piframe/docs/munin.md

Resource Monitoring

The below commands will setup munin for monitoring resource utilization on your PiFrame. This is wholly optional but can provide insights if your PiFrame is exhibiting odd behavior.

Important Notes

• This setup will deploy a dedicated instance of lighttpd to handle access to the munin data. Given how lean lighttpd is on resources, this saves many hassles with virtual hosts and the like.
• This setup uses cgi to generate munin graphs. The Raspberry Pi cpu can take awhile to generate graphs. Please be patient. This approach was chosen to keep munin from consuming resource generating graphs every time it collects statistics. This also helps prevent excessive disk writes to the micro sd card extending its life.

Setup

apt install munin
nano -w /etc/munin/munin.conf
    graph_strategy cgi
    html_strategy cron
    [piframe]
        address 127.0.0.1
        use_node_name yes
touch /var/log/munin/munin-cgi-graph.log
chown munin: /var/log/munin/munin-cgi-graph.log
munin-node-configure --shell # activate useful plugins
sudo -sHu munin munin-cron # prime munin data
systemctl enable --now munin-node
systemctl restart munin-node
cat > /etc/lighttpd/lighttpd-munin.conf <<EOF
# Apply the following tweaks to the /etc/munin/munin.conf file ahead of running lighttpd for munin
## Use cgi rendering for graph and html
#graph_strategy cgi
#html_strategy cron

server.username = "munin"
server.groupname = "munin"

server.document-root = "/var/www/html"
server.port = 2813

server.errorlog         = "/dev/stdout"
accesslog.filename      = "/dev/stdout"
dir-listing.activate    = "disable"
server.modules          = (
                            "mod_access",
                            "mod_accesslog",
                            "mod_alias",
                            "mod_rewrite",
                            "mod_redirect",
                            "mod_cgi",
                            "mod_fastcgi",
                            "mod_auth",
                            "mod_authn_file",
                            )
auth.backend                = "htdigest" 
auth.backend.htdigest.userfile = "/etc/lighttpd/munin.auth" 
auth.require = ( "/" =>
        (
                "method" => "basic",
                "realm" => "Munin",
                "require" => "valid-user" 
        )
        )
server.pid-file         = "/run/lighttpd-munin.pid"
server.follow-symlink = "enable"
index-file.names = ( "index.html", "index.htm" )

url.redirect += ( "^/*$" => "/munin/" )

\$HTTP["url"] =~ "/munin-cgi/munin-cgi-graph" {
  alias.url += ( "/munin-cgi/munin-cgi-graph" => "/usr/lib/munin/cgi/munin-cgi-graph" )
  cgi.assign = ( "" => "" )
}

alias.url += ( "/munin/static" => "/etc/munin/static" )
alias.url += ( "/munin" => "/var/cache/munin/www" )

mimetype.assign         = (
                                ".html" => "text/html",
                                ".txt" => "text/plain",
                                ".css" => "text/css",
                                ".js" => "application/x-javascript",
                                ".jpg" => "image/jpeg",
                                ".jpeg" => "image/jpeg",
                                ".gif" => "image/gif",
                                ".png" => "image/png",
                                "" => "application/octet-stream"
                        )
EOF
cat > /etc/systemd/system/lighttpd-munin.service <<EOF
[Unit]
Description=Lighttpd Web Server (munin)
After=syslog.target network.target

[Service]
PrivateTmp=true
ExecStart=/usr/sbin/lighttpd -D -f /etc/lighttpd/lighttpd-munin.conf
ExecReload=/bin/kill -HUP $MAINPID
KillSignal=SIGINT

[Install]
WantedBy=multi-user.target
EOF
cat > /root/lighttpd-auth.pl <<EOF
#!/usr/bin/perl

print "User: ";
\$user = <>;
chomp \$user;
print "Realm: ";
\$realm = <>;
chomp \$realm;

use Term::ReadKey;
{
  ReadMode('noecho');
  print "Password: ";
  \$password = ReadLine(0);
  chomp \$password;
  print "\\nPassword again: ";
  \$password2 = ReadLine(0);
  chomp \$password2;
  ReadMode('normal');
  print "\\n";

  if(\$password ne \$password2)
  {
    print "Passwords don't match\\n";
    redo;
  }
}

print "\$user:\$realm:";
open(MD5, "|md5sum | cut -b -32") or die;
print MD5 "\$user:\$realm:\$password";
close(MD5);
EOF
chmod a+x /root/lighttpd-auth.pl
apt install libterm-readkey-perl
/root/lighttpd-auth.pl
echo "above_output" >> /etc/lighttpd/munin.auth
systemctl daemon-reload
systemctl enable --now lighttpd-munin
firewall-cmd --zone=public --permanent --add-port=2813/tcp
firewall-cmd --reload