138 lines
5.3 KiB
Markdown
138 lines
5.3 KiB
Markdown
# Angel3 Production Runner
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[](https://dart.dev/null-safety)
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[](https://gitter.im/angel_dart/discussion)
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[](https://github.com/dart-backend/angel/tree/master/packages/production/LICENSE)
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Helpers for concurrency, message-passing, rotating loggers, and other production functionality in Angel3 framework.
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This will become the de-facto way to run Angel3 applications in deployed environments, as it takes care of inter-isolate communication, respawning dead processes, and other housekeeping for you automatically. Most users will want to use the `Runner` class.
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## `Runner`
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`Runner` is a utility, powered by `package:args`, that is intended to be the entry point of your application.
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Instantiate it as follows, and your file will become a command-line executable that spawns multiple instances of your application:
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```dart
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import 'dart:async';
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import 'dart:isolate';
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import 'package:angel3_framework/angel3_framework.dart';
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import 'package:angel3_production/angel3_production.dart';
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void main(List<String> args) => Runner('example', configureServer).run(args);
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Future configureServer(Angel app) async {
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app.get('/', (req, res) => 'Hello, production world!');
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app.get('/crash', (req, res) {
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// We'll crash this instance deliberately, but the Runner will auto-respawn for us.
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Timer(const Duration(seconds: 3), Isolate.current.kill);
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return 'Crashing in 3s...';
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});
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}
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```
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`Runner` will automatically re-spawn crashed instances, unless `--no-respawn` is passed. This can prevent your server from entirely going down at the first error, and adds a layer of fault tolerance to your infrastructure.
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When combined with `systemd`, deploying Angel3 applications on Linux can be very simple.
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## Message Passing
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The `Runner` class uses [`belatuk_pub_sub`](<https://pub.dev/packages/belatuk_pub_sub>) to coordinate
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message passing between isolates. When one isolate sends a message, all other isolates will receive the same message, except for the isolate that sent it. It is injected into your application's `Container` as `pub_sub.Client`, so you can use it as follows:
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```dart
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// Use the injected `pub_sub.Client` to send messages.
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var client = app.container.make<Client>();
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// We can listen for an event to perform some behavior.
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//
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// Here, we use message passing to synchronize some common state.
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var onGreetingChanged = await client.subscribe('user_upgraded');
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onGreetingChanged
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.cast<User>()
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.listen((user) {
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// Do something...
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});
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```
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## Customising Response Header
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Additional parameters can be passed to the `Runner` class to:
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1. Remove headers from HTTP response.
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2. Add headers to HTTP response.
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For example, the following code snippet removes `X-FRAME-OPTIONS` and adds `X-XSRF-TOKEN` to the response header.
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```dart
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void main(List<String> args) {
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// Remove 'X-FRAME-OPTIONS'
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var removeHeader = {'X-FRAME-OPTIONS': 'SAMEORIGIN'};
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// Add 'X-XSRF-TOKEN'
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var customHeader = {
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'X-XSRF-TOKEN':
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'a591a6d40bf420404a011733cfb7b190d62c65bf0bcda32b57b277d9ad9f146e'
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};
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Runner('example', configureServer,
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removeResponseHeaders: removeHeader, responseHeaders: customHeader)
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.run(args);
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}
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```
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## Run-time Metadata
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At run-time, you may want to know information about the currently-running instance, for example, which number instance. For this, the `InstanceInfo` class is injected into each instance:
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```dart
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var instanceInfo = app.container.make<InstanceInfo>();
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print('This is instance #${instanceInfo.id}');
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```
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## Command-line Options
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The `Runner` class supplies options like the following:
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```bash
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appuser$ dart example/main.dart --help
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_ _ _ ____ _____ _ _____
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/ \ | \ | |/ ___| ____| | |___ /
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/ _ \ | \| | | _| _| | | |_ \
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/ ___ \| |\ | |_| | |___| |___ ___) |
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/_/ \_\_| \_|\____|_____|_____|____/
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A batteries-included, full-featured, full-stack framework in Dart.
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https://angel3-framework.web.app
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Options:
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-h, --help Print this help information.
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--[no-]respawn Automatically respawn crashed application instances.
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(defaults to on)
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--use-zone Create a new Zone for each request.
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--quiet Completely mute logging.
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--ssl Listen for HTTPS instead of HTTP.
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--http2 Listen for HTTP/2 instead of HTTP/1.1.
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-a, --address The address to listen on.
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(defaults to "127.0.0.1")
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-j, --concurrency The number of isolates to spawn.
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(defaults to "4")
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-p, --port The port to listen on.
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(defaults to "3000")
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--certificate-file The PEM certificate file to read.
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--certificate-password The PEM certificate file password.
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--key-file The PEM key file to read.
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--key-password The PEM key file password.
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```
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