Fix data being replicated on VM's metadata file in VR

[GutoVeronezi]

Description

While creating VMs, ACS configures HTTPd on the VR to serve metadata files to be consumed by CloudInit. However, the file /var/www/html/meta-data/<vm-ip>/metadata is appended with the same content every time a VM is started through CloudStack, causing the file to have replicated lines; as VMs are created/started, this file grows ad infinitum, consuming the VR's storage.

This PR intends to fix this metadata replication on the VRs.

Types of changes

• Breaking change (fix or feature that would cause existing functionality to change)
• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Enhancement (improves an existing feature and functionality)
• Cleanup (Code refactoring and cleanup, that may add test cases)
• build/CI
• test (unit or integration test code)

Feature/Enhancement Scale or Bug Severity

Bug Severity

• BLOCKER
• Critical
• Major
• Minor
• Trivial

Screenshots (if appropriate):

How Has This Been Tested?

Without the changes:

1. I created a network;
2. I created a VM;
3. I checked the VM's metadata file in the VR, and observed that it had only a single entry for each attribute;
4. I checked the metadata in the VM;
5. I stopped the VM;
6. I started the VM again;
7. I checked that the VM's metadata file in the VR had duplicated entries for every attribute;
8. I checked the metadata in the VM;

With the changes:

1. I created a network;
2. I created a VM;
3. I checked the VM's metadata file in the VR, and observed that it had only a single entry for each attribute;
4. I checked the metadata in the VM;
5. I stopped the VM;
6. I started the VM again;
7. I checked the VM's metadata file in the VR, and observed that it had only a single entry for each attribute;
8. I checked the metadata in the VM;

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 16.57%. Comparing base (41b4f0a) to head (2172c9e).
Report is 27 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #10987      +/-   ##
============================================
- Coverage     16.57%   16.57%   -0.01%     
+ Complexity    13870    13869       -1     
============================================
  Files          5719     5719              
  Lines        507200   507200              
  Branches      61574    61574              
============================================
- Hits          84093    84075      -18     
- Misses       413688   413711      +23     
+ Partials       9419     9414       -5     

Flag	Coverage Δ
uitests	3.96% <ø> (ø)
unittests	17.45% <ø> (-0.01%)	⬇️

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[DaanHoogland]

@GutoVeronezi , I think your intention is

Suggested change

	fh = open(metamanifest, "a+")
	self.__exflock(fh)
	fh.seek(0)
	fh = open(metamanifest, “w+")
	self.__exflock(fh)

opeing with a+ will not truncate the previous version, but only overwrite data afaik.

[GutoVeronezi]

a is for appending; + is for allow reading, however, the pointer must be set to 0 to the validation work properly. w would overwrite the data. This is the same as #10254

[DaanHoogland]

you are right, I missed the fh.read() on the next line

[DaanHoogland]

clgtm

[weizhouapache]

code lgtm
Not tested

[harikrishna-patnala]

tested in my existing VR with these changes, LGTM