204: Handle proxies when using Slack WebClient

README.md

@@ -234,6 +234,23 @@ Incoming Webhooks conform to the same rules and functionality as any of Slack's
     SLACK_WEBHOOK_TYPE: INCOMING_WEBHOOK
 ```
 
+### HTTPS Proxy
+
+If you need to use a proxy to connect with Slack, you can use the `HTTPS_PROXY` (or `https_proxy`) environment variable. In this example we use the Slack App technique, but configuring a proxy works the same way for all of them:
+
+```yaml
+- name: Post to a Slack channel via a proxy
+  id: slack
+  uses: slackapi/slack-github-action@v1.24.0
+  with:
+    channel-id: 'CHANNEL_ID'
+    slack-message: 'This message was sent through a proxy'
+  env:
+    SLACK_BOT_TOKEN: ${{ secrets.SLACK_BOT_TOKEN }}
+    # Set the HTTPS_PROXY environment variable to whatever your policy requires
+    HTTPS_PROXY: 'http://proxy.example.org:8080'
+```
+
 ## Contributing
 
 See [CONTRIBUTING](.github/contributing.md).

src/slack-send.js

@@ -1,5 +1,4 @@
 const github = require('@actions/github');
-const { WebClient } = require('@slack/web-api');
 const flatten = require('flat');
 const axios = require('axios');
 const { promises: fs } = require('fs');
@@ -8,6 +7,8 @@ const markup = require('markup-js');
 const HttpsProxyAgent = require('https-proxy-agent');
 const { parseURL } = require('whatwg-url');
 
+const { createWebClient } = require('./web-client');
+
 const SLACK_WEBHOOK_TYPES = {
   WORKFLOW_TRIGGER: 'WORKFLOW_TRIGGER',
   INCOMING_WEBHOOK: 'INCOMING_WEBHOOK',
@@ -63,7 +64,8 @@ module.exports = async function slackSend(core) {
     if (typeof botToken !== 'undefined' && botToken.length > 0) {
       const message = core.getInput('slack-message') || '';
       const channelIds = core.getInput('channel-id') || '';
-      const web = new WebClient(botToken);
+      const httpsProxy = process.env.HTTPS_PROXY || process.env.https_proxy || '';
+      const web = createWebClient(botToken, httpsProxy);
 
       if (channelIds.length <= 0) {
         console.log('Channel ID is required to run this action. An empty one has been provided');

src/web-client.js

@@ -0,0 +1,20 @@
+const { WebClient } = require('@slack/web-api');
+const HttpsProxyAgent = require('https-proxy-agent');
+
+/**
+ *
+ * @param {string} botToken token used to authenticate as the Slack Bot user
+ * @param {string?} httpsProxy (optional) URL for the proxy to use for HTTPS requests
+ * @returns { WebClient } a WebClient configured with the bot token and proxy agent (if needed)
+ */
+function createWebClient(botToken, httpsProxy) {
+  if (httpsProxy) {
+    const httpsProxyAgent = new HttpsProxyAgent(httpsProxy);
+    return new WebClient(botToken, { agent: httpsProxyAgent });
+  }
+  return new WebClient(botToken);
+}
+
+module.exports = {
+  createWebClient,
+};

test/slack-send-test.js

@@ -189,6 +189,7 @@ describe('slack-send', () => {
       });
       describe('proxy config', () => {
         beforeEach(() => {
+          delete process.env.https_proxy;
           delete process.env.HTTPS_PROXY;
         });
         it('should use https proxy agent when proxy uses HTTP', async () => {

test/web-client-test.js

@@ -0,0 +1,33 @@
+const { assert } = require('chai');
+const sinon = require('sinon');
+const rewiremock = require('rewiremock/node');
+
+/* eslint-disable-next-line global-require */
+rewiremock(() => require('@slack/web-api')).with({
+  WebClient: class {
+    constructor(token, options) {
+      this.token = token;
+      this.options = options || {};
+    }
+  },
+});
+rewiremock.enable();
+const { createWebClient } = require('../src/web-client');
+
+rewiremock.disable();
+
+describe('web-client', () => {
+  beforeEach(() => {
+    sinon.reset();
+  });
+
+  it('should create WebClient with an https proxy agent if given a proxy URL', async () => {
+    const web = createWebClient('xoxb-xxxxx', 'http://test.proxy:8080/');
+    assert.equal(typeof web.options.agent, 'object');
+  });
+
+  it('should create WebClient with default settings if not given a proxy URL', async () => {
+    const web = createWebClient('xoxb-xxxxx');
+    assert.equal(web.options.agent, undefined);
+  });
+});