check_rest_api

Rework of the check_rest_api Nagios plugin, to make it work on new systems, written in rust

Dependancies

rustc, rust and cargo

Debian systems

sudo apt install rust rustc cargo

Other

Rust installation documentation

Install program

Clone repository

git clone https://github.com/TiborKoderman/check_rest_api

CD into repository

cd check_rest_api

run ./install.sh

chmod +x install.sh
./install.sh

build program

cargo build --release

Usage

copy to the libexec directory of the nagios instalation, usually in /usr/local/nagios/libexec

Configuration example

define service{
        use                     generic-service
        host_name               name
        service_description     System Info
        check_command           check_rest_api!http://$HOSTADDRESS$/api/nagios/system/!cpu,ram!\~:80,\~:85!\~:100,\~:95
}

Standalone command line

The below usage assumes you are running the program stand-alone on a command line. Usage for a Nagios Command will be nearly identical.

Name/Option	Shorthand	Description
--hostname	-H	Full address to the REST API endpoint
--auth-basic	-b	A string in the form <username>:<password> that is used for HTTP Basic Auth
--auth-basic-file	-bf	Filepath to a file that contains one line in the format <username>:<password> that is used for HTTP Basic Auth
--key	-K	A comma-delimited list of JSON keys to check. More detail on accessing JSON keys are below
--critical	-c	A comma-delimited list of 'critical' value criteria. Each entry corresponds to a --key entry. See Nagios Plugin documentation on critical values
--warning	-w	A comma-delimited list of 'warning' value criteria. Each entry corresponds to a --key entry. See Nagios Plugin documentation on warning values
--timeout	-t	Sets a custom timeout, in seconds, to abort the HTTP request should the remote server not respond. Defaults to 10 seconds.
--debug	-d	Enable trace mode to see low level data flow in ASCII and HEXADECIMAL representation.
--header	-D	A string to be added into HTTP request header.
--insecure	-k	Disables checking peer's SSL certificate (if using SSL/HTTPS). Not recommended to use
--http-method	-m	Optional; the HTTP method for the API call. Only 'GET', 'POST', and 'PUT' are supported at this time. If omitted 'GET' is assumed.

Example Usage

Note: Tildes (~) are escaped here as a normal BaSH will expand that to the users home directory. You needn't escape a tilde when writing a custom Nagios Command.

# Check an API endpoint and send a 'critical' value if 
# the JSON key `cpu` is above `80`
./check_rest_api -H http://www.contoso.com/api/endpoint -K cpu -c \~:80

# Check an API endpoint and send a 'warning' value if the 
# JSON key `files` is less than `23`
./check_rest_api -H http://www.contoso.com/api/endpoint2 -K files 23:

# Check an API endpoint and send a 'warning' if the JSON key `ram` is above `75` 
# and a 'critical' if it is above `80`
./check_rest_api -H http://www.contoso.com/api/endpoint3 -K ram -w \~:75 -c \~:80
  
# Check an API endpoint. Send a 'warning' if `cpu` is above 
# 60 or `ram` is above `63`, and a 'critical' if `cpu` 
 #is above `70` or `ram` is above `83`
./check_rest_api -H http://www.contoso.com/api/endpoint4 -K cpu,ram -w \~:60,\~:63 -c \~:70,\~:83

# Check an API endpoint with HTTP Basic Auth (via CLI)
./check_rest_api -H http://www.contoso.com --auth-basic username:password

# Check an API endpoint with HTTP Basic Auth (with file). The file ./test has one line with the string "username:password" to use for HTTP Basic Auth
./check_rest_api -H http://www.contoso.com --auth-basic-file ./test

Range definitions

Range definition Generate an alert if x...

Notation	Description
n	x < 0 or x > n, (outside the range of {0 .. 10})
n:	x < n, (outside {n .. ∞})
~:n	x > n, (outside the range of {-∞ .. 10})
n:m	x < n or x > m, (outside the range of {10 .. 20})
@n:m	x ≥ n and x ≤ m, (inside the range of {10 .. 20})