From 970708dd00fb99d6676a23212b2e7160a1f45ddd Mon Sep 17 00:00:00 2001
From: Steve Baker <sbaker@redhat.com>
Date: Tue, 13 Nov 2018 17:20:03 +1300
Subject: [PATCH] Use a tempfile for the modified Dockerfile

When using modify_image.yml directly with a multiple image prepare,
the Dockerfile.modified can be overwritten multiple times in a race
which causes the wrong images to be built.

This change uses a tempfile for the modified Dockerfile, avoiding this
issue.

yum_update.yml and rpm_install.yml is not affected by this because
they write out the Dockerfile to a temp directory for each image.

Change-Id: I374f76650ef0b0211d92435d66fdead2b7730b21
---
 tasks/modify_image.yml | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/tasks/modify_image.yml b/tasks/modify_image.yml
index 769a6ed..4b4851d 100644
--- a/tasks/modify_image.yml
+++ b/tasks/modify_image.yml
@@ -13,25 +13,31 @@
     modified_append_tag: "{{ lookup('pipe','date +-modified-%Y%m%d%H%M%S') }}"
   when: modified_append_tag is undefined
 
-- name: Copy Dockerfile to Dockerfile.modified
+- name: Create Dockerfile tempfile name
+  tempfile:
+    path: "{{ modify_dir_path }}"
+    prefix: Dockerfile.
+  register: dockerfile
+
+- name: Copy Dockerfile to {{ dockerfile.path }}
   copy:
     src: "{{ modify_dir_path }}/Dockerfile"
-    dest: "{{ modify_dir_path }}/Dockerfile.modified"
+    dest: "{{ dockerfile.path }}"
 
 - name: Replace FROM directive
   lineinfile:
-    path: "{{ modify_dir_path }}/Dockerfile.modified"
+    path: "{{ dockerfile.path }}"
     regexp: "^FROM "
     line: "FROM {{ source_image }}"
 
 - name: Add LABEL modified_append_tag={{ modified_append_tag }}
   lineinfile:
-    path: "{{ modify_dir_path }}/Dockerfile.modified"
+    path: "{{ dockerfile.path }}"
     insertafter: "^FROM "
     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.modified --network host ./"
+  command: "{{ build_commands[container_build_tool] }} --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: "{{ true if build_commands[container_build_tool] == 'buildah' else false }}"
   args: