Docker Healthchecks Confirm Process Response, Not Application Health

Docker's HEALTHCHECK instruction periodically runs a command inside a container and marks it healthy or unhealthy based solely on the exit code returned. The mechanism does not read response bodies, parse JSON, or verify whether dependencies like databases or queues are functioning correctly. Most common implementations simply confirm that a server process is accepting TCP connections, which can mask deeper failures such as exhausted connection pools or expired API tokens. When teams equate a green 'healthy' status with full application health, they tend to overlook logs, metrics, and other diagnostic signals. The real risk lies not in what the healthcheck measures, but in the broader assumptions developers and operators build around its limited output.