arcane-rmcp

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

Surface	This repo
Repository	arcane-rmcp
Rust crate	rarcane
Binary / CLI	rarcane
npm package	arcane-rmcp
npm binary alias	rarcane
MCP server name	rarcane in bundled plugin/client config
MCP tool	arcane
Config home	~/.rarcane on hosts, /data in containers
Env prefixes	RARCANE_*, RARCANE_MCP_*, RARCANE_RMCP_* for npm launcher controls

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.

This repo owns	Arcane owns	Explicitly out of scope
MCP/CLI projection, request validation, auth policy, response shaping, setup checks, schema/resource exposure, and destructive gates.	Docker state, Arcane projects and environments, upstream authorization, registry credentials, GitOps secrets, vulnerability scanner output, and API semantics.	Direct Docker socket access, shell execution, credential storage, generic REST proxy behavior, multi-tenant sandboxing, scheduler behavior, and replacing the Arcane UI/API.

Install

Path	Command	Best for	Notes
npm / npx	npx -y arcane-rmcp --help	Local MCP clients and quick trials.	Downloads the matching rarcane binary from GitHub Releases.
Release installer	curl -fsSL https://raw.githubusercontent.com/jmagar/arcane-rmcp/main/scripts/install.sh | bash	Host installs without Node.	Installs rarcane for the current Linux host.
Docker / Compose	docker compose up -d	Shared HTTP MCP deployments.	Reads .env and exposes container port 40110.
Build from source	cargo build --release	Development and audits.	Produces target/release/rarcane.
Plugin	claude plugin install plugins/rarcane	Claude Code local plugin setup from this checkout.	Uses the packaged setup hook, skill, and monitor metadata.

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:

Variable	Purpose
RARCANE_RMCP_SKIP_DOWNLOAD=1	Skip postinstall binary download.
RARCANE_RMCP_VERSION or RARCANE_RMCP_BINARY_VERSION	Select the GitHub Release tag.
RARCANE_RMCP_REPO	Select the GitHub repo used for release downloads.
RARCANE_RMCP_RELEASE_BASE_URL	Select a custom release base URL.

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

Surface	Status	Entry point	Purpose
MCP stdio	Supported	rarcane mcp, npx -y arcane-rmcp mcp	Local child-process MCP clients.
MCP HTTP	Supported	rarcane serve, POST /mcp	Streamable HTTP MCP for local or shared server deployments.
CLI	Supported	rarcane <command>	Scriptable parity and debugging.
Prompt	Supported	quick_start	Guides a client through status and public help.
Resource	Supported	rarcane://schema/mcp-tool	JSON schema for the arcane tool.
REST API	Not shipped	N/A	Arcane already owns the REST API.
Web UI	Not shipped	N/A	Arcane already owns the web UI.

MCP Tool Reference

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

Action	Common subactions	Scope
help	action reference or domain-specific help	public
status	local bridge and Arcane config status	rarcane:read
elicit_name	MCP elicitation demonstration	rarcane:read
scaffold_intent	side-effect-free scaffold planning handoff	rarcane:read
environment	list, get, create, update, delete, test	read/write
project	list, get, create, up, down, restart, pull, destroy, redeploy, build	read/write
container	list, get, create, start, stop, restart, update, delete, stats	read/write
image	list, get, pull, delete, prune, scan	read/write
network	list, get, create, delete, prune	read/write
volume	list, get, create, delete, prune, browse, backup and restore actions	read/write
system	docker-info, prune, start-all, stop-all, convert	read/write
image-update	check-all, check, check-batch, summary	read
vulnerability	summary, list, scanner-status, ignore, unignore, list-ignored	read/write
registry	list, get, create, update, delete, test	read/write
gitops	list, get, create, update, delete, sync, status, browse	read/write

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.

Variable	Default	Purpose
RARCANE_API_URL	unset	Arcane API base URL.
RARCANE_API_KEY	unset	Arcane API key or bearer token.
RARCANE_MCP_HOST	127.0.0.1	HTTP bind host.
RARCANE_MCP_PORT	40110	HTTP bind port.
RARCANE_MCP_SERVER_NAME	arcane-rmcp	Advertised MCP server name.
RARCANE_MCP_TOKEN	unset	Static bearer token for HTTP MCP.
RARCANE_MCP_NO_AUTH	false	Disable auth only for loopback development.
RARCANE_NOAUTH	false	Trust an upstream gateway to enforce auth.
RARCANE_MCP_ALLOWED_HOSTS	unset	Extra accepted Host header values.
RARCANE_MCP_ALLOWED_ORIGINS	unset	Extra accepted CORS origins.
RARCANE_MCP_AUTH_MODE	bearer	bearer or oauth.

Authentication

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

HTTP MCP auth policy:

State	Condition	Behavior
Loopback dev	Bound to 127.0.0.1, localhost, or [::1]	Local unauthenticated development is allowed.
Mounted bearer	Non-loopback with RARCANE_MCP_TOKEN	Requires Authorization: Bearer <token> and action scopes.
Mounted OAuth	RARCANE_MCP_AUTH_MODE=oauth	Uses Google OAuth/JWT through lab-auth; static bearer remains supported.
Trusted gateway	RARCANE_NOAUTH=true	Assumes a reverse proxy or gateway already enforced auth.

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

OAuth mode is single-replica: client/session state and signing keys are local to one host. Do not run multiple OAuth replicas until those stores are externalized or safely shared.

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

Symptom	Check
RARCANE_API_URL is required	Set RARCANE_API_URL in env or ~/.rarcane/.env.
Arcane calls return unauthorized	Refresh RARCANE_API_KEY in Arcane and restart the bridge.
HTTP /mcp returns unauthorized	Set RARCANE_MCP_TOKEN and send Authorization: Bearer <token>.
Stdio client hangs or logs JSON errors	Ensure client config runs arcane-rmcp mcp, not the default HTTP server mode.
Destructive action is rejected	Add CLI --confirm or MCP params.confirm=true after verifying the target.
Port conflict	Set RARCANE_MCP_PORT or stop the process already using 40110.

Related Servers

• soma - RMCP runtime for provider-backed MCP servers.
• unifi-rmcp - UniFi controller REST API bridge.
• tailscale-rmcp - Tailscale API bridge for devices, users, and tailnet operations.
• unraid-rmcp - 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 - Media-stack bridge for Sonarr, Radarr, Prowlarr, Plex, and related services.
• ytdl-rmcp - Media download and metadata workflow server.
• synapse-rmcp - 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.
• labby - Homelab control plane and MCP gateway project.
• lumen - Local semantic code search MCP server.

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.