Port Conflict Checker

Port Conflict Checker — Detect host-port conflicts across docker-compose services: port is already allocated errors, duplicated host bindings, IP-aware checks. Line-by-line report. 100% client-side. This browser-side generator builds the exact commands or files you need without sending data to a server. All processing happens locally with native JavaScript, so your image names, secrets, and compose files stay private and the output is reproducible. It is designed to remove guesswork from Docker workflows where a missing flag or an outdated Compose key causes a failed build.

Docker workflows fail most often on small syntax details: a missing flag, an incorrect volume mount, a mis-typed registry host, or an outdated Compose key. Port Conflict Checker exposes every option through a validated form and emits spec-compliant output that works with Docker Engine 24+, Buildx, and Compose v2. For registries it uses the canonical login-server format (NAME.azurecr.io, ACCOUNT.dkr.ecr.REGION.amazonaws.com, gcr.io) and for Compose it omits the deprecated top-level version key. The output is copy-paste ready for a shell, a docker-compose.yml, a Dockerfile, or a CI YAML file.

Use it to bootstrap new projects, to standardize team workflows, or to convert legacy commands into maintainable files. The tool validates ports (HOST:CONTAINER), environment syntax (KEY=value), and file paths before generation, so you catch errors early rather than during a failed build or a leaked secret in docker inspect. Because generation is 100% client-side, the same output works locally and in GitHub Actions or GitLab CI without hidden state.

• Spec-compliant output — Port Conflict Checker emits syntax that validates with docker compose config, hadolint, or docker build --check where applicable, avoiding deprecated keys and ambiguous quoting.
• Validated inputs — ports, env, volumes, and registry names are checked (e.g., ports match HOST:CONTAINER, env matches NAME=value) and the UI shows an inline error instead of silently producing a broken file.
• One-click copy & download — the result appears in a dark, monospaced preview with Copy (with clipboard fallback via execCommand) and Download (.yml, Dockerfile, .sh) so the artifact is immediately reusable in any editor or pipeline.
• Client-side & private — no upload, no account, no external API for the generation itself. Optional live lookups (e.g., OSV for vulnerabilities) are done from the browser and degrade to a curated offline fallback when offline.
• Team-friendly scaffolding — generates repeatable, commented files that can be checked into git, shared in pull requests, and used as golden paths for onboarding or for migrating docker run to Compose or Kubernetes.
• Edge-case aware — handles spaces in volume paths, secrets via secrets: vs environment:, and multi-line env files, so the output does not leak secrets into docker inspect or image history.

1. Fill the form — enter the required fields for port conflict checker (image name, registry host, ports, or Dockerfile instructions). Add rows with “Add row” where repeatable inputs like ports, env, or volumes are supported.
2. Review validation — the tool highlights missing required values (e.g., image name) and malformed entries before generation. Correct any inline errors; the generator will not emit a file until inputs are valid.
3. Generate — click Generate/Build. The preview renders in a scrollable, syntax-aware block with line numbers and a dark background for readability. Stats show line count and file size.
4. Copy or download — use Copy to place the result on the clipboard (with execCommand fallback for insecure contexts) or Download to save with the correct extension.
5. Validate locally — run docker compose config, hadolint Dockerfile, or docker build --dry-run to confirm, then commit the file or paste the command into your shell/CI.

Example 1 — Minimal. Click Generate with the default sample for Port Conflict Checker, replace placeholder values with your real names and re-generate.

Example 2 — Edge case. A volume path with spaces is quoted and a secret is moved to secrets: to avoid docker inspect exposure.

Example 3 — Verification. After copying, run docker compose config or hadolint Dockerfile. For image tools compare with dive or docker history to confirm size or ordering.

• Saves time — no more hand-typing long flags; the form ensures correct quoting, the most common source of pull failures.
• Best-practice by default — multi-stage, slim/alpine, non-root, and secrets via secrets: are baked in, so files are smaller and pass linters.
• Reproducible — deterministic text that can be versioned and used in CI without hidden state.
• Private — 100% client-side; no data leaves the browser. Live data degrades gracefully offline.
• Educational — exposes every Docker option with help text and live preview for beginners and experts.