[GitHub] [airflow] mik-laj commented on a change in pull request #13424: Disables reverse IP lookup for environment check

[GitBox <gi...@apache.org>]

mik-laj commented on a change in pull request #13424:
URL: https://github.com/apache/airflow/pull/13424#discussion_r550819382



##########
File path: scripts/in_container/check_environment.sh
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@@ -21,6 +21,21 @@ EXIT_CODE=0
 
 DISABLED_INTEGRATIONS=""
 
+# We want to perform only forward lookup of the service IP address. Netcat when run without -n
+# Performs both forward and reverse lookup and fails if the reverse lookup name does not match
+# original name even if the host is reachable via IP. This happens randomly with docker-compose
+# in Github Actions (apparently it is some race condition when one service starts before DNS)
+# Since we are not using reverse lookup elsewhere we can perform forward lookup in python
+# and use the IP in NC and add '-n' switch to disable any DNS use.

Review comment:
       ```suggestion
   # We want to perform only forward lookup of the service IP address to remove the irrelevant
   # log message - "DNS fwd/rev mismatch"
   #
   # Long explanation:
   # Netcat when run without -n, performs both forward and reverse lookup and fails if the reverse lookup name
   # does not match original name even if the host is reachable via IP. Then it displays message 
   # "DNS fwd/rev mismatch",  which introduces additional noise in the log.
   # To mitigate, we are not using reverse lookup elsewhere we can perform forward lookup in python
   # and use the IP in NC and add '-n' switch to disable any DNS use.
   ```




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