From 1f5da4c20b306e725a84e4681e3836f84a9167ed Mon Sep 17 00:00:00 2001
From: Tanu Kaskinen <tanuk@iki.fi>
Date: Fri, 20 Dec 2019 08:00:59 +0200
Subject: [PATCH] gitlab: explain the container image tag better

---
 .gitlab-ci.yml | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 51feab9..dcb4a98 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -16,7 +16,8 @@ stages:
 
 variables:
   # Update this tag when you want to trigger a rebuild the container in which
-  # CI runs
+  # CI runs, for example when adding new packages to UBUNTU_DEBS. The tag is
+  # an arbitrary string that identifies the exact container contents.
   UBUNTU_TAG: '2019-11-21-01'
   UBUNTU_VERSION: '18.04'
   UBUNTU_IMAGE: "$CI_REGISTRY_IMAGE/ubuntu/$UBUNTU_VERSION:$UBUNTU_TAG"
@@ -31,6 +32,9 @@ build-container:
   stage: container
   variables:
     GIT_STRATEGY: none # no need to pull the whole tree for rebuilding the image
+
+    # Remember to update UBUNTU_TAG when modifying this package list! Otherwise
+    # the changes won't have effect since an old container image will be used.
     UBUNTU_DEBS: >-
       autoconf
       automake
-- 
2.7.4