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Why do my Docker containers randomly stop responding after running fine for several hours on a cloud VM?
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 leRead more
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:
dmesg | grep -i kill
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:
docker run -m 1g --memory-swap 1g myapp
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.
See lesswhy does Terraform ignore changes I make in the console?
Terraform only notices changes when you run a plan or refresh. If ignore_changes is configured, Terraform will intentionally skip certain attributes. Otherwise, console changes will appear as drift the next time Terraform evaluates state. Manual changes and Terraform don’t mix well long-term. TakeawRead more
Terraform only notices changes when you run a plan or refresh.
If
ignore_changesis configured, Terraform will intentionally skip certain attributes. Otherwise, console changes will appear as drift the next time Terraform evaluates state.Manual changes and Terraform don’t mix well long-term.
Takeaway: Terraform works best as the single source of truth.
See lessWhy does my application lose permissions after a Kubernetes pod restart?
Pods are ephemeral, and anything stored locally disappears on restart. If credentials are written to the filesystem instead of injected dynamically, they won’t survive restarts. Secrets, identity bindings, or token projection are the correct approach. Takeaway: Never rely on local storage for credenRead more
Pods are ephemeral, and anything stored locally disappears on restart.
If credentials are written to the filesystem instead of injected dynamically, they won’t survive restarts. Secrets, identity bindings, or token projection are the correct approach.
Takeaway: Never rely on local storage for credentials in containers.
See lessWhy does my Docker container run as root even though I specified a user?
The base image or entrypoint likely overrides the user setting. If the specified user doesn’t exist or the entrypoint switches back to root, Docker silently falls back. Checking the final image configuration usually reveals this. Takeaway: User settings only work if nothing overrides them later.
The base image or entrypoint likely overrides the user setting.
If the specified user doesn’t exist or the entrypoint switches back to root, Docker silently falls back. Checking the final image configuration usually reveals this.
Takeaway: User settings only work if nothing overrides them later.
See lessWhy does my Docker container run as root even though I specified a user?
The base image or entrypoint likely overrides the user setting. If the specified user doesn’t exist or the entrypoint switches back to root, Docker silently falls back. Checking the final image configuration usually reveals this. Takeaway: User settings only work if nothing overrides them later.
The base image or entrypoint likely overrides the user setting.
If the specified user doesn’t exist or the entrypoint switches back to root, Docker silently falls back. Checking the final image configuration usually reveals this.
Takeaway: User settings only work if nothing overrides them later.
See lessWhy does my Kubernetes pod show ImagePullBackOff even though the image exists?
When Kubernetes reports ImagePullBackOff, it’s almost never saying the image doesn’t exist. What it’s actually telling you is that it can’t pull the image, usually because it doesn’t have permission to do so. This most commonly happens with private registries. Even if you created an image pull secreRead more
When Kubernetes reports
ImagePullBackOff, it’s almost never saying the image doesn’t exist. What it’s actually telling you is that it can’t pull the image, usually because it doesn’t have permission to do so.This most commonly happens with private registries. Even if you created an image pull secret, Kubernetes won’t automatically use it unless it’s attached to the service account the pod is running under, and it must exist in the same namespace. Another surprisingly common issue is a tiny typo or case mismatch in the image name or tag. Container registries are strict, and Kubernetes won’t try to guess what you meant.
People often waste time rebuilding or re-pushing images when the real issue is simply authentication.
Takeaway: Treat
See lessImagePullBackOffas a credentials or reference problem before assuming the image itself is broken.Why does Kubernetes Horizontal Pod Autoscaler not scale even when CPU usage is high?
Autoscaling relies on metrics and resource requests, not just raw CPU usage. If the metrics server isn’t working or your pods don’t define CPU requests, Kubernetes has nothing to scale against. CPU limits alone are not enough, which surprises many people the first time they configure autoscaling. WhRead more
Autoscaling relies on metrics and resource requests, not just raw CPU usage.
If the metrics server isn’t working or your pods don’t define CPU requests, Kubernetes has nothing to scale against. CPU limits alone are not enough, which surprises many people the first time they configure autoscaling.
When autoscaling doesn’t react, the issue is usually missing data rather than incorrect thresholds.
Takeaway: Autoscaling only works when metrics and requests are both present.
See lessWhy does Terraform fail with “provider configuration not present” during destroy?
Terraform still needs the provider configuration that was used to create the resource, even during destruction. If you removed or renamed a provider after resources were created, Terraform can no longer manage them. This often happens after refactoring modules or cleaning up unused providers too earRead more
Terraform still needs the provider configuration that was used to create the resource, even during destruction.
If you removed or renamed a provider after resources were created, Terraform can no longer manage them. This often happens after refactoring modules or cleaning up unused providers too early.
Reintroducing the provider temporarily allows Terraform to finish cleanup safely.
Takeaway: Never remove a provider until all resources using it are gone.
See lessWhy does my Kubernetes service work internally but not from outside the cluster?
Internal access proves the service works, but external access depends on how it’s exposed. If the service type or networking setup isn’t correct, traffic never reaches the cluster from outside. Security rules and load balancer provisioning are frequent blockers here. Takeaway: External access probleRead more
Internal access proves the service works, but external access depends on how it’s exposed.
If the service type or networking setup isn’t correct, traffic never reaches the cluster from outside. Security rules and load balancer provisioning are frequent blockers here.
Takeaway: External access problems are almost always networking issues.
See lessWhy does my Terraform backend initialization fail with a state lock error?
Terraform is being cautious here. The state lock error means Terraform believes another process is using the state file, even if that process no longer exists. This usually happens after an interrupted run—someone closes their laptop, a CI job gets canceled, or a network connection drops during applRead more
Terraform is being cautious here. The state lock error means Terraform believes another process is using the state file, even if that process no longer exists.
This usually happens after an interrupted run—someone closes their laptop, a CI job gets canceled, or a network connection drops during
apply. Terraform leaves the lock behind to protect the state, but it has no way to know the process died.If you’re sure no one else is running Terraform, manually unlocking the state is safe. The key thing is to avoid force-unlocking while another deployment is genuinely in progress, because that’s when state corruption happens.
Takeaway: State locks are normal, and stale locks are a routine operational issue, not a Terraform bug.
See less