capsul cloud compute provider web application
Simplify disk setup process
Correct minor doc mistakes
Change mailto links from halp to help



You can also use your local clone with git send-email.


Python Flask web application for capsul.org

#how to run locally

Ensure you have the pre-requisites for the psycopg2 Postgres database adapter package

sudo apt install python3-dev libpq-dev
pg_config --version

Ensure you have the wonderful pipenv python package management and virtual environment cli

sudo apt install pipenv

Create python virtual environment and install packages

# install deps
pipenv install

Run an instance of Postgres (I used docker for this, you can use whatever you want, point is its listening on localhost:5432)

docker run --rm -it -e POSTGRES_PASSWORD=dev -p 5432:5432 postgres

Create a .env file to set up the application configuration:

nano .env

Enter your SMTP credentials like this:


Run the app

pipenv run flask run

Run the app in gunicorn:

pipenv run gunicorn --bind app:app


You can manually mess around with the database like this:

pipenv run flask cli sql -f test.sql
pipenv run flask cli sql -c 'SELECT * FROM vms'

This one selects the vms table with the column name header:

pipenv run flask cli sql -c "SELECT string_agg(column_name::text, ', ') from information_schema.columns WHERE table_name='vms'; SELECT * from vms"

How to modify a payment manually, like if you get a chargeback or to fix customer payment issues:

$ pipenv run flask cli sql -c "SELECT id, created, email, dollars, invalidated from payments"
1, 2020-05-05T00:00:00, forest.n.johnson@gmail.com, 20.00, FALSE

$ pipenv run flask cli sql -c "UPDATE payments SET invalidated = True WHERE id = 1"
1 rows affected.

$ pipenv run flask cli sql -c "SELECT id, created, email, dollars, invalidated from payments"
1, 2020-05-05T00:00:00, forest.n.johnson@gmail.com, 20.00, TRUE

How you would kick off the scheduled task:

pipenv run flask cli cron-task

#postgres database schema management

capsulflask has a concept of a schema version. When the application starts, it will query the database for a table named schemaversion that has one row and one column (version). If the version it finds is not equal to the desiredSchemaVersion variable set in db.py, it will run migration scripts from the schema_migrations folder one by one until the schemaversion table shows the correct version.

For example, the script named 02_up_xyz.sql should contain code that migrates the database from schema version 1 to schema version 2. Likewise, the script 02_down_xyz.sql should contain code that migrates from schema version 2 back to schema version 1.

IMPORTANT: if you need to make changes to the schema, make a NEW schema version. DO NOT EDIT the existing schema versions.

In general, for safety, schema version upgrades should not delete data. Schema version downgrades will simply throw an error and exit for now.

#how to setup btcpay server

Generate a private key and the accompanying bitpay SIN for the btcpay API client.

I used this code as an example: https://github.com/bitpay/bitpay-python/blob/master/bitpay/key_utils.py#L6

$ pipenv run python ./readme/generate_btcpay_keys.py

It should output something looking like this:



In order to register the key with the btcpay server, you have to first generate a pairing token using the btcpay server interface. This requires your btcpay server account to have access to the capsul store. Ask Cass about this.

Navigate to Manage store: Access Tokens at: https://btcpay.cyberia.club/stores/<store-id>/Tokens

Finally, send an http request to the btcpay server to complete the pairing:

curl -H "Content-Type: application/json" https://btcpay.cyberia.club/tokens -d "{'id': 'EXAMPLEwzAEXAMPLEEXAMPLEURD7EXAMPLE', 'pairingCode': 'XXXXXXX'}"

It should respond with a token:


And you should see the token in the btcpay server UI:

Now simply set your BTCPAY_PRIVATE_KEY variable in .env

NOTE: make sure to use single quotes and replace the new lines with \n.


#testing cryptocurrency payments

I used litecoin to test cryptocurrency payments, because its the simplest & lowest fee cryptocurrency that BTCPay server supports. You can download the easy-to-use litecoin SPV wallet electrum-ltc from github.com/pooler/electrum-ltc or electrum-ltc.org, set up a wallet, and then either purchase some litecoin from an exchange, or ask Forest for some litecoin to use for testing.

#sequence diagram explaining how BTC payment process works


This diagram was created with https://app.diagrams.net/. To edit it, download the diagram file and edit it with the https://app.diagrams.net/ web application, or you may run the application from source if you wish.