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Jan-Otto KröpkeandClaude Opus 5.5
1302cf6899
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com> Signed-off-by: Jan-Otto Kröpke <mail@jkroepke.de>
41 lines
2.6 KiB
Markdown
41 lines
2.6 KiB
Markdown
# mscluster agent notes
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- All subcollectors read through ClusAPI
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([`internal/headers/clusapi`](../../headers/clusapi)) instead of the
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`root\MSCluster` WMI provider (ClusWMI.dll). The WMI provider is a thin layer
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over ClusAPI: most WMI properties are common properties from
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`CLUSCTL_<OBJECT>_GET_RO_COMMON_PROPERTIES` and
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`CLUSCTL_<OBJECT>_GET_COMMON_PROPERTIES`; `Characteristics`, `Flags` and
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`State` come from their own control codes and `GetCluster<Object>State`.
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Some WMI values are synthesized or never filled (published as 0 from NULL);
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the parity tests show which ones, and the collector reproduces them.
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- Keep WMI types when publishing: `sint32` properties (for example
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`FailbackWindowStart`) are converted from the raw 32-bit value with
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`int32`, `uint32` properties keep the unsigned bit pattern. Unknown states
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(-1) are values, as in WMI, not errors.
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- Each subcollector owns its own `clusapi.Cluster`. A `Cluster` runs one call
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at a time without holding its lock: ClusAPI RPCs cannot be cancelled, so a
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second call fails with `clusapi.ErrBusy`, and `Close` leaves the handle to
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the running call. `callSource` stops waiting at the scrape budget, so one
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stuck RPC does not hold `Collect` and the other subcollectors.
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- `closeSources` drops a source even when its `Close` fails, so `Build` can
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recreate it. Grafana Alloy calls `Build`/`Close` repeatedly.
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- Every subcollector has a fixture test that checks gathered metric families
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and a parity test against its WMI class. The CI cluster (`setup-mscluster`
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in `.github/workflows/ci.yml`) is a single node without storage or
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administrative access point. It has online, offline and failed resources in
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two groups (`CIResources`, `CIFailedResources`) on a private network of an
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internal Hyper-V switch; the parity tests require them. It has no clustered
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disks, so shared volume parity still compares empty sets.
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- Property lists returned by the cluster service end with an extra
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`CLUSPROP_SYNTAX_ENDMARK` after the last value list; fixtures built only from
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the documentation miss this. The parser validates only the structure and
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accepts zero padding. `TestDumpPropertyLists` logs real lists as hex when
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`WINDOWS_EXPORTER_TEST_CLUSAPI_DUMP` is set on a cluster node.
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- `clusapi.Open` reports an unconfigured cluster or a missing ClusAPI with
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`errors.ErrUnsupported`; the shared collector test treats that as an
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unsupported role on hosts where `mscluster` is not a required fixture.
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- Use `ClusterOpenEnum` and the `Open*Ex` functions (Windows Server 2008 R2+),
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not `ClusterOpenEnumEx` (Windows Server 2016+), to keep Windows Server
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2012 R2 support.
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