octokit client should follow proxy settings (#314)

packages/github/src/github.ts

@@ -4,10 +4,15 @@ import {graphql} from '@octokit/graphql'
 // we need this type to set up a property on the GitHub object
 // that has token authorization
 // (it is not exported from octokit by default)
-import {graphql as GraphQL} from '@octokit/graphql/dist-types/types'
+import {
+  graphql as GraphQL,
+  RequestParameters as GraphQLRequestParameters
+} from '@octokit/graphql/dist-types/types'
 
 import Octokit from '@octokit/rest'
 import * as Context from './context'
+import * as http from 'http'
+import {HttpClient} from '@actions/http-client'
 
 // We need this in order to extend Octokit
 Octokit.prototype = new Octokit()
@@ -17,11 +22,113 @@ export const context = new Context.Context()
 export class GitHub extends Octokit {
   graphql: GraphQL
 
-  constructor(token: string, opts: Omit<Octokit.Options, 'auth'> = {}) {
-    super({...opts, auth: `token ${token}`})
+  /* eslint-disable no-dupe-class-members */
+  // Disable no-dupe-class-members due to false positive for method overload
+  // https://github.com/typescript-eslint/typescript-eslint/issues/291
 
-    this.graphql = graphql.defaults({
-      headers: {authorization: `token ${token}`}
-    })
+  /**
+   * Sets up the REST client and GraphQL client with auth and proxy support.
+   * The parameter `token` or `opts.auth` must be supplied. The GraphQL client
+   * authorization is not setup when `opts.auth` is a function or object.
+   *
+   * @param token  Auth token
+   * @param opts   Octokit options
+   */
+  constructor(token: string, opts?: Omit<Octokit.Options, 'auth'>)
+  constructor(opts: Octokit.Options)
+  constructor(token: string | Octokit.Options, opts?: Octokit.Options) {
+    super(GitHub.getOctokitOptions(GitHub.disambiguate(token, opts)))
+
+    this.graphql = GitHub.getGraphQL(GitHub.disambiguate(token, opts))
+  }
+
+  /**
+   * Disambiguates the constructor overload parameters
+   */
+  private static disambiguate(
+    token: string | Octokit.Options,
+    opts?: Octokit.Options
+  ): [string, Octokit.Options] {
+    return [
+      typeof token === 'string' ? token : '',
+      typeof token === 'object' ? token : opts || {}
+    ]
+  }
+
+  private static getOctokitOptions(
+    args: [string, Octokit.Options]
+  ): Octokit.Options {
+    const token = args[0]
+    const options = {...args[1]} // Shallow clone - don't mutate the object provided by the caller
+
+    // Auth
+    const auth = GitHub.getAuthString(token, options)
+    if (auth) {
+      options.auth = auth
+    }
+
+    // Proxy
+    const agent = GitHub.getProxyAgent(options)
+    if (agent) {
+      // Shallow clone - don't mutate the object provided by the caller
+      options.request = options.request ? {...options.request} : {}
+
+      // Set the agent
+      options.request.agent = agent
+    }
+
+    return options
+  }
+
+  private static getGraphQL(args: [string, Octokit.Options]): GraphQL {
+    const defaults: GraphQLRequestParameters = {}
+    const token = args[0]
+    const options = args[1]
+
+    // Authorization
+    const auth = this.getAuthString(token, options)
+    if (auth) {
+      defaults.headers = {
+        authorization: auth
+      }
+    }
+
+    // Proxy
+    const agent = GitHub.getProxyAgent(options)
+    if (agent) {
+      defaults.request = {agent}
+    }
+
+    return graphql.defaults(defaults)
+  }
+
+  private static getAuthString(
+    token: string,
+    options: Octokit.Options
+  ): string | undefined {
+    // Validate args
+    if (!token && !options.auth) {
+      throw new Error('Parameter token or opts.auth is required')
+    } else if (token && options.auth) {
+      throw new Error(
+        'Parameters token and opts.auth may not both be specified'
+      )
+    }
+
+    return typeof options.auth === 'string' ? options.auth : `token ${token}`
+  }
+
+  private static getProxyAgent(
+    options: Octokit.Options
+  ): http.Agent | undefined {
+    if (!options.request?.agent) {
+      const proxyUrl = process.env['https_proxy'] || process.env['HTTPS_PROXY']
+      if (proxyUrl) {
+        const httpClient = new HttpClient()
+        return httpClient.getAgent('https://api.github.com')
+      }
+    }
+
+    return undefined
   }
 }