Run a shell script on dokku app deployment

Question

I've been looking for a way to run a one time script that loads data into our database. Currently we're using dokku-alt for our development environment and we have a python script that runs to update our schema, data and functions we need available for our application. The problem that I'm facing is trying to find a way to run our script on application deployment through dokku-alt.

I've ventured into using a worker, but the workers themselves don't perform how I would expect them to. From what I've noticed is that a worker will terminate every process once it's complete. This is NOT what we need. We need to run the script once to load up our data and schema and close gracefully. We still want our web process to continue working, so the child process sending a kill signal to the other process.

So my question is, is there a way to run a script just one time on deployment without having to write a custom plugin?

05:23:07 schema.1   | started with pid 15
05:23:07 function.1 | started with pid 17
05:23:07 data.1     | started with pid 19
05:23:07 web.1      | started with pid 21
05:23:07 web.1      | Picked up JAVA_TOOL_OPTIONS: -Xmx384m -Xss512k -Dfile.encoding=UTF-8 -Djava.rmi.server.useCodebaseOnly=true
05:23:12 function.1 | Begin dbupdater
05:23:12 function.1 | pq://user:UcW3P587Eki8Fqrr@postgresql:5432/db
05:23:13 schema.1   | Begin dbupdater
05:23:13 data.1     | Begin dbupdater
05:23:13 data.1     | pq://user:UcW3P587Eki8Fqrr@postgresql:5432/db
05:23:13 schema.1   | pq://user:UcW3P587Eki8Fqrr@postgresql:5432/db
05:23:13 schema.1   | do (AccountCrosstabKey_create.sql)
05:23:13 schema.1   | Done
05:23:13 data.1     | do (Accountinfo_data.sql)
05:23:13 function.1 | do (Connectby_create.sql)
05:23:13 function.1 | Done
05:23:13 data.1     | Done
05:23:13 schema.1   | exited with code 0
05:23:13 system     | sending SIGTERM to all processes
05:23:13 function.1 | terminated by SIGTERM
05:23:13 data.1     | terminated by SIGTERM
05:23:13 web.1      | terminated by SIGTERM

Python script:

#!/usr/bin/python
import os
import sys
import glob
import shlex
import subprocess
import postgresql
import postgresql.driver as pg_driver

try:
  print('Begin dbupdater')
  dbhost = os.environ.get('DATABASE_URL','localhost').replace('postgres://', 'pq://')
  print(dbhost)
  targetDir = sys.argv[1]

  db = postgresql.open(dbhost)
  os.chdir(targetDir)
  currDir = os.getcwd()
  for file in glob.glob("*.sql"):
    sqlCmd = ''
    with open(file,'r') as myfile:
      sqlCmd = myfile.read().replace('DO', '').replace('$do$', '')
    db.do('plpgsql',sqlCmd)
    print('do (' + file + ')')
  db.close()
  print('Done')

except (ValueError, KeyError, TypeError) as error:
  print (error)

Answer 1

You can execute this, to rum custom python script in dokku instance.

dokku --rm-container run [APP_NAME] python [your_script_name.py]

--rm-container flag delete the container after script finished.