Add iBGP workflow and LibreNMS client

@Aleksandr.Kurbatov We will need to test this together to verify that no info is missing for the Ansible playbooks I've added Simone as a reviewer just to keep him in the loop.

gso/services/librenms.py

+"""
+The LibreNMS module interacts with the LibreNMS instance when
+- Creating a device.
+- Validating the input of a device.
+- Terminating a device.
+"""
+import json
+import logging
+import requests
+from gso import settings
+
+
+logger = logging.getLogger(__name__)
+
+
+class CfgStruct(object):
+    pass
+
+
+def _get_cfg():
+    """
+    Internal function to retrieve all needed configuration.
+    """
+    oss = settings.load_oss_params()
+    cfg = CfgStruct()
+    # Hack for later ease: 1st setattr will fill in the inner's dict
+    setattr(cfg, "_hack", "")
+    # Update inner dict
+    cfg.__dict__.update(oss.MONITORING)
+    assert cfg.__dict__ is not None
+
+    # Add parameters on-the-fly
+    cfg.headers = {"X-Auth-Token": cfg.LIBRENMS.token}
+
+    sep = "/"
+    if cfg.LIBRENMS.endpoint.endswith("/"):
+        sep = ""
+    cfg.base_url = f"{cfg.LIBRENMS.endpoint}{sep}api/v0"
+    cfg.url_devices = f"{cfg.base_url}/devices"
+    cfg.url_switches = f"{cfg.base_url}/devicegroups/switches"
+    cfg.device_groups = cfg.LIBRENMS.DEVICE_GROUPS
+    cfg.environment = oss.GENERAL.environment
+    if cfg.environment.startswith("lab"):
+        cfg_dg_rtr_lab = cfg.device_groups.routers_lab
+        cfg.url_routers = f"{cfg.base_url}/devicegroups/{cfg_dg_rtr_lab}"
+    elif cfg.environment.startswith("prod"):
+        cfg_dg_rtr_prod = cfg.device_groups.routers_prod
+        cfg.url_routers = f"{cfg.base_url}/devicegroups/{cfg_dg_rtr_prod}"
+
+    return cfg
+
+
+def validate_device(fqdn: str):
+    """
+    Function that validates the existence of a device in LibreNMS.
+
+    :param FQDN of the device to validate.
+    """
+    CFG = _get_cfg()
+
+    # Validate existence
+    nms_result = requests.get(
+        CFG.url_devices, headers=CFG.headers)
+    assert nms_result is not None
+
+    device_id = list(map(
+        lambda x: x.get("device_id"),
+        filter(lambda x: x.get("hostname") == fqdn,
+               nms_result.json().get("devices"))))
+
+    if len(device_id) != 1 or device_id[0] is None:
+        error_msg = f"Device with FQDN={fqdn} is not registered in LibreNMS"
+        print(error_msg)
+        raise AssertionError(error_msg)
+
+    # Validate correctness
+    device_id = device_id[0]
+    url_device = f"{CFG.url_devices}/{device_id}"
+    logger.debug(f"Connecting to URL: {url_device}"
+                 f"with headers: {CFG.headers}")
+    nms_result = requests.get(
+        url_device, headers=CFG.headers)
+    logger.debug(f"LibreNMS response={nms_result.content}")
+
+    if nms_result.status_code != 200:
+        print(nms_result.content)
+        raise AssertionError(nms_result.content)
+
+    # nms_dev_sysname = nms_result.json().get("sysName")
+    nms_dev_hostname = nms_result.json().get("devices")[0].get("hostname")
+    if fqdn != nms_dev_hostname:
+        error_msg = f"Device with FQDN={fqdn} may not be correctly "\
+                f"registered in LibreNMS (expected FQDN: {nms_dev_hostname})"
+        print(error_msg)
+        raise AssertionError(error_msg)
+
+
+def register_device(fqdn: str):
+    """
+    Function that registers a new device in LibreNMS.
+
+    :param FQDN of the device to register.
+    """
+    CFG = _get_cfg()
+    logger.debug(f"Registering FQDN={fqdn} in LibreNMS")
+
+    device_data = {
+        "display": fqdn,
+        "hostname": fqdn,
+        "sysName": fqdn,
+        # "override_icmp_disable": "true",
+        # IMPORTANT: uncomment if testing with FQDNs that are not reachable
+        # from LibreNMS (e.g. ContainerLab routers)
+        # "force_add": "true"
+    }
+    if CFG.SNMP.version == "v2c":
+        device_data.update({
+            "community": CFG.SNMP.V2.community
+            })
+
+    elif CFG.SNMP.version == "v3":
+        for key in [
+                "authlevel", "authname", "authpass", "authalgo",
+                "cryptopass", "cryptoalgo"]:
+            device_data.update({key: getattr(CFG.SNMP.V3, key)})
+
+    logger.debug(f"Connecting to URL: {CFG.url_devices}"
+                 f"with headers: {CFG.headers} and"
+                 f"payload: {device_data}")
+    nms_result = requests.post(
+        CFG.url_devices, headers=CFG.headers,
+        data=json.dumps(device_data))
+    logger.debug(f"LibreNMS response={nms_result.content}")
+
+    if nms_result.status_code != 200:
+        print(nms_result.content)
+        raise AssertionError(nms_result.content)
+
+
+def deregister_device(fqdn: str):
+    """
+    Function that reregisters a device from LibreNMS.
+
+    :param FQDN of the device to deregister.
+    """
+    CFG = _get_cfg()
+    logger.debug(f"Deregistering FQDN={fqdn} from LibreNMS")
+
+    nms_result = requests.get(
+        CFG.url_devices, headers=CFG.headers)
+    assert nms_result is not None
+    device_id = list(map(
+        lambda x: x.get("device_id"),
+        filter(lambda x: x.get("hostname") == fqdn,
+               nms_result.json().get("devices"))))
+    if len(device_id) != 1:
+        return
+    device_id = device_id[0]
+
+    # https://docs.librenms.org/API/Devices/#endpoint-categories
+    device_data = {
+        "field": "disabled",
+        "data": "1"
+    }
+    url_device = f"{CFG.url_devices}/{device_id}"
+    logger.debug(f"Connecting to URL: {url_device}"
+                 f"with headers: {CFG.headers} and"
+                 f"payload: {device_data}")
+    nms_result = requests.patch(
+        url_device, headers=CFG.headers,
+        data=json.dumps(device_data))
+    logger.debug(f"LibreNMS response={nms_result.content}")
+
+    # Fail silently if device was not registered
+    if nms_result.status_code != 200:
+        print(nms_result.content)