#!/bin/bash

# Little monitoring script to check the readiness of a Gitlab instance.
#
# Remember that you have to whitelist the IP of your monitoring system :
# gitlab.rb:
#  gitlab_rails['monitoring_whitelist'] = ['127.0.0.0/8', '::1/128', ...]
# See https://docs.gitlab.com/ee/administration/monitoring/health_check.html
#
# Licence: WTFPL
# Copyright: chl-dev@bugness.org 2024

PROGPATH=$( echo $0 | sed -e 's,[\\/][^\\/][^\\/]*$,,' )
REVISION="0.1"

# Default values
GITLAB_HOSTNAME="localhost"
GITLAB_URL=""
GITLAB_URL_PROTOCOL="https"
NB_CHECKS_RANGE="15:20"

# Include check_range() and STATE_OK, STATE_WARNING, ... variables
. $PROGPATH/utils.sh

# Output
OUTPUT_CPT_CHECKS=0
OUTPUT_EXIT_STATUS=0
OUTPUT_DETAIL_OK=""
OUTPUT_DETAIL_WARNING=""
OUTPUT_DETAIL_CRITICAL=""
OUTPUT_DETAIL_UNKNOWN=""
OUTPUT_PERFDATA=""


# Stop at first uncaught error
set -eu

# Wrapper to use whatever is available to make HTTP queries
fetch_with_curl_wget_or_whatever () {
	if which "wget" >/dev/null 2>&1; then
		wget -q -O - "$1"
	elif which "curl" >/dev/null 2>&1 ; then
		curl -s "$1"
	else
		echo "UNKNOWN: no wget/curl/whatever available to make HTTP queries."
		exit $STATE_UNKNOWN
	fi
}

check_http_status_200() {
	if which "wget" >/dev/null 2>&1; then
		wget -q --spider "$1"
	elif which "curl" >/dev/null 2>&1 ; then
		test "$( curl -s -o /dev/null -I -w "%{http_code}" "$1" )" == "200"
	else
		echo "UNKNOWN: no wget/curl/whatever available to make HTTP queries."
		exit $STATE_UNKNOWN
	fi
}

print_full_url() {
	if [ -n "$GITLAB_URL" ]; then
		echo "$GITLAB_URL"
	else
		echo "$GITLAB_URL_PROTOCOL://$GITLAB_HOSTNAME/-/readiness?all=1"
	fi
}

# Help function
usage() {
	cat <<EOF
Usage :
  $0 [-H hostname] [-U full_URL] [-sS] [ -c nb_checks_range ]

	-c Expected number of checks
	-s Use HTTP to query the hostname
	-S Use HTTPS to query the hostname (default)

Examples:
	./check_gitlab.sh -H forge.example.net
	./check_gitlab.sh -U https://forge.example.net/ -c 20:42

Default values:
	full_URL: $( print_full_url )
	nb_checks_range: $NB_CHECKS_RANGE
EOF
}

# Loop on parameters
while getopts c:hH:sSU: f; do
	case "$f" in
		'c')
			NB_CHECKS_RANGE="$OPTARG"
			;;

		'h')
			usage
			exit
			;;

		'H')
			GITLAB_HOSTNAME="$OPTARG"
			GITLAB_URL=""  # To generate the URL from the hostname, see print_full_url()
			;;

		's')
			GITLAB_URL_PROTOCOL="http"
			;;

		'S')
			GITLAB_URL_PROTOCOL="https"
			;;

		'U')
			GITLAB_URL="$OPTARG"
			;;

		?)
			usage
			exit 1
			;;
	esac
done

if ! which jq >/dev/null; then
	echo "UNKNOWN command 'jq' not available."
	exit $STATE_UNKNOWN
fi

# First, let's check that the URL responds with 200/OK
#if ! check_http_status_200 "$( print_full_url )"; then
#	echo TODO later. Since it needs 2 queries, it could lead to inconsistencies if we get a 200 now and an error later.
#           Would the best way be to set another probe ?
#           check_https!-H $HOSTNAME$ -f warning -u /-/readiness?all=1
#           check_https!-H $HOSTNAME$ -f warning -u /-/health -s "GitLab OK"
#fi

if ! JSONDATA="$( fetch_with_curl_wget_or_whatever "$( print_full_url )" )"; then
	echo "UNKNOWN error fetching the URL '$( print_full_url )'"
	exit $STATE_UNKNOWN
fi

while read KEY; do
	OUTPUT_CPT_CHECKS=$(( $OUTPUT_CPT_CHECKS + 1 ))
	if [ "$KEY" == "status" ]; then
		STATUS="$( printf "%s\n" "$JSONDATA" | jq ".$KEY" )"
	else
		STATUS="$( printf "%s\n" "$JSONDATA" | jq ".$KEY[0].status" )"
	fi
	if [ "$STATUS" != '"ok"' ]; then
		OUTPUT_DETAIL_CRITICAL="$( printf "%s Status for key '$KEY': %s" "$OUTPUT_DETAIL_CRITICAL" "$STATUS" )"
		OUTPUT_EXIT_STATUS=$STATE_CRITICAL
	fi
done <<EOF
$( printf "%s\n" "$JSONDATA" | jq 'keys[]' | sed 's/\(^"\|"$\)//g' )
EOF

# Let's check that the number of checks checks out
set +e
check_range "$OUTPUT_CPT_CHECKS" "$NB_CHECKS_RANGE"
STATUS="$?"
set -e
if [ "$STATUS" -eq 0 ]; then
	if [ "$OUTPUT_EXIT_STATUS" == "$STATE_OK" ]; then
		OUTPUT_EXIT_STATUS=$STATE_WARNING
		OUTPUT_DETAIL_WARNING="$OUTPUT_DETAIL_WARNING Nb checks outside of range: $OUTPUT_CPT_CHECKS / $NB_CHECKS_RANGE"
	fi
elif [ "$STATUS" -eq 2 ]; then
	if [ "$OUTPUT_EXIT_STATUS" != "$STATE_CRITICAL" ]; then
		OUTPUT_EXIT_STATUS=$STATE_UNKNOWN
		OUTPUT_DETAIL_UNKNOWN="$OUTPUT_DETAIL_UNKNOWN check_range() on error: $OUTPUT_CPT_CHECKS / $NB_CHECKS_RANGE"
	fi
fi

# final output
case "$OUTPUT_EXIT_STATUS" in
	"$STATE_OK")
		printf "OK $OUTPUT_DETAIL_OK"
		;;

	"$STATE_WARNING")
		printf "WARNING $OUTPUT_DETAIL_WARNING"
		;;

	"$STATE_CRITICAL")
		printf "CRITICAL $OUTPUT_DETAIL_CRITICAL"
		;;

	"$STATE_UNKNOWN")
		printf "UNKNOWN $OUTPUT_DETAIL_UNKNOWN"
		;;

	*)
		printf "WTF"
		;;
esac

# Add the checks counter to the perfdata
OUTPUT_PERFDATA="$( printf "%s\n%s" "$OUTPUT_PERFDATA" "nb_checks=$OUTPUT_CPT_CHECKS;$NB_CHECKS_RANGE;;0" )"

# We sort the perfdata because of a weird bug in some icinga/pnp4nagios interactions
printf "|%s\n" "$( printf "%s" "$OUTPUT_PERFDATA" | sort | grep -v "^$" | tr "\n" " " )"
exit "$OUTPUT_EXIT_STATUS"