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Simple API Part 2 - Building a Deep Work Logger with Flask, Slack and Google Docs

Posted by Bob on Fri 10 March 2017 in Flask • 3 min read

After Simple API - part 1 a more practical app in this part 2 tutorial: a Deep Work logger integrating Google docs and Slack, including deployment of the app to Heroku.

Sometimes you come across an article you think: "I definitely need to play with this!", enter Google Spreadsheets and Python.

I decided to make a Flask app to log the amount of deep work. Why? Read the book, in short: it is a powerful success habit.


So we have the API = Flask, the back-end = Google Docs. What about the interface?

I wanted something for both laptop and mobile = Slack. Enter the Slack API / Slash Commands. I defined this super basic interface:

/dw <time> (<activity>)
- /dw is the slack command
- time can be an int (hour) or more specifically hh:mm
- activity is optional, if not provided it defaults to the name of the channel

Step by step

Here is roughly what I did. I document it here so you can start building something similar to scratch your own itch. The code so far is here.

  • To be able to write to a Google Doc follow Google Spreadsheets and Python to create an app via the Google API and obtain the client_secret.json file.

  • pip install flask and pygsheets, implement GET and POST, again more details here. I used Flask's HTTP Basic Auth snippet to protect the GET. For the POST I verify the Slack token. As good practice I stored user/pw in (OS) env variables. I defined some helpers in

  • Deploy the app to Heroku (Free plan), I was so glad I took notes some time ago (section "Deployment to Heroku"). I captured the steps as good as I could here (I will adjust next time I deploy an app to Heroku).

  • Deploying an app is a challenge in itself. For example how do you get the client_secret.json file in Heroku? I had to go with this (not ideal) workaround.

    # put client_secret.json in .gitignore on master
    # commit it to secret-branch you keep between localhost and Heroku (not Github)
    $ git push heroku secret-branch:master
  • Create a Slack app, then a Slash Command where I defined:

    • Command: /dw
    • URL = API endpoint on Heroku
    • Method = POST
    • Token = generated, I put that in env variable SLACK_DW_CMD_TOKEN above
    • You can set an Autocomplete help text which is useful to your team
    • This is the payload Slack sends to your API for consumption:

      user_name=bbelderbos  -> cool: the app can be used by the whole team on Slack

      See the parsing of it in the post_entry method.

The app in action

the complete flow

Lessons learned

  • Scratch your own itch. This was a nice exercise to integrate with apps I often use. It taught me a lot because I got stuck so had to debug.

  • For example Slack does not seem to use JSON so in my Flask I had to change request.json to request.form, using ngrok speeded up the debugging.

  • I lost quite some time struggling with gspread (used in the mentioned Twilio article) which was way too slow (2 min for a POST request?!), using pygsheets response times went down to 1-2 seconds or less which made Slack, Heroku and me happy. Lesson: fail fast and small, compare different libraries, and obviously read article comments first before trying!

Keep Calm and Code in Python!

-- Bob

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