feat: expose plugin extension points into main package, developer docs + sample

- update PluginLoader to use load-plugin's native Node module resolution. this library already
  handles loading of files vs modules in node_modules/ so let's use that directly
- add configuration-based plugin loading and deprecate environment variables
- new documentation page for plugin development. loading, writing, etc.
- add PullActionPlugin + unify config on just "plugins"
- add explicit exports to make importing @finos/git-proxy more straight forward for plugins

In addition, this commit adds both CommonJS and ES module examples of plugins and refactors them
into a more reflective package. It also includes updates to the site documentation, specifically
in the Development section, which now includes details about plugins and contribution guidelines.

- fix issue with json-schema-for-humans producing bad output due to post-processing (script step
  no longer required)
- docs: add section on docs on how to update the config schema + re-generate reference doc
- fix: don't package website with git-proxy, update .npmignore on npm pack/publish

Author: coopernetes

.npmignore

@@ -1 +1,3 @@
-# This file required to override .gitignore when publishing to npm
+# This file required to override .gitignore when publishing to npm
+website/
+plugins/

config.schema.json

@@ -36,6 +36,13 @@
       "description": "Flag to enable CSRF protections for UI",
       "type": "boolean"
     },
+    "plugins": {
+      "type": "array",
+      "description": "List of plugins to integrate on Git Proxy's push or pull actions. Each value is either a file path or a module name.",
+      "items": {
+        "type": "string"
+      }
+    },
     "authorisedList": {
       "description": "List of repositories that are authorised to be pushed to through the proxy.",
       "type": "array",

package.json

@@ -23,6 +23,10 @@
     "git-proxy": "./index.js",
     "git-proxy-all": "concurrently 'npm run server' 'npm run client'"
   },
+  "exports": {
+    "./plugin": "./src/plugin.js",
+    "./proxy/actions": "./src/proxy/actions/index.js"
+  },
   "workspaces": [
     "./packages/git-proxy-cli"
   ],

packages/git-proxy-notify-hello/index.js

@@ -0,0 +1,10 @@
+# Git Proxy plugins & samples
+Git Proxy supports extensibility in the form of plugins. These plugins are specified via [configuration](/docs/category/configuration) as NPM packages or JavaScript code on disk. For each plugin configured, Git Proxy will attempt to load each package or file as a standard [Node module](https://nodejs.org/api/modules.html). Plugin authors will create instances of the extension classes exposed by Git Proxy and use these objects to implement custom functionality.
+
+For detailed documentation, please refer to the [Git Proxy development resources on the project's site](https://git-proxy.finos.org/docs/development/plugins)
+
+## Included plugins
+These plugins are maintained by the core Git Proxy team. As a future roadmap item, organizations can choose to omit
+certain features of Git Proxy by simply removing the dependency from a deployed version of the application.
+
+- `git-proxy-plugin-samples`: "hello world" examples of the Git Proxy plugin system

plugins/README.md

@@ -0,0 +1,45 @@
+/**
+ * This is a sample plugin that logs a message when the pull action is called. It is written using
+ * CommonJS modules to demonstrate the use of CommonJS in plugins.
+ */
+
+// Peer dependencies; its expected that these deps exist on Node module path if you've installed @finos/git-proxy
+const { PushActionPlugin } = require('@finos/git-proxy/plugin');
+const { Step } = require('@finos/git-proxy/proxy/actions');
+'use strict';
+
+/**
+ * 
+ * @param {object} req Express Request object
+ * @param {Action} action Git Proxy Action
+ * @return {Promise<Action>} Promise that resolves to an Action
+ */
+async function logMessage(req, action) {
+  const step = new Step('LogRequestPlugin');
+  action.addStep(step);
+  console.log(`LogRequestPlugin: req url ${req.url}`);
+  console.log(`LogRequestPlugin: req user-agent ${req.header('User-Agent')}`);
+  console.log('LogRequestPlugin: action', JSON.stringify(action));
+  return action;
+}
+
+class LogRequestPlugin extends PushActionPlugin {
+  constructor() {
+    super(logMessage)
+  }
+}
+
+
+module.exports = {
+  // Plugins can be written inline as new instances of Push/PullActionPlugin
+  // A custom class is not required
+  hello: new PushActionPlugin(async (req, action) => {
+    const step = new Step('HelloPlugin');
+    action.addStep(step);
+    console.log('Hello world from the hello plugin!');
+    return action;
+  }),
+  // Sub-classing is fine too if you require more control over the plugin
+  logRequest: new LogRequestPlugin(),
+  someOtherValue: 'foo', // This key will be ignored by the plugin loader
+};

plugins/git-proxy-plugin-samples/example.cjs

@@ -0,0 +1,22 @@
+/**
+ * This is a sample plugin that logs a message when the pull action is called. It is written using
+ * ES modules to demonstrate the use of ESM in plugins.
+ */
+
+// Peer dependencies; its expected that these deps exist on Node module path if you've installed @finos/git-proxy
+import { PullActionPlugin } from "@finos/git-proxy/plugin";
+import { Step } from "@finos/git-proxy/proxy/actions";
+
+class RunOnPullPlugin extends PullActionPlugin {
+  constructor() {
+    super(function logMessage(req, action) {
+      const step = new Step('RunOnPullPlugin');
+      action.addStep(step);
+      console.log('RunOnPullPlugin: Received fetch request', req.url);
+      return action;
+    })
+  }
+}
+
+// Default exports are supported and will be loaded by the plugin loader
+export default new RunOnPullPlugin();

plugins/git-proxy-plugin-samples/index.js

@@ -0,0 +1,21 @@
+{
+  "name": "@finos/git-proxy-plugin-samples",
+  "version": "0.1.0-alpha.0",
+  "description": "A set of sample (dummy) plugins for Git Proxy to demonstrate how plugins are authored.",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "author": "Thomas Cooper",
+  "license": "Apache-2.0",
+  "type": "module",
+  "exports": {
+    ".": "./index.js",
+    "./example": "./example.cjs"
+  },
+  "dependencies": {
+    "express": "^4.18.2"
+  },
+  "peerDependencies": {
+    "@finos/git-proxy": "1.3.5-alpha.5"
+  }
+}

plugins/git-proxy-plugin-samples/package.json

@@ -20,7 +20,6 @@ try {
   console.log(genDocOutput);
 
   const schemaDoc = readFileSync(`${tempdir}${sep}schema.md`, 'utf-8')
-    .replace(/\n\n<\/summary>/g, '</summary>')
     .replace(/# GitProxy configuration file/g, '# Schema Reference'); // https://github.com/finos/git-proxy/pull/327#discussion_r1377343213
   const docString = `---
 title: Schema Reference

scripts/doc-schema.js

@@ -17,6 +17,7 @@ let _cookieSecret = defaultSettings.cookieSecret;
 let _sessionMaxAgeHours = defaultSettings.sessionMaxAgeHours;
 let _sslKeyPath = defaultSettings.sslKeyPemPath;
 let _sslCertPath = defaultSettings.sslCertPemPath;
+let _plugins = defaultSettings.plugins;
 let _commitConfig = defaultSettings.commitConfig;
 let _attestationConfig = defaultSettings.attestationConfig;
 let _privateOrganizations = defaultSettings.privateOrganizations;
@@ -160,6 +161,14 @@ const getCSRFProtection = () => {
   return _csrfProtection;
 };
 
+// Get loadable push plugins
+const getPlugins = () => {
+  if (_userSettings && _userSettings.plugins) {
+    _plugins = _userSettings.plugins;
+  }
+  return _plugins;
+}
+
 const getSSLKeyPath = () => {
   if (_userSettings && _userSettings.sslKeyPemPath) {
     _sslKeyPath = _userSettings.sslKeyPemPath;
@@ -195,5 +204,6 @@ exports.getPrivateOrganizations = getPrivateOrganizations;
 exports.getURLShortener = getURLShortener;
 exports.getContactEmail = getContactEmail;
 exports.getCSRFProtection = getCSRFProtection;
+exports.getPlugins = getPlugins;
 exports.getSSLKeyPath = getSSLKeyPath;
 exports.getSSLCertPath = getSSLCertPath;