On Thu 2022-12-29 @ 01:56:51 PM, Richard Purdie wrote:
> There are variations on this, such as a conditional append on some
> override to SRC_URI but the fundamental problem is one of cleanup when
> unpack is to rerun.

...just to elaborate a bit more on this variation for everyone's benefit
(Richard already understands the details of my scenario):

Some recipes require us to generate config files by hand in order to get a
piece of software/service to work a correctly in our environment. A concrete
example could be specifying the IP address of a time server to use for clock
synchronization in chrony's /etc/chrony.conf file. Another example could be to
provide a /etc/network/interfaces file so networking works on a given device
in our specific network.

In my case I might want to build the same image, for the same device, but use
two different sets of config files. If the device is going to run on my
non-routable network then it will use CONDITION1 config files. If I want to
build a set of images for devices running on my routable network then I'll
need to use the CONDITION2 set of config files:

        meta-project
        ├── README
        ├── conf
        │   └── layer.conf
        └── recipes-configfiles
            ├── chrony
            │   ├── chrony_%.bbappend
            │   └── files
            │       ├── condition1
            │       │   └── chrony.conf
            │       └── condition2
            │           └── chrony.conf
            └── init-ifupdown
                ├── files
                │   ├── condition1
                │   │   └── interfaces
                │   └── condition2
                │       └── interfaces
                └── init-ifupdown_%.bbappend

Then, somewhere, I either specify:

        MACHINEOVERRIDES .= ":condition1"

or:

        MACHINEOVERRIDES .= ":condition2"

NOTE: using "OVERRIDES .= ":conditionX" doesn't work, it has to be a
      MACHINEOVERRIDES since not all overrides are evaluated for the fetcher
      in order to save parsing time (is that correct?)

If I do a:

        $ bitbake <recipe> -c cleansstate

(perhaps "-c clean" would be enough?) then perform a build, I always get the
correct set of config files in my image. If I don't do a clenastate between
builds in which I change the override, then I simply get the last config file
that's in the WORKDIR.