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How to set application specific values ?
I have been trying to find out how application specific values can be gathered during the first boot and then later used to configure the application.
I guess this is done with inithooks: /docs/inithooks but I fail to see how the magic happens.
E.g. I have been checking jenkins. In overlay/usr/lib/inithooks/firstboot.d/40jenkins
#!/bin/bash -e # set jenkins admin password . /etc/default/inithooks [ -e $INITHOOKS_CONF ] && . $INITHOOKS_CONF $INITHOOKS_PATH/bin/setpass.py admin --pass="$APP_PASS"
Here the APP_PASS variable has got the value somehow automatically ? The setpass.py script is part of TKLCore as it's not found from jenkins repository ? How TKLCore knows how to configure jenkins ? Obviously I have to set my application specific settings myself ? How the inithooks knows what settings I want to ask from the user ?
Replies (2)
Yes inithooks do the magic...
Reply 1The magic revealed
Reply 2I checked Gitlab's inithooks and finally figured this out.
There is two components that contains general boilerplate code and appliance specific code.
First is inithooks/firstboot.d/40oracle:
#!/bin/bash -e . /etc/default/inithooks [ -e $INITHOOKS_CONF ] && . $INITHOOKS_CONF $INITHOOKS_PATH/bin/oracle.py --dbpass="$DB_PASS"
This file is the hook so that appliance specific inithooks/bin/oracle.py file will be executed. The value for DB_PASS variable can be set in preseeding (in file /etc/inithooks.conf), but I don't use preseeding so in my case it is unnecessary. The name of DB_PASS has no magic and it could be e.g. FOO instead.
If the value has not been preseeded then inithooks/bin/oracle.py uses dialog_wrapper Python module to ask it from the user. Below is an example of the minimal script that reads a single piece of information from a user:
#!/usr/bin/python
"""Set Oracle XE SYS-user password for silent installation
Option:
--dbpass= unless provided, will ask interactively
"""
import sys
import getopt
from dialog_wrapper import Dialog
def usage(s=None):
if s:
print >> sys.stderr, "Error:", s
print >> sys.stderr, "Syntax: %s [options]" % sys.argv[0]
print >> sys.stderr, __doc__
sys.exit(1)
def main():
try:
opts, args = getopt.gnu_getopt(sys.argv[1:], "h",
['help', 'dbpass='])
except getopt.GetoptError, e:
usage(e)
dbpassword = ""
for opt, val in opts:
if opt in ('-h', '--help'):
usage()
elif opt == '--dbpass':
dbpassword = val
if not dbpassword:
d = Dialog('TurnKey Linux - First boot configuration')
dbpassword = d.get_password(
"Oracle XE SYS Password",
"Enter new password for the Oracle XE SYS-user.")
#
# appliance specific code that uses dbpassword variable goes here
#
if __name__ == "__main__":
main()
All this is in fact described in /docs/inithooks but it took me some time understand that.
I can't speak for Jenkins, but the point of having them as variables is so that they can be preseeded (e.g. by the values entered in the TKL Hub pre-launch WebUI). If the variables have no value then the firstboot scripts will ask...
TBH I just had a look and you appear to be right (in the fact that setpass.py doesn't seem to be a part of Jenkins itself) so as you suggest perhaps it's a part of Core (although TBH I wouldn't think that Core would need it...). Unfortunately I (still) haven't had time to play with TKLDev yet and so can't help much in that regard, but it must be somewhere and I suspect that you may be able to leverage that same script for your own password creation...
inithooks will just run each script in ../firstboot.d (in order). And as I said above, if a value hasn't already been fed in (via preseeding) then it will ask... Different appliances will have different firstboot scripts...