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Docker Compose Validator

Validate docker-compose.yml files for correct syntax, structure, and required fields like services, images, and ports.

Docker Compose YAML

Validation Results

What Is a Docker Compose Validator?

A Docker Compose validator checks your docker-compose.yml files for correct syntax, structure, and required fields. Docker Compose defines multi-container applications with services, networks, and volumes. Common mistakes like missing image references, invalid port mappings, or misconfigured environment variables can cause deployment failures. Our Compose file linter helps you catch these issues before running docker compose up.

What We Check in Your Compose File

Services

The top-level services field must exist and contain at least one service definition.

Image / Build

Each service must specify image or build to define how the container is created.

Port Mappings

Port mappings should use the "host:container" format (e.g., "8080:80").

Environment

Environment variables can be a mapping or an array of KEY=VALUE strings.

How to Use This Docker Compose Validator

Paste your docker-compose.yml content into the textarea and click Validate. The tool checks for the version field, verifies that services is defined, validates each service has an image or build, and inspects port mappings, environment variables, and volume/network references. Results show green checkmarks for valid fields and red crosses for issues. Use Load Example for a sample with web and database services. All processing is done client-side.

Tips for Valid Docker Compose Files

Use the correct version — Version 3.8+ is recommended for modern Docker Compose features.
Always quote port mappings — Use "8080:80" (quoted) to prevent YAML parsing issues with colons.
Define networks explicitly — If services communicate, define a custom network at the top level and reference it in each service.
Use .env files for secrets — Reference environment variables via env_file rather than embedding secrets in the Compose file.
Pin image versions — Always specify image tags (e.g., postgres:16-alpine) instead of using latest.

How to Do This in Code

docker compose config --quiet
docker compose config --services
docker compose config --volumes

const yaml = require('js-yaml');
const fs = require('fs');
const doc = yaml.load(fs.readFileSync('docker-compose.yml', 'utf8'));
console.log('Services:', Object.keys(doc.services));

import yaml
with open('docker-compose.yml') as f:
    data = yaml.safe_load(f)
for svc, config in data.get('services', {}).items():
    print(f'{svc}: {config.get("image", "build")}')

import ("os"; "gopkg.in/yaml.v3")

data, _ := os.ReadFile("docker-compose.yml")
var config map[string]any
yaml.Unmarshal(data, &config)

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Docker Compose Validator FAQ

What does this Docker Compose validator check?

It validates YAML syntax and checks your docker-compose.yml for required top-level fields (services), valid service definitions with image or build references, correct port mapping format, environment variable syntax, and volume configurations.

Does this replace docker compose config?

This is a quick client-side check for syntax and structure. For full validation against the Docker Compose specification, use 'docker compose config' from the CLI.

What Docker Compose versions are supported?

The validator checks version 2 and 3 format files, which are the most commonly used versions in production.