Makefile order is never satisfied

I have the following project Structure:

| .
| ..
| 
| Makefile
| a
  | .
  | ..
  | Dockerfile
  \ Makefile
\ b
  | .
  | ..
  | Dockerfile
  \ Makefile

a/Makefile:

all:
<TAB>docker build -t a-image .

b/Makefile:

all:
<TAB>docker build -t b-image .

b/Dockerfile:

FROM a-image
...

Makefile:

all: a b

a:
<TAB>make -C a/ all

b: a
<TAB>make -C b/ all

For some reason, when I run make all in the root directory of the ptoject, I never get a built and receive an error while building b as it depends on a.

...
pull access denied for a-image, repository does not exist or may require 'docker login': denied: requested access to the resource is denied
...

What am I doing wrong?

Make's principal mode of operations is around files. Your Makefile says, if a file a doesn't exist, here are rules to create it; and if b doesn't exist, a must (build it if necessary), and here are rules to create it.

In your example, though, both a and b are directories that exist on disk. Make is able to look at the disk and say "a filesystem entry named a already exists" and skip the corresponding rules.

If you're using GNU Make and are just trying to use Make as a script runner rather than a build system, you can declare the directory rules as .PHONY. This will cause Make to ignore the fact that the files already exist, and always consider those rules out-of-date.

# in the top-level Makefile, anywhere, unindented
.PHONY: a b

I might suggest a better approach is to embrace Make's file-oriented model. Whenever you do something, make sure you create a file and update its timestamp with touch(1) to record that fact. In a/Makefile, for example, you could use a sentinel file to record the image build

.PHONY: all
all: .docker-build

.docker-build: Dockerfile
        docker build -t a-image .
        touch "$@"

Now in the parent Makefile, you know that make -C a will create a/.docker-build, and you can use that as the dependency target.

.PHONY: all
all: b/.docker-build

a/.docker-build:
        $(MAKE) -C a

b/.docker-build: a/.docker-build
        $(MAKE) -C b

If you delete the .PHONY lines this will work with any Make implementation.