Fix diskimage-create tox, add ``build`` and ``test`` targets

Improve end user experience with building a Octavia Amphora
diskimage through tox/virtualenv.

Change-Id: I8672d039a5b7ded57323aeb99f484fe7f2838fef
Task: 29059
Story: 2004847

diskimage-create/README.rst

@@ -48,7 +48,7 @@ Ubuntu
 
 .. code:: bash
 
-   $ sudo apt install qemu git kpartx debootstrap
+   $ sudo apt install qemu-utils git kpartx debootstrap
 
 Fedora, CentOS and Red Hat Enterprise Linux
 
@@ -228,6 +228,18 @@ an OSP repository):
 
     $ export REG_SAT_URL="<satellite url>" REG_ORG="<satellite org>"
 
+Building in a virtualenv with tox
+---------------------------------
+To make use of a virtualenv for Python dependencies you may run ``tox``.  Note that
+you may still need to install binary dependencies on the host for the build to succeed.
+
+If you wish to customize your build modify ``tox.ini`` to pass on relevant
+environment variables or command line arguments to the ``diskimage-create.sh`` script.
+
+.. code:: bash
+
+    $ tox -e build
+
 
 Container Support
 =================

diskimage-create/diskimage-create.sh

@@ -284,10 +284,11 @@ fi
 
 # Make sure we have the required packages installed
 if [ "$platform" = 'NAME="Ubuntu"' ]; then
-    PKG_LIST="qemu git"
+    PKG_LIST="qemu-utils git kpartx debootstrap"
     for pkg in $PKG_LIST; do
         if ! dpkg --get-selections | grep -q "^$pkg[[:space:]]*install$" >/dev/null; then
             echo "Required package " $pkg " is not installed.  Exiting."
+	    echo "Binary dependencies on this platform are: ${PKG_LIST}"
             exit 1
         fi
     done
@@ -307,6 +308,7 @@ elif [[ $platform =~ "SUSE" ]]; then
     for pkg in $PKG_LIST; do
         if ! rpm -q $pkg &> /dev/null; then
             echo "Required package " ${pkg/\*} " is not installed.  Exiting."
+	    echo "Binary dependencies on this platform are: ${PKG_LIST}"
             exit 1
         fi
     done
@@ -318,6 +320,7 @@ else
     for pkg in $PKG_LIST; do
         if ! rpm -qa $pkg ; then
             echo "Required package " ${pkg/\*} " is not installed.  Exiting."
+	    echo "Binary dependencies on this platform are: ${PKG_LIST}"
             exit 1
         fi
     done

diskimage-create/tox.ini

@@ -1,10 +1,13 @@
 [tox]
 minversion = 1.8
-envlist = bashate,docs,py27
+envlist = bashate,docs,build,test
 skipsdist = True
 
 [testenv]
+basepython = python3
+envdir = {toxworkdir}/venv
 setenv = VIRTUAL_ENV={envdir}
+passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
 install_command = pip install -U {opts} {packages}
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
@@ -13,12 +16,6 @@ whitelist_externals =   virt-filesystems
                         awk
                         mkdir
                         rm
-commands =  mkdir -p {toxinidir}/.amp_tox_test
-            ./diskimage-create.sh -o {toxinidir}/.amp_tox_test/amphora-x64-haproxy -w {toxworkdir}
-# Work around tox limitations with command pipes
-# https://bitbucket.org/hpk42/tox/issue/73/pipe-output-of-command-into-file
-            ./image-tests.sh {toxinidir}/.amp_tox_test
-            rm -rf {toxinidir}/.amp_tox_test
 
 [testenv:docs]
 commands = doc8 README.rst ../elements/haproxy-octavia/README.rst ../elements/root-passwd/README.rst
@@ -27,3 +24,14 @@ commands = doc8 README.rst ../elements/haproxy-octavia/README.rst ../elements/ro
 commands = bashate diskimage-create.sh
             bashate image-tests.sh
 
+[testenv:build]
+# NOTE: specify cache directory explicitly with -c as the `diskimage-create.sh`
+# default is based off of `$HOME` which is not passed on in a `tox` environment.
+commands =  mkdir -p {toxinidir}/.amp_tox_test
+            ./diskimage-create.sh -o {toxinidir}/.amp_tox_test/amphora-x64-haproxy -w {toxworkdir} -c {toxworkdir}/.cache
+
+[testenv:test]
+# Work around tox limitations with command pipes
+# https://bitbucket.org/hpk42/tox/issue/73/pipe-output-of-command-into-file
+commands =  ./image-tests.sh {toxinidir}/.amp_tox_test
+            rm -rf {toxinidir}/.amp_tox_test