[PYTHON] A story about a 503 error on Heroku open

This is the first post. Even if it is too long, I will get tired, so I write it in rough sentences. Please note that it may be difficult to read. This article is based on the article here .

environment

WSL2（Ubuntu-20.04 LTS） Docker Heroku Line-bot-sdk=1.18.0 Flask=1.1.2

Deploy to Heroku

As a premise

--Registration of line developers --Install Flask and line-bot-sdk --Register with Heroku --Application registration --Environment variable settings --webhook settings --Creating a configuration file

I would like to proceed as if it is over.

Reflect and deploy changes

# git add .
# git commit -am "make it better"
# git push heroku main

Confirm deployment

 # heroku open
  ▸    Error opening web browser.
  ▸    Error: Exited with code 3
  ▸

▸ Manually visit https: // your application name.herokuapp.com/ in your browser.

When I opened "https: // your application name.herokuapp.com/" in chrome, an application error occurred on the screen below.

• Normally, Hello World is displayed.

Try heroku logs --tail! It is said that it will be confirmed.

# heroku logs --tail

2020-12-22T11:49:11.712077+00:00 heroku[router]: at=error code=H14 desc="No web processes running" method=GET 

path = "/" host = your application name.herokuapp.com ... 2020-12-22T11:49:12.443226+00:00 heroku[router]: at=error code=H14 desc="No web processes running" method=GET p ath = "/ favicon.ico" host = your application name.herokuapp.com ...

Code = H14, status = 503, so consider countermeasures. I searched online and found the following method.

Method 1

 # heroku ps:scale web=1

Method 2

Restart Heroku

 # heroku restart --app application_name
 # heroku stack:set container

There was a method such as, but it failed. After that, the result of various investigations.

 # cd `your-app-dir`
 echo "web: $(basename `pwd`)" > Procfile

As a result of doing, the error statement changed. Apparently, it was a misspelling of "Procfile" as "Profile": sweat_smile :. The error statement after changing the Procfile is as follows.

2020-12-22T12: 38: 17.494371 + 00: 00 heroku [router]: at = error code = H10 desc = "App crashed" method = GET path = "/" host = Anna Application name.herokuapp.com ... 2020-12-22T12: 38: 18.016959 + 00: 00 heroku [router]: at = error code = H10 desc = "App crashed" method = GET path = "/" host = Ah Your application name.herokuapp.com ... 2020-12-22T12:38:18.602766+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path = "/ favicon.ico" host = your application name.herokuapp.com ...

Since Code = H10, status = 503, I tried methods 1 and 2 again, but failed. Trial and error for several hours ... When I was looking at main.py, the cause was found.

The cause was a misspelling in an environment variable: joy :. 「SECRET」→「SELECT」

Wrong code:

$ heroku config: set YOUR_CHANNEL_SELECT = "Channel Secret string" --app Your application name

Correct code:

$ heroku config: set YOUR_CHANNEL_SECRET = "Channel Secret string" --app Your application name

It turned out that the environment variable was wrong, so I corrected the relevant part of the code in main.py to "SECRET" and From Heroku.com The problem was solved by manually resetting the environment variables in Applications-> Settings-> Config Vars.

Safely, "Hello World" was displayed on the browser.

References

https://qiita.com/shimajiri/items/cf7ccf69d184fdb2fb26 https://qiita.com/yagi_eng/items/9308b680e6ee41ab1d6d