@COLDTURNIP Can you help the ticket?

PR: #9952
PR target to 1.6.x: #9961

Pre Ready-For-Testing Checklist

• Where is the reproduce steps/test steps documented?
  The reproduce steps/test steps are at: [IMPROVEMENT] Check NFS versions in /etc/nfsmount.conf instead #9830

• Is there a workaround for the issue? If so, where is it documented?
  No workaround.

• Does the PR include the explanation for the fix or the feature?
  This is a backport PR: feat(script/env_check): check overriden NFS version #9952
  See also the initial ticket [IMPROVEMENT] Check NFS versions in /etc/nfsmount.conf instead #9830 , which is a longhornctl check change.

• Does the PR include deployment change (YAML/Chart)? If so, where are the PRs for both YAML file and Chart?
  No deployment change.

• Have the backend code been merged (Manager, Engine, Instance Manager, BackupStore etc) (including backport-needed/*)?
  No backend change needed.

• Which areas/issues this PR might have potential impacts on?
  No impact.

• If labeled: require/LEP Has the Longhorn Enhancement Proposal PR submitted?
  No LEP.

• If labeled: area/ui Has the UI issue filed or ready to be merged (including backport-needed/*)?
  No UI change.

• If labeled: require/doc Has the necessary document PR submitted or merged (including backport-needed/*)?
  No document change.

• If labeled: require/automation-e2e Has the end-to-end test plan been merged? Have QAs agreed on the automation test case? If only test case skeleton w/o implementation, have you created an implementation issue (including backport-needed/*)
  No automation.

• If labeled: require/automation-engine Has the engine integration test been merged (including backport-needed/*)?
  No engine automation PR.

• If labeled: require/manual-test-plan Has the manual test plan been documented?
  The updated manual test plan is at [BACKPORT][v1.6.4][IMPROVEMENT] Check NFS versions in /etc/nfsmount.conf instead #9832 (comment)

• If the fix introduces the code for backward compatibility Has a separate issue been filed with the label release/obsolete-compatibility?
  No compatibility issue.

Test Steps

Note: this is a backport version of #9830 .

• Step 1. a new cluster that fulfill Longhorn dependencies, and the environment_check.sh of v1.6.4 is ready.
• Step 2. backup host's /etc/nfsmount.conf if present
• Step 3. create/modify host's /etc/nfsmount.conf, change the Defaultvers to specific version (see below)
• Step 4. check the nodes using environment_check.sh. If the Defaultvers is not acceptable, it prints an error item: NFS4 is supported, but default protocol version (...) is not 4, 4.1, or 4.2. Please refer to the NFS mount configuration manual page for more information: man 5 nfsmount.conf
• Step 5. change Defaultvers to another version, and back to Step 5.
• Step 6. After test, restore the /etc/nfsmount.conf which is backup at Step 3.

A minimal /etc/nfsmount.conf sample:

[ NFSMount_Global_Options ]
Defaultvers=4

The Defaultvers configuration override the system default NFS version. Longhorn supports only NFS 4.0, 4.1, and 4.2. If Defaultvers is not overriden in /etc/nfsmount.conf, it would be 4, which is an acceptable version:

• Defaultvers=4 -> acceptable
• Defaultvers=4.0 -> acceptable
• Defaultvers=4.1 -> acceptable
• Defaultvers=4.2 -> acceptable
• Defaultvers=4.3 -> NOT acceptable
• Defaultvers=5 -> NOT acceptable
• Defaultvers=3 -> NOT acceptable
• any other Defaultvers are NOT acceptable
• /etc/nfsmount.conf absent -> acceptable
• /etc/nfsmount.conf present without Defaultvers definded -> acceptable
• /etc/nfsmount.conf present and Defaultvers is commented (e.g. # Defaultvers=4.3) -> acceptable

Verification passed on v1.6.x-head (longhorn/longhorn b729cc6) following the test steps.