arcane-rmcp

arcane-rmcp is a Rust MCP server and CLI for managing Docker through an Arcane API server.

It exposes one MCP tool, arcane, plus the rarcane CLI. Agents can inspect Arcane environments, manage compose projects, containers, images, networks, volumes, registries, GitOps syncs, image updates, vulnerability findings, and system operations through stdio MCP, Streamable HTTP MCP, or direct shell commands.

30-second path: set RARCANE_API_URL and RARCANE_API_KEY, then run npx -y arcane-rmcp status -> start loopback HTTP with RARCANE_MCP_HOST=127.0.0.1 npx -y arcane-rmcp serve -> call tools/call with {"action":"status"}.

Status: operational RMCP upstream-client server. Write-capable; destructive Docker and Arcane operations require explicit confirmation. HTTP MCP supports loopback dev mode, static bearer tokens, and Google OAuth through lab-auth.

Not for: replacing Arcane, bypassing Docker or Arcane authorization, running arbitrary shell commands, storing registry or Git credentials, multi-tenant isolation, or passing Arcane API keys through MCP tool arguments.

Contents

• Naming
• Capabilities And Boundaries
• Install
• Quickstart
• Client Configuration
• Runtime Surfaces
• MCP Tool Reference
• CLI Reference
• Configuration
• Authentication
• Safety And Trust Model
• Architecture
• Distribution Contract
• Development
• Verification
• Deployment
• Troubleshooting
• Related Servers
• Documentation
• License

Naming

The repo and npm package use the upstream service name, while the shipped binary keeps the historical Rust CLI name rarcane. The MCP server may be registered as rarcane, but the tool clients call is arcane.

Capabilities And Boundaries

• Read Arcane status plus Docker environment, project, container, image, network, volume, registry, GitOps, update, vulnerability, and system state.
• Create, update, start, stop, restart, delete, prune, deploy, sync, scan, and back up supported Arcane resources through action/subaction dispatch.
• Enforce action scopes and destructive-operation confirmation before forwarding write operations to Arcane.
• Expose the quick_start prompt and rarcane://schema/mcp-tool resource for client-side discovery.
• Provide setup, doctor, and watch commands for local plugin/runtime checks.

Install

npm / npx

Run the stdio MCP server or CLI without a manual binary install:

npx -y arcane-rmcp --help
npx -y arcane-rmcp mcp
npx -y arcane-rmcp status

The npm package downloads rarcane during postinstall. Override download behavior only when testing packaging:

Build From Source

git clone https://github.com/jmagar/arcane-rmcp
cd arcane-rmcp
cargo build --release
./target/release/rarcane --help

Minimum supported Rust version: 1.90.

Quickstart

1. Configure Arcane

Point the bridge at an existing Arcane API server:

export RARCANE_API_URL=https://arcane.example.com
export RARCANE_API_KEY=...

The API key is read from env or config only. Do not pass it in MCP tool arguments or CLI --params-json.

2. Run A Safe CLI Call

npx -y arcane-rmcp status

3. Start Loopback HTTP MCP

RARCANE_MCP_HOST=127.0.0.1 npx -y arcane-rmcp serve

In another shell:

curl -sf http://127.0.0.1:40110/health

4. Make A First MCP Call

curl -s -X POST http://127.0.0.1:40110/mcp \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"arcane","arguments":{"action":"status"}}}'

Client Configuration

Claude Code Stdio

{
  "mcpServers": {
    "rarcane": {
      "command": "npx",
      "args": ["-y", "arcane-rmcp", "mcp"],
      "env": {
        "RARCANE_API_URL": "https://arcane.example.com",
        "RARCANE_API_KEY": "..."
      }
    }
  }
}

Claude Code HTTP

{
  "mcpServers": {
    "rarcane": {
      "type": "http",
      "url": "http://127.0.0.1:40110/mcp",
      "headers": {
        "Authorization": "Bearer ${RARCANE_MCP_TOKEN}"
      }
    }
  }
}

Codex / Labby Gateway

Register Arcane through Labby as an HTTP upstream when sharing one long-running server, or run it directly as stdio for local-only use.

[mcp_servers.rarcane]
command = "npx"
args = ["-y", "arcane-rmcp", "mcp"]

Generic MCP JSON

{
  "command": "rarcane",
  "args": ["mcp"],
  "env": {
    "RARCANE_API_URL": "https://arcane.example.com"
  }
}

Do not put RARCANE_API_KEY, registry credentials, Git credentials, OAuth secrets, SSH keys, passwords, or upstream bearer tokens in MCP tool arguments. Use env, config files, or the MCP client's secret storage. MCP callers never provide credentials, tokens, keys, or secrets as action arguments.

Runtime Surfaces

MCP Tool Reference

One MCP tool is exposed: arcane. Pass the required action argument and, for most domains, a required subaction.

Action specs in src/actions.rs and the generated schema notes in docs/MCP_SCHEMA.md are the source of truth for required parameters.

Example read-only tool arguments:

{
  "action": "container",
  "subaction": "list",
  "envId": "default"
}

Example destructive operation:

{
  "action": "container",
  "subaction": "stop",
  "envId": "default",
  "id": "my-container",
  "params": {
    "confirm": true
  }
}

CLI Reference

rarcane exposes the same service layer as the MCP tool:

rarcane status
rarcane help --domain container
rarcane call --action container --subaction list --env-id default
rarcane call --action system --subaction docker-info --env-id default
rarcane call --action container --subaction stop --env-id default --id my-container --confirm
rarcane doctor --json
rarcane watch --url http://127.0.0.1:40110
rarcane setup check
rarcane setup repair

--params-json accepts action-specific JSON payloads. Do not use it to pass credentials.

Configuration

Host installs read ~/.rarcane/.env, ~/.rarcane/config.toml, and process env. Containers read /data/.env, /data/config.toml, and process env.

Authentication

Stdio MCP runs as a local trusted child process and does not use HTTP auth.

HTTP MCP auth policy:

OAuth mode uses the RARCANE_MCP_* Google OAuth variables documented in docs/CONFIG.md.

Safety And Trust Model

• Arcane API credentials are loaded from config/env only.
• MCP callers select actions and payloads, not upstream credentials.
• Destructive subactions reject unless params.confirm=true or CLI --confirm is present.
• Unknown actions, unknown subactions, missing environment IDs, missing IDs, and unsafe volume paths are rejected before upstream calls.
• Non-loopback HTTP deployments must use bearer auth, OAuth, or a trusted authenticated gateway.
• This bridge does not sandbox Arcane itself. Arcane remains responsible for Docker authorization and the effects of Docker operations.

Architecture

ArcaneClient  (src/arcane.rs)      HTTP transport and redacted errors
      |
ArcaneService (src/app.rs)         action validation, confirmation, response normalization
      |
MCP shim      (src/mcp/tools.rs)   JSON args -> service -> Value
CLI shim      (src/cli.rs)         argv -> service -> stdout

Distribution Contract

• Cargo.toml, Cargo.lock, packages/arcane-rmcp/package.json, .release-please-manifest.json, and server.json must agree on the released version.
• GitHub Releases publish the rarcane binary consumed by the npm launcher.
• The npm package name is arcane-rmcp; the installed binary alias is rarcane.
• Docker/OCI metadata uses ghcr.io/jmagar/arcane-rmcp:<version>.
• plugins/rarcane/.mcp.json must launch npx -y arcane-rmcp mcp so stdio clients start the MCP transport rather than the HTTP server.
• The root README is curated. Generated or source-of-truth details live in src/actions.rs, docs/MCP_SCHEMA.md, and the package/registry manifests.

Development

cargo fmt --check
cargo test
cargo clippy -- -D warnings
cargo build --release
npm --prefix packages/arcane-rmcp run check

Verification

python3 /home/jmagar/workspace/soma/scripts/check-readme-guide.py README.md
npm --prefix packages/arcane-rmcp run check
cargo check
cargo test
git diff --check

Runtime smoke:

RARCANE_API_URL=https://arcane.example.com \
RARCANE_API_KEY=... \
rarcane status

HTTP smoke:

RARCANE_MCP_HOST=127.0.0.1 rarcane serve
curl -sf http://127.0.0.1:40110/health

Deployment

Use loopback for local development:

RARCANE_MCP_HOST=127.0.0.1 rarcane serve

Use Docker Compose for shared HTTP deployment:

cp .env.example .env
docker compose up -d

When binding to a non-loopback address, configure RARCANE_MCP_TOKEN, RARCANE_MCP_AUTH_MODE=oauth, or RARCANE_NOAUTH=true behind an authenticated gateway.

Troubleshooting

Related Servers

• unifi-rmcp / rustifi - UniFi controller REST API bridge.
• tailscale-rmcp / rustscale - Tailscale API bridge for devices, users, and tailnet operations.
• unraid-rmcp / unrust - Unraid GraphQL bridge for NAS and server management.
• apprise-rmcp - Apprise notification fan-out bridge for many delivery backends.
• gotify-rmcp - Gotify push notification bridge for sends, messages, apps, and clients.
• yarr-rmcp - Media-stack bridge for Sonarr, Radarr, Prowlarr, Plex, and related services.
• ytdl-mcp - Media download and metadata workflow server.
• synapse - Local Synapse workflow server for scout and flux actions.
• cortex - Syslog and homelab log aggregation MCP server.
• axon - RAG, crawl, scrape, extract, and semantic search project.
• lab - Homelab control plane and Labby gateway project.
• lumen - Local semantic code search MCP server.
• nugs - Project/package management helper for local agent workflows.
• agentcast - Agent transcript and activity publishing project.
• soma - RMCP scaffold/runtime template for new provider-backed servers.

Documentation

• docs/API.md is the curated action-contract overview.
• docs/CONFIG.md is the curated configuration and auth reference.
• docs/QUICKSTART.md is the curated smoke-test guide.
• docs/MCP_SCHEMA.md is the generated/schema-drift contract for actions, resources, prompts, and validation rules.
• plugins/rarcane/skills/rarcane/SKILL.md is the agent usage guide.

License

MIT. See LICENSE.