Deployer
The Deployer handles the deployment of Mastra applications by packaging code, managing environment files, and serving applications using the Hono framework. Concrete implementations must define the deploy method for specific deployment targets.
Usage Example
import { Deployer } from "@mastra/deployer";
// Create a custom deployer by extending the abstract Deployer class
class CustomDeployer extends Deployer {
constructor() {
super({ name: 'custom-deployer' });
}
// Implement the abstract deploy method
async deploy(outputDirectory: string): Promise<void> {
// Prepare the output directory
await this.prepare(outputDirectory);
// Bundle the application
await this._bundle('server.ts', 'mastra.ts', outputDirectory);
// Custom deployment logic
// ...
}
}
Parameters
Constructor Parameters
args:
object
Configuration options for the Deployer.
args.name:
string
A unique name for the deployer instance.
deploy Parameters
outputDirectory:
string
The directory where the bundled and deployment-ready application will be output.
Methods
getEnvFiles:
() => Promise<string[]>
Returns a list of environment files to be used during deployment. By default, it looks for '.env.production' and '.env' files.
deploy:
(outputDirectory: string) => Promise<void>
Abstract method that must be implemented by subclasses. Handles the deployment process to the specified output directory.
Inherited Methods from Bundler
The Deployer class inherits the following key methods from the Bundler class:
prepare:
(outputDirectory: string) => Promise<void>
Prepares the output directory by cleaning it and creating necessary subdirectories.
writeInstrumentationFile:
(outputDirectory: string) => Promise<void>
Writes an instrumentation file to the output directory for telemetry purposes.
writePackageJson:
(outputDirectory: string, dependencies: Map<string, string>) => Promise<void>
Generates a package.json file in the output directory with the specified dependencies.
_bundle:
(serverFile: string, mastraEntryFile: string, outputDirectory: string, bundleLocation?: string) => Promise<void>
Bundles the application using the specified server and Mastra entry files.
Core Concepts
Deployment Lifecycle
The Deployer abstract class implements a structured deployment lifecycle:
- Initialization: The deployer is initialized with a name and creates a Deps instance for dependency management.
- Environment Setup: The
getEnvFiles
method identifies environment files (.env.production, .env) to be used during deployment. - Preparation: The
prepare
method (inherited from Bundler) cleans the output directory and creates necessary subdirectories. - Bundling: The
_bundle
method (inherited from Bundler) packages the application code and its dependencies. - Deployment: The abstract
deploy
method is implemented by subclasses to handle the actual deployment process.
Environment File Management
The Deployer class includes built-in support for environment file management through the getEnvFiles
method. This method:
- Looks for environment files in a predefined order (.env.production, .env)
- Uses the FileService to find the first existing file
- Returns an array of found environment files
- Returns an empty array if no environment files are found
getEnvFiles(): Promise<string[]> {
const possibleFiles = ['.env.production', '.env.local', '.env'];
try {
const fileService = new FileService();
const envFile = fileService.getFirstExistingFile(possibleFiles);
return Promise.resolve([envFile]);
} catch {}
return Promise.resolve([]);
}
Bundling and Deployment Relationship
The Deployer class extends the Bundler class, establishing a clear relationship between bundling and deployment:
- Bundling as a Prerequisite: Bundling is a prerequisite step for deployment, where the application code is packaged into a deployable format.
- Shared Infrastructure: Both bundling and deployment share common infrastructure like dependency management and file system operations.
- Specialized Deployment Logic: While bundling focuses on code packaging, deployment adds environment-specific logic for deploying the bundled code.
- Extensibility: The abstract
deploy
method allows for creating specialized deployers for different target environments.