Drop docker support

.github/workflows/linux.yml

@@ -19,6 +19,3 @@ jobs:
       - name: Run the test suite
         run: ./mktree.oci check --interactive=false -j$(nproc)
         working-directory: ./tests
-
-    env:
-      MKTREE_ENGINE: podman

INSTALL

@@ -201,9 +201,9 @@ This also creates and installs the new platform file e.g.
 
 
 Rpm comes with an automated self-test suite. The test-suite requires podman
-(https://github.com/containers/podman/) or docker (https://github.com/docker/).
-It is disabled by default to avoid the dependencies but can be enabled with
--DENABLE_TESTSUITE=ON.  The test-suite can be executed with:
+(https://github.com/containers/podman/). It is disabled by default to avoid the
+dependencies but can be enabled with -DENABLE_TESTSUITE=ON. The test-suite can
+be executed with:
 
     make check
 

tests/CMakeLists.txt

@@ -78,13 +78,12 @@ endif()
 # Set up mktree
 set(MKTREE_BACKEND oci CACHE STRING "Mktree backend to use")
 if (MKTREE_BACKEND STREQUAL oci)
-	find_program(PODMAN podman)
-	find_program(DOCKER docker)
-	mark_as_advanced(PODMAN DOCKER)
+	find_program(PODMAN podman REQUIRED)
+	mark_as_advanced(PODMAN)
 	os_release(OS_NAME ID)
 	os_release(OS_VERSION VERSION_ID)
 	set(DOCKERFILE ${CMAKE_CURRENT_SOURCE_DIR}/Dockerfile.${OS_NAME})
-	if (PODMAN AND EXISTS ${DOCKERFILE})
+	if (EXISTS ${DOCKERFILE})
 		set(MKTREE_NATIVE yes)
 		configure_file(${DOCKERFILE} Dockerfile COPYONLY)
 		add_custom_target(ci
@@ -97,7 +96,6 @@ if (MKTREE_BACKEND STREQUAL oci)
 		set(MKTREE_NATIVE no)
 		configure_file(Dockerfile Dockerfile COPYONLY)
 	endif()
-	find_program(PODMAN NAMES podman docker REQUIRED)
 elseif (MKTREE_BACKEND STREQUAL rootfs)
 	set(MKTREE_NATIVE yes)
 	find_program(BWRAP bwrap REQUIRED)

tests/README.md

@@ -9,10 +9,8 @@ interactive shell (via `make shell`).
 
 ## Prerequisites
 
-To use this test-suite, you need either of:
-
-1. [Podman](https://github.com/containers/podman/)
-2. [Docker](https://github.com/docker/)
+To use this test-suite, you'll need to have
+[Podman](https://github.com/containers/podman/) installed.
 
 > [!IMPORTANT]
 > CMake integration (*native* mode) is currently only available on **Fedora

tests/mktree.oci

@@ -9,13 +9,11 @@ if [ "$PROGRAM" == "mktree" ]; then
     # Running from build directory
     CMAKE=yes
     NATIVE=@MKTREE_NATIVE@
-    PODMAN=@PODMAN@
     CONTEXT=@CMAKE_SOURCE_DIR@
 else
     # Running from source directory
     CMAKE=no
     NATIVE=no
-    PODMAN=${MKTREE_ENGINE:-podman}
     CONTEXT=..
 fi
 
@@ -25,6 +23,7 @@ else
     FROM=
 fi
 
+PODMAN=podman
 CACHE_DIR="mktree.cache"
 IID_FILE="$CACHE_DIR/image-id"
 IMAGE_ID=$(cat $IID_FILE 2>/dev/null || echo "")