[Qemu-devel] [RFC PATCH 2/2] add debian-bootstrap.docker target

[Alex Bennée]

Together with some changes to the docker script you can now build an
arbitrary architecture of Debian using debootstrap. To achieve this I
introduce the concept of a HOST_CMD in the docker config file. While
copying the file into workspace the HOST_CMD is run in the docker build
context. This allows debootstrap to set up its first stage before the
container is built.

To build a container you need a command line like:

  DEB_ARCH=armhf DEB_TYPE=testing \
    ./tests/docker/docker.py build --qemu=qemu-arm debian:armhf \
    ./tests/docker/dockerfiles/debian-bootstrap.docker

The DEB_ARCH/DEB_TYPE are expanded in the docker file by the HOST_CMD:

  HOST_CMD fakeroot debootstrap --variant=minbase --foreign \
    --arch=$DEB_ARCH $DEB_TYPE . \
    http://httpredir.debian.org/debian

Signed-off-by: Alex Bennée <address@hidden>
---
 tests/docker/docker.py                           | 27 +++++++++++++++++-------
 tests/docker/dockerfiles/debian-bootstrap.docker | 22 +++++++++++++++++++
 2 files changed, 41 insertions(+), 8 deletions(-)
 create mode 100644 tests/docker/dockerfiles/debian-bootstrap.docker

diff --git a/tests/docker/docker.py b/tests/docker/docker.py
index e9242f3..3ba3d4e 100755
--- a/tests/docker/docker.py
+++ b/tests/docker/docker.py
@@ -21,7 +21,7 @@ import uuid
 import argparse
 import tempfile
 import re
-from shutil import copyfile
+from shutil import copy
 
 def _text_checksum(text):
     """Calculate a digest string unique to the text content"""
@@ -46,7 +46,6 @@ def _find_user_binary(binary_name):
     for x in linux_user:
         check_path = "%s/%s/%s" % (top, x, binary_name)
         if os.path.isfile(check_path):
-            print ("found %s" % check_path)
             return check_path
     return None
 
@@ -58,7 +57,7 @@ def _copy_with_mkdir(src, root_dir, sub_path):
     except OSError:
         print "skipping %s" % (full_path)
 
-    copyfile(src, "%s/%s" % (full_path, os.path.basename(src)))
+    copy(src, "%s/%s" % (full_path, os.path.basename(src)))
 
 class Docker(object):
     """ Running Docker commands """
@@ -117,11 +116,23 @@ class Docker(object):
         tmp_dir = tempfile.mkdtemp(prefix="docker_build")
 
         # Copy the dockerfile into our work space
-        tmp = dockerfile + "\n" + \
-              "LABEL com.qemu.dockerfile-checksum=%s" % \
-              _text_checksum(dockerfile)
+        # line by line, stripping and executing HOST_CMDs
+        #
         tmp_df = tempfile.NamedTemporaryFile(dir=tmp_dir, suffix=".docker")
-        tmp_df.write(tmp)
+
+        for l in open(dockerfile).readlines():
+            m = re.match("HOST_CMD ", l)
+            if m:
+                print "l=%s" % (l)
+                cmd = l[m.end():]
+                r = subprocess.check_call(cmd, cwd=tmp_dir, shell=True)
+                tmp_df.write("# HOST_CMD %s# HOST_RES = %d\n" % (cmd, r))
+            else:
+                tmp_df.write(l)
+
+        tmp_df.write("\n")
+        tmp_df.write("LABEL com.qemu.dockerfile-checksum=%s" %
+                     _text_checksum(dockerfile))
         tmp_df.flush()
 
         # Do we want to copy QEMU into here?
@@ -210,7 +221,7 @@ class BuildCommand(SubCommand):
                 print "Image is up to date."
             return 0
 
-        dkr.build_image(tag, dockerfile, quiet=args.quiet, qemu=qbin, 
argv=argv)
+        dkr.build_image(tag, args.dockerfile, quiet=args.quiet, qemu=qbin, 
argv=argv)
         return 0
 
 class CleanCommand(SubCommand):
diff --git a/tests/docker/dockerfiles/debian-bootstrap.docker 
b/tests/docker/dockerfiles/debian-bootstrap.docker
new file mode 100644
index 0000000..44d107d
--- /dev/null
+++ b/tests/docker/dockerfiles/debian-bootstrap.docker
@@ -0,0 +1,22 @@
+# Create Debian Bootstrap Image
+#
+# This is intended to be pre-poluated by:
+#  - a first stage debootstrap
+#  - a native qemu-$arch that binfmt_misc will run
+FROM scratch
+
+# HOST_CMD is executed by docker.py while building the context
+HOST_CMD fakeroot debootstrap --variant=minbase --foreign --arch=$DEB_ARCH 
$DEB_TYPE . http://httpredir.debian.org/debian
+
+# Add everything from the context into the container
+ADD . /
+
+# Patch all mounts as docker already has stuff set up
+RUN sed -i 's/in_target mount/echo not for docker in_target mount/g' 
/debootstrap/functions
+
+# Run stage 2
+RUN /debootstrap/debootstrap --second-stage
+
+# At this point we can install additional packages if we want
+#RUN apt-get update
+#RUN apt-get dist-upgrade
-- 
2.7.4