Applications Monitoring Process

Thanks to Glances and its AMP module, you can add specific monitoring to running processes. AMPs are defined in the Glances configuration file.

You can disable AMP using the --disable-plugin amps option or pressing the A key.

Simple AMP

For example, a simple AMP that monitor the CPU/MEM of all Python processes can be defined as follows:

[amp_python]
enable=true
regex=.*python.*
refresh=3

Every 3 seconds (refresh) and if the enable key is true, Glances will filter the running processes list thanks to the .*python.* regular expression (regex).

The default behavior for an AMP is to display the number of matching processes, CPU and MEM:

../_images/amp-python.png

You can also define the minimum (countmin) and/or maximum (countmax) process number. For example:

[amp_python]
enable=true
regex=.*python.*
refresh=3
countmin=1
countmax=2

With this configuration, if the number of running Python scripts is higher than 2, then the AMP is displayed with a purple color (red if less than countmin):

../_images/amp-python-warning.png

If the regex option is not defined, the AMP will be executed every refresh time and the process count will not be displayed (countmin and countmax will be ignored).

For example:

[amp_conntrack]
enable=false
refresh=30
one_line=false
command=sysctl net.netfilter.nf_conntrack_count && sysctl net.netfilter.nf_conntrack_max

Note: for multiple command, please use the ‘&&’’ separator.

For security reason, pipe is not directly allowed in a AMP command but you create a shell script with your command:

$ cat /usr/local/bin/mycommand.sh
#!/bin/sh
ps -aux | wc -l

and use it in the amps:

[amp_amptest]
enable=true
regex=.*
refresh=15
one_line=false
command=/usr/local/bin/mycommand.sh

User defined AMP

If you need to execute a specific command line, you can use the command option. For example, if you want to display the Dropbox process status, you can define the following section in the Glances configuration file:

[amp_dropbox]
# Use the default AMP (no dedicated AMP Python script)
enable=true
regex=.*dropbox.*
refresh=3
one_line=false
command=dropbox status
countmin=1

The dropbox status command line will be executed and displayed in the Glances UI:

../_images/amp-dropbox.png

You can force Glances to display the result in one line setting one_line to true.

Security considerations

AMP command and service_cmd values are read verbatim from the configuration file and executed. The execution helper interprets three shell-like operators:

  • && to chain commands

  • | to pipe one command output into the next one

  • > to redirect the output to a file

These operators are convenient but mean that anyone able to edit the Glances configuration file can run arbitrary commands or write to arbitrary files through an AMP section.

For system services or any deployment where the configuration file is not fully trusted, start Glances with the --disable-config-exec option. In addition to disabling backtick command execution in configuration values, this option makes AMP commands run as a single process: &&, | and > are then treated as literal arguments and are no longer interpreted, so an AMP command can neither chain commands, pipe, nor write to an arbitrary file.

$ glances --disable-config-exec

Note: with --disable-config-exec set, AMP commands that rely on these operators stop working. Move such logic into a dedicated shell script and point the command option to that script instead.

Embedded AMP

Glances provides some specific AMP scripts (replacing the command line). You can write your own AMP script to fill your needs. AMP scripts are located in the amps folder and should be named glances_*.py. An AMP script define an Amp class (GlancesAmp) with a mandatory update method. The update method call the set_result method to set the AMP return string. The return string is a string with one or more line (n between lines). To enable it, the configuration file section should be named [amp_*].

For example, if you want to enable the Nginx AMP, the following definition should do the job (Nginx AMP is provided by the Glances team as an example):

[amp_nginx]
enable=true
regex=\/usr\/sbin\/nginx
refresh=60
one_line=false
status_url=http://localhost/nginx_status

Here’s the result:

../_images/amps.png

In client/server mode, the AMP list is defined on the server side.