If job requires rhel8 container, use slc7 python libraries

Trying the new map of OS_ARCH

replace slc7 by rhel7

apply Valentins suggestion

etc/submit_py3.sh

@@ -54,6 +54,7 @@ PY3_FUTURE_VERSION=0.18.2
 # Saving START_TIME and when job finishes END_TIME.
 WMA_MIN_JOB_RUNTIMESECS=300
 START_TIME=$(date +%s)
+WMA_DEFAULT_OS=rhel7
 # assign arguments
 SANDBOX=$1
 INDEX=$2
@@ -132,20 +133,17 @@ echo "======== WMAgent COMP Python bootstrap starting at $(TZ=GMT date) ========
 # slc6_ppc64le_gcc493 (from CMSSW): py2-future/0.18.2 python/2.7.15 py3-future/0.18.2 python3/3.8.2
 #
 # NOTE: all the ppc64le ScramArchs are actually pointing to: slc7_ppc64le_gcc820
+### UPDATE on 11 April, 2022: See a new map of CVMFS packages in:
+# https://github.com/dmwm/WMCore/pull/11077#issuecomment-1094814966
+
 # First, decide which COMP ScramArch to use based on the required OS and Architecture
 THIS_ARCH=`uname -m`  # if it's PowerPC, it returns `ppc64le`
-if [ "$THIS_ARCH" = "x86_64" ]
-then
-    THIS_ARCH="amd64"
-fi
-if [ "$REQUIRED_OS" = "rhel7" ]
-then
-    WMA_SCRAM_ARCH=slc7_${THIS_ARCH}_gcc630
-elif [ "$THIS_ARCH" = "amd64" ]
+# if this job can run at any OS, then use rhel7 as default
+if [ "$REQUIRED_OS" = "any" ]
 then
-    WMA_SCRAM_ARCH=slc6_${THIS_ARCH}_gcc700
+    WMA_SCRAM_ARCH=${WMA_DEFAULT_OS}_${THIS_ARCH}
 else
-    WMA_SCRAM_ARCH=slc6_${THIS_ARCH}_gcc493
+    WMA_SCRAM_ARCH=${REQUIRED_OS}_${THIS_ARCH}
 fi
 echo "Job requires OS: $REQUIRED_OS, thus setting ScramArch to: $WMA_SCRAM_ARCH"