Logs — are records that capture actions, errors, or other significant events occurring in a program. Logs are recorded in chronological order and can be used for tracking, analyzing, and diagnosing events.
Logging is also used for recording user actions, a type of log recording known as audit.
Each logged event can have different levels of importance, which is why event criticality levels — logging levels — were introduced. Their names may vary slightly from program to program depending on the programming language used.
| Level | Description |
|---|---|
| DEBUG | Secondary information. This logging level is usually enabled during testing or debugging to obtain execution details. |
| INFO | Informational messages. |
| WARNING | Warnings about potential issues. |
| ERROR | Errors during program execution. |
Testers often need to modify the application configuration themselves or with the help of colleagues to enable a more detailed DEBUG logging level. This allows access to detailed descriptions of events occurring in the program, provided that the developers have logged them.
Logs can be written in various formats depending on the program and requirements. Below are the key fields.
2023-08-17 12:13:32.731 DEBUG [main] This is a debug-level log message
2023-08-17 12:13:32.731 INFO [main] This is an info-level log message
2023-08-17 12:13:32.731 WARNING [main] This is a warning-level log message
2023-08-17 12:13:32.731 ERROR [main] This is an error-level log message
When reading logs, you should first pay attention to events with a high criticality level. These usually indicate deviations in the program’s operation, where certain functions may not work correctly.
2023-08-17 12:13:32.731 ERROR [main] Application run failed
During testing, logs are useful for tracking program execution according to the scenario. Additionally, always check the date and time when a specific event was recorded to see if it matches the time of your testing.
It is also important to consider that issues may arise with the logging process itself.
An application can run on a virtual machine, in a container orchestrator (Kubernetes), or a cloud service. Depending on this, the tools for accessing logs may vary and expand.
In the console (PowerShell, Bash, Terminal). For this, you need to log into a remote server, where the application is running.
Connection is made via the ssh in format
ssh [user]@[ip]
In the graphical interface of application orchestration tools, in the
Pods -> application_instance -> Logs
or via a console query:
kubectl logs pod_nameoc logs pod_nameIn a log visualization tool. In Kibana, you can create queries to filter logs using Kibana Query Language (KQL).
DevOps must first configure log transportation.
Check that events are logged. Feed the cat with candies!
Scenario: the user clicks the “Feed” button the cat's state changes the event is logged the log is displayed in the console.
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