sample.env

Overview

The `sample.env` file serves as a template for environment variable configuration in the application. It defines key-value pairs that specify critical runtime parameters such as API keys, network URLs, logging levels, and endpoints. These variables are essential for configuring the application's interaction with external services (such as blockchain indexers and RPC nodes), controlling logging verbosity, and selecting the operational network environment.

This file is typically used as a reference or starting point to create a `.env` file that the application reads during startup to load environment-specific settings securely and consistently.

Detailed Explanation

File Type and Purpose

Type: Environment variables template file.
Format: Plain text with KEY=VALUE pairs.
Purpose: Provide default or example environment variables that the application expects to be set before running.

Variables Defined

Variable	Description	Example Value	Notes
`ETHERSCAN_API_KEY`	API key for accessing Etherscan services (blockchain explorer and analytics).	(empty in sample, to be filled by user)	Kept secret; used for blockchain queries or analytics.
`INDEXER_URL`	HTTP endpoint URL for the blockchain indexer service (used to query blockchain state).	https://dev-indexer.arbitrum-nova.shapeshift.com	Points to a development indexer instance.
`INDEXER_WS_URL`	WebSocket URL for real-time communication with the blockchain indexer.	wss://dev-indexer.arbitrum-nova.shapeshift.com/websocket	Enables subscription or push notifications.
`LOG_LEVEL`	Sets the verbosity level of application logs.	`debug`	Common levels: debug, info, warn, error.
`NETWORK`	Specifies the blockchain network environment the application targets.	`mainnet`	Could also be `testnet`, `devnet`, etc.
`RPC_URL`	Remote Procedure Call URL for interacting with the blockchain node or daemon.	https://dev-daemon.arbitrum-nova.shapeshift.com	Used for submitting transactions or querying chain state.

Usage

How to Use `sample.env`

Copy the file: Typically, you copy sample.env to .env in the root of your project.
```
cp sample.env .env
```
Edit .env: Populate the empty or placeholder values with valid credentials and URLs specific to your environment.
Load environment variables: The application or its configuration loader reads .env to set environment variables for runtime.
Run the application: The app uses these variables to configure services such as logging, blockchain network connections, and API integrations.

Example

# Copy the sample env file
cp sample.env .env

# Edit the .env file to insert your Etherscan API key
# For example, open in an editor and modify:
# ETHERSCAN_API_KEY=your_real_api_key_here

# Run the application (assuming a Node.js app using dotenv)
node app.js

Implementation Details

This file does not contain executable code but is critical for configuration.
The file follows the conventional .env format supported by many configuration libraries (e.g., dotenv in Node.js, python-dotenv in Python).
Secrets like API keys are left blank intentionally for security.
URLs provided are typically development or staging endpoints and should be replaced with production URLs as appropriate.
Changing LOG_LEVEL affects the verbosity of logs globally, aiding in debugging or monitoring.
NETWORK variable can be used by the application to toggle logic specific to mainnet or testnet environments.

Interaction with Other System Components

Configuration Loader Module: Reads the .env file (following the pattern set by sample.env) and injects environment variables into the application.
Blockchain Indexer Client: Uses INDEXER_URL and INDEXER_WS_URL to query blockchain state and subscribe to events.
RPC Client: Uses RPC_URL to communicate with the blockchain node for submitting transactions and queries.
Logging Framework: Reads LOG_LEVEL to determine log output granularity.
Network-specific Logic: Uses NETWORK to adjust behavior based on the blockchain environment (e.g., mainnet vs testnet).
Security Layer: Ensures sensitive keys (e.g., ETHERSCAN_API_KEY) are not exposed publicly and are handled securely.

Mermaid Diagram: Environment Variable Relationships and Usage Flow

flowchart TD
    subgraph ENV_FILE
        SAMPLE_ENV[sample.env<br/>(KEY=VALUE pairs)]
        DOT_ENV[.env<br/>(User customized)]
    end

    subgraph APP[Application]
        CONFIG[Config Loader<br/>(reads .env)]
        LOGGING[Logging Module<br/>(uses LOG_LEVEL)]
        INDEXER_CLIENT[Indexer Client<br/>(uses INDEXER_URL, INDEXER_WS_URL)]
        RPC_CLIENT[RPC Client<br/>(uses RPC_URL)]
        NETWORK_LOGIC[Network Logic<br/>(uses NETWORK)]
        API_KEYS[API Keys<br/>(ETHERSCAN_API_KEY)]
    end

    SAMPLE_ENV -->|Copy & Edit| DOT_ENV
    DOT_ENV --> CONFIG
    CONFIG --> LOGGING
    CONFIG --> INDEXER_CLIENT
    CONFIG --> RPC_CLIENT
    CONFIG --> NETWORK_LOGIC
    CONFIG --> API_KEYS

Summary

sample.env is a foundational configuration template file.
It defines essential environment variables to configure blockchain network access, logging, and API credentials.
The file is non-executable but critical for environment-specific customization.
It interacts indirectly with many core modules by providing them with necessary configuration values.
Proper setup and maintenance of this file enable secure, scalable, and environment-aware application deployments.

*End of Documentation for `sample.env`*