Ambari-25333 branch 2.7

[apappu]

What changes were proposed in this pull request?

1. Checking if the file present/exist in the file system - if not re-creating the keytab file.

(Please fill in changes proposed in this fix)

1. Checking if the file present/exist in the file system - if not re-creating the keytab file.

How was this patch tested?

1. Deployed the changes in Kerberos cluster, deleted the files under ambari-server/data/cache folder and tried to re-generate keytabs for missing. it has re-created the files.

(Please explain how this patch was tested. Ex: unit tests, manual tests)
(If this patch involves UI changes, please attach a screen-shot; otherwise, remove this)

Please review Ambari Contributing Guide before opening a pull request.

[asfgit]

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[hapylestat]

we can't create here a keytab as password would be always null and keytab would be invalid at the end

[hapylestat]

I guess the proper place to do the change is CreatePrincipalsServerAction, there is a place like:

      } else if (!StringUtils.isEmpty(kerberosPrincipalEntity.getCachedKeytabPath())) {
        // This principal has been processed and a keytab file has been cached for it... do not process it.
        processPrincipal = false;
      } else {

if we change it to something like:

      } else if (!StringUtils.isEmpty(kerberosPrincipalEntity.getCachedKeytabPath())) {
        File file = new File(kerberosPrincipalEntity.getCachedKeytabPath());

        // Process the principal if the cache is missing, otherwise skip it
        processPrincipal = !file.exists();
      } else {

It would process with the the proper keytab re-generation

[apappu]

@hapylestat I thought changing CreateKeytab operation code is more relevant - in the above recommendation we are touching the CreatePrincipleAction right.

[apappu]

we can't create here a keytab as password would be always null and keytab would be invalid at the end

Look like we don't need password here - see https://github.com/apache/ambari/blob/branch-2.7/ambari-server/src/main/java/org/apache/ambari/server/serveraction/kerberos/KDCKerberosOperationHandler.java#L177

[hapylestat]

for Kerberos yes, but check please code for non-Kerberos handlers