sample.env

Overview

The `sample.env` file serves as a template for environment variable configuration in the project. It defines both secret and non-secret environment variables that are essential for the application to connect to external services and control runtime behavior.

Secret Environment Variables: Placeholders for sensitive keys such as API keys that should never be shared publicly or committed to version control.
Non-Secret Environment Variables: Configuration values such as URLs, network identifiers, and logging levels that guide the application's external connectivity and internal logging.

This file is primarily used to establish the necessary environment at runtime by loading these variables into the system environment or application context. It is typically copied or renamed (e.g., `.env`) and updated with actual values during deployment or local development.

Detailed Explanation of Variables

Secret Environment Variables

Variable	Description	Example Value (Do Not Use in Production)
`INDEXER_API_KEY`	API key for authenticating requests to the indexer service.	(empty placeholder)
`RPC_API_KEY`	API key for accessing the RPC (Remote Procedure Call) service securely.	(empty placeholder)

**Note:** These keys must be kept private and should be securely stored in vaults or CI/CD secrets management systems.

Environment Variables

Variable	Description	Example Value
`INDEXER_URL`	Base HTTPS URL for the indexer service, used for making REST API calls to retrieve blockchain-related data.	`https://ltcbook.nownodes.io`
`INDEXER_WS_URL`	WebSocket URL for real-time data streaming from the indexer service.	`wss:/ltcbook.nownodes.io/wss` (Note: typo likely, see Implementation Details)
`LOG_LEVEL`	Controls the verbosity of application logs. Common levels include `debug`, `info`, `warn`, `error`.	`debug`
`NETWORK`	Specifies the blockchain network environment the application interacts with.	`mainnet`
`RPC_URL`	HTTPS URL for the RPC endpoint to communicate directly with the blockchain node.	`https://ltc.nownodes.io`

Usage Example

Assuming the project uses a Node.js environment with the `dotenv` package:

# Copy the sample file to .env and fill in secrets
cp sample.env .env
# Edit .env to add secret keys

// Load environment variables
require('dotenv').config();

console.log(process.env.INDEXER_URL);  // Outputs: https://ltcbook.nownodes.io
console.log(process.env.LOG_LEVEL);    // Outputs: debug

Implementation Details & Notes

The sample.env file uses a simple KEY=VALUE format, which is widely supported by environment loaders across languages and frameworks.
The file intentionally leaves secret keys blank to avoid accidental exposure.
The INDEXER_WS_URL contains a probable typo: wss:/ltcbook.nownodes.io/wss — it should likely be wss://ltcbook.nownodes.io/wss (double slashes after protocol). This should be corrected in your actual .env file.
The LOG_LEVEL is set to debug by default, intended for development. For production, it is often set to warn or error.
The NETWORK variable allows the application to switch between blockchain networks, such as mainnet, testnet, or others, enabling environment-specific behavior.

Interaction with the Application

The environment variables defined here configure how the application connects with external services:
- Indexer Service: Provides blockchain data indexing functionalities.
- RPC Service: Enables direct blockchain node interaction for transactions and queries.
Logging levels and network selection control runtime diagnostics and blockchain environment context.
This file is typically loaded early in the application lifecycle (e.g., during startup) to configure global settings.
Other parts of the system read these variables to:
- Authenticate API requests.
- Establish HTTP/WebSocket connections.
- Adjust logging verbosity.
- Identify the network context for blockchain operations.

Visual Diagram

This file is a utility configuration file without classes or functions but defines key-value pairs used globally. The following flowchart illustrates how the environment variables are categorized and consumed by the application:

flowchart TD
    A[sample.env] --> B[Secret Environment Variables]
    A --> C[Environment Variables]

    B --> B1[INDEXER_API_KEY]
    B --> B2[RPC_API_KEY]

    C --> C1[INDEXER_URL]
    C --> C2[INDEXER_WS_URL]
    C --> C3[LOG_LEVEL]
    C --> C4[NETWORK]
    C --> C5[RPC_URL]

    B1 --> D[Indexer Service Authentication]
    B2 --> E[RPC Service Authentication]

    C1 --> F[Indexer REST API Client]
    C2 --> G[Indexer WebSocket Client]
    C3 --> H[Application Logging Module]
    C4 --> I[Network Configuration]
    C5 --> J[RPC Node Client]

    style B fill:#f9f,stroke:#333,stroke-width:1px
    style C fill:#bbf,stroke:#333,stroke-width:1px

Summary

sample.env is a template for environment configuration.
Secret keys placeholders ensure security best practices.
URLs and flags configure external service endpoints and application behavior.
The file forms the foundation for environment-specific settings, enabling scalable and secure application deployment.
Correct and secure management of this file is critical for the system’s connectivity and security posture.