Docker Compose File Generator

What this generator does

Builds a two-service compose file as data, renders it to YAML, then reads that YAML back with an independent parser and compares the result field for field. It then checks what compose itself requires: every service has an image or a build, every published port is a valid host:container mapping, every dependency names a service in the same file, and every network a service joins is declared.

How to use this tool

1. Generate a compose file.
2. Read the two services and how they are wired together.
3. Check the verification note under the file.
4. Copy it, replace the placeholder password, and adjust the image tags for your project.

Understanding the controls

Generate

Draws a fresh combination of application image, data store, ports and project name. Everything else about the file's shape stays the same, because that shape is what makes it a compose file.

Worked examples

A generated api + postgres stack

services: api (image golang:1.23-alpine, port 6009:80, DATABASE_URL pointing at postgres by service name) and postgres (a named volume, no published port — reachable only inside the compose network) joined on a shared quarry-net network with a bridge driver.

Common use cases

• Starting a local development stack without writing YAML from memory
• Showing someone the shape of a compose file with a database in it
• Producing a fixture for testing a tool that reads compose files
• Checking your own file against a known-good structure
• Teaching how compose networking lets one service address another by name

How this generator works

The file is built as a data structure first, which is what makes the check possible: the YAML is written from it, and then read back into a second data structure by a parser that knows nothing about the writer. If the two differ — an indentation off by a level, a value containing a colon that should have been quoted — the page says so under the file and warns that it should not be used. Port mappings like 8080:80 are exactly the case that breaks naive YAML writers, since unquoted they can be read as a sexagesimal number.

Randomness and fairness

Images, ports, project names and the data store are drawn with the browser's cryptographic random source. Published ports are always in the 3000-9999 range, so a sample never suggests binding a privileged port.

For how randomness is produced across the whole site, see how Generate Random works.

Limitations and good to know

• It writes the modern schema with no top-level version key, which recent Docker Compose expects and very old versions do not.
• Two services only — a real stack often has more, and this is a starting shape rather than a finished deployment.
• Healthchecks, build contexts, secrets and profiles are not covered.
• The check confirms the file is well-formed compose, not that the images exist or that the services would actually start.

Privacy and your data

The file is built entirely in your browser from built-in sample values. You enter nothing, nothing is uploaded or stored, and analytics records only that the tool ran.

Frequently asked questions

Why can the app service reach the database using its service name as a hostname?

Compose gives every service in the same file a DNS entry on the shared network matching its service name, so postgres:5432 resolves to the data store container without any manual network configuration — this is the networking behaviour the generated file demonstrates by using that hostname directly in DATABASE_URL.

Is the generated password safe to use?

No — it's a fixed placeholder (change-me) that appears specifically so it's obvious you need to replace it. Never deploy a compose file with the placeholder credentials from a sample generator still in it.