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About the Docker Compose Validator
Paste a docker-compose.yml to catch common mistakes before you run docker compose up: a service with neither image nor build, malformed port/volume mappings, depends_on referencing a service that doesn’t exist, and other structural issues. This is a static, client-side check — it doesn’t validate that referenced images actually exist or that the file will build successfully.
How to use the Docker Compose Validator
- Paste your docker-compose.yml.
- Click Validate.
- Results are grouped into ERROR, WARNING, and INFO.
- Fix and re-check as needed — nothing is sent to a server.
Step-by-step walkthrough with examples and the errors people hit: How to Validate a Docker Compose File.
Example
Common warning
services:
web:
image: myapp:latest
→
WARNING: service "web" uses the "latest" tag — pin a version for reproducible deploys
Common errors and how to fix them
Service has neither image nor build
Compose needs to know what to run. Add image: name:tag to pull, or build: ./path to build from a Dockerfile.
Port mapping looks wrong
Write ports as quoted strings, "8080:80". Unquoted, YAML may parse 8080:80 as a base-60 number.
More problems and fixes in the tutorial
FAQ
Does this replace docker compose config?
No — that command validates against your actual installed Compose version and resolves environment variables and includes. This tool only catches structural and best-practice issues visible in the YAML itself.
Does it check that images exist?
No — it doesn’t contact a registry. It only flags structural issues, like a missing image/build key or an obviously risky tag choice.
Is my compose file uploaded anywhere?
No, checks run entirely in your browser — compose files often contain internal service names and ports, so nothing leaves your device.