This happens because the host machine is running out of memory and the Linux OOM killer is silently terminating container processes.

In cloud VMs, Docker containers share the host’s memory unless limits are explicitly set. When memory pressure increases, Linux kills whichever process it considers least important, which is often a containerized app. Docker does not always report this clearly, so from the outside it looks like the service just froze.

You can confirm this by checking the VM’s system logs:

If you see messages about processes being killed due to memory, that’s the cause. The fix is to set proper memory limits and ensure the VM has enough RAM for peak load:

In Kubernetes, this is done through resource requests and limits. Without them, nodes can overcommit memory and start killing pods unpredictably.

A less obvious variation is memory leaks inside the container, which slowly push the host into OOM even if the initial footprint looks fine.