Update NIC naming and Readme file

Update systemd NIC naming scheme to match previous behavior.

Various updates made to README.md.

Change-Id: Iba5e6d845794e555ccd6ce8f0a84118461380330

image-builder/Makefile

@@ -26,10 +26,14 @@ DISTRO          ?= ubuntu_focal
 WORKDIR         ?= ./config
 # Specify if you want to specify qcow config directories manually instead of using default naming conventions
 QCOW_CONF_DIRS  ?=
-# Set to true if you want to skip multistrap build step for testing
+# Set to true to skip multistrap.sh script. Useful for testing
 SKIP_MULTISTRAP ?=
-# Set to true if you want to skip the other playsbooks except osconfig for osconfig playbook testing
+# Set to true to skip multistrap playbook. Useful for testing
-OSCONFIG_TEST   ?=
+SKIP_MULTI_ROLE ?=
+# Set to true to skip osconfig playbook. Useful for testing
+SKIP_OSCONFIG_ROLE ?=
+# Set to true to skip livecdcontent playbook. Useful for testing
+SKIP_LIVECDCONTENT_ROLE ?=
 IMAGE           ?= ${DOCKER_REGISTRY}/${IMAGE_PREFIX}/${IMAGE_NAME}:${IMAGE_TAG}-${DISTRO}
 QCOW_IMAGE      ?= ${DOCKER_REGISTRY}/${IMAGE_PREFIX}/${QCOW_IMAGE_NAME}:${IMAGE_TAG}-${DISTRO}
 PROXY           ?=

image-builder/README.md

@@ -45,7 +45,7 @@ sudo make IMAGE_TYPE=qcow cut_image
 
 In the above example, set ``IMAGE_TYPE`` to ``iso`` or ``qcow`` as appropriate. This will be passed into the container to instruct it which type of image to build. Also include ``DOCKER_REGISTRY`` override if you wish to use a local docker image as described in the previous section.
 
-This makefile target uses config files provided in the images/image-builder/config directory. Modify these files as needed in order to customize your iso and qcow generation.
+This makefile target uses config files provided in the `images/image-builder/config` directory. **Modify these files as needed in order to customize your iso and qcow generation.** This provides a good place for adding and testing customizations to build parameters, without needing to modify the ansible playbooks themselves.
 
 # Building behind a proxy
 
@@ -63,6 +63,16 @@ sudo make DOCKER_REGISTRY=mylocalreg PROXY=http://proxy.example.com:8080 IMAGE_T
 sudo make DOCKER_REGISTRY=mylocalreg PROXY=http://proxy.example.com:8080 IMAGE_TYPE=qcow cut_image
 ```
 
+# Useful testing flags
+
+The `SKIP_MULTI_ROLE` build flag is useful if you would like to test local updates to the `osconfig` playbook, or updates to custom configs for this playbook. This saves time since you do not need to rebuild the target filesystem. For example:
+
+```
+sudo make SKIP_MULTI_ROLE=true build
+```
+
+Similiarly, osconfig and livecdcontent roles can be skipped using `SKIP_OSCONFIG_ROLE` and `SKIP_LIVECDCONTENT_ROLE` respectively. `SKIP_LIVECDCONTENT_ROLE` may be useful in combination with `SKIP_MULTI_ROLE` if you want to test out playbook changes to `osconfig` (however, it won't show up in the final bootable ISO image unless you don't skip `SKIP_LIVECDCONTENT_ROLE`).
+
 # Division of Configuration Management responsibilities
 
 Configuration management of the base OS is divided into several realms, each with their own focus:
@@ -87,3 +97,8 @@ Configuration management of the base OS is divided into several realms, each wit
 # Supported OSes
 
 - Ubuntu 20.04 LTS
+
+# FAQ
+
+Q: Why is the build target slow?
+A: There is a `mksquashfs` command which runs as part of the build target, and performs slowly if your build environment lacks certain CPU flags which accelerate compression. Use "host-passthrough" or equivalent in your build environment to pass through these CPU flags. In libvirt domain XML, you would change your `cpu` mode element as follows: `<cpu mode='host-passthrough' check='none'/>`

image-builder/assets/playbooks/roles/multistrap/defaults/main.yaml

@@ -3,7 +3,7 @@ rootfs_arch: amd64
 k8s_version: 1.18.6-00
 kernel_base_pkg: linux-image-generic
 kernel_headers_pkg: linux-headers-generic
-systemd_nic_names_policy: keep kernel database onboard path slot
+systemd_nic_names_policy: kernel database onboard path slot
 systemd_nic_alternative_names_policy: database onboard path slot
 ubuntu_packages:
     - apparmor

image-builder/tools/multistrap.sh

@@ -113,7 +113,7 @@ cp assets/playbooks/inventory.yaml $build_dir/opt/assets/playbooks/inventory.yam
 cp assets/playbooks/base-chroot.yaml $build_dir/opt/assets/playbooks/base-chroot.yaml
 cp -r assets/playbooks/roles/multistrap $build_dir/opt/assets/playbooks/roles
 # Run multistrap
-if [ -z $OSCONFIG_TEST ]; then
+if [ -z $SKIP_MULTI_ROLE ]; then
   sudo -E ansible-playbook -i assets/playbooks/inventory.yaml assets/playbooks/base-chroot.yaml -vv
 fi
 
@@ -126,13 +126,15 @@ else
   mkdir -p $build_dir/config
 fi
 cp -r $workdir/scripts $build_dir/config/
-sudo -E ansible-playbook -i assets/playbooks/inventory.yaml assets/playbooks/base-osconfig.yaml --extra-vars "run_context=common" -vv
+if [ -z "$SKIP_OSCONFIG_ROLE" ]; then
+  sudo -E ansible-playbook -i assets/playbooks/inventory.yaml assets/playbooks/base-osconfig.yaml --extra-vars "run_context=common" -vv
+fi
 
 umount_chroot
 
 cp assets/playbooks/base-livecdcontent.yaml $build_dir/opt/assets/playbooks/base-livecdcontent.yaml
 cp -r assets/playbooks/roles/livecdcontent $build_dir/opt/assets/playbooks/roles
-if [ -z $OSCONFIG_TEST ]; then
+if [ -z "$SKIP_LIVECDCONTENT_ROLE" ]; then
   sudo -E ansible-playbook -i assets/playbooks/inventory.yaml assets/playbooks/base-livecdcontent.yaml -vv
 fi