vROPs Python Client and Unexpected “Resource not found”

Using the vRealize Operations Manager 6.6 Python nagini client (version 1.0), I encountered an interesting unexpected result when using the client to push custom metrics to vROPs.  For context, see this blog post on creating a custom metric adapter for vROPs.

This error occurred when pushing resource metrics to vROPS:

In particular, last line indicates the vROPS API returned an error “resource… already exists”, which means the nagini client is attempting to create the resource:

The method find_create_resource_push_data() is supposed to find existing resources and not attempt to recreate them. So what is going wrong?

To figure this out, I followed my normal debugging procedure of breaking this down into smaller parts. Reading through the nagini client Python code, the nagini client makes a call to get_resources_with_adapter_and_resource_kind() and parses the results to determine if the resource already exists.

So, I ran just that method with my specific parameters, and to my unfortunate surprise received two results back – two resources were found. However the method find_create_resource_with_adapter_key() expects only a single result, otherwise it goes into its “create resource” mode. A more helpful error message here would be great and easy to add, something like “if len(results) > 1 throw an error that you have too many resource hits.” Oh well.

From the API documentation page for the underlying method, getResourcesWithAdapterandResourceKind, I identified the root cause:

Query for Resources within a particular Adapter Kind and Resource Kind.
Optionally filter these resources based on resource name. The resource name (specified as a query parameter) will be used for doing a partial match.

In my case, the specific resource name is also a subset of another resource name.  Hence the bug.

Without any way to control partial vs. exact match in the API currently, my two options are to re-implement this portion of the nagini client logic and do the exact name match filtering in Python, or to use the richer resource identifier method which allows specifying multiple keys for a resource to help identify it with more than simple name matching.

Hope this helps.


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