#!/bin/sh

GOBIN=/opt/gocode/bin  # where to find go binaries
CONF_DIR=/etc/prometheus
CONF=$CONF_DIR/prometheus.yml
LOGLEVEL=info

config="$(cat "$__object/parameter/config")"
retention_days="$(cat "$__object/parameter/retention-days")"
storage_path="$(cat "$__object/parameter/storage-path")"
listen_address="$(cat "$__object/parameter/listen-address")"
alertmanager_url="$(cat "$__object/parameter/alertmanager-url")"
target_heap_size="$(cat "$__object/parameter/target-heap-size")"
rule_files="$(cat "$__object/parameter/rule-files")"

# explorer in kB => convert; by default we go with 1/2 RAM
[ "$target_heap_size" = "auto" ] && target_heap_size=$(($(cat $__global/explorer/memory)*1024/2))


FLAGS="config.file '$CONF'
storage.local.path '$storage_path'
storage.local.target-heap-size $(($target_heap_size))  # in bytes; should be 2/3 of available memory because it may be hungry
storage.local.retention $(($retention_days*24))h  # golang doesn't have days :D
web.listen-address '$listen_address'
alertmanager.url '$alertmanager_url'
log.level $LOGLEVEL"

REAL_FLAGS="$(echo "$FLAGS" | sed -nE 's/^([^#]+).*/ --\1 \\/p')"

__go_get github.com/prometheus/prometheus/cmd/...

__user prometheus --system
require="__user/prometheus" __directory "$storage_path" --owner prometheus
require="__user/prometheus" __directory "$CONF_DIR" --owner prometheus

__daemontools_service prometheus --run "setuidgid prometheus $GOBIN/prometheus $REAL_FLAGS"

require="$require __directory/$storage_path __user/prometheus" \
__config_file $CONF \
	--source $config \
	--group prometheus --mode 640 \
	--onchange "$GOBIN/promtool check-config $CONF && svc -h /service/prometheus"

for file in $rule_files; do
	dest=$CONF_DIR/$(basename $file)
	require="$require __directory/$CONF_DIR __user/prometheus" \
	__config_file "$dest" \
		--source "$file" \
		--owner prometheus \
		--onchange "$GOBIN/promtool check-rules '$dest' && svc -h /service/prometheus"
done