How to Configure the Graph Database Directory Using Environment Variables in Code-Review-Graph

Set the CRG_GRAPH_DB_PATH environment variable to any filesystem path before invoking the Code-Review-Graph library, and it will store its SQLite-backed knowledge graph at that location instead of the default .crg/graph.db project subdirectory.

The Code-Review-Graph library (tirth8205/code-review-graph) persists code analysis data in a SQLite file-based database. To support flexible deployment across development, CI/CD, and production environments, you can configure the graph database directory using environment variables rather than relying on hard-coded paths.

How CRG_GRAPH_DB_PATH Controls Database Location

When the library initializes a connection to its knowledge graph, it checks for the CRG_GRAPH_DB_PATH environment variable. If present, the library uses this value as the filesystem path for the SQLite database file. If absent, it falls back to a default location within your project root.

In code_review_graph/graph.py, the GraphStore class constructor accepts a db_path argument that determines where the .db file resides. The CLI entry point in code_review_graph/cli.py automatically reads CRG_GRAPH_DB_PATH from the environment and passes it to this constructor, ensuring consistent behavior across command-line and programmatic usage.

The Configuration Resolution Flow

Variable Detection and Path Resolution

The configuration process follows a strict resolution hierarchy:

1. Environment lookup – The code evaluates os.environ.get("CRG_GRAPH_DB_PATH") to retrieve the custom path.
2. Path instantiation – The string value passes through Path(), which resolves relative paths against the current working directory.
3. Directory creation – Inside GraphStore.__init__ (lines 88‑95 of code_review_graph/graph.py), the library calls self.db_path.parent.mkdir(parents=True, exist_ok=True) to ensure the parent directory exists.
4. Connection establishment – The resolved path opens as the SQLite database file backing the graph.

Default Behavior

When CRG_GRAPH_DB_PATH is unset, the library defaults to <project-root>/.crg/graph.db, creating the .crg directory if necessary. This ensures out-of-the-box functionality while allowing explicit override for containerized or multi-tenant environments.

Configuration Examples

Setting the Variable in Your Shell

For Unix-like systems, export the variable before running the CLI:

export CRG_GRAPH_DB_PATH=/var/tmp/my_project/graph.db
python -m code_review_graph.cli index ./src

This directs all graph operations to /var/tmp/my_project/graph.db instead of the local project folder.

Configuring via the Python API

When embedding the library in Python applications, set the environment variable before instantiating GraphStore:

import os
from pathlib import Path
from code_review_graph.graph import GraphStore

os.environ["CRG_GRAPH_DB_PATH"] = str(Path("/tmp/custom_dir/graph.db"))

# The GraphStore automatically uses the path from the env var

with GraphStore(os.getenv("CRG_GRAPH_DB_PATH")) as store:
    # Perform graph operations...

    pass

Overriding with Explicit Paths

To bypass the environment variable entirely, pass an explicit path directly to the constructor:

from code_review_graph.graph import GraphStore

custom_path = "/opt/data/graph.sqlite"
store = GraphStore(custom_path)  # Ignores CRG_GRAPH_DB_PATH

This approach prioritizes the explicit argument over any environment configuration.

Summary

• Set CRG_GRAPH_DB_PATH to control where the SQLite graph database file resides on your filesystem.
• The library automatically creates parent directories using mkdir(parents=True, exist_ok=True) if they don't exist.
• Default location: .crg/graph.db relative to the project root when the environment variable is unset.
• Both the CLI (code_review_graph/cli.py) and Python API (code_review_graph/graph.py) respect this variable when initializing GraphStore.
• Explicit path arguments passed directly to GraphStore(db_path) override the environment variable.

Frequently Asked Questions

What is the default graph database directory if I don't set the environment variable?

If CRG_GRAPH_DB_PATH is not set, the library stores the database at .crg/graph.db relative to your project root. The GraphStore class creates this directory automatically if it doesn't exist.

Can I use relative paths with CRG_GRAPH_DB_PATH?

Yes. The library passes the environment variable value through Path(), which resolves relative paths against the current working directory. For predictable behavior in production, absolute paths are recommended.

Does the library create the database directory automatically?

Yes. According to the implementation in code_review_graph/graph.py, the GraphStore.__init__ method calls self.db_path.parent.mkdir(parents=True, exist_ok=True), ensuring the full directory hierarchy exists before opening the SQLite connection.

How do I override the environment variable when using the Python API?

Pass an explicit db_path argument when constructing GraphStore. The constructor accepts a string or Path object directly, and this value takes precedence over any environment variable configuration.

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