Attribute Syntax for JSON query in check_json.pl

Question

So, I'm trying to set up check_json.pl in NagiosXI to monitor some statistics. https://github.com/c-kr/check_json

I'm using the code with the modification I submitted in pull request #32, so line numbers reflect that code.

The json query returns something like this:

[
    {
        "total_bytes": 123456,
        "customer_name": "customer1",
        "customer_id": "1",
        "indices": [
            {
                "total_bytes": 12345,
                "index": "filename1"
            },
            {
                "total_bytes": 45678,
                "index": "filename2"
            },

        ],
        "total": "765.43gb"
    },
   {
        "total_bytes": 123456,
        "customer_name": "customer2",
        "customer_id": "2",
        "indices": [
            {
                "total_bytes": 12345,
                "index": "filename1"
            },
            {
                "total_bytes": 45678,
                "index": "filename2"
            },

        ],
        "total": "765.43gb"
    }
]

I'm trying to monitor the sized of specific files. so a check should look something like:

/path/to/check_json.pl -u https://path/to/my/json -a "SOMETHING" -p "SOMETHING"

...where I'm trying to figure out the SOMETHINGs so that I can monitor the total_bytes of filename1 in customer2 where I know the customer_id and index but not their position in the respective arrays.

I can monitor customer1's total bytes by using the string "[0]->{'total_bytes'}" but I need to be able to specify which customer and dig deeper into file name (known) and file size (stat to monitor) AND the working query only gives me the status (OK,WARNING, or CRITICAL). Adding -p all I get are errors....

The error with -p no matter how I've been able to phrase it is always:

Not a HASH reference at ./check_json.pl line 235.

Even when I can get a valid OK from the example "[0]->{'total_bytes'}", using that in -p still gives the same error.

Links pointing to documentation on the format to use would be very helpful. Examples in the README for the script or in the -h output are failing me here. Any ideas?

Answer 1

Once you have the decoded json, if you have a customer_id to search for, you can do:

my ($customer_info) = grep {$_->{customer_id} eq $customer_id} @$json_response;

Regarding the error on line 235, this looks odd:

foreach my $key ($np->opts->perfvars eq '*' ? map { "{$_}"} sort keys %$json_response : split(',', $np->opts->perfvars)) {
    # ....................................... ^^^^^^^^^^^^^
    $perf_value = $json_response->{$key};

if perfvars eq "*", you appear to be looking for $json_reponse->{"{total}"} for example. You might want to validate the user's input:

    die "no such key in json data: '$key'\n" unless exists $json_response->{$key};

This entire business of stringifying the hash ref lookups just smells bad.

A better question would look like:

I have this JSON data. How do I get the sum of total_bytes for the customer with id 1?