# Joern MCP Playground
This directory is mounted to Joern Docker containers at `/playground`, providing a shared workspace for codebases and CPGs.
## Directory Structure
```
playground/
├── codebases/ # Source code to analyze
│ └── sample/ # Example C codebase
│ └── sample.c
└── cpgs/ # Generated Code Property Graphs (optional)
```
## Usage
### For Local Codebases
When creating a CPG session with `source_type="local"`, provide paths relative to or within `playground/codebases/`:
```python
# Example: Analyze the sample codebase
create_cpg_session(
source_type="local",
source_path="playground/codebases/sample", # Or absolute path
language="c"
)
```
The Joern container will access this at `/playground/codebases/sample`.
### For GitHub Repositories
When using `source_type="github"`, repositories are automatically cloned into `playground/codebases/{session_id}/`:
```python
create_cpg_session(
source_type="github",
source_path="https://github.com/user/repo",
language="java"
)
```
### CPG Storage
CPGs are stored in the session workspace (`/tmp/joern-mcp/repos/{session_id}/cpg.bin`), but you can optionally store them in `playground/cpgs/` for persistence.
## Benefits
1. **Shared Access**: All Joern containers can access the same codebases
2. **Persistence**: Codebases survive container restarts
3. **Easy Management**: Add/remove codebases without rebuilding containers
4. **Testing**: Perfect for testing with multiple sample projects
## Adding New Codebases
Simply create a new directory under `playground/codebases/`:
```bash
mkdir -p playground/codebases/my-project
cp -r /path/to/source/* playground/codebases/my-project/
```
Then analyze it:
```python
create_cpg_session(
source_type="local",
source_path="playground/codebases/my-project",
language="java"
)
```
