Spawner

spawner-cli

The command line and MCP server of Spawner. Spawner is an open source, self-hosted preview environment manager: a copy of your app for each git branch, on your own server, with its own URLs, database and logs, for teams and their coding agents.

With spawner, developers and coding agents create, update and delete environments from a worktree, uncommitted changes included, run commands in them and read their logs.

Install

npm install -g spawner-cli

It needs Node.js 20 or later, and a Spawner server: install one with a single command. Every server also serves the CLI of its own version at /api/v1/cli/spawner.

Log in

spawner login https://spawner.preview.example.com

Type the code it shows in the dashboard and approve the login: the CLI stores a personal token. In CI or a container, SPAWNER_URL and SPAWNER_TOKEN replace the login.

Commands

# write .spawner/, and offer to add the instructions for coding agents

spawner init

the environment of the current branch, from this worktree

spawner up --wait

run a command in a service

spawner exec feat-login db -- psql -U app -c "select * from users"

only the error lines, stack traces kept whole

spawner logs feat-login api --errors

a link for someone without an account

spawner share feat-login

spawner down feat-login

Before the first spawner up of a project, an admin adds the project in the dashboard (Projects, New project). The other commands: status, ls, stats, capacity, url, shell, stop, start, sleep, wake, extend, token, whoami and logout.

Commands print JSON with --json and exit with stable codes: 4 when the environment failed, 6 when the quota or the server's capacity is reached, 7 when .spawner/ was refused.

MCP server

spawner mcp is an MCP server on stdio, with the login and the rights of the CLI. In Claude Code:

claude mcp add spawner -- spawner mcp

In a project's .mcp.json, or Cursor's .cursor/mcp.json:

{

"mcpServers": { "spawner": { "command": "spawner", "args": ["mcp"] } } }

It has nine tools: spawner_up, spawner_status, spawner_list, spawner_logs, spawner_exec, spawner_stats, spawner_url, spawner_share and spawner_down. spawner_exec and spawner_down are marked destructive: whether a client asks before running them depends on the client and its permission settings.

Documentation

• The CLI and the MCP server: every command, JSON outputs, exit codes
• Coding agents: Claude Code, Codex, Cursor, and the instructions spawner init adds
• Quick start: from a fresh server to the first environment

Source: github.com/Flosk6/Spawner. License: Apache-2.0.