net-mgmt/alertmanager: Fix logging

Redirect stdout and stderr of the Alertmanager to its log file with
the daemon(8) -o flag instead of shell redirections. The reason for
this change is that shell redirections simply do not work in this case.

While here, remove an unnecessary env(1) invocation.

Approved by:	portmgr blanket (runtime fix)
Fixes:		df292e7
MFH:		2022Q1
Sponsored by:	Ekco
Sponsored by:	Klara Inc

net-mgmt/alertmanager/Makefile

@@ -3,6 +3,7 @@
 PORTNAME=	alertmanager
 PORTVERSION=	0.23.0
 DISTVERSIONPREFIX=	v
+PORTREVISION=	1
 CATEGORIES=	net-mgmt
 
 MAINTAINER=	michal@hanu.la

net-mgmt/alertmanager/files/alertmanager.in

@@ -43,10 +43,10 @@ command="/usr/sbin/daemon"
 procname="%%PREFIX%%/bin/alertmanager"
 sig_reload=HUP
 extra_commands="reload"
-command_args="-p ${pidfile} /usr/bin/env ${procname} \
+command_args="-o ${alertmanager_log_file} -p ${pidfile} ${procname} \
                 --config.file=${alertmanager_config} \
                 --storage.path=${alertmanager_data_dir} \
-                ${alertmanager_args} > ${alertmanager_log_file} 2>&1"
+                ${alertmanager_args}"
 
 start_precmd=alertmanager_startprecmd