How would you troubleshoot a container that exits immediately with a crash loop after changing the entrypoint?

A container crashing immediately after an entrypoint change is often a signal that the command is invalid, the working directory is wrong, or the application expects a different runtime environment than the image provides. In a production setting I would not change the container blindly; I would inspect the container’s last logs and compare the current command with the expected startup sequence. The goal is to determine whether the failure is caused by a bad binary path, missing permissions, an invalid argument, or an environment variable that the app no longer accepts.

The first step is to reproduce the issue locally or in the environment where the image is built. I would inspect the Dockerfile or compose definition to see whether the entrypoint or command changed and whether the app should be invoked with a shell wrapper or directly. I would also look at the container’s filesystem permissions, because a common mistake is changing the entrypoint to a script that cannot be executed.

From an operations standpoint, the important detail is whether the crash loop is caused by a bad startup configuration or by a runtime dependency. If the application exits because a required service is unavailable, restarting the container will not solve the issue. The proper response is to inspect logs, verify environment variables, and confirm that dependencies such as database hosts, secrets, and config files are all present.

At scale, container startup failures are often caused by configuration drift between environments. The same image may work in a dev host but fail in production because the entrypoint expects a different working directory, a different file permission model, or a different secret mount. I would validate this by running the container with the same environment and mapping the same volumes or secrets that the service expects.

The subtle gotcha is that the entrypoint can appear correct while the real failure is in the startup script it launches. Senior engineers look beyond the obvious command line and inspect the actual process tree, environment, and logs because the startup bug is rarely in the shell syntax alone.