How to use the command 'kubetail' (with examples)

Kubetail is a powerful and efficient utility to simultaneously tail logs from multiple Kubernetes pods. It consolidates the task of viewing logs from different pods and containers into one command, providing a cleaner and more streamlined workflow for Kubernetes developers and administrators. By aggregating logs, it helps in efficiently debugging, monitoring, and managing Kubernetes applications.

Use case 1: Tail the logs of multiple pods (whose name starts with “my_app”) in one go

Code:

kubetail my_app

Motivation:
In a Kubernetes environment, a specific application might be deployed across multiple pods due to load balancing or scalability requirements. To monitor the health and performance of the application, a developer often needs to view logs from all instances of that application simultaneously. This is where kubetail offers a seamless solution, as it consolidates logs from all pods that match a certain naming pattern, in this case, those that start with “my_app”.

Explanation:

• kubetail: This is the command that invokes the kubetail utility.
• my_app: This argument specifies the prefix of pod names whose logs you wish to aggregate. Any pod whose name begins with “my_app” will have its logs featured in the output.

Example output:

*** Tailing logs of pod 'my_app-abc123' ***
2023-01-01 12:00:01 Starting application...
2023-01-01 12:00:02 Application running...

*** Tailing logs of pod 'my_app-def456' ***
2023-01-01 12:00:03 Connected to database
2023-01-01 12:00:04 Fetching data...

Use case 2: Tail only a specific container from multiple pods

Code:

kubetail my_app -c my_container

Motivation:
In a microservices architecture, each pod may contain multiple containers serving different functionalities. If an issue arises within a specific container in multiple pods, a focused approach is necessary. Tailing logs for only the affected container across all pods provides concentrated data relevant to the issue, facilitating more efficient troubleshooting.

Explanation:

• kubetail: The command used to initiate kubetail.
• my_app: Indicates the set of pods, selected by the prefix, from which logs are needed.
• -c my_container: This flag specifies that only logs from the container named “my_container” should be tailed, filtering out logs from other containers within those pods.

Example output:

*** Tailing logs of container 'my_container' in pod 'my_app-abc123' ***
2023-01-01 12:05:01 Connected to service A
2023-01-01 12:05:02 Error: Connection timeout

*** Tailing logs of container 'my_container' in pod 'my_app-def456' ***
2023-01-01 12:05:03 Service B response delayed
2023-01-01 12:05:04 Retry request...

Use case 3: To tail multiple containers from multiple pods

Code:

kubetail my_app -c my_container_1 -c my_container_2

Motivation:
Certain scenarios require monitoring two or more containers within each pod simultaneously to identify potential issues arising from inter-container communications or dependencies. This use case is particularly relevant in environments where containers are interdependent, and visibility into their logs concurrently can preempt performance stagnations or errors.

Explanation:

• kubetail: Activates kubetail functionality.
• my_app: Identifies the pod group from which logs need to be tailed.
• -c my_container_1 -c my_container_2: These flags target the specific containers named “my_container_1” and “my_container_2”, permitting the monitoring of their logs together from all eligible pods.

Example output:

*** Tailing logs of container 'my_container_1' in pod 'my_app-abc123' ***
2023-01-01 12:10:01 Initializing module X
2023-01-01 12:10:02 Module X ready

*** Tailing logs of container 'my_container_2' in pod 'my_app-abc123' ***
2023-01-01 12:10:01 Listening on port 8080
2023-01-01 12:10:02 Connection established

*** Tailing logs of container 'my_container_1' in pod 'my_app-def456' ***
2023-01-01 12:10:03 Broadcasting status...

*** Tailing logs of container 'my_container_2' in pod 'my_app-def456' ***
2023-01-01 12:10:03 Alert: Increase in latency

Use case 4: To tail multiple applications at the same time separated by a comma

Code:

kubetail my_app_1,my_app_2

Motivation:
In complex Kubernetes environments, multiple applications often interact or rely on each other to offer a complete service. Simultaneously monitoring logs from different applications can aid in understanding system-wide behaviors, identify cross-application issues, and ensure that they are operating harmoniously.

Explanation:

• kubetail: Launches the kubetail tool.
• my_app_1,my_app_2: Using a comma-separated list, this specifies that logs should be tailed for all pods that match either of these prefixes, thus enabling the simultaneous analysis of multiple applications.

Example output:

*** Tailing logs of pod 'my_app_1-xyz987' ***
2023-01-01 12:15:01 User requested data
2023-01-01 12:15:02 Data provided successfully

*** Tailing logs of pod 'my_app_2-uvw987' ***
2023-01-01 12:15:03 Initiating backup procedure
2023-01-01 12:15:04 Backup completed

Conclusion

Kubetail significantly enhances the ability to manage and debug Kubernetes-deployed applications by streamlining access to logs across pods and containers. Its ability to tail logs by pod prefixes, single and multiple containers, or across different applications, makes it an invaluable tool for developers and operators needing rapid insights into K8s environments. By aggregating tailored logs into a single view, kubetail enables a more coherent, precise monitoring and debugging process.