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Automatic Server Status Page Creation Update

Linux, Raspberry Pi, Raspberry Pi Server, Server, , , , , , , , , , , , , , , , ,

In January 2015 I created a post about automatically creating a status page for a Linux server that I have. Typically this is put under a restricted directory and allows you to see a snapshot of what is happening with the server. I run it by putting the scripts in the /etc/cron.hourly directory on a Linux PC and a Raspberry Pi running Linux.

It serves as a simple way to check up on the server without having to use a tool such as Webmin that requires a login. It also keeps a trail of log files that get rotated on a monthly basis, so there is always a few old ones around to track down any problems and patterns in the operation.

I have found this information useful when I have traced down malfunctions that can occur when setting up a server and also when I was trying to get a webcam up and running and had the USB bus hang up a few times when the cam was overloaded with too much light.

In the new script file I fixed a bug by adding parenthesis around a line that I was trying to echo and I added code to run the w command to show a quick picture on who is logged in, how long the server has been up and running and the values for the average load on the server at the 1, 5 and 15 minute marks.

Logcreate Script

#!/bin/dash
# Remove old log
rm /var/www/status/log.txt
# Print logged outputs into new log.txt
date >> /var/www/status/log.txt
echo >> /var/www/status/log.txt
tail /var/log/syslog >> /var/www/status/log.txt
echo >> /var/www/status/log.txt
free >> /var/www/status/log.txt
echo >> /var/www/status/log.txt
df -h >> /var/www/status/log.txt
echo >> /var/www/status/log.txt
# Top memory using processes http://www.commandlinefu.com/commands/view/3/display-the-top-ten-running-processes-sorted-by-memory-usage
#ps aux | sort -nk +4 | tail >> log.txt
echo "USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND" >> /var/www/status/log.txt
ps aux | sort -nrk 4 | head >> /var/www/status/log.txt
echo >> /var/www/status/log.txt
# Logged in User info using w command
w >> /var/www/status/log.txt
echo >> /var/www/status/log.txt
echo >> /var/www/status/log.txt
# Copy log.txt into the full log that is collected
cat /var/www/status/log.txt >> /var/www/status/fulllog.txt
# Create a free standind copy of the process tree
pstree > /var/www/status/pstree.txt

Alternate Version

I also created a version of the script for a desktop Linux PC that does not have Apache installed.  In it I use a DIR variable to contain the directory that I want the log.txt file stored.

 #!/bin/dash

# User defined variables
# No trailing / on DIR!
DIR=/home/erick/status

# Remove old log
rm $DIR/log.txt
# Print logged outputs into new log.txt
date >> $DIR/log.txt
echo >> $DIR/log.txt
tail /var/log/syslog >> $DIR/log.txt
echo >> $DIR/log.txt
free >> $DIR/log.txt
echo >> $DIR/log.txt
df -h >> $DIR/log.txt
echo >> $DIR/log.txt
# Top memory using processes http://www.commandlinefu.com/commands/view/3/display-the-top-ten-running-processes-sorted-by-memory-usage
#ps aux | sort -nk +4 | tail >> log.txt
echo "USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND" >> $DIR/log.txt
ps aux | sort -nrk 4 | head >> $DIR/log.txt
echo >> $DIR/log.txt
# Logged in User info using w command
w >> $DIR/log.txt
echo >> $DIR/log.txt
echo >> $DIR/log.txt
# Copy log.txt into the full log that is collected
cat $DIR/log.txt >> $DIR/fulllog.txt
# Create a free standing copy of the process tree
pstree > $DIR/pstree.txt

Rotation of Log

In the /etc/cron.monthly directory I have created a file that is called status-log-rotate and it will save backup copies of 2 months worth of the full concatenated server status logs.

#! /bin/bash
DIR=/home/erick/status
mv $DIR/fulllog.txt.1 $DIR/fulllog.txt.2
mv $DIR/fulllog.txt $DIR/fulllog.txt.1

Tweaks for Raspberry Pi

For the Raspberry Pi which has an SD card that I am trying to be conscious of writing to often. I have recently made some modifications to put the /tmp folder onto RAM using tmpfs. I create the hourly log underneath a folder there. Daily via a script it cron.hourly it gets concatenated into a daily log which is under a status folder that has restricted access. This gets appended once per day to the fulllog which actually lives on the SD card. The end result, no multiple hourly writes to the log file, just one append to the full log per day. The only downside is if the power drops and then some log entries will be lost for the day.

Logcreate runs from /etc/cron.hourly for Raspberry Pi

#!/bin/dash
# Set DIR, on Pi this is a temp location for log
DIR=/tmp/web

# Set fixed DIR FIXDIR for files that have to be stored on SD card
# Nevermind, just make a daily log and then copy that to the full log daily.
#FIXDIR=/var/www/status

# Remove old log

rm $DIR/log.txt
# Print logged outputs into new log.txt
date >> $DIR/log.txt
echo >> $DIR/log.txt
tail /var/log/syslog >> $DIR/log.txt
echo >> $DIR/log.txt
free >> $DIR/log.txt
echo >> $DIR/log.txt
df -h >> $DIR/log.txt
echo >> $DIR/log.txt
# Top memory using processes http://www.commandlinefu.com/commands/view/3/display-the-top-ten-running-processes-sorted-by-memory-usage
echo "USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND" >> $DIR/log.txt

ps aux | sort -nrk 4 | head >> $DIR/log.txt
echo >> $DIR/log.txt
# Logged in User info using w command
w >> $DIR/log.txt
echo >> $DIR/log.txt
echo >> $DIR/log.txt
# Copy log.txt into the full log that is collected
cat $DIR/log.txt >> $DIR/dailylog.txt
# Create a free standing copy of the process tree
pstree > $DIR/pstree.txt

dailylog-to-fulllog script, runs from /etc/cron.daily

#! /bin/bash

DIR=/tmp/web
FIXDIR=/var/www/status

echo "----------------------------------------------" >> $DIR/dailylog.txt
date >> $DIR/dailylog.txt
echo "----------------------------------------------" >> $DIR/dailylog.txt
cat $DIR/dailylog.txt >> $FIXDIR/fulllog.txt
rm $DIR/dailylog.txt

Logcreate Output from Raspberry Pi

Below is what the logcreate script will output to the log.txt file on a Raspberry Pi that I have running as a web server.

Sun Jul 12 14:17:01 EDT 2015

Jul 12 13:47:51 raspberrypi dhclient: DHCPACK from 192.168.1.1
Jul 12 13:47:52 raspberrypi dhclient: bound to 192.168.1.17 -- renewal in 40673 seconds.
Jul 12 13:59:01 raspberrypi /USR/SBIN/CRON[28010]: (erick) CMD (aplay /opt/sonic-pi/etc/samples/guit_e_fifths.wav)
Jul 12 13:59:07 raspberrypi /USR/SBIN/CRON[28009]: (CRON) info (No MTA installed, discarding output)
Jul 12 14:00:01 raspberrypi /USR/SBIN/CRON[28013]: (erick) CMD (/home/erick/fswebcam/cron-timelapse.sh >> timelapse.log)
Jul 12 14:00:23 raspberrypi /USR/SBIN/CRON[28012]: (CRON) info (No MTA installed, discarding output)
Jul 12 14:01:01 raspberrypi /USR/SBIN/CRON[28022]: (root) CMD (/home/erick/bin/usbreset /dev/bus/usb/001/004)
Jul 12 14:01:02 raspberrypi /USR/SBIN/CRON[28021]: (CRON) info (No MTA installed, discarding output)
Jul 12 14:09:01 raspberrypi /USR/SBIN/CRON[28053]: (root) CMD (  [ -x /usr/lib/php5/maxlifetime ] && [ -x /usr/lib/php5/sessionclean ] && [ -d /var/lib/php5 ] && /usr/lib/php5/sessionclean /var/lib/php5 $(/usr/lib/php5/maxlifetime))
Jul 12 14:17:01 raspberrypi /USR/SBIN/CRON[28064]: (root) CMD (   cd / && run-parts --report /etc/cron.hourly)

             total       used       free     shared    buffers     cached
Mem:        445804     424488      21316          0     106768     260516
-/+ buffers/cache:      57204     388600
Swap:       102396          0     102396

Filesystem      Size  Used Avail Use% Mounted on
rootfs          6.3G  3.1G  3.0G  51% /
/dev/root       6.3G  3.1G  3.0G  51% /
devtmpfs        214M     0  214M   0% /dev
tmpfs            44M  240K   44M   1% /run
tmpfs           5.0M  8.0K  5.0M   1% /run/lock
tmpfs            88M     0   88M   0% /run/shm
/dev/mmcblk0p5   60M   19M   41M  32% /boot

USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root      2071  0.0  3.0  24896 13652 ?        Ss   Jun28   2:24 /usr/sbin/apache2 -k start
www-data 27745  0.0  1.5  25412  7084 ?        S    09:58   0:00 /usr/sbin/apache2 -k start
www-data 27744  0.0  1.5  24960  6760 ?        S    09:58   0:00 /usr/sbin/apache2 -k start
www-data 27743  0.0  1.5  25428  7116 ?        S    09:58   0:00 /usr/sbin/apache2 -k start
www-data 27742  0.0  1.5  25396  7036 ?        S    09:58   0:00 /usr/sbin/apache2 -k start
www-data 27538  0.0  1.5  25396  7032 ?        S    06:25   0:00 /usr/sbin/apache2 -k start
www-data 27502  0.0  1.5  25404  7036 ?        S    06:25   0:00 /usr/sbin/apache2 -k start
www-data 27501  0.0  1.5  25396  7044 ?        S    06:25   0:00 /usr/sbin/apache2 -k start
www-data 27747  0.0  1.3  24936  6188 ?        S    09:58   0:00 /usr/sbin/apache2 -k start
www-data 27746  0.0  1.3  24936  6188 ?        S    09:58   0:00 /usr/sbin/apache2 -k start

 14:17:02 up 14 days, 12:56,  1 user,  load average: 0.00, 0.01, 0.05
USER     TTY      FROM             LOGIN@   IDLE   JCPU   PCPU WHAT
erick    pts/0    192.168.1.5      14:04   10:39   1.70s  1.70s -bash

Simple WebDAV

Linux, Raspberry Pi Server, Server, , , , , ,

WebDAV, the DAV stands for Distributed Authoring and Version. In its simplest form would be a folder that can be accessed from the web that has a username and password to keep the content locked. There are two versions basically, plain and SSL which is secure in that the data that flows in and out of the folder is encrypted as it moves through the web. In this post I am covering the simple non-SSL form for starters.

This post assumes that Apache is installed, if you need to install it do…

sudo apt-get install apache2

Then load the Apache modules for DAV…

sudo a2enmod dav
sudo a2enmod dav_fs

Create a folder for WebDAV

I created a directory at…

/srv/homes/webdav

…the command…

mkdir -p /srv/homes/webdav

…will allow the folders above webdav, such as homes be created if they do not exist.

Edit the Apache default file

The WebDAV folder access is simply controlled by the sites-available/default file. To edit it run…

sudo nano /etc/apache2/sites-available/default

Towards the bottom of the file right above the section that has the ScriptAlias for the /cgi-bin/ directory, I placed the following code…

Alias /webdav  /srv/homes/webdav
<Location /webdav>
 Options Indexes
 DAV On
 AuthType Basic
 AuthName "webdav"
 AuthUserFile /etc/apache2/webdav.password
 Require valid-user
 </Location>

Adding the Password

Use the htpasswd command to add a password to a webdav.password file. it will prompt you for a password. The file will contain hashed passwords which are not readable.

sudo htpasswd -c /etc/apache2/webdav.password username

For an extra level of protection you can change ownership of the file to root with the group of www-data, so no regular users can access the file. Setting the permission to read-write for owner root and read only for the www-data group…

sudo chown root:www-data /etc/apache2/webdav.password
sudo chmod 640 /etc/apache2/webdav.password

Access the Folder

With everything setup the folder will now appear at http://your-url-here.com/webdav, you can browse to it to test it out. You will be prompted for the user-name and password created earlier in the adding the password step.

Further Potential for WebDAV

  • Setup multiple WebDAV folders.
  • Put a web folder on expanded storage on a Raspberry Pi, such as use a bind mount to point to a USB stick plugged into the Pi for extra storage space.
  • It is possible to set up WebDAV with SSL to secure it in a way that the data flowing in and out of the folder will be secured from prying eyes. With my non-SSL WebDAV folder, I don’t put anything up there that is critical or really private data.
  • It is possible to use DAV for support of calendars across devices, something I will explore in the future.
  • There is an app for the iPhone that I have tried that allows easy uploading and downloading to the WebDAV folder. It is easy to drop attachments from email and etc. to the folder for access on a PC.

Resources

https://www.digitalocean.com/community/tutorials/how-to-configure-webdav-access-with-apache-on-ubuntu-12-04 

WebDAV Resources

 

Automatic Server Status Page Creation

Linux, Server, , , , , , , , , , ,

On one of the servers I ran in 2013-14, I used Webmin to keep track of what was going on with the server, memory usage, drive space and so on. It was a bit overkill, I thought I would need it more than I really did.

The server I am trying this out on is resource limited, low RAM mostly, only 512MB. So I was concerned about too many processes weighing it down and was trimming RAM use for Apache, mySql and PHP. I wanted an easy way to look at what is going on with the server, web based, so putting the info on a dynamically created page seemed like the way to go.

Restricting Directory Access with Apache

I don’t want just anyone to have access to the status directory. Clever folks might gain too much insight from what is shown there, a potential hack risk. On the server the location /var/www/status is restricted. What I mean by this is that I have edited the Apache default file to restrict access by IP, as I am only accessing this from a few IP’s. Below is an example of the mod to the Apache default file. Obviously I want to allow from my local net, so that is 192.168.1 ranging from 0-255. In the default file you don’t have to list the entire IP if you want to cover a range. Additionally at the time, there were a few IP’s in the 74.67.XX.XX range so I opened that range up for testing access to. Basically you can add as many as you want. Another option would be to password protect the directory, but for now this is all I need.

To edit the Apache default file, make a backup copy first, then on Ubuntu at least…

sudo nano /etc/apache2/sites-available/default
Example code from Apache default file to allow certain IP’s access to a directory and deny all others
<Directory /var/www/status/>
        Order deny,allow
        Allow from 192.168.1
                Allow from 74.67
    
        Deny from all
</Directory>

Logcreate

With this server instead of using Webmin to look at the status of the server,  I made a simple file called logcreate, ran by putting it in the cron.hourly folder and chmodding it +x! It makes a status page at /var/www/status/log.txt. Also generated is /var/www/status/fulllog.txt a concatenated version of the log.txt added to on an hourly basis. I used dash instead of bash, it’s a slight improvement in memory use when called. Don’t use an extension, cron won’t run files such as logcreate.sh.

Logcreate basically it gives you a synopsis of the servers state in text form…

  • Date and time stamp on top ( date )
  • Tail of the syslog ( tail /var/log/syslog )
  • Memory usage ( free )
  • Drive space usage ( df -h )
  • Processes sorted by RAM usage ( ps aux | sort -nrk 4 | head )
  • Free standing copy of the process tree ( pstree )

 

The code for logcreate, the file to be placed in /etc/cron.hourly
#!/bin/dash
# Remove old log
rm /var/www/status/log.txt
# Print logged outputs into new log.txt 
# Starting with date stamp
date >> /var/www/status/log.txt
echo >> /var/www/status/log.txt
# Grab the tail of the syslog file
tail /var/log/syslog >> /var/www/status/log.txt
echo >> /var/www/status/log.txt
# Log RAM usage
free >> /var/www/status/log.txt
echo >> /var/www/status/log.txt
# Disk Usage
df -h >> /var/www/status/log.txt
echo >> /var/www/status/log.txt
# Top memory using processes http://www.commandlinefu.com/commands/view/3/display-the-top-ten-running-processes-sorted-by-memory-usage
#ps aux | sort -nk +4 | tail >> log.txt
#echo 'USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND ' >> log.txt
ps aux | sort -nrk 4 | head >> /var/www/status/log.txt
echo >> /var/www/status/log.txt
echo >> /var/www/status/log.txt
# Copy log.txt into the full log that is collected from the hourly updates.
cat /var/www/status/log.txt >> /var/www/status/fulllog.txt
# Create a free standing copy of the process tree
pstree > /var/www/status/pstree.txt

 

Resources

Figuring out a good command to list the running processes sorted by RAM use was something I needed some help figuring out as far as the best way to do it. The link below was where I got my info from.

Top memory using processes:  http://www.commandlinefu.com/commands/view/3/display-the-top-ten-running-processes-sorted-by-memory-usage