Applying Makejails

Maybe you have a jail already created to which you want to make some changes, but simply running a Makejail is not useful for your case since it will be recreated, so you create a script in the language of your choice, but you realize that you need to write more things than simply creating a Makejail. The solution to this problem is to apply a Makejail to an existing jail to take advantage of the Makejail instructions.

Suppose we create a jail that has xrdp and some DE like lxde and we forget to install some applications that we use daily, so to solve it we create a Makejail that by convention we name Makejail.apply.

Makejail.apply:

STAGE apply

PKG telegram-desktop \
    xpdf \
    librewolf
    mesa-dri

As you can see, we need to put STAGE apply before the instructions are executed.

To apply this Makejail just execute appjail-apply(1).

appjail apply xrdp Makejail.apply

appjail-apply(1) does not require the jail to be started, it only needs an existing jail. This implies that some instructions that are intended to be executed in a started jail should not work.

Notes

Note that applying a Makejail is not executed in the same way as executing instructions in the build stage. The build stage uses a buildscript (simply a script that is executed in this stage) and the apply stage uses an initscript that is temporarily generated to execute the instructions you defined in your Makejail. The problem is the actual directory as you can see below:

# cat Makejail
OPTION start
OPTION overwrite=force

INCLUDE a/Makejail

CMD --local echo "main:"
CMD --local pwd
# cat a/Makejail
INCLUDE b/Makejail

CMD --local echo "a:"
CMD --local pwd
# cat a/b/Makejail
INCLUDE c/Makejail

CMD --local echo "b:"
CMD --local pwd
# cat a/b/c/Makejail
CMD --local echo "c:"
CMD --local pwd
# appjail makejail -j jtest
...
c:
/tmp/a/a/b/c
b:
/tmp/a/a/b
a:
/tmp/a/a
main:
/tmp/a
...

As you can see above, by not defining any stage the build stage is used in those Makejails, so the current directory is implicitly defined. But if we use the apply stage:

# cat Makejail
OPTION start
OPTION overwrite=force

INCLUDE a/Makejail

STAGE apply

CMD --local echo "main:"
CMD --local pwd
# cat a/Makejail
INCLUDE b/Makejail

STAGE apply

CMD --local echo "a:"
CMD --local pwd
# cat a/b/Makejail
INCLUDE c/Makejail

STAGE apply

CMD --local echo "b:"
CMD --local pwd
# cat a/b/c/Makejail
STAGE apply

CMD --local echo "c:"
CMD --local pwd
# appjail apply jtest
...
c:
/tmp/a
b:
/tmp/a
a:
/tmp/a
main:
/tmp/a
...