mcp-rancher

<!-- mcp-name: io.github.rex/rancher-mcp -->

<p align="center">
  <img src="https://raw.githubusercontent.com/rex/mcp-rancher/main/docs/assets/header.png" alt="MCP Rancher — the capability-aware control plane for AI-assisted Rancher operations" />
</p>

<p align="center">
  <a href="https://github.com/rex/mcp-rancher/actions/workflows/validate.yml"><img src="https://img.shields.io/github/actions/workflow/status/rex/mcp-rancher/validate.yml?branch=main&label=CI" alt="CI" /></a>
  <a href="https://modelcontextprotocol.io"><img src="https://img.shields.io/badge/MCP-server-2b6cd0" alt="MCP server" /></a>
  <a href="docs/tool-manifest.json"><img src="https://img.shields.io/badge/tools-321-2b6cd0" alt="321 tools" /></a>
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</p>

<p align="center">
  Operate Rancher-managed Kubernetes through any MCP client —
  discovery, generic resource access, and curated operator workflows,
  wrapped in an audit-logged, rate-limited, confirmation-guarded safety model.
</p>

<p align="center">
  <a href="#quick-start">Quick start</a> ·
  <a href="#the-tool-surface">Tool surface</a> ·
  <a href="#architecture">Architecture</a> ·
  <a href="#safety-model">Safety model</a> ·
  <a href="#compatibility">Compatibility</a> ·
  <a href="#development">Development</a>
</p>

---

## Why this exists

Rancher is how real fleets run Kubernetes — and it speaks **two APIs** (the legacy
Norman `/v3` plane and the modern Steve `/v1` plane), varies by version, and wraps
every cluster behind its own proxy. Pointing a generic Kubernetes MCP server at it
misses everything Rancher-specific; pointing an agent at raw `kubectl` gives up
auditability, guardrails, and the management-plane view entirely.

**MCP Rancher** is built for that reality:

- **Capability-aware, not version-naive.** It detects what each connected Rancher
  actually supports instead of assuming. One binary spans **2.6.5 → 2.9.3** with
  the same tool surface.
- **Multi-instance first.** Lab, staging, prod — configure them all; mark prod
  `read_only: true` and every mutation is refused at the config layer, before any
  guard even has to fire.
- **Nothing is out of reach.** Curated tools cover the common 95%; the generic
  engine reaches *every* resource either API plane exposes — even types nobody
  wrote a tool for yet.

## The tool surface

**321 tools: 178 read-only · 143 writes · 38 destructive** — counted from the
registry itself, not by hand. [`docs/tool-manifest.json`](docs/tool-manifest.json)
is **generated from the live FastMCP registry** (`make tool-manifest`) and a CI
gate fails the build if it ever drifts from the code. Per-tool descriptions,
safety annotations, and parameters all live there; the narrative registry with
slice tracking is [`docs/tool-catalog.md`](docs/tool-catalog.md).

| Layer | What it does | Examples |
|---|---|---|
| **Discovery & schema** | Explore what any instance can do | `rancher_server_version`, `rancher_norman_schema_list`, `rancher_capability_domain_list` |
| **Generic engine** | CRUD + actions + links + watch on *any* resource, both planes | `rancher_steve_resource_list`, `rancher_norman_resource_action_invoke`, `rancher_steve_resource_watch` |
| **Curated reads** | Typed, shaped responses across ~25 domains | `rancher_pods_list`, `rancher_deployments_list`, `rancher_longhorn_volumes_list`, `rancher_policy_reports_list` |
| **Curated writes** | Guarded mutations | `rancher_deployment_scale`, `rancher_deployment_restart`, `rancher_cron_job_suspend`, `rancher_node_cordon`, `rancher_secret_create` |
| **Operator rollups** | One-call triage | `rancher_cluster_health_check`, `rancher_find_failing_pods`, `rancher_find_stalled_rollouts`, `rancher_project_health_summary` |

Domains covered: clusters & nodes · projects & namespaces · workloads · pods &
services · storage · networking · config & secrets *(values masked)* ·
certificates *(keys masked)* · RBAC · auth & identity · apps & catalogs ·
logging pipeline · Prometheus monitoring · policy reports · CIS compliance ·
backup operator · etcd backups · Longhorn · Fleet · provisioning · settings &
features · alerts & notifiers.

## Quick start

### Requirements

- Python 3.12+ and [uv](https://docs.astral.sh/uv/)
- A Rancher API token ([creating one](https://ranchermanager.docs.rancher.com/reference-guides/user-settings/api-keys))

### Install & run

```bash
# From source
git clone https://github.com/rex/mcp-rancher.git
cd mcp-rancher
make setup                 # deps, .env scaffold, pre-commit hooks
cp .env.example .env       # set RANCHER_URL + RANCHER_TOKEN
make dev                   # run the MCP server (stdio)
```

Once published to PyPI, it's one line: `uvx rancher-mcp`.

### Claude Code

```bash
claude mcp add rancher \
  -e RANCHER_URL=https://rancher.example.com \
  -e RANCHER_TOKEN=token-xxxxx:yyyyyyyyy \
  -- uv run --directory /path/to/mcp-rancher rancher-mcp
```

### Claude Desktop

```json
{
  "mcpServers": {
    "rancher": {
      "command": "uv",
      "args": ["run", "--directory", "/path/to/mcp-rancher", "rancher-mcp"],
      "env": {
        "RANCHER_URL": "https://rancher.example.com",
        "RANCHER_TOKEN": "token-xxxxx:yyyyyyyyy"
      }
    }
  }
}
```

### Multiple instances

```env
RANCHER_INSTANCES_JSON='{
  "production": {"url": "https://rancher.prod.example.com",    "token": "token-a:xxx", "verify_ssl": true, "read_only": true},
  "lab":        {"url": "https://rancher.lab.example.com",     "token": "token-b:yyy", "verify_ssl": false, "read_only": false}
}'
RANCHER_DEFAULT_INSTANCE=production
```

Every tool takes an optional `instance` argument. Instances flagged
`read_only: true` refuse **all** mutations at the settings layer.

## Architecture

```mermaid
flowchart LR
    A[MCP client<br/>Claude Code · Claude Desktop · any] -- stdio --> S

    subgraph S[rancher-mcp]
        direction TB
        L1[Discovery & schema<br/>planes · schemas · capabilities]
        L2[Generic engine<br/>any resource · both planes<br/>CRUD · actions · links · watch]
        L3[Curated tools<br/>typed models · shaped output<br/>next-step hints]
        G[Safety layer<br/>read-only guard · confirmation phrases<br/>audit log · rate limit · masking]
        L1 --> L2 --> L3
        L3 --> G
        L2 --> G
    end

    G -- Norman /v3 --> R1[(Rancher<br/>instance A)]
    G -- Steve /v1 + k8s proxy --> R1
    G -- Norman + Steve --> R2[(Rancher<br/>instance B)]
```

Three layers, deliberately separate: **discovery** tells you what an instance can
do, the **generic engine** can touch anything it exposes, and **curated tools**
make the common paths typed, shaped, and self-describing (every response carries
`suggested_next_steps`). Most curated tools are **generated from YAML descriptors**
(`catalog/curated_tools/`) with a drift gate — the editorial decisions live in
descriptors, not boilerplate.

## Safety model

Built for the day an agent is pointed at the cluster that pays your salary:

| Guard | Behavior |
|---|---|
| **Read-only instances** | `read_only: true` refuses every mutation for that instance, before tool logic runs |
| **Destructive confirmation** | Deletes require an explicit typed phrase (e.g. `"delete steve namespace foo"`) — no phrase, no delete |
| **Tool annotations** | Every tool declares `readOnlyHint` / `destructiveHint` / `idempotentHint`, so clients can gate UX on them |
| **Audit log** | Every mutation emits a structured `event="audit"` record — tool, operation, plane, instance, resource, outcome. Argument *names* only; values never logged |
| **Rate limiting** | Token-bucket on writes (default 60/min) — a runaway loop can't machine-gun your API |
| **Secret & key masking** | Secret values and certificate private keys are structurally absent from curated responses (reveal is an explicit generic-tool opt-in) |
| **Structured errors** | Guard rejections return typed `error_code` envelopes agents can branch on — never raw strings |

## Compatibility

| | |
|---|---|
| **Primary target** | Rancher **2.9.3** (production-validated) |
| **Compatibility floor** | Rancher **2.6.5** (kept green via capability detection) |
| **API planes** | Norman `/v3` + Steve `/v1` (+ per-cluster Kubernetes proxy) |
| **Transport** | stdio |

Capability detection bridges version differences at runtime — no
version-pinned builds, no "works on my Rancher." Both targets are exercised by
the same test suite, and read paths have been validated live against both a
2.6.5 lab and a 2.9.3 production fleet
([validation report](docs/live-validation-2026-05-06.md)).

## Configuration

| Variable | Default | Purpose |
|---|---|---|
| `RANCHER_URL` | — | Rancher server URL (single-instance mode) |
| `RANCHER_TOKEN` | — | API token (`token-xxxxx:yyyyyyyyy`) |
| `RANCHER_VERIFY_SSL` | `true` | TLS verification |
| `RANCHER_INSTANCES_JSON` | — | Multi-instance config (see above) |
| `RANCHER_DEFAULT_INSTANCE` | first defined | Instance used when a tool call names none |
| `RANCHER_MCP_SERVER_NAME` | `rancher-mcp` | Server identity announced to clients |
| `RANCHER_MCP_SERVER_DESCRIPTION` | built-in | Server description announced to clients |
| `RANCHER_MCP_WRITE_RATE_LIMIT_PER_MIN` | `60` | Write rate limit (`0` disables) |

## Project status

Shipping and stable for **read, triage, and guarded write** operations. Honest
ledger of what's beyond that:

- **Destructive workflows** (node drain, etcd/backup restore, cert rotation,
  cluster upgrade/delete) are **roadmap** — deliberately staged after real-world
  read-path mileage. The generic engine + confirmation guard already covers
  these cases for operators who need them