3 files changed, 200 insertions, 0 deletions
diff --git a/docker/runtime/backup-init.sh b/docker/runtime/backup-init.sh
new file mode 100644
index 00000000..07298c5d
--- /dev/null
+++ b/docker/runtime/backup-init.sh
@@ -0,0 +1,140 @@
+#!/usr/bin/env bash
+set -e
+
+BACKUP_PATH="/backup"
+
+# Make sure that required directories exist
+mkdir -p "${BACKUP_PATH}"
+mkdir -p "/etc/crontabs"
+chown git:git /backup
+chmod 2770 /backup
+
+# [string] BACKUP_INTERVAL   Period expression
+# [string] BACKUP_RETENTION  Period expression
+if [ -z "${BACKUP_INTERVAL}" ]; then
+	echo "Backup disabled: BACKUP_INTERVAL has not been found" 1>&2
+	exit 1
+fi
+
+if [ -z "${BACKUP_RETENTION}" ]; then
+	echo "Backup retention period is not defined, default to 7 days" 1>&2
+	BACKUP_RETENTION='7d'
+fi
+
+# Parse BACKUP_INTERVAL environment variable and generate appropriate cron expression. Backup cron task will be run as scheduled.
+# Expected format: nu (n - number, u - unit) (eg. 3d means 3 days)
+# Supported units: h - hours, d - days, M - months
+parse_generate_cron_expression() {
+	CRON_EXPR_MINUTES="*"
+	CRON_EXPR_HOURS="*"
+	CRON_EXPR_DAYS="*"
+	CRON_EXPR_MONTHS="*"
+
+	TIME_INTERVAL=$(echo "${BACKUP_INTERVAL}" | sed -e 's/[hdM]$//')
+	TIME_UNIT=$(echo "${BACKUP_INTERVAL}" | sed -e 's/^[0-9]\+//')
+
+	if [ "${TIME_UNIT}" = "h" ]; then
+		if [ ! "${TIME_INTERVAL}" -le 23 ]; then
+			echo "Parse error: Time unit 'h' (hour) cannot be greater than 23" 1>&2
+			exit 1
+		fi
+
+		CRON_EXPR_MINUTES=0
+		CRON_EXPR_HOURS="*/${TIME_INTERVAL}"
+	elif [ "${TIME_UNIT}" = "d" ]; then
+		if [ ! "${TIME_INTERVAL}" -le 30 ]; then
+			echo "Parse error: Time unit 'd' (day) cannot be greater than 30" 1>&2
+			exit 1
+		fi
+
+		CRON_EXPR_MINUTES=0
+		CRON_EXPR_HOURS=0
+		CRON_EXPR_DAYS="*/${TIME_INTERVAL}"
+	elif [ "${TIME_UNIT}" = "M" ]; then
+		if [ ! "${TIME_INTERVAL}" -le 12 ]; then
+			echo "Parse error: Time unit 'M' (month) cannot be greater than 12" 1>&2
+			exit 1
+		fi
+
+		CRON_EXPR_MINUTES=0
+		CRON_EXPR_HOURS=0
+		CRON_EXPR_DAYS="1"
+		CRON_EXPR_MONTHS="*/${TIME_INTERVAL}"
+	else
+		echo "Parse error: BACKUP_INTERVAL expression is invalid" 1>&2
+		exit 1
+	fi
+
+	echo "${CRON_EXPR_MINUTES} ${CRON_EXPR_HOURS} ${CRON_EXPR_DAYS} ${CRON_EXPR_MONTHS} *"
+}
+
+# Parse BACKUP_RETENTION environment variable and generate appropriate find command expression.
+# Expected format: nu (n - number, u - unit) (eg. 3d means 3 days)
+# Supported units: m - minutes, d - days
+parse_generate_retention_expression() {
+	FIND_TIME_EXPR='mtime'
+
+	TIME_INTERVAL=$(echo "${BACKUP_RETENTION}" | sed -e 's/[mhdM]$//')
+	TIME_UNIT=$(echo "${BACKUP_RETENTION}" | sed -e 's/^[0-9]\+//')
+
+	if [ "${TIME_UNIT}" = "m" ]; then
+		if [ "${TIME_INTERVAL}" -le 59 ]; then
+			echo "Warning: Minimal retention is 60m. Value set to 60m" 1>&2
+			TIME_INTERVAL=60
+		fi
+
+		FIND_TIME_EXPR="mmin"
+	elif [ "${TIME_UNIT}" = "h" ]; then
+		echo "Error: Unsupported expression - Try: eg. 120m for 2 hours." 1>&2
+		exit 1
+	elif [ "${TIME_UNIT}" = "d" ]; then
+		FIND_TIME_EXPR="mtime"
+	elif [ "${TIME_UNIT}" = "M" ]; then
+		echo "Error: Unsupported expression - Try: eg. 60d for 2 months." 1>&2
+		exit 1
+	else
+		echo "Parse error: BACKUP_RETENTION expression is invalid" 1>&2
+		exit 1
+	fi
+
+	echo "${FIND_TIME_EXPR} +${TIME_INTERVAL:-7}"
+}
+
+add_backup_cronjob() {
+	CRONTAB_USER="${1:-git}"
+	CRONTAB_FILE="/etc/crontabs/${CRONTAB_USER}"
+	CRONJOB_EXPRESSION="${2:-}"
+	CRONJOB_EXECUTOR="${3:-}"
+	CRONJOB_EXECUTOR_ARGUMENTS="${4:-}"
+  CRONJOB_TASK="${CRONJOB_EXPRESSION} /bin/sh ${CRONJOB_EXECUTOR} ${CRONJOB_EXECUTOR_ARGUMENTS}"
+
+	if [ -f "${CRONTAB_FILE}" ]; then
+		CRONJOB_EXECUTOR_COUNT=$(grep -c "${CRONJOB_EXECUTOR}" "${CRONTAB_FILE}" || exit 0)
+		if [ "${CRONJOB_EXECUTOR_COUNT}" != "0" ]; then
+			echo "Cron job already exists for ${CRONJOB_EXECUTOR}. Updating existing." 1>&2
+			CRONJOB_TASK=$(echo "{CRONJOB_TASK}" | sed 's/\//\\\//g' )
+			CRONJOB_EXECUTOR=$(echo "{CRONJOB_EXECUTOR}" | sed 's/\//\\\//g' )
+			sed -i "/${CRONJOB_EXECUTOR}/c\\${CRONJOB_TASK}" "${CRONTAB_FILE}"
+			return 0
+		fi
+	fi
+
+	# Finally append new line with cron task expression
+	echo "${CRONJOB_TASK}" >>"${CRONTAB_FILE}"
+}
+
+CRONTAB_USER=$(awk -v val="${PUID}" -F ":" '$3==val{print $1}' /etc/passwd)
+
+# Up to this point, it was desirable that interpreter handles the command errors and halts execution upon any error.
+# From now, we handle the errors our self.
+set +e
+RETENTION_EXPRESSION="$(parse_generate_retention_expression)"
+
+if [ -z "${RETENTION_EXPRESSION}" ]; then
+	echo "Couldn't generate backup retention expression. Aborting backup setup" 1>&2
+	exit 1
+fi
+
+# Backup rotator cron will run every 5 minutes
+add_backup_cronjob "${CRONTAB_USER}" "*/5 * * * *" "/app/gogs/docker/runtime/backup-rotator.sh" "'${BACKUP_PATH}' '${RETENTION_EXPRESSION}'"
+add_backup_cronjob "${CRONTAB_USER}" "$(parse_generate_cron_expression)" "/app/gogs/docker/runtime/backup-job.sh" "'${BACKUP_PATH}'"
diff --git a/docker/runtime/backup-job.sh b/docker/runtime/backup-job.sh
new file mode 100644
index 00000000..2b8efd70
--- /dev/null
+++ b/docker/runtime/backup-job.sh
@@ -0,0 +1,33 @@
+#!/usr/bin/env sh
+
+execute_backup_job() {
+	BACKUP_ARG_PATH="${1:-}"
+	BACKUP_ARG_CONFIG="${BACKUP_ARG_CONFIG:-}"
+	BACKUP_ARG_EXCLUDE_REPOS="${BACKUP_ARG_EXCLUDE_REPOS:-}"
+	cd "/app/gogs" || exit 1
+
+	BACKUP_ARGS="--target=${BACKUP_ARG_PATH}"
+
+	if [ -n "${BACKUP_ARG_CONFIG}" ]; then
+		BACKUP_ARGS="${BACKUP_ARGS} --config=${BACKUP_ARG_CONFIG}"
+	fi
+
+	if [ -n "${BACKUP_ARG_EXCLUDE_REPOS}" ]; then
+		BACKUP_ARGS="${BACKUP_ARGS} --exclude-repos=${BACKUP_ARG_EXCLUDE_REPOS}"
+	fi
+
+	./gogs backup "${BACKUP_ARGS}" || echo "Error: Backup job returned non-successful code." && exit 1
+}
+
+main() {
+	BACKUP_PATH="${1:-}"
+
+	if [ -z "${BACKUP_PATH}" ]; then
+		echo "Required argument missing BACKUP_PATH" 1>&2
+		exit 1
+	fi
+
+	execute_backup_job "${BACKUP_PATH}"
+}
+
+main "$@"
diff --git a/docker/runtime/backup-rotator.sh b/docker/runtime/backup-rotator.sh
new file mode 100644
index 00000000..51665f57
--- /dev/null
+++ b/docker/runtime/backup-rotator.sh
@@ -0,0 +1,27 @@
+#!/usr/bin/env sh
+
+# This is very simple, yet effective backup rotation script.
+# Using find command, all files that are older than BACKUP_RETENTION_DAYS are accumulated and deleted using rm.
+main() {
+	BACKUP_PATH="${1:-}"
+	FIND_EXPRESSION="${2:-mtime +7}"
+
+	if [ -z "${BACKUP_PATH}" ]; then
+		echo "Error: Required argument missing BACKUP_PATH" 1>&2
+		exit 1
+	fi
+
+	if [ "$(realpath "${BACKUP_PATH}")" = "/" ]; then
+		echo "Error: Dangerous BACKUP_PATH: /" 1>&2
+		exit 1
+	fi
+
+	if [ ! -d "${BACKUP_PATH}" ]; then
+	  echo "Error: BACKUP_PATH does't exist or is not a directory" 1>&2
+		exit 1
+	fi
+
+	find "${BACKUP_PATH}/" -type f -name "gogs-backup-*.zip" -${FIND_EXPRESSION} -print -exec rm "{}" +
+}
+
+main "$@"