@Hinata Katsunori , In addition to the details shared by Sander in the answer, the following are additional resources that should help you.
- The metric "Function Execution Count" would show details of function execution time and instances. The detailed step to review this metric is available here - Analyzing Azure Functio App Metric.
You may also check the following page for additional metrics which are available by default for Function App - Azure Functions specific metrics.
- I would also suggest looking at Azure Functions hosting options, especially to review the hosting plan being used and relevant configuration. Based on the symptoms mentioned in the question, the content under following topics should be reviewed
- Function app timeout duration
- Service limits
- The "Availability and Performance" option under "Diagbose and solve problems" also contains a number of scenarios and data points that should help analyze scenarios like
- Web App Down
- Web App Restarted
- Function App down or reporting error etc.
This should be a good point to cover most of the basic scenarios.
- Lastly, the best practices available in the following doc should serve as a guideline related to perf and reliability - Improve the performance and reliability of Azure Functions
Hope this helps.
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