sam-python-slackapp-template

This repository is an a simple template to create a ready working slack events api using serverless application model and hosted on AWS. Clone the repository and follow the setup process detailed below. The basic template slack API will create a an events api that will respond with the reversed text of the message sent to the event. It also correctly responds to the slack challenge. It will also verify slack requests if it is a prod deployment/stage.

This is based of the sam cli init template.

The application when deployed will allow you to configure a slack bot that will return what the user says reversed.

.
├── Pipfile                     <-- Pipfile
├── Pipfile.lock                <-- Pipfile.lock
├── README.md                   <-- This instructions file
├── src                         <-- Source code for a lambda function
│   ├── __init__.py
│   ├── version.py              <-- Holds version of your code/template
│   └── app.py                   <-- Lambda function code
│   └── helpers.py              <-- Lambda function code
├── requirements.txt            <-- Python dependencies
├── templates
│       ├── template.yml        <-- SAM template
        ├── variables.json      <-- Variables for sam local testing
└── tests                       <-- Unit tests
    └── unit
        ├── __init__.py
        └── test_handler.py     <-- Slack challenge test
└── scripts                     <-- Hosts scripts
    └── build.sh                <-- Builds application
    └── test.sh                 <-- Runs tests
    └── deploy.sh               <-- Deploys application to aws
    └── sam-local.sh            <-- Runs the applicaiton locally

Requirements

AWS CLI already configured with at least PowerUser permission
Python 3.6+ installed
Docker installed
Python Virtual Environment
An Aws Account

See Serverless Application Model (SAM) HOWTO Guide for more details on SAM.

AWS Requirements

When you deploy the slack app it assumes that you have 2 things.

An S3 bucket that you can store lambda code in
A secrets manager secret that you can store Slack API secrets

S3 Bucket

You will need to set up a simple S3 bucket that sam can use to upload your code to S3 so it can be imported and used in lambda. Make sure when you are replacing variables in the script that your profile has the ability to upload to S3.

Secrets Manager

For the slack app we need to store 2 secrets in one secret in AWS Secrets manager.

Your signing secret
Your bot token so that your bot can accept requests.

Your secret will look like the following.

{
  "BOT_TOKEN": "REPLACE_WITH_YOUR_BOT_TOKEN",
  "SIGNING_SECRET": "REPLACE_WITH_YOUR_SIGNING_SECRET"
}

The application will use these secrets to perform checks to verify requests and send messages.

Setup process

NOTE: When you run scripts it should be run from the root directory e.g. ./scripts/scriptname.sh NOTE: Before running the scripts change variables in the scripts

Installing dependencies

AWS Lambda requires a flat folder with the application as well as its dependencies. Therefore, we need to have a 2 step process in order to enable local testing as well as packaging/deployment later on.

pipenv install

I have simplified the build process you can run it with the following

./scripts/build.sh

Local development

Invoking function locally through local API Gateway

./scripts/sam-local.sh

If the previous command ran successfully you should now be able to hit the following local endpoint to invoke your function http://localhost:3000/

Packaging

AWS Lambda Python runtime requires a flat folder with all dependencies including the application. SAM will use CodeUri property to know where to look up for both application and dependencies:

...
    ApiLambdaFunction:
        Type: AWS::Serverless::Function
        Properties:
            CodeUri: ../src/build/
            ...

You can package the application using the following command.

./scripts/build.sh

Deployment

You can deploy your application using the following script

./scripts/deploy.sh dev/test/prod

The argument for this script should be dev/test/prod depending on what stage you are deploying too.

After deployment is complete stack outputs will be printed. You can grab the one labeled SlackApiUrl and put that into your slack bots event URL.

Testing

We use Pytest for testing our code and you can install it using pip: pipenv install --dev

You can run one of the scripts in the scripts folder to run your tests.

./scripts/test.sh

Uses

Python Slack Client

Todo

Change the automation to be built with ansible. Not hard im just lazy.
Fix the shell scripts to be work not from root directory
Write some documentation around deploying to code pipeline.
Fix that issue that causes the bot to reply twice. Needs to send a response quicker.

Beartime234/sam-python-slackapp-template