syntropylog/dist/config/loadLoggerConfig.js

An instance manager with observability for Node.js applications

import fs from 'fs';
import yaml from 'js-yaml';
import path from 'path';
/**
 * Loads logger configuration from a YAML file.
 * The function determines the file path with the following priority:
 * 1. The path from the environment variable specified by `configPathEnvVar` (e.g., `LOGGER_CONFIG`).
 * 2. The environment-specific path (e.g., `{configDir}/{defaultBase}-production.yaml`).
 * 3. The default base path (e.g., `{configDir}/{defaultBase}.yaml`).
 *
 * If no file is found, it returns an empty object, making the config file optional.
 * @param opts - Options to customize the loading behavior.
 * @returns A partial `LoggerOptions` object, or an empty object if no file is found.
 * @throws An error if a config file is found but fails to be read or parsed.
 */
export function loadLoggerConfig(opts) {
    const { configPathEnvVar = 'LOGGER_CONFIG', fallbackEnvVar = 'NODE_ENV', configDir = './config', defaultBase = 'logger', } = opts || {};
    // 1. Check for the direct path from the primary environment variable.
    let configPath;
    const envPath = process.env[configPathEnvVar];
    if (envPath && fs.existsSync(envPath)) {
        configPath = envPath;
    }
    // 2. If not found, construct and check for an environment-specific file.
    if (!configPath) {
        const env = process.env[fallbackEnvVar];
        if (env) {
            const envSpecificPath = path.join(configDir, `${defaultBase}-${env}.yaml`);
            if (fs.existsSync(envSpecificPath)) {
                configPath = envSpecificPath;
            }
        }
    }
    // 3. If still not found, check for the default base file.
    if (!configPath) {
        const defaultPath = path.join(configDir, `${defaultBase}.yaml`);
        if (fs.existsSync(defaultPath)) {
            configPath = defaultPath;
        }
    }
    // If no configuration file was found after all checks, return an empty object.
    if (!configPath) {
        return {};
    }
    try {
        // Load and parse the YAML file.
        const fileContents = fs.readFileSync(configPath, 'utf8');
        const yamlConfig = yaml.load(fileContents);
        // If the YAML has the config under a 'logger' key, extract it.
        // Otherwise, assume the root object is the configuration.
        return yamlConfig?.logger || yamlConfig || {};
    }
    catch (error) {
        throw new Error(`[BeaconLog] Failed to load or parse config file at ${configPath}: ${error instanceof Error ? error.message : String(error)}`);
    }
}
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