Overview: One of our developers was asking about a log he was struggling to trace, and it took me awhile and a lot of help from the community to truly understand the issue. My scenario is shown below:
Scenario: I have a Dataverse change triggering a flow, the flow calls a Custom Connector, that in turn calls an Azure Function (that I control). So the flow fails, and I have used a pattern in the flow to catch the error and log it into Log Analytics. All good, then I don't see the event where the action calls the function, my function has logging enabled. I can see I am getting a 401 unauthorized error.
Initial Hypothesis: The Power Platform use APIM internally to implement Custom Connectors, and there is no access for clients/tenants to see the internal logging/traffic. Microsoft have provide the ability to use iLogger on the custom connector to log the traffic.
We have flows that intermittently get a 401, when the flow is manually rerun, the flow works and I can see the traffic coming into the Function.
The failure rate is extremely low and retries almost always fix the issue, and a third try always ensures the transaction goes thru.
Resolution: Add logging to the custom connector so we can speak with MS support about the issue. Add alerting to notify support, they can contact the user or chose to rerun the flow.
Alternative: If I enable the code, I can override the behaviour and inject C# code to work with the backend, or handle logic such as replacing text,...
1. In step "4. Code" tab of the custom connector, add the code below:
 |
| You can do any C# logic, I'm sending the original request thru and if it doesn't return me a 200, I'm logging it as critical. |
2. Update the connector, go to the next step "5. Test" > "Update Connector" (Tip: follow the steps)
3. Run the "Test operation", open the Response and validate the response body is correct, then open the "Code logs" tab. If it is blank, re-run the "Update Connector" (irritating but true).
 |
| 304 return from the API, which is cached and not a problem, but 400, 500 would be an issue, could also look out for 429s. |
public class Script : ScriptBase
{
public override async Task<HttpResponseMessage> ExecuteAsync()
{
this.Context.Request.Method = HttpMethod.Get;
HttpResponseMessage response = await this.Context.SendAsync(this.Context.Request, this.CancellationToken).ConfigureAwait(continueOnCapturedContext: false);
Context.Logger.LogTrace("Custom Connector ListBooks called ");
if (response.StatusCode == HttpStatusCode.OK)
{ Context.Logger.LogTrace("Success"); }
{ Context.Logger.LogCritical("Critical | " + response); }
return response;
}
}
More Info:
https://learn.microsoft.com/en-us/connectors/custom-connectors/write-code (NB)
https://never-stop-learning.de/logging-in-custom-connector-code/ (NB) The 2nd part of this post on the Alternative , is a rehash of this amazing post - I amended the logic and now I'm wondering is I could write to App Insights using the SDK?
Series
App Insights for Power Platform - Part 1 - Series Overview
App Insights for Power Platform - Part 2 - App Insights and Azure Log Analytics
App Insights for Power Platform - Part 3 - Canvas App Logging (Instrumentation key)
App Insights for Power Platform - Part 4 - Model App Logging
App Insights for Power Platform - Part 5 - Logging for APIM
App Insights for Power Platform - Part 6 - Power Automate Logging
App Insights for Power Platform - Part 7 - Monitoring Azure Dashboards
App Insights for Power Platform - Part 8 - Verify logging is going to the correct Log analytics
App Insights for Power Platform - Part 9 - Power Automate Licencing
App Insights for Power Platform - Part 10 - Custom Connector enable logging (this post)
App Insights for Power Platform - Part 11 - Custom Connector Behaviour from Canvas Apps Concern
