How to perform periodic task with Flask in Python

Question

I\'ve been using Flask to provide a simple web API for my k8055 USB interface board; fairly standard getters and putters, and Flask really made my life a lot easier.

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Answer 1

You could use cron for simple tasks.

Create a flask view for your task.

# a separate view for periodic task
@app.route('/task')
def task():
    board.read()
    board.digital_outputs = board.digital_inputs

Then using cron, download from that url periodically

# cron task to run each minute
0-59 * * * * run_task.sh

Where run_task.sh contents are

wget http://localhost/task

Cron is unable to run more frequently than once a minute. If you need higher frequency, (say, each 5 seconds = 12 times per minute), you must do it in tun_task.sh in the following way

# loop 12 times with a delay
for i in 1 2 3 4 5 6 7 8 9 10 11 12
do
    # download url in background for not to affect delay interval much
    wget -b http://localhost/task
    sleep 5s
done