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Observations on DevOps tooling, observability, and the small gaps in the ecosystem worth filling — written for the engineers who hit them.
36 posts and counting.
Pushkar Kumar 10 min read
Why provisioned Grafana dashboards say Datasource ${DS_PROMETHEUS} was not found, how to find every placeholder with jq, and four fixes that survive CI.
Pushkar Kumar 8 min read
The chown command in Linux explained: user:group syntax, chown -R and symlinks, --reference, chgrp, chmod vs chown, and fixing Docker volume permission errors with numeric IDs.
Pushkar Kumar 10 min read
The chmod command in Linux explained: octal and symbolic modes, chmod +x, chmod -R and its traps, setuid, setgid and sticky bits, umask, and how to fix Permission denied.
Pushkar Kumar 10 min read
A Kubernetes Service has no endpoints, or a Deployment says selector does not match template labels? One bug, two symptoms, and how to trace both to a fix.
Pushkar Kumar 10 min read
Terraform forces replacement when an attribute can't change in place: what -/+ means, how to find the cause with show -json and jq, and how to stop it.
Pushkar Kumar 12 min read
Why curl, git, npm and pip print unable to get local issuer certificate, which trust store each one reads, and the fixes that add a CA instead of replacing it.
Pushkar Kumar 6 min read
GitHub Actions cron timezone UTC explained: why schedule: cron: always fires on UTC, how DST shifts the wall-clock time, and how to check the real next run.
Pushkar Kumar 6 min read
An IPv6 subnet calculator explained: why classic ipcalc is IPv4-only, how sipcalc adds IPv6 support, and the exact math behind splitting a /48 into /64s.
Pushkar Kumar 8 min read
The three RFC 1918 private IP ranges, why 172.16.0.0/12 catches people out, the addresses that look private but aren't, and how to pick a range that won't collide.
Pushkar Kumar 8 min read
How to read CIDR notation: what the number after the slash means, a prefix-to-netmask table from /8 to /32, and real examples from VPCs, firewalls and Kubernetes.
Pushkar Kumar 9 min read
Looking for a jwt.io alternative? What a browser-based JWT decoder can and can't prove about your data, how to check it yourself, and an offline option.
Pushkar Kumar 8 min read
Is Base64 encryption? No. What Base64 actually does, where encoded secrets leak, what really protects an API key, and when Base64 is the right tool.
Pushkar Kumar 7 min read
How to test GitHub Actions locally: run whole workflows with act in Docker, and check a single if: expression instantly with a browser-based expression tester.
Pushkar Kumar 7 min read
BuildKit tells you which line failed but not why. How to read the error, get the real output back, and fix the four structural causes behind most of them.
Pushkar Kumar 6 min read
Exit code 137 means the kernel killed your container for exceeding its memory limit. How to confirm it, and why raising the limit is usually the wrong fix.
Pushkar Kumar 9 min read
What the error actually means, the four causes ranked by how often they bite, and the one-line openssl check that shows whether an intermediate is missing.
Pushkar Kumar 7 min read
A free day-by-day path from Linux to Kubernetes with playable incident missions. The full plan, the design decisions, and the honest tradeoffs.
Pushkar Kumar 12 min read
Alerts going to the wrong receiver, or none at all? Debug Alertmanager routing — first-match-wins, missing continue, matcher regex and catch-all defaults.
Pushkar Kumar 10 min read
Alertmanager route config reference: the matchers, match and match_re forms, anchored regexes, the four grouping fields, and what a child route inherits.
Pushkar Kumar 10 min read
A target vanished or a label disappeared after relabeling. Debug Prometheus relabel_configs vs metric_relabel_configs, regex anchoring and keep/drop logic.
Pushkar Kumar 8 min read
GitHub Actions if condition always running true? It is the literal-text footgun: any text outside ${{ }} coerces to a truthy string. The cause and the fix.
Pushkar Kumar 10 min read
A field reference for all 11 Prometheus relabel actions — replace, keep, drop, labelmap, labeldrop, hashmod, keepequal, lowercase — each with an example.
Pushkar Kumar 9 min read
The .gitlab-ci.yml mistakes that turn pipelines red: undefined stages, jobs without scripts, broken needs and rules, anchor misuse — each with a fix.
Pushkar Kumar 9 min read
Stop pushing broken pipelines. Validate your .gitlab-ci.yml for YAML and structural errors in your browser — before the commit, not after the red pipeline.
Pushkar Kumar 10 min read
Which one to reach for, and what actually changes when you switch — default network, restart policy, detached mode — plus Compose back to a run line.
Pushkar Kumar 10 min read
Convert any docker run command to a docker-compose.yml service, flag by flag — ports, volumes, environment, restart and more. A practical, copy-paste guide.
Pushkar Kumar 5 min read
A PromQL query reads inside out, not left to right. The four layers — selectors, ranges, functions and aggregations — so you can decode any expression fast.
Pushkar Kumar 7 min read
Branch name mismatches, the AND-semantics of branches + paths, the ** glob requirement and paths-ignore on pull_request — with the fix for each.
Pushkar Kumar 6 min read
LogQL borrows PromQL’s shape but starts from log lines, not metrics. How the two query languages line up, where they translate cleanly, and where they don’t.
Pushkar Kumar 6 min read
Your .env.example is documentation that silently rots. Why env drift breaks onboarding and deploys, how to detect missing and unused keys, and how to fix it.
Pushkar Kumar 5 min read
Building regexes that parse log lines reliably — anchoring, capture groups, escaping, greediness, and the failure modes that bite you in production.
Pushkar Kumar 7 min read
Converting crontab entries into systemd .timer and .service units — OnCalendar syntax, logging, randomized delays, catch-up runs and the migration gotchas.
Pushkar Kumar 6 min read
A field-by-field guide to reading cron expressions — the five time fields, ranges, steps, lists and @macros — plus the gotchas that misfire schedules.
Pushkar Kumar 6 min read
YAML validators catch syntax, not exposure. Five high-impact GitHub Actions misconfigurations — pull_request_target, script injection and more — with fixes.
Pushkar Kumar 5 min read
One triaged suppression, re-encoded in .trivyignore, .grype.yaml, .snyk and osv-scanner.toml — what maps cleanly between them, and what is lossy.
Pushkar Kumar 5 min read
Prometheus has promtool test rules. Loki has nothing equivalent. Why testing LogQL alert rules matters, what a Loki rule unit test looks like, and how to do it.