Remove config of container_build_tool

Because there is no docker supported anymore, remove all custom
config of "container_build_tool", only "buildah" is supported.

Change-Id: I57720cc1d7da96f9277b62298cabce9ff7765f47

README.rst

@@ -25,9 +25,6 @@ Role Variables
    * - `target_image`
      - `[undefined]`
      - If set, the modified image will be tagged with `target_image + modified_append_tag`. If `target_image` is not set, the modified image will be tagged with `source_image + modified_append_tag`. If the purpose of the image is not changing, it may be enough to rely on the `source_image + modified_append_tag` tag to identify that this is a modified version of the source image.
-   * - `container_build_tool`
-     - `buildah`
-     - Tool used to build containers, can be only 'buildah'
 
 .. list-table:: Variables used for yum update
    :widths: auto
@@ -55,13 +52,10 @@ Role Variables
    * - `yum_repos_dir_path`
      - `None`
      - Optional path of directory to be used as `/etc/yum.repos.d` during the update
-   * - `container_build_tool`
-     - See modify image variables
    * - `yum_cache`
      - `None`
      - Optional path to the host directory for yum cache during the update.
        Requires an overlay-enabled FS that also supports SE context relabling.
-       Works only with container_build_tool=buildah.
    * - `force_purge_yum_cache`
      - `False`
      - Optional argument that tells buildah to forcefully re-populate the yum
@@ -89,8 +83,6 @@ Role Variables
    * - `yum_repos_dir_path`
      - `None`
      - Optional path of directory to be used as `/etc/yum.repos.d` during the update
-   * - `container_build_tool`
-     - See modify image variables
 
 
 .. list-table:: Variables used for dev install
@@ -109,8 +101,6 @@ Role Variables
    * - `target_image`
      - `''`
      - See modify image variables
-   * - `container_build_tool`
-     - See modify image variables
    * - `refspecs`
      - `[]`
      - An array of project/refspec pairs that will be installed into the generated container. Currently only supports python source projects.
@@ -151,7 +141,6 @@ The following playbook will produce a modified image with the tag
         vars:
           source_image: docker.io/tripleomaster/centos-binary-nova-api:latest
           modify_dir_path: /path/to/example_modify_dir
-          container_build_tool: buildah
 
 The directory `example_modify_dir` contains the `Dockerfile` which will perform
 the modification, for example:
@@ -192,7 +181,6 @@ In this playbook the tasks\_from is set as a variable instead of an
           source_image: docker.io/tripleomaster/centos-binary-nova-api:latest
           yum_repos_dir_path: /etc/yum.repos.d
           modified_append_tag: updated
-          container_build_tool: buildah
           yum_cache: /tmp/containers-updater/yum_cache
           rpms_path: /home/stack/rpms
 
@@ -207,7 +195,6 @@ In this playbook the tasks\_from is set as a variable instead of an
           tasks_from: yum_update.yml
           source_image: docker.io/tripleomaster/centos-binary-nova-api:latest
           modified_append_tag: updated
-          container_build_tool: buildah
           rpms_path: /home/stack/rpms/
 
 Note, if you have a locally installed gating repo, you can add
@@ -235,7 +222,6 @@ a variable instead of an `import_role` parameter.
           source_image: docker.io/tripleomaster/centos-binary-nova-api:latest
           yum_repos_dir_path: /etc/yum.repos.d
           yum_packages: ['foobar-nova-plugin', 'fizzbuzz-nova-plugin']
-          container_build_tool: buildah
 
 RPM install
 ~~~~~~~~~~~

defaults/main.yml

@@ -1,6 +1,5 @@
 ---
 update_repo: ''
-container_build_tool: 'buildah'
 python_dir: []
 refspecs: []
 yum_packages: []

tasks/modify_image.yml

@@ -34,11 +34,12 @@
     line: "LABEL modified_append_tag={{ modified_append_tag }}"
 
 - name: Modify image from {{ modify_dir_path }}
-  command: |
-     {{ build_commands[container_build_tool] }} \
-         --tag {{ target_image | default(source_image) }}{{ modified_append_tag }} \
-         --file {{ dockerfile.path }} --network host ./
+  command: >-
+    buildah bud
+    --format docker
+    --tag {{ target_image | default(source_image) }}{{ modified_append_tag }}
+    --file {{ dockerfile.path }} --network host ./
   # FIXME: buildah should not required root commands to build an image
-  become: "{{ container_build_tool == 'buildah' }}"
+  become: true
   args:
     chdir: "{{ modify_dir_path }}"

tasks/precheck.yml

@@ -5,11 +5,6 @@
       - source_image is defined
       - source_image | length > 0
 
-- name: Ensure that container_build_tool is correctly set
-  fail: msg="{{ container_build_tool }} is not a valid value for
-             container_build_tool. Use 'buildah'."
-  when: container_build_tool != 'buildah'
-
 - name: Set default modified_append_tag
   set_fact:
     modified_append_tag: "{{ lookup('pipe','date +-modified-%Y%m%d%H%M%S') }}"

tasks/yum_install.yml

@@ -4,4 +4,3 @@
     - always
 
 - import_tasks: yum_install_buildah.yml
-  when: container_build_tool == 'buildah'

tasks/yum_update.yml

@@ -4,4 +4,3 @@
     - always
 
 - import_tasks: yum_update_buildah.yml
-  when: container_build_tool == 'buildah'

vars/main.yml

@@ -1,3 +0,0 @@
----
-build_commands:
-  buildah: buildah bud --format docker