Docker Compose Validator — Multi-Container YAML Syntax & Logic Check
Validate docker-compose.yml syntax, service definitions, networks, volumes, and environment variables. Catches YAML errors, broken depends_on references, missing image/build, invalid restart policies, and more — with context-aware hints.
How to Use Docker Compose Validator — Multi-Container YAML Syntax & Logic Check
How to Use the Docker Compose Validator
Step 1: Paste Your docker-compose.yml
Copy the full contents of your docker-compose.yml file and paste it into the input area. The validator runs instantly as you type.
Step 2: Check YAML Validity First
If the YAML is malformed (bad indentation, wrong quoting, duplicate keys), a parse error banner appears with the exact line and column from the YAML parser. Fix this before addressing schema issues.
Step 3: Review the Issue Summary
Once the YAML is valid, the summary shows how many services were parsed and the issue count broken down by severity — errors (must fix), warnings (best practice), and info (recommendations).
Step 4: Expand Issues for Hints
Click any issue row that shows a ▼ indicator to expand a detailed hint with suggested fixes. Issues include the context (e.g., "service: web", "volume: db-data") so you can locate the problem quickly.
Step 5: Try the Example Files
Use the three example buttons to see the validator in action on an invalid YAML file, a file with schema errors (missing image, broken depends_on, undeclared volumes), and a clean production Compose file.
Checks Performed
| Severity | Check |
|---|---|
| Error | YAML parse failure (line + column reported) |
| Error | Missing "services" top-level key |
| Error | Service missing both "image" and "build" |
| Error | "depends_on" references a non-existent service |
| Error | Service depends on itself |
| Error | Invalid "image", "build", or "container_name" type |
| Error | Invalid restart policy value |
| Error | "network_mode" and "networks" both set |
| Warning | Base image using :latest tag |
| Warning | Unpinned or unrecognised port format |
| Warning | Service network not declared in top-level "networks" |
| Warning | Named volume used but not declared in top-level "volumes" |
| Warning | Unknown top-level or service-level keys |
| Warning | Empty "depends_on" |
| Warning | Environment list item with bad format |
| Warning | Healthcheck missing "test" key |
| Info | "version" field (obsolete in Compose Specification) |
Frequently Asked Questions
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