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wiki[bot] edited this page Aug 23, 2026 · 1 revision

Bootstrap

Bootstrap utilities for NestJS applications.

Constants

API_DOCS

Swagger UI path constant.

export const API_DOCS = "api-docs";

API_DOCS_JSON

Swagger JSON endpoint path constant.

export const API_DOCS_JSON = "api-docs-json";

DEFAULT_BODY_LIMIT

Default body limit for request parsing (16777216 bytes / 16MB).

export const DEFAULT_BODY_LIMIT = 16777216;

DEFAULT_LOG_LEVELS

Default NestJS log levels array.

export const DEFAULT_LOG_LEVELS: Array<LogLevel> = [
  "warn",
  "error",
  "debug",
  "log",
  "verbose",
  "fatal",
];

Functions

getBodyLimit

Parses a body limit value from an environment variable string. Returns the default if the value is null/undefined or cannot be parsed.

export const getBodyLimit = (value?: string | null): number;

Parameters:

  • value - Environment variable value (optional)

Returns: Parsed integer or DEFAULT_BODY_LIMIT

getLogLevel

Parses a comma-separated string of log levels into a NestJS LogLevel array.

export const getLogLevel = (value?: string): Array<LogLevel>;

Parameters:

  • value - Comma-separated log levels (e.g., "error,warn,log")

Returns: Array of LogLevel values, or DEFAULT_LOG_LEVELS if value is falsy

logConfigObject

Logs configuration object keys if printConfig is enabled. Strips the leading underscore from environment variable keys.

export function logConfigObject(
  logger: Logger,
  factory: Record<string, unknown>,
  printConfig = false
): void;

Parameters:

  • logger - NestJS Logger instance
  • factory - Object with environment variable keys (e.g., { _port: 3000 })
  • printConfig - Whether to actually log the config

logServerPath

Logs the server URL with a "REST API" label.

export function logServerPath(logger: Logger, appConfig: AppConfig): void;

Parameters:

  • logger - NestJS Logger instance
  • appConfig - Application configuration object

logSwaggerPath

Logs the Swagger JSON and UI paths if swagger is enabled in appConfig.

export function logSwaggerPath(logger: Logger, appConfig: AppConfig): void;

Parameters:

  • logger - NestJS Logger instance
  • appConfig - Application configuration object

findUp

Recursively searches for a file by traversing up the directory tree from the current working directory.

export function findUp(
  filename: string,
  startDir: string = process.cwd()
): string | null;

Parameters:

  • filename - The name of the file to find (e.g., "README.md", "package.json")
  • startDir - Optional directory to start searching from (defaults to process.cwd())

Returns: The absolute path to the found file, or null if the file is not found up to the filesystem root

Example:

const readmePath = findUp("README.md");
if (readmePath) {
  console.log(`Found README at ${readmePath}`);
}

readPackageJsonFromRoot

Reads and parses package.json from the current working directory or specified path.

export function readPackageJsonFromRoot(
  filename: string = "package.json",
  startDir: string = process.cwd()
): PackageConfig;

Parameters:

  • filename - Optional filename to read (defaults to "package.json")
  • startDir - Optional directory to start searching from (defaults to process.cwd())

Returns: Object containing name, version, and description

Throws: Error if the file is not found

Pre-built Instances

VALIDATION_PIPE

Pre-configured NestJS ValidationPipe with the following options:

export const VALIDATION_PIPE = new ValidationPipe({
  whitelist: true,
  transform: true,
  forbidUnknownValues: true,
  forbidNonWhitelisted: true,
});

SWAGGER_DOCUMENT

Pre-built Swagger document using values from package.json:

export const SWAGGER_DOCUMENT = new DocumentBuilder()
  .setTitle(PACKAGE_JSON.name.toUpperCase())
  .setDescription(PACKAGE_JSON.description)
  .setVersion(PACKAGE_JSON.version)
  .build();

Types

AppConfig

interface AppConfig {
  /** Port number for the server (1-65535) */
  port: number;
  /** Environment: development, production, test, or local */
  nodeEnv: string;
  /** IP address to bind to (IPv4 or IPv6) */
  address: string;
  /** Whether to log the config object at startup */
  printConfig: boolean;
  /** Request body size limit in bytes (min: 1) */
  bodyLimit: number;
  /** Whether to enable Swagger UI at /api-docs */
  enableSwagger: boolean;
  /** NestJS log levels for output (defaults to all levels if not set) */
  logLevel?: Array<LogLevel>;
  cors?: {
    /** Allowed origin for CORS (string, wildcard "*", or RegExp) */
    origin?: string;
    /** Allowed HTTP methods (e.g., "GET,POST,PUT,DELETE") */
    methods?: string;
    /** Whether to pass CORS preflight to next handler instead of handling it */
    preflightContinue?: boolean;
    /** HTTP status code for successful OPTIONS responses (default: 204) */
    optionsSuccessStatus?: number;
    /** Whether to allow credentials (cookies, authorization headers) */
    credentials?: boolean;
    /** Custom headers to expose via Access-Control-Expose-Headers (null clears defaults) */
    allowedHeaders?: string;
  };
  health?: {
    /** Maximum heap memory threshold before health check fails (use getByteSizeEnv to parse env like "256MB") */
    memoryHeap?: number;
    /** Maximum RSS (Resident Set Size) memory threshold before health check fails */
    memoryRSS?: number;
    /** Disk path to check available space (defaults to root "/") */
    diskPath?: string;
    /** Disk usage threshold (0.8 = 80% used / 20% available). Fails if usage exceeds this threshold */
    diskThresholdPercent?: number;
  };
}

AppConfigSchema

Joi validation schema for AppConfig with the following rules:

Field Validation
printConfig Required boolean - whether to log config at startup
enableSwagger Required boolean - whether to enable Swagger UI
bodyLimit Required number >= 1 - max request body size in bytes
address Required valid IPv4 or IPv6 address
port Required integer 1-65535 - server port
nodeEnv Required string: development, production, test, or local
logLevel Optional array of log levels: warn, error, debug, log, verbose, fatal (defaults to all)
cors Optional CORS configuration object
cors.origin Optional string - allowed origin for CORS (string, wildcard, or RegExp)
cors.methods Optional string - allowed HTTP methods (e.g., "GET,POST,PUT,DELETE")
cors.preflightContinue Optional boolean - whether to pass preflight to next handler
cors.optionsSuccessStatus Optional number - HTTP status for successful OPTIONS (default: 204)
cors.credentials Optional boolean - whether to allow credentials
cors.allowedHeaders Optional string - custom headers to expose (null clears defaults)
health Optional health check configuration object
health.memoryHeap Optional number >= 0 - max heap memory in bytes (use getByteSizeEnv to parse "256MB")
health.memoryRSS Optional number >= 0 - max RSS memory in bytes (use getByteSizeEnv to parse "512MB")
health.diskPath Optional string - path to check disk space (defaults to "/")
health.diskThresholdPercent Optional number >= 0 - disk usage threshold (0.8 = 80% used, fails if exceeded)

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