What is Semgrep and where does it fit in a DevSecOps pipeline?

Describe Semgrep by the failure it prevents, not by its feature list. It belongs to SAST (static application security testing) and runs at the code stage of delivery, which matters because the cost of fixing a defect rises sharply the later it is found — the core argument behind shifting security left.

Strong answers cover writing and tuning custom rules, pattern syntax vs regex, per-language rulesets, autofix, baseline scanning on diffs only, false-positive suppression with nosemgrep, and running as a fast pre-commit and CI gate. Interviewers also listen for the operational side: who owns the rules, how findings reach the developer who introduced them, how false positives get suppressed without silently disabling coverage, and what the break-glass path is when a fix genuinely cannot ship in time.

Tie it to the wider toolchain. Security scanning is only useful when its output is actionable, deduplicated across tools, and attached to a specific commit, image digest or resource — otherwise teams learn to ignore it.