Library › Book 19 › Log Analysis in Depth
Log Analysis in Depth
5.1🔒Why Log Analysis is a Core QA SkillLogs are your primary debugging tool when tests fail in CI or on remote servers. You cannot set breakpoints in a CI runner. You cannot open…
5.2🔒Basic Log ReadingPro Tip: less is dramatically more useful than you might think. It can search forwards and backwards with / and ?, mark positions with m +…
5.3🔒Filtering Logs by TimeThe awk '/pattern1/,/pattern2/' syntax is called a range pattern. It prints all lines starting from the first pattern match through the…
5.4🔒Structured (JSON) LogsMany modern applications log in JSON format. Use jq to parse them:
5.5🔒Container Logs
5.6🔒Common Log Patterns to Search For
5.7🔒The Debug WorkflowWhen a test fails in CI, here is a systematic approach using command-line tools:
5.8🔒Exercises41. Find and read the last 50 lines of a log file on your system (check /var/log/ for candidates). 42. Use grep to count the number of…
5.9🔒Career Translation- Led root-cause analysis for production incidents using structured log analysis, correlating errors across microservices via trace IDs to…
5.10🔒Q&AInterview Depth CheckPrompt: At 2 AM, an alert fires: the checkout service is returning 500 errors at a 15% rate. You SSH into the server. Walk through your…