Using JMESPath, how to filter Consul services which have at least one label defined?

Question

I have a list of services defined in my Consul catalog, and I would like to remove the ones that have no label defined.

This list of services looks like this:

{
    "json": {
        "consul": [],
        "consul-exporter": [],
        "consul-8600": [
            "traefik.enable=false",
            "udp"
        ],
        "snmp-gateway": [],
    }
}

I would like to filter it using JMESPath to have the result containing only

{
    "json": {
        "consul-8600": [
            "traefik.enable=false",
            "udp"
        ],
    }
}

But the syntax of JMESPath filtering remains obscure to me.

I think I should use the length function to get the size of the attributes array, but how?

So far, I have a json.[length(*)>0] filter, but it shows no value.

What should I change to have a non-null result?

Answer 1

^{In Ansible 2.5 and later:}

It is possible by combining JMESPath query with Ansible dict2items filter and Jinja2 dict function:

- debug:
    msg: "{{ dict(json | dict2items | json_query('@[?value].[key, value]')) }}"