feat(mongodb-runner): add --json output to start and ls

[autarch]

Description

This adds a --json output option. When this is enabled, the only output the runner prints to stdout is a JSON object containing information about the started cluster. The JSON always contains an id and connectionString key.

This is handy for scripting with the runner, and makes it easy to save the cluster information in a structured way, which is particularly helpful if you want to save multiple clusters.

Open Questions

None.

Checklist

• I have signed the Contributor License Agreement (https://www.mongodb.com/legal/contributor-agreement)
• New tests and/or benchmarks are included
• Documentation is changed or added

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[gribnoysup]

I'd maybe suggest to take a look at #626. There's already some interfaces for serialization of these instances that should probably be used instead of building these from scratch right in the method

[autarch]

I'd maybe suggest to take a look at #626. There's already some interfaces for serialization of these instances that should probably be used instead of building these from scratch right in the method

@gribnoysup What's the state of #626? It would be good to build on top of that, but it's been open since March. I could fold those changes into this PR, which might be simplest.

[gribnoysup]

@autarch

I could fold those changes into this PR, which might be simplest.

This works I think, this patch Anna opened is practically ready, was just waiting for feedback and got a bit lost over time, so would be good to use it as a starting point here

[Copilot]

🟢 Approval recommended

No unresolved blocking issues were identified.

Pull request overview

Adds --json output for mongodb-runner start and ls, enabling scripting with structured cluster metadata.

Changes:

• Implements JSON output handling.
• Adds tests for start and ls.
• Updates usage and disaggregated-storage documentation.

File summaries

File	Summary
packages/mongodb-runner/src/cli.ts	Implements JSON output modes.
packages/mongodb-runner/src/cli.spec.ts	Tests structured JSON output.
packages/mongodb-runner/README.md	Documents the new option and formats.
packages/mongodb-runner/docs/disaggregated-storage.md	Documents JSON output for DSC clusters.

Review details

• Files reviewed: 4/4 changed files
• Comments generated: 0
• Review effort level: Lite

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