How can I know when a DNS change has propagated and that the record is resolving?

user_4118892 0
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A frequent problem I face is that the when deploying a new ingress to Kubernetes, the DNS creation takes time. The external-dns service in Kubernetes writes to route53 and creates the record as specified in the ingress, but it takes time for this DNS to propagate to our company DNS server.

dns python
1 Answers

In order not to have to wait longer than necessary, I wrote the following little python3 script that I am sharing below:

#!/usr/bin/python3
from socket import gethostbyname, gaierror
import time
import sys

class bcolors:
    HEADER = '\033[95m'
    OKBLUE = '\033[94m'
    OKCYAN = '\033[96m'
    OKGREEN = '\033[92m'
    WARNING = '\033[93m'
    FAIL = '\033[91m'
    ENDC = '\033[0m'
    BOLD = '\033[1m'
    UNDERLINE = '\033[4m'

def main(arg):
    print ("Waiting for dns to be ready for: %s%s%s" % (bcolors.OKGREEN, arg, bcolors.ENDC))
    while True:
        try:
            addr = gethostbyname(arg)
            print ("%s%s%s%s is up now\n" % ("\n", bcolors.OKGREEN, arg, bcolors.ENDC ))
            break
        except gaierror:
            try:
              print(".", end="")
              sys.stdout.flush()
              time.sleep(1)
              continue
            except KeyboardInterrupt:
              print ("\nInterrupt - aborting")
              exit()


if __name__ == '__main__':
    main(sys.argv[1])

Save the python code to wait4dns, and move the file to a place on your path. Execute chmod +x [path]/wait4dns.

Usage is wait4dns dns-name.com

user_41188920
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