From 16cde364cb0bb100ab7e2a66b31be6c082108c09 Mon Sep 17 00:00:00 2001
From: Jan Kaluza <jkaluza@redhat.com>
Date: Apr 15 2020 13:54:24 +0000
Subject: Initial readme.


---

diff --git a/README.md b/README.md
index 04a0952..fbfb403 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,37 @@
-# cccc
+# Compose Configuration Compare and Check tool (CCCC)
 
-Compose Configuration Compare and Check tool
\ No newline at end of file
+
+## Motivation
+
+Before merging any compose configuration change, we should be able to verify
+how the resulting compose changes. For example, when adding new packages
+to a comps file, we should be able to see all the packages pulled-in as
+dependencies and we should also ensure this compose passes basic sanity tests.
+
+
+## CCCC tool
+
+The CCCC tool takes following inputs:
+
+- git repository/commit with default Pungi configuration (For example pointing to some commit/branch in https://pagure.io/pungi-fedora/).
+- default Pungi configuration file name (For example ``fedora.conf``).
+- git repository with PR for Pungi configuration repository.
+- git repository with PR for Comps repository.
+- git repository with PR for module-defaults repository.
+
+The CCCC tool then uses this input to create two minimal composes using the ODCS (On Demand Compose Service):
+
+- The default compose using the unchanged configuration from git repository with default Pungi configuration.
+- The PR compose with the PRs applied.
+
+The CCCC tool compares these two composes and prints the difference to stdout.
+
+
+## CCCC tool use-case
+
+The plan is to have the Jenkins Job running the CCCC tool on any PR against
+pungi-fedora, comps and module-defaults repositories. The summary of
+compose difference will be added as comment to the PR.
+
+It should therefore be clear if the most important parts of the compose still
+works with the PR applied and how the PR changed the compose.