nfvbenchvm: fix broken build after dib update

Attempting to build nfvbench VM images with diskimage_builder (dib)
3.16.0 leads to the following error:

diskimage_builder.element_dependencies.MissingElementException: Element
'block-device' not found

Something changed at some point of diskimage_builder history, and the
updated doc states: "When using the vm element, an element that provides
block-device should be included".

To fix this and prevent future similar issues, this patch:
- adds the "block-device-mbr" element to the dependency list
- sets diskimage_builder version

By the way:
- replace the deprecated "centos7" element with the more generic
  "centos" element.
- add missing dependencies in the pre-requisites section of nfvbenchvm
  doc
- install pip with package manager (the current latest version of
  get-pip.py is not compatible with python 3.6, so let's use the
  occasion to stop getting pip directly from the Internet)
- use Python 3 in build-image.sh

Change-Id: I3198a1042eca04224b2a62db443c39a76903cf22
Signed-off-by: Gwenael Lambrouin <gwenael.lambrouin@orange.com>

1 files changed, 9 insertions, 5 deletions

diff --git a/nfvbenchvm/dib/build-image.sh b/nfvbenchvm/dib/build-image.sh
index 6339f01..4559bb6 100755
--- a/nfvbenchvm/dib/build-image.sh
+++ b/nfvbenchvm/dib/build-image.sh
@@ -3,7 +3,8 @@
 # A shell script to build the VPP VM image or NFVbench+TRex VM image using diskinage-builder
 #
 # The following packages must be installed prior to using this script:
-# sudo apt-get -y install python-virtualenv qemu-utils kpartx
+# Ubuntu: sudo apt-get -y install python3 python3-venv qemu-utils kpartx
+# CentOS: sudo yum install -y python3 qemu-img kpartx
 
 usage() {
     echo "Usage: $0 [-l] [-g] [-v]"
@@ -77,9 +78,9 @@ function build_image {
         if [ -d dib-venv ]; then
            . dib-venv/bin/activate
         else
-           virtualenv dib-venv
+           python3 -m venv dib-venv
            . dib-venv/bin/activate
-           pip install diskimage-builder
+           pip install diskimage-builder==3.16.0
         fi
 
         # Add nfvbenchvm_centos elements directory to the DIB elements path
@@ -110,8 +111,11 @@ function build_image {
            export TREX_VER=$(awk '/ENV TREX_VER/ {print $3}' ../../docker/Dockerfile | sed 's/"//g' | sed 's/\r//g')
         fi
 
+        # Specify CentOS version
+        export DIB_RELEASE=7
+
         echo "Building $1.qcow2..."
-        time disk-image-create -o $1 centos7 nfvbenchvm
+        time disk-image-create -o $1 centos nfvbenchvm
     fi
 
     ls -l $1.qcow2
@@ -146,4 +150,4 @@ else
        echo "Build generator image"
        build_image $generator_image_name
     fi
-fi
\ No newline at end of file
+fi