Quickstart: Create an add-on in any coding language

Follow the steps below to create a simple Google Workspace Add-on in Google Cloud Functions without using Apps Script.

Before you begin

This quickstart requires:

A cloud project with billing enabled.
The Cloud SDK logged in and configured with the project.
Terminal open and in an empty directory

Step 1: Create a Google Cloud Function

Enable Cloud Functions, Cloud Build, and the Add-ons API:

gcloud services enable cloudfunctions cloudbuild.googleapis.com gsuiteaddons.googleapis.com

Create the file functions.js containing the source below:

/**
 * Google Cloud Function that loads the homepage for a
 * Google Workspace Add-on.
 *
 * @param {Object} req Request sent from Google
 * @param {Object} res Response to send back
 */
exports.loadHomePage = function addonsHomePage (req, res) {
  res.send(createAction());
};

/** Creates a card with two widgets. */
function createAction() {
  return {
    "action": {
      "navigations": [
        {
          "pushCard": {
            "header": {
              "title": "Cats!"
            },
            "sections": [
              {
                "widgets": [
                  {
                    "textParagraph": {
                      "text": "Your random cat:"
                    }
                  },
                  {
                    "image": {
                      "imageUrl": "https://cataas.com/cat"
                     }
                  }
                ]
              }
            ]
          }
        }
      ]
    }
  };
}

Deploy the function:

gcloud functions deploy loadHomePage --runtime nodejs10 --trigger-http

Verify the function is deployed:
```
gcloud functions call loadHomePage
```

Step 2: Authorize Google to invoke the add-on

Find the service account email for the add-on:
```
gcloud workspace-add-ons get-authorization
```

Grant the service account the cloudfunctions.invoker role:

gcloud functions add-iam-policy-binding loadHomePage --role roles/cloudfunctions.invoker --member serviceAccount:SERVICE_ACCOUNT_EMAIL

Step 3: Create an add-on deployment

Create the file deployment.json with the source below, using the URL of the deployed function:

{
  "oauthScopes": ["https://www.googleapis.com/auth/gmail.addons.execute"],
  "addOns": {
    "common": {
      "name": "My HTTP Add-on",
      "logoUrl": "https://github.com/webdog/octicons-png/raw/master/black/beaker.png",
      "homepageTrigger": {
        "runFunction": "URL"
      }
    },
    "gmail": {},
    "drive": {},
    "calendar": {},
    "docs": {},
    "sheets": {},
    "slides": {}
  }
}

Create the deployment:

gcloud workspace-add-ons deployments create quickstart --deployment-file=deployment.json

Step 4: Install the add-on

Install the deployment in development mode:

gcloud workspace-add-ons deployments install quickstart

Open or reload gmail to view the add-on. In the toolbar on the right, look for a beaker icon.
Click the icon to open the add-on.