Function to wait for an RDS instance to be deleted.
#
# Arguments
#   - $1: The identifier of the RDS instance to wait for.
#

wait_for_db_delete_status() {
    local instance_name=$1
    local status=""
    while [ "$status" != "" ]; do
        status=$(aws rds describe-db-instances --db-instance-identifier $instance_name | jq -r '.DBInstances[].DBInstanceStatus')
        if [ "$status" != "" ]; then
            echo "Current status: $status. Waiting for removal..."
            sleep 5
        fi
    done
    echo "Instance $instance_name is now removed"
}

# Function to reset the master password of an RDS instance.
#
# Arguments
#   - $1: The identifier of the RDS instance to be reset.
#   - $2: The new password for the master user.
#

reset_master_password() {
  local instance_name="$1"
  local new_password="$2"
  echo "Resetting master password for $instance_name..."
  error=$(aws rds modify-db-instance \
    --db-instance-identifier "$instance_name" \
    --master-user-password "$new_password" \
    --apply-immediately 2>&1 > /dev/null)
  if [ -n "$error" ]; then
    echo "An error occurred: $error"
  else
    echo "The command completed successfully."
    echo "Waiting for instance to be available..."
    sleep 30
    wait_for_db_status $instance_name
  fi
}

# Function to get the endpoint of an RDS instance.
#
# Arguments
#   - $1: The identifier of the RDS instance to get the endpoint for.
#
# Returns:
#   - endpoint: the endpoint of the RDS instance

get_db_instance_endpoint () {
  local db_instance_identifier=$1
  local endpoint=$(aws rds describe-db-instances --query "DBInstances[?DBInstanceIdentifier=='$db_instance_identifier'].Endpoint.Address" --output text)
  echo "$endpoint"
}

staging="staging-instance"
production="production-instance"
latest_snapshot=$(get_latest_snapshot $production)
staging_password="hunter2"

echo "Cloning prod database to staging..."
echo "Deleting staging instance"
delete_instance $staging
echo "Latest snapshot: $latest_snapshot"
restore_db_from_snapshot $latest_snapshot $staging
reset_master_password $staging $staging_password

staging_endpoint=$(get_db_instance_endpoint $staging)
echo "New Staging endpoint: $staging_endpoint"

# TODO - update env files with new endpoint
echo "All done."