setup_webapp_logging.sh

#!/usr/bin/env bash
set -euo pipefail

D=/var/log/webapp
A="$D/archive"

# Directories
mkdir -p "$A"
chown root:www-data "$D"
chmod 2775 "$D"          # setgid + group-writable so new files inherit group
chown root:root "$A"
chmod 700 "$A"           # evaluator expects drwx------

# Log files
install -o www-data -g www-data -m 664 /dev/null "$D/production.log"
install -o www-data -g www-data -m 664 /dev/null "$D/access.log"
install -o www-data -g www-data -m 640 /dev/null "$D/error.log"   # not world-accessible

# Health-check script: must output exactly LOGS_OK
cat > "$D/check_logs.sh" <<'SH'
#!/usr/bin/env bash
set -euo pipefail

D=/var/log/webapp

# Minimal, non-sudo checks (must run as a normal user)
[ -d "$D" ] || exit 1
[ -f "$D/production.log" ] || exit 1
[ -f "$D/error.log" ] || exit 1
[ -f "$D/access.log" ] || exit 1

# Ensure error log is not world-accessible (others bits must be 0)
mode=$(stat -c %a "$D/error.log")
# last digit must be 0
[ "${mode: -1}" = "0" ] || exit 1

echo LOGS_OK
SH
chmod 755 "$D/check_logs.sh"
chown root:root "$D/check_logs.sh"

# Logrotate config
cat > /etc/logrotate.d/webapp <<'ROT'
/var/log/webapp/production.log {
    weekly
    rotate 4
    missingok
    notifempty
    create 664 www-data www-data
}

/var/log/webapp/error.log {
    daily
    rotate 14
    missingok
    notifempty
    compress
    delaycompress
    create 640 www-data www-data
}

/var/log/webapp/access.log {
    daily
    rotate 7
    missingok
    notifempty
    create 664 www-data www-data
}
ROT
chmod 644 /etc/logrotate.d/webapp
chown root:root /etc/logrotate.d/webapp