ngx_http_sysguard_module
Description
This module monitors memory usage (including the swap partition), load of CPUs and average response time of requests of the system and cpu usage. If any guideline that is monitored exceeds the threshold set by user, the current request will be redirected to a specific url. To be clarified, this module can only be full functional when the system supports sysinfo function and loadavg function. The sysguard module also need to read memory information from /proc file system.
Configuration
server {
sysguard on;
sysguard_mode or;
sysguard_load load=10.5 action=/loadlimit;
sysguard_mem swapratio=20% action=/swaplimit;
sysguard_mem free=100M action=/freelimit;
sysguard_rt rt=0.01 period=5s action=/rtlimit;
location /loadlimit {
return 503;
}
location /swaplimit {
return 503;
}
location /freelimit {
return 503;
}
location /rtlimit {
return 503;
}
location /cpulimit {
return 503;
}
}
Directives
sysguard on | off
Default: sysguard off
Context: http, server, location
Enable or disable the sysguard module.
sysguard_load load=[ncpu*]number [action=/url]
Default: none
Context: http, server, location
This directive tells the module to protect the system by monitoring the load of CPUs. If the system's loads reach the value that is specified by 'number' in one minute, the incoming request will be redirected to the url specified by 'action' parameter. If 'action' is not specified, tengine will respond with 503 error directly. It's also possible to use ncpu* to make the configuration, in which case, ncpu stands for the number of the CPU cores. For instance, load = ncpu*1.5.
sysguard_cpu usage=num [period=time] [action=/url]
Default: period=3s
Context: http, server, location
This directive tells the module to protect the system by monitoring the CPU usage. When the system in the period (units: s) within the CPU reach to num (note: the num is a integer. such as protection CPU is 50% and could be set the usage = 50), the incoming request will be redirected to the url specified by 'action' parameter. If the action is not configured, tengine will return 503 directly.
cpu usage formula：
cpu_usage = [(cur.usr + cur.nice + cur.sys) - (pre.usr + pre.nice + pre.sys)]/
[(cur.usr + cur.nice + cur.sys + cur.iowait + cur.irq
+ cur.softirq + cur.idle)
- (pre.usr + pre.nice + pre.sys + pre.iowait + pre.irq
+ pre.softirq + pre.idle)] * 100
sysguard_mem [swapratio=ratio%] [free=size] [action=/url]
Default: -
Context: http, server, location
This directive is used to tell the module to protect the system by monitoring memroy usage. 'swapratio' is used to specify how many percent of the swap partition of the system, and 'free' is used to specify the miminum size of current memory. If any condition is fulfilled, the incoming request will be redirected to specified url, which is defined by parameter 'action'. If 'action' is not specified, the request will be responded with 503 error directly. Besides, if the user disables the swap partition in the system, this directive will not be functional. 'free' is calculated by /proc/meminfo, the algorithm is 'memfree = free + buffered + cached'.
sysguard_rt [rt=seconds] [period=time] [action=/url]
Default: -
Context: http, server, location
This directive is used to tell the module to protect the system by monitoring average response time of requests in a specified period. Parameter rt is used to set a threshold of the average response time, in second. Parameter period is used to specifiy the period of the statistics cycle. If the average response time of the system exceeds the threshold specified by the user, the incoming request will be redirected to a specified url which is defined by parameter 'action'. If no 'action' is presented, the request will be responded with 503 error directly.
sysguard_mode and | or
Default: sysguard_mode or
Context http, server, location
If there are more than one type of monitor, this directive is used to specified the relations among all the monitors which are: 'and' for all matching and 'or' for any matching.
sysguard_interval time
Default sysguard_interval 1s
Context http, server, location
Specify the time interval to update your system information.
sysguard_log_level [info | notice | warn | error]
Default sysguard_log_level error
Context http, server, location
Specify the log level of sysguard.
Installation
Compile sysguard module
configure [--with-http_sysguard_module | --with-http_sysguard_module=shared]
--with-http_sysguard_module, sysguard module will be compiled statically into tengine.
--with-http_sysguard_module=shared, sysguard module will be compiled dynamically into tengine.
Build and install
make&make install
Make sysguard configuration
Run