Fool around with a crane MCP server for exploring registries with Claude code

Signed-off-by: Matt Moore <[email protected]>

Author: mattmoor

.gitignore

@@ -8,5 +8,6 @@ dist/
 cmd/crane/crane
 cmd/gcrane/gcrane
 cmd/krane/krane
+cmd/crane/mcp/crane-mcp
 
 .DS_Store

CLAUDE.md

@@ -0,0 +1,22 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Build Commands
+- Run all tests: `go test ./...`
+- Run specific test: `go test ./path/to/package -run TestName`
+- Run linter: `staticcheck ./pkg/...`
+- Verify formatting: `gofmt -d -e -l ./`
+- Full presubmit checks: `./hack/presubmit.sh`
+- Update generated docs: `./hack/update-codegen.sh`
+
+## Code Style
+- Use standard Go formatting (gofmt)
+- Import ordering: standard library, third-party, internal packages
+- Naming: follow Go conventions (CamelCase for exported, camelCase for unexported)
+- Error handling: return errors with context rather than logging
+- Testing: use standard Go testing patterns, include table-driven tests
+- Copyright header required at top of each file
+- Interface-driven design, with immutable view resources
+- Implement minimal subset interfaces, use partial package for derived accessors
+- Avoid binary data in logs (use redact.NewContext)

cmd/crane/mcp/README.md

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+# Crane MCP Server
+
+This is an implementation of the [Model Context Protocol (MCP)](https://modelcontextprotocol.io/) for the `crane` CLI tool. It allows AI assistants and other MCP clients to interact with container registries using the functionality provided by the `crane` command line tool.
+
+## Overview
+
+The server exposes several tools from the `crane` CLI as MCP tools, including:
+
+- `digest`: Get the digest of a container image
+- `pull`: Pull a container image and save it as a tarball
+- `push`: Push a container image from a tarball to a registry
+- `copy`: Copy an image from one registry to another
+- `catalog`: List repositories in a registry
+- `ls`: List tags for a repository
+- `config`: Get the config of an image
+- `manifest`: Get the manifest of an image
+
+## Usage
+
+### Building
+
+```bash
+go build -o crane-mcp
+```
+
+### Running
+
+```bash
+./crane-mcp
+```
+
+The server communicates through stdin/stdout according to the MCP protocol. It can be integrated with any MCP client.
+
+## Authentication
+
+The server uses the same authentication mechanisms as the `crane` CLI. For private registries, you may need to:
+
+1. Log in to the registry with `docker login` or `crane auth login`
+2. Set up appropriate environment variables or credentials files
+
+## Example Client Requests
+
+To get the digest of an image:
+
+```json
+{
+  "type": "call_tool",
+  "id": "1",
+  "params": {
+    "name": "digest",
+    "arguments": {
+      "image": "docker.io/library/ubuntu:latest",
+      "full-ref": true
+    }
+  }
+}
+```
+
+To copy an image between registries:
+
+```json
+{
+  "type": "call_tool",
+  "id": "2",
+  "params": {
+    "name": "copy",
+    "arguments": {
+      "source": "docker.io/library/nginx:latest",
+      "destination": "otherregistry.io/nginx:latest"
+    }
+  }
+}
+```
+
+## License
+
+Licensed under the Apache License, Version 2.0. See LICENSE file for details.