feat(metrics): Initial implemenation of package install/download metr…

…ics capturing and metrics endpoint

.babelrc

@@ -0,0 +1,5 @@
+{
+  "presets": [
+    ["@verdaccio", { "typescript": true }]
+  ]
+}

.circleci/config.yml

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+version: 2.1
+
+orbs:
+  node: circleci/node@4.7.0
+
+jobs:
+  test:
+    docker:
+      - image: 'node:lts-alpine'
+    steps:
+      - checkout
+      - node/install-packages
+      - run:
+          command: npm run test
+      # https://circleci.com/docs/2.0/collect-test-data
+      - store_test_results:
+          path: ./coverage/
+
+workflows:
+  test:
+    jobs:
+      - test

.editorconfig

@@ -0,0 +1,12 @@
+# top-most EditorConfig file
+root = true
+
+[*]
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+charset = utf-8
+indent_style = space
+
+[*.{ts,js,mjs,json,txt,yml,yaml}]
+indent_size = 2

.eslintignore

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+coverage/
+lib/
+node_modules/

.eslintrc

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+{
+  "extends": ["@verdaccio"],
+  "rules": {
+    "no-case-declarations": "off",
+    "@typescript-eslint/ban-ts-ignore": 0,
+    "@typescript-eslint/ban-ts-comment": 0
+  }
+}

.gitignore

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+_storage/
+lib/
+node_modules/
+coverage/
+.idea/
+
+npm-debug.log*

.husky/pre-commit

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+#!/bin/sh
+. "$(dirname "$0")/_/husky.sh"
+
+npm test

.npmignore

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+src/
+test/
+
+.babelrc
+.editorconfig
+.eslintignore
+.eslintrc
+.gitignore
+.npmignore
+metrics.ts
+jest.config.js
+README.md
+tsconfig.json

README.md

@@ -1,2 +1,79 @@
 # verdaccio-metrics-middleware
-Verdaccio middleware plugin used to collect prometheus compatible metrics
+Metrics middleware plugin for Verdaccio. Collects metrics specifically for package install/download requests and
+exposes them at a configurable metrics endpoint (defaults to `/-/metrics`). The metrics are produced in the standard
+[prometheus metrics text format](https://prometheus.io/docs/instrumenting/exposition_formats/#text-format-example).
+
+A [counter](https://prometheus.io/docs/concepts/metric_types/#counter) metric is used to track the number of package
+installs/downloads. The following [labels](https://prometheus.io/docs/practices/naming/#labels) are applied to _every_
+request:
+- `username` - The Verdaccio username of the user attempting to install/download a package. If the request is
+  unauthenticated then the value `UNKNOWN` is used.
+- `userAgentName` - The name of the user agent the client used to make the request. It is derived from the `user-agent`
+  header on the request. If no `user-agent` header is provided it defaults to `UNKNOWN`.
+- `statusCode` - The status code of the response from Verdaccio.
+
+Optionally, an additional `packageGroup` label can be applied *if* a `packageGroups` option is added to the plugin
+configuration.
+
+## Configuration
+Complete configuration example:
+```yaml
+middlewares:
+  metrics:
+    ## Optional. Defaults to `false` so make sure to set this to `true` if you want to collect metrics.
+    enabled: true
+
+    ## Optional. Defaults to `/-/metrics`.
+    metricsPath: /custom/path/metrics
+
+    ## Optional. A map of regular expressions to package grouping names.
+    packageGroups:
+      ## NOTE: The order of items below matters. The first matched regex is the package grouping that will be applied
+      ## to the metric generated for a request.
+      '@angular[/][^/]*': angular
+      'react': react
+      '.*': other
+```
+
+## Package Groups
+The `packageGroups` configuration option accepts an object map whose keys are expected to be a regular expression string
+and the value the name of the package group that should be used for the `packageGroup` metric label. If no
+`packageGroups` are defined, a `packageGroup` [label](https://prometheus.io/docs/practices/naming/#labels) will NOT be
+applied to the [counter](https://prometheus.io/docs/concepts/metric_types/#counter) metric.
+
+The regular expression key is evaluated against the request path in the following manner:
+```javascript
+// scoped packages generally have the `/` url encoded to `%2f`
+new RegExp(packageGroupRegex).test(decodeURIComponent(request.path))
+```
+
+The order of the keys/values in the object map matters. The regular expressions are evaluated from first to last in the
+order they are listed under the `packageGroups` configuration option and the first matching regex will have the
+corresponding package grouping value applied when the install/download counter metric is collected.
+
+Given the following example configuration:
+```yaml
+# Verdaccio config file
+middlewares:
+  metrics:
+    enabled: true
+    packageGroups:
+      '@babel[/]plugin': 'babel-plugin'
+      'babel[-]plugin': 'babel-plugin'
+      'babel': 'babel'
+      '@.*': scoped
+      '.*': other
+```
+... the following packages would resolve to the `packageGroup` as listed in the table:
+
+| Package Name                      | Package Group |
+|-----------------------------------|---------------|
+| `@babel/core`                     | babel         |
+| `@babel/parser`                   | babel         |
+| `@babel/plugin-transform-runtime` | babel-plugin  |
+| `babel-plugin-istanbul`           | babel-plugin  |
+| `babel-jest`                      | babel         |
+| `@angular/core`                   | scoped        |
+| `@apollo/client`                  | scoped        |
+| `react`                           | other         |
+| `apollo-server-express`           | other         |

jest.config.js

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+module.exports = {
+  name: 'verdaccio-metrics-middleware',
+  verbose: true,
+  collectCoverage: true,
+  collectCoverageFrom: ['src/**/*.ts', '!src/index.ts'],
+  moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx'],
+  transform: {
+    '^.+\\.(js|jsx|ts|tsx)$': 'babel-jest',
+  },
+  reporters: ['default', ['jest-junit', { outputDirectory: './coverage/jest', outputName: 'results.xml' }]],
+};