custom-tests.md

Custom tests

AreWeDown? supports calling shell scripts for tests. For example, you can write your tests directly in settings.yml. To test if NFS is running at a remote, you can use

watchers:
     nfs-test:
        cmd : /usr/bin/rpcinfo -u <MY-SERVER-IP> mountd | grep "ready and waiting"

Grep in particular is useful for tests as it will automatically exit with an error code if it finds no matches for a string.

You can also call your own Python (>=v3), Bash or NodeJS (>=v12) scripts. In the docker-compose example above we mounted a directory to /etc/arewedown/custom-tests in our container. If you put the a Python script in that folder

import sys
# parse arg --foo, do some test, if fails exit with code 1, else code 0
sys.exit(1)

Then call it

watchers:
     my-custom-test:
        cmd : python3 /etc/arewedown/custom-tests/mytest.py --foo bar

You can do the same with NodeJS, Bash or anything linux-supported script

watchers:
     my-custom-test:
        cmd : node /etc/arewedown/custom-tests/mytest.js --foo bar

If your script requires external dependencies or setup, use onstart to fire a shell command.

onstart: cd /etc/arewedown/custom-tests && npm install && sudo apt-get install <some-package> -y
watchers:
    ...

Your script should signal an error to AreWeDown? by exiting with a non-zero exit code, as is the convention with any shell application. Anything you write to console will be treated as the error message in this case.

Arguments

If you're passing arguments to your tests, you'll want to read them.

Getting args in Python3

Reading args in Python3 is easily done with built-in argparse

import sys
import argparse

parser = argparse.ArgumentParser()
parser.add_argument('--foo', '-f')
args, unknown = parser.parse_known_args()

# args.foo > 

Getting args in NodeJS

The easiest way to read arguments passed to a NodeJS script is with minimist. If you don't want to install npm packages you can try

function getArg(arg){
    for (let i = 0 ; i < process.argv.length ; i ++)
        if (process.argv[i] == `--${arg}` && process.argv.length >= i)
            return process.argv[i + 1]
    return null
}

const foo = getArg('foo') // > "bar"

Getting args in sh

Parsing args in bash or similar is done thusly

FOO="not set"

while [ -n "$1" ]; do 
    case "$1" in
    -f|--foo)
        FOO="$2" shift;;
    esac 
    shift
done

echo $FOO