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When you start a Docker container, you often assign it a name with --name, but this doesn’t change the hostname inside the container. Understanding the difference between a container’s name and its hostname is crucial when your application uses hostname-based logic for logging, inter-service communication, or constructing URLs.

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Container Name vs Hostname

The container name and hostname serve different purposes. Some applications generate logs or metrics based on the hostname, so setting it appropriately simplifies debugging and monitoring.

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Default Hostname Behavior

By default, Docker sets the hostname to the short version of the container’s unique ID. For example:
Inside that container, checking the hostname shows the truncated ID:
Here, 3484d738 is the container ID—not the friendly webapp name you provided.

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Overriding the Hostname

To assign a meaningful hostname inside your container, use the --hostname (or -h) flag. This helps when services rely on consistent hostnames:
Now, the hostname command returns your custom name:
Your application can now reference a predictable, human-readable hostname.

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References

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