DevOps.

DevOps

Docker Compose Interpolation: Prove Which Value Wins

Docker Compose interpolation is the substitution that turns expressions such as ${IMAGE_TAG} and ${HOST_PORT:-8080} into a resolved application model. It happens before…

Aug 15, 202614 min read

DevOps

Recover a Deleted Git Branch Before Its Commit Is Pruned

At 12:02 UTC, incident/checkout-fix pointed to a two-commit change in a Git 2.47.3 fixture. Seconds later, the lab deleted the branch, leaving…

Aug 14, 202618 min read

DevOps

Redis PING Stays Green While Maxmemory Changes Writes

A Redis PING can return PONG while the next write is rejected or while an older key is silently removed. The difference…

Aug 13, 202614 min read

DevOps

Measure What Git Sparse Checkout Actually Saves

Git sparse checkout and partial clone reduce different things. Sparse checkout limits which tracked paths appear in the working tree. Partial clone…

Aug 13, 202613 min read

DevOps

Inspect an OCI Image’s Platform Before You Pull It

A container tag can look like one deployable object while actually naming an OCI image index: a small content-addressed document whose descriptors…

Aug 12, 202615 min read

DevOps

Kubernetes Ingress to Gateway API: A Parallel Cutover Plan

On March 24, 2026, the ingress-nginx project was retired. Existing controllers did not suddenly stop routing traffic, but retirement ended releases, bug…

Aug 5, 202610 min read

DevOps

WHMCS Cron Ran but Daily Automation Did Not Finish

Cron Job: Started proves that WHMCS began a run. It does not prove that invoice generation, payment capture, usage polling, suspensions, notices…

Aug 5, 20268 min read

DevOps

Kubernetes DiskPressure: Find the Filesystem Kubelet Sees

Kubernetes sets DiskPressure=True when available bytes or free inodes cross a kubelet eviction threshold on nodefs, imagefs, or containerfs. That condition does…

Aug 4, 202611 min read

DevOps

Why Does OpenTelemetry Collector OOM During a Backend Outage?

An OpenTelemetry Collector can run out of memory during a backend outage because exporter queues retain telemetry as live objects while new…

Aug 4, 20269 min read

DevOps

NATS JetStream Redelivery Is Not the Same as Consumer Lag

An illustrative JetStream incident snapshot can look contradictory: num_pending is 18,240, num_ack_pending is fixed at 64, and num_redelivered is 27. One dashboard…

Aug 4, 20269 min read

DevOps

Docker Healthchecks Report Failure; Restart Policies Wait for Exit

A Docker healthcheck reports whether its command succeeds. It does not stop the container, replace it, or activate a restart policy by…

Aug 4, 202610 min read

DevOps

HAProxy Backend DOWN: Separate Probe Failure from Service Failure

HAProxy marks a backend server DOWN when its configured health-check contract fails often enough. That result does not, by itself, prove the…

Aug 4, 202610 min read

DevOps

Kafka Consumer Lag Can Belong to One Hot Partition

Kafka consumer lag is not one queue waiting behind one worker. Lag belongs to a consumer group, topic and partition, so a…

Aug 3, 202611 min read

DevOps

When etcd Raises NOSPACE, Compact Before You Defragment

An etcd NOSPACE alarm means at least one member's backend crossed its configured quota, so the cluster entered limited-operation maintenance mode. Reads…

Aug 3, 20269 min read

DevOps

Docker Build Cache Is Filling Your VPS: Reclaim Space Safely

If repeated Docker builds are consuming VPS storage, do not begin with a system-wide prune. First prove that BuildKit owns the missing…

Aug 3, 20269 min read

DevOps

A RabbitMQ Disk Alarm Can Block Every Publisher

A RabbitMQ node can be running, answering health checks and delivering messages to consumers while every publishing connection is stalled. That split…

Aug 3, 202610 min read

DevOps

Before You Drain a Kubernetes Node, Prove the Workload Can Move

A Kubernetes node drain is safe only when the workload can complete four separate moves: the Eviction API may remove the Pod,…

Aug 3, 202611 min read

DevOps

Cloud-Init Says Done, but Your VPS Is Not Ready

A new VPS can carry three different clocks. The provider may label it running when the virtual machine starts, cloud-init may report…

Aug 2, 202610 min read

DevOps

Harbor on a VPS: Operate a Recoverable Private Registry

A private registry becomes part of the deployment path the moment CI pushes an image that production must later pull. Installing Harbor…

Aug 2, 202615 min read

DevOps

Caddy Reverse Proxy Reloads Without VPS Downtime

Quick answer: put Caddy on public ports 80 and 443, keep the application on a loopback address such as 127.0.0.1:3000, and leave…

Aug 2, 202610 min read

DevOps

GitHub Actions Self-Hosted Runner on a VPS: Safe CI/CD Setup

GitHub Actions Self-Hosted Runner on a VPS: Safe CI/CD Setup A GitHub Actions self-hosted runner can run on a VPS when builds…

Aug 2, 20268 min read