Kubernetes Discover External IPs

get-k8s-external-ips.py

## If running in an RBAC-enabled cluster, the `default` service account in that namespace must have the following role,
## taking note to update the namespace: value

#---
# apiVersion: rbac.authorization.k8s.io/v1
# kind: Role
# metadata:
#   name: default
#   namespace: $NAMESPACE
# rules:
# - apiGroups: [""]
#   resources: ["services"]
#   verbs: ["get", "watch", "list"]
# - apiGroups: [""]
#   resources: ["configmaps"]
#   verbs: ["create", "update", "patch"]

# ---
# apiVersion: rbac.authorization.k8s.io/v1
# kind: RoleBinding
# metadata:
#   name: default
#   namespace: $NAMESPACE
# roleRef:
#   apiGroup: rbac.authorization.k8s.io
#   kind: Role
#   name: default
# subjects:
# - kind: ServiceAccount
#   name: default


### Run this in a Cronjob resource like so, the image only needs Python3 and to copy the python code in the Dockerfile
### taking note to update the namespace: value again

# apiVersion: batch/v1beta1
# kind: CronJob
# metadata:
#   name: info-gatherer
#   namespace: $NAMESPACE
# spec:
#   schedule: "*/1 * * * *"
#   jobTemplate:
#     spec:
#       template:
#         spec:
#           restartPolicy: OnFailure
#           containers:
#           - name: info-gatherer
#             image: homemadeImageWithPython3/info-gatherer:latest
#             command: ["python"]
#             args: ["get-k8s-external-ips.py", "--namespace", "$NAMESPACE"]
#             imagePullPolicy: Always


import sys, yaml, json, argparse, requests
from requests.packages.urllib3.exceptions import InsecureRequestWarning

requests.packages.urllib3.disable_warnings(InsecureRequestWarning)
parser = argparse.ArgumentParser()

parser.add_argument('--namespace', action="store", default=False, required=True)
args = parser.parse_args()

token_file = "/var/run/secrets/kubernetes.io/serviceaccount/token"
kubernetes_api = "https://kubernetes.default.svc.cluster.local/api/v1/"
configmap_name = "external-ips-configmap"

try:
    with open(token_file, "r") as token:
        data=token.readlines()
    header = {
        "Content-Type": "application/json",
        "Authorization": "Bearer " + data[0]
    }
    url = kubernetes_api + "namespaces/" + args.namespace + "/services"
    req = requests.get(url, headers=header, verify=False)
    if req.status_code <= 201:
        service_payload = req.content
    else:
        print("Non-200 status code returned: " + str(req.status_code))
except:
    print("Error with getting services, status code returned: " + str(req.status_code))

services = json.loads(service_payload)

configmap_data = []
service_name_list = []
service_external_ip_list = []

for item in services["items"]:
    try:
        service_name_list.append("EXTERNAL_" + item["metadata"]["name"].upper().replace("-","_"))
        service_external_ip_list.append(item["status"]["loadBalancer"]["ingress"][0]["ip"])
    except: # If the service does not have a loadBalancer ingress IP, populate it as "none" string
        service_name_list.append("EXTERNAL_" + item["metadata"]["name"].upper().replace("-","_"))
        service_external_ip_list.append("none")

configmap_data = {k:v for k,v in zip(service_name_list,service_external_ip_list)}

configmap_format = { "apiVersion": "v1", "kind": "ConfigMap", "data": configmap_data, "metadata": { "name": configmap_name, "namespace": args.namespace } }
configmap_payload = json.dumps(configmap_format)


try:
    with open(token_file, "r") as token:
        data=token.readlines()
    header = {
        "Content-Type": "application/json",
        "Authorization": "Bearer " + data[0]
    }
    url = kubernetes_api + "namespaces/" + args.namespace + "/configmaps"
    req = requests.post(url, headers=header, data=configmap_payload, verify=False)
    if req.status_code <= 201:
        service_payload = req.content
    elif req.status_code == 409:
        print(configmap_name + " already exists, will attempt to PUT")
        url = kubernetes_api + "namespaces/" + args.namespace + "/configmaps/" + configmap_name
        req = requests.put(url, headers=header, data=configmap_payload, verify=False)
        if req.status_code == 200:
          print("PUT successful")
        else:
          print("PUT Failed, status code returned: " + str(req.status_code))
          print(req.content)
    else:
        print("Non-200 status code returned: " + str(req.status_code))
        print(req.content)
except:
    print("Error with getting services, status code returned: " + str(req.status_code))