#!/bin/bash

# The MIT License (MIT)
#
# Copyright (c) 2014-2018 Greg Messner, greg@messners.com
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

#
# This is the service utility script for running Postgres in a docker container.  It is intended
# to be called from upstart or systemd service scripts, but can also be used from the command line
# to start, stop, and check the status of a running Postgres container.
#

# Load the docker utility functions
SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
source $SCRIPT_DIR/docker-functions.sh

#
# Print the help information for the Postgres service container.
#
function help {

	echo
	echo "  This script performs one or more actions on the Postgres service container."
	echo
	echo "  Usage : $(basename $0) action ..."
	echo
	echo "  Available actions"
	echo "  ------------------------------------------------------------------------"
	echo "  attach  Attaches the current process to the running Postgres service,"
	echo "          usually only used by actual OS services"
	echo "  cleanup Cleans up (removes) the Postgres service container"
	echo "  destroy Stops and removes the Postgres service container, and deletes"
	echo "          the associated database data (docker volume)"
	echo "  help    Prints this help information and exits"
	echo "  start   Starts the Postgres service container. When starting the service"
	echo "          the following environment variables must be set:"
	echo "          POSTGRES_DB, POSTGRES_USER, and POSTGRES_PASSWORD"
	echo "  status  Returns a one word status for the Postgres service"
	echo "  stop    Stops the Postgres service container"
	echo
	echo "  NOTE: Multiple actions may be combined on a single command line, for example:"
	echo "          $(basename $0) start attach"
	echo
}


#
# Stops the service container if it is running and deletes the associated docker volume.
#
destroy() {

	# Make sure the container is stopped and removed
	df_kill_container ${POSTGRES_CONTAINER}

	# Remove the docker volume if it is present
	if docker volume inspect ${POSTGRES_DATA_VOLUME} >/dev/null 2>&1 ; then
		echo -n "Removing ${POSTGRES_DATA_VOLUME} data volume..."
		docker volume rm --force ${POSTGRES_DATA_VOLUME} >/dev/null 2>&1
		echo "done"
	fi
}


#
# Launches the container and waits for it to be fully started.  After calling 'start', you can
# call the 'attach' method to attach a service script to the log output of the container.
#
start() {

	# Make sure the database name, username, and password is set, if not, abort
	ENV_ERRORS="false"
	if [ -z "$POSTGRES_DB" ]; then
		echo "POSTGRES_DB env variable is not set!" 1>&2
		ENV_ERRORS="true"
	fi

	if [ -z "$POSTGRES_USER" ]; then
		echo "POSTGRES_USER env variable is not set!" 1>&2
		ENV_ERRORS="true"
	fi

	if [ -z "$POSTGRES_PASSWORD" ]; then
		echo "POSTGRES_PASSWORD env variable is not set!" 1>&2
		ENV_ERRORS="true"
	fi

	if [ "$ENV_ERRORS" == "true" ]; then
		exit 1
	fi

	# If the data volume does not exist, create it
	if ! docker volume inspect ${POSTGRES_DATA_VOLUME} >/dev/null 2>&1 ; then
		echo "Creating ${POSTGRES_DATA_VOLUME} data volume"
		docker volume create ${POSTGRES_DATA_VOLUME} >/dev/null 2>&1
	fi

	# If the local postgres config file is set and exists, set the container up to use it
	LOCAL_POSTGRES_CONFIG=()
	if [[ ! -z $LOCAL_POSTGRES_CONFIG_FILE ]] && [[ -f $LOCAL_POSTGRES_CONFIG_FILE ]]; then
		echo "Setting up container to use local postgres configuration"
		LOCAL_POSTGRES_CONFIG=("-c" "config_file=$LOCAL_POSTGRES_CONFIG_FILE")
	fi

	# Make sure that docker does not have the service container present
	df_kill_container ${POSTGRES_CONTAINER}

	# Run the docker container
	CONTAINER_ID=$(docker run --name "${POSTGRES_CONTAINER}" \
		--detach --restart=no \
		--health-cmd="pg_isready -h localhost" \
		-p ${POSTGRES_PORT}:5432 \
		-e POSTGRES_DB=${POSTGRES_DB} \
		-e POSTGRES_USER=${POSTGRES_USER} \
		-e POSTGRES_PASSWORD="${POSTGRES_PASSWORD}" \
		-v ${POSTGRES_DATA_VOLUME}:/var/lib/postgresql/data \
		${POSTGRES_IMAGE_NAME}:${POSTGRES_IMAGE_VERSION} ${LOCAL_POSTGRES_CONFIG[*]})

	if [ $? -ne 0 ]; then
		echo "Error starting ${POSTGRES_CONTAINER}"
		exit 1
	fi

	# Wait a maximum of 60 seconds for the container to be fully started and healthy
	echo "Started ${POSTGRES_CONTAINER}, container ID=${CONTAINER_ID}"
	echo "Waiting for ${POSTGRES_CONTAINER} to become healthy"
	df_wait_for_container 60 ${POSTGRES_CONTAINER}
}

#############################################################################

# Need at least a single argumet (action), if none are provided putput usage info and exit with error.
if [ $# -lt 1 ]; then
	echo "Usage : $(basename $0) attach|cleanup|destroy|help|status|start|stop"
	exit 1
fi

if [ "$1" == "help" ]; then
	help
	exit 0
fi

# Default the env variables if they are not set.
POSTGRES_IMAGE_NAME=${POSTGRES_IMAGE_NAME:-postgres}
POSTGRES_IMAGE_VERSION=${POSTGRES_IMAGE_VERSION:-"9.6.8"}
POSTGRES_CONTAINER=${POSTGRES_CONTAINER:-postgres-db}
POSTGRES_DATA_VOLUME=${POSTGRES_DATA_VOLUME:-postgres-db-data}
POSTGRES_PORT=${POSTGRES_PORT:-5432}

#
# Loop thru the arguments (actions). Some actions may be paired together, for example:
#
#	start attach  -  Will start the container and attach the current process to it
#	stop cleanup  -  Will stop the container and then clean it up (remove it)
#
for ARG in "$@"
do
	case "$ARG" in

		"attach")
			df_attach_container $POSTGRES_CONTAINER
			;;

		"cleanup")
			df_cleanup_container $POSTGRES_CONTAINER
			;;

		"destroy")
			destroy
			;;

		"start")
			start
			;;

		"status")
			df_container_status $POSTGRES_CONTAINER
			;;

		"stop")
			df_stop_container $POSTGRES_CONTAINER
			;;

		*)
			echo "'$1' is not a valid $(basename $0 '.sh') command, aborting!"
			exit 1
			;;
	esac

	RESULTS=$?
	if [ $RESULTS -ne 0 ]; then
		exit $RESULTS
	fi
done

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