tests/docker: add basic user mapping support

Currently all docker builds are done by exporting a tarball to the
docker container and running the build as the containers root user.
Other use cases are possible however and it is possible to map a part
of users file-system to the container. This is useful for example for
doing cross-builds of arbitrary source trees. For this to work
smoothly the container needs to have a user created that maps cleanly
to the host system.

This adds a -u option to the docker script so that:

  DEB_ARCH=armhf DEB_TYPE=stable ./tests/docker/docker.py build \
    -u --include-executable=arm-linux-user/qemu-arm \
    debian:armhf ./tests/docker/dockerfiles/debian-bootstrap.docker

Will build a container that can then be run like:

  docker run --rm -it -v /home/alex/lsrc/qemu/risu.git/:/src \
    --user=alex:alex -w /src/ debian:armhf \
    sh -c "make clean && ./configure -s && make"

All docker containers built will add the current user unless
explicitly disabled by specifying NOUSER when invoking the Makefile:

  make docker-image-debian-armhf-cross NOUSER=1

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Fam Zheng <famz@redhat.com>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20170220105139.21581-2-alex.bennee@linaro.org>
Signed-off-by: Fam Zheng <famz@redhat.com>

tests/docker/Makefile.include

@@ -50,6 +50,7 @@ docker-image-%: $(DOCKER_FILES_DIR)/%.docker
 	$(call quiet-command,\
 		$(SRC_PATH)/tests/docker/docker.py build qemu:$* $< \
 		$(if $V,,--quiet) $(if $(NOCACHE),--no-cache) \
+		$(if $(NOUSER),,--add-current-user) \
 		$(if $(EXECUTABLE),--include-executable=$(EXECUTABLE)),\
 		"BUILD","$*")
 
@@ -99,6 +100,7 @@ docker:
 	@echo '                         (default is 1)'
 	@echo '    DEBUG=1              Stop and drop to shell in the created container'
 	@echo '                         before running the command.'
+	@echo '    NOUSER               Define to disable adding current user to containers passwd.'
 	@echo '    NOCACHE=1            Ignore cache when build images.'
 	@echo '    EXECUTABLE=<path>    Include executable in image.'
 

tests/docker/docker.py

@@ -25,6 +25,7 @@ import signal
 from tarfile import TarFile, TarInfo
 from StringIO import StringIO
 from shutil import copy, rmtree
+from pwd import getpwuid
 
 
 DEVNULL = open(os.devnull, 'wb')
@@ -149,13 +150,21 @@ class Docker(object):
         labels = json.loads(resp)[0]["Config"].get("Labels", {})
         return labels.get("com.qemu.dockerfile-checksum", "")
 
-    def build_image(self, tag, docker_dir, dockerfile, quiet=True, argv=None):
+    def build_image(self, tag, docker_dir, dockerfile,
+                    quiet=True, user=False, argv=None):
         if argv == None:
             argv = []
 
         tmp_df = tempfile.NamedTemporaryFile(dir=docker_dir, suffix=".docker")
         tmp_df.write(dockerfile)
 
+        if user:
+            uid = os.getuid()
+            uname = getpwuid(uid).pw_name
+            tmp_df.write("\n")
+            tmp_df.write("RUN id %s 2>/dev/null || useradd -u %d -U %s" %
+                         (uname, uid, uname))
+
         tmp_df.write("\n")
         tmp_df.write("LABEL com.qemu.dockerfile-checksum=%s" %
                      _text_checksum(dockerfile))
@@ -225,6 +234,9 @@ class BuildCommand(SubCommand):
                             help="""Specify a binary that will be copied to the
                             container together with all its dependent
                             libraries""")
+        parser.add_argument("--add-current-user", "-u", dest="user",
+                            action="store_true",
+                            help="Add the current user to image's passwd")
         parser.add_argument("tag",
                             help="Image Tag")
         parser.add_argument("dockerfile",
@@ -261,7 +273,7 @@ class BuildCommand(SubCommand):
                                        docker_dir)
 
             dkr.build_image(tag, docker_dir, dockerfile,
-                            quiet=args.quiet, argv=argv)
+                            quiet=args.quiet, user=args.user, argv=argv)
 
             rmtree(docker_dir)