feat(azure): report failure if missing customdata by cadejacobson · Pull Request #6779 · canonical/cloud-init

cadejacobson · 2026-03-02T20:57:52Z

Proposed Commit Message

feat(azure): report failure if missing customdata

Add experimental Azure datasource config key
experimental_fail_on_missing_customdata with a default of
false and use it to control reporting when OVF custom data is
missing despite IMDS indicating that hasCustomData=true.

Additional Context

Test Steps

Merge type

Squash merge using "Proposed Commit Message"

When ovf-env.xml is present but does not contain custom data, yet IMDS indicates that custom data was provided to the VM (via hasCustomData), report a provisioning failure. This helps surface cases where custom data is silently lost during provisioning. The behavior is gated behind a new feature flag, EXPERIMENTAL_FAIL_ON_MISSING_CUSTOMDATA, which is disabled by default while undergoing scale testing. Once validated, it will be renamed and enabled for new distro releases. Changes: - Add EXPERIMENTAL_FAIL_ON_MISSING_CUSTOMDATA feature flag - Add _hascustomdata_from_imds() helper to query IMDS metadata - Report ReportableErrorImdsInvalidMetadata when custom data is expected but missing from OVF provisioning media

github-actions · 2026-03-17T00:35:31Z

Hello! Thank you for this proposed change to cloud-init. This pull request is now marked as stale as it has not seen any activity in 14 days. If no activity occurs within the next 7 days, this pull request will automatically close.

If you are waiting for code review and you are seeing this message, apologies! Please reply, tagging blackboxsw, and he will ensure that someone takes a look soon.

(If the pull request is closed and you would like to continue working on it, please do tag blackboxsw to reopen it.)

cjp256 · 2026-03-27T17:36:35Z

cloudinit/sources/DataSourceAzure.py

    "apply_network_config": True,  # Use IMDS published network configuration
    "apply_network_config_for_secondary_ips": True,  # Configure secondary ips
    "experimental_skip_ready_report": False,  # Skip final ready report
+    "experimental_fail_on_missing_customdata": False,


try to keep in alphabetical order

Updated to move it above the other experimental key.

cjp256 · 2026-03-27T17:41:04Z

cloudinit/sources/DataSourceAzure.py

        # only use userdata from imds if OVF did not provide custom data
        # userdata provided by IMDS is always base64 encoded
        if not userdata_raw:
+            # first, check to see if the OVF was supposed to provide custom


nit, I know it's inconsistent throughout, but use punctuation for multi-sentence/line comments, it just looks incomplete without that final period (and initial caps).

just my opinion anyhow

Updated to use proper sentence structure and punctuation.

cjp256 · 2026-03-27T17:42:30Z

cloudinit/sources/DataSourceAzure.py

+                and _hascustomdata_from_imds(imds_md)
+            ):
+                report_diagnostic_event(
+                    "IMDS did not return userdata as expected",


custom data != user data. custom data only comes from provisioning media in ovf-env.xml (or reprovisiondata endpoint for PPS re-use)

Sounds good, that's my mistake. I saw the userdata_raw and included that into the log. Updated to show custom data.

cjp256 · 2026-03-27T17:45:28Z

tests/unittests/sources/test_azure.py

        assert ret
        assert dsrc.userdata_raw == userdataOVF.encode("utf-8")

+    def test_missing_customdata_no_report_when_feature_flag_disabled(


combine these two tests into single test with pytest.parametrize() so the differences are obvious on what happens whether flag is enabled, or not

Combined these into one list.

cjp256 · 2026-03-27T17:51:34Z

tests/unittests/sources/test_azure.py

+class TestHasCustomDataFromImds:
+    """Unit tests for the _hascustomdata_from_imds helper."""
+
+    def test_returns_true_when_present(self):


all these tests can be combined into one parametrized list

Updated these to be a single list.

cjp256 · 2026-03-30T19:50:56Z

cloudinit/sources/azure/errors.py

+        ovf_env_xml_found: bool,
+    ) -> None:
+        super().__init__(
+            "failed finding customData but extended.compute.hasCustomData=true"


for consistency with other errors:

Suggested change

"failed finding customData but extended.compute.hasCustomData=true"

"failure to read customData while hasCustomData=true"

cadejacobson added 5 commits March 2, 2026 12:56

azure: test missing customdata path

b5a68cb

Move location of experimental flag

044f1eb

Remove unused feature flag

6c3d1f3

Linting

9418021

cadejacobson changed the title ~~Azure missing customdata~~ feat(azure): report failure if missing customdata Mar 2, 2026

github-actions bot added the stale-pr Pull request is stale; will be auto-closed soon label Mar 17, 2026

cadejacobson added 2 commits March 17, 2026 07:48

Merge main into branch azure-missing-customdata

a042b66

Linting

a598ca1

github-actions bot removed the stale-pr Pull request is stale; will be auto-closed soon label Mar 18, 2026

cjp256 reviewed Mar 27, 2026

View reviewed changes

cjp256 suggested changes Mar 27, 2026

View reviewed changes

cadejacobson added 6 commits March 30, 2026 11:29

Create ReportableErrorCustomData

3b3b08f

Structure comments like sentences

819e0e8

Parametrize the TestHasCustomDataFromImds

917c498

Update userdata reference to custom data

7bcc33a

Correct linting

2761645

Black formatter

3abbad3

cjp256 reviewed Mar 30, 2026

View reviewed changes

cadejacobson added 2 commits March 30, 2026 15:21

Improve reportableError string

2b58a18

Support PPS != None versions

414a9ae

cadejacobson marked this pull request as ready for review March 30, 2026 22:39

	"failed finding customData but extended.compute.hasCustomData=true"
	"failure to read customData while hasCustomData=true"

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cadejacobson commented Mar 2, 2026 •

edited

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