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##### SUMMARY
@LKaemmerling As discussed in https://github.com/ansible/ansible/issues/59133#issuecomment-515133800, you said there would be network filtering in the hcloud dynamic inventory plugin (https://docs.ansible.com/ansible/latest/plugins/inventory/hcloud.html) in Ansible 2.9. But this functionality still doesn't appear. Could it be added? There are many cases where you only want to run ansible commands against servers in some networks only.

##### ISSUE TYPE
- Feature Idea

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->
hcloud dynamic inventory


<!--- Describe how the feature would be used, why it is needed and what it would solve -->

<!--- Paste example playbooks or commands between quotes below -->
```yaml

```

<!--- HINT: You can also paste gist.github.com links for larger files -->

self.inventory.set_variable(server.name, "ipv6_network_mask", to_native(server.public_net.ipv6.network_mask))
        if self.get_option("connect_with") == "public_ipv4":
            self.inventory.set_variable(server.name, "ansible_host", to_native(server.public_net.ipv4.ip))
        elif self.get_option("connect_with") == "hostname":
            self.inventory.set_variable(server.name, "ansible_host", to_native(server.name))
        elif self.get_option("connect_with") == "ipv4_dns_ptr":
            self.inventory.set_variable(server.name, "ansible_host", to_native(server.public_net.ipv4.dns_ptr))
        
        if server.image is not None and server.image.name is not None:
            self.inventory.set_variable(server.name, "server_type", to_native(server.image.name))
        else:
            self.inventory.set_variable(server.name, "server_type", to_native("No Image name found."))
        
        self.inventory.set_variable(server.name, "datacenter", to_native(server.datacenter.name))
        self.inventory.set_variable(server.name, "location", to_native(server.datacenter.location.name))
        
        if server.image is not None:
            self.inventory.set_variable(server.name, "image_id", to_native(server.image.id))
            self.inventory.set_variable(server.name, "image_os_flavor", to_native(server.image.os_flavor))
            if server.image.name is not None:
                self.inventory.set_variable(server.name, "image_name", to_native(server.image.name))
            else:
                self.inventory.set_variable(server.name, "image_name", to_native(server.image.description))
        else:
            self.inventory.set_variable(server.name, "image_id", to_native("No Image ID found"))
            self.inventory.set_variable(server.name, "image_name", to_native("No Image Name found"))
            self.inventory.set_variable(server.name, "image_os_flavor", to_native("No Image OS Flavor found"))
        
        self.inventory.set_variable(server.name, "labels", dict(server.labels))
    def verify_file(self, path):