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This guide walks you through taking any GitHub repository that runs as a web app, starting it on a Celesto computer, and getting a public URL that anyone (including you, your team, or an agent) can open in a browser. Use this when you want a quick way to:
  • Preview a Vite, React, or Node app without deploying it to a hosting provider.
  • Share a work-in-progress build with someone for review.
  • Let an AI agent spin up a repo and verify it actually runs.
By the end, you will have a public HTTPS URL pointing at port 8000 on a Celesto computer running your app.

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Before you start

You need:
  • The Celesto CLI installed and authenticated.
  • The GitHub URL of a repo that runs as a web app (for example, a Vite or Node project).
  • The repo’s install and start commands. If you don’t know them, the project’s README.md usually tells you.
Confirm you are logged in: 
celesto auth status

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Step 1: Create a computer

Create a coding-agent computer. This template comes with Node, npm, and git already installed, which is what most web apps need. 
celesto computer create --template coding-agent --json
Save the name from the output. The rest of this guide uses einstein as an example name — replace it with your computer’s name.

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Step 2: Clone and install the app

Clone the repo into a fresh directory on the computer and install its dependencies. 
celesto computer run einstein "rm -rf /my-app && git clone https://github.com/<owner>/<repo> /my-app && cd /my-app && npm install" --timeout 300
Pick a directory name that matches your project. The rm -rf at the start makes the command safe to re-run if something fails partway through.

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Step 3: Start the app on port 8000

Bind the app to 0.0.0.0:8000 so Celesto can forward traffic to it. The exact command depends on the framework — these are the common ones: 
celesto computer run einstein "cd /my-app && setsid -f sh -c 'npm run dev -- --host 0.0.0.0 --port 8000 > /tmp/app.log 2>&1 < /dev/null'" --timeout 60
setsid -f detaches the server from the shell session so it keeps running after the command returns.
If your app needs environment variables (API keys, database URLs, and so on), set them in the same command, for example: setsid -f sh -c 'OPENAI_API_KEY=sk-... npm run dev -- --host 0.0.0.0 --port 8000 > /tmp/app.log 2>&1 < /dev/null'.

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Step 4: Verify the app is running

Before exposing the app publicly, confirm it is actually serving traffic inside the computer. 
celesto computer run einstein "curl -I --max-time 5 http://127.0.0.1:8000"
You should see an HTTP/1.1 200 OK response. If you don’t, check the log: 
celesto computer run einstein "tail -50 /tmp/app.log"

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Step 5: Publish port 8000

Expose port 8000 to the public internet. 
celesto computer port publish einstein --port 8000 --json
The response includes a url field — that’s your public HTTPS link. Open it in a browser to confirm the app loads. You can also list everything currently published for the computer: 
celesto computer port list einstein --json

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Step 6: Clean up when you’re done

Public URLs are meant for short-lived previews. Unpublish the port and delete the computer when you no longer need them. 
celesto computer port unpublish einstein --port 8000
celesto computer delete einstein

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Troubleshooting

The app probably isn’t listening on 0.0.0.0:8000. Re-run the verification curl from Step 4 and check /tmp/app.log for errors. Many frameworks default to localhost only — pass --host 0.0.0.0 or the equivalent flag.
Run celesto auth login and try again. If you’re running inside a sandboxed environment, your OS keychain may not be visible — re-run the CLI command from your normal shell.
Increase --timeout on the celesto computer run call. Large dependency trees can take several minutes on first install.
  • Publish ports — the underlying primitive for exposing services from a computer.
  • Computers — full reference for creating and managing computers.
  • CLI reference — every celesto command and flag.
Last modified on June 11, 2026