Problem: debian containers not run on Travis

Solution: add infrastructure to run both CentOS and Debian

.travis.yml

 language: minimal
 env:
-    - PYTHON_VER=2.7
-    - PYTHON_VER=3.5
-    - PYTHON_VER=3.6
-    - PYTHON_VER=3.7
-    - PYTHON_VER=3.8
-    - PYTHON_VER=3.9
+    - PYTHON_VER=2.7 BUILD_TYPE=centos_containers
+    - PYTHON_VER=3.5 BUILD_TYPE=centos_containers
+    - PYTHON_VER=3.6 BUILD_TYPE=centos_containers
+    - PYTHON_VER=3.7 BUILD_TYPE=centos_containers
+    - PYTHON_VER=3.8 BUILD_TYPE=centos_containers
+    - PYTHON_VER=3.9 BUILD_TYPE=centos_containers
+    - PYTHON_VER=2.7 BUILD_TYPE=debian_containers
+    - PYTHON_VER=3.5 BUILD_TYPE=debian_containers
+    - PYTHON_VER=3.6 BUILD_TYPE=debian_containers
+    - PYTHON_VER=3.7 BUILD_TYPE=debian_containers
+    - PYTHON_VER=3.8 BUILD_TYPE=debian_containers
+    - PYTHON_VER=3.9 BUILD_TYPE=debian_containers
 
 jobs:
   allow_failures:
-  - env: PYTHON_VER=3.9
+  - env: PYTHON_VER=3.9 BUILD_TYPE=centos_containers
+  - env: PYTHON_VER=3.9 BUILD_TYPE=debian_containers
 
 services:
     - docker
@@ -18,8 +25,5 @@ notifications:
   email:
     - buildout-development@googlegroups.com
 
-install:
-    - docker build -f .github/workflows/Dockerfile --tag centos_buildout:python${PYTHON_VER} --build-arg PYTHON_VER=${PYTHON_VER} .
-
 script:
-    - docker run centos_buildout:python${PYTHON_VER} /bin/bash -c 'RUN_COVERAGE= COVERAGE_REPORT= /buildout/bin/test -c -vvv'
+    - ./ci_build.sh

builds/centos_containers/ci_build.sh

+#!/bin/bash
+
+set -x
+set -e
+
+cd ../..
+docker build -f .github/workflows/Dockerfile --tag centos_buildout:python${PYTHON_VER} --build-arg PYTHON_VER=${PYTHON_VER} .
+docker run centos_buildout:python${PYTHON_VER} /bin/bash -c 'RUN_COVERAGE= COVERAGE_REPORT= /buildout/bin/test -c -vvv'

builds/debian_containers/ci_build.sh

+#!/bin/bash
+
+set -x
+set -e
+
+cd ../..
+docker build -f .github/workflows/Dockerfile-debian --tag debian_buildout:python${PYTHON_VER} --build-arg PYTHON_VER=${PYTHON_VER} .
+docker run debian_buildout:python${PYTHON_VER} /bin/bash -c 'RUN_COVERAGE= COVERAGE_REPORT= /buildout/bin/test -c -vvv'

ci_build.sh

+#!/bin/bash
+
+set -x
+set -e
+
+cd ./builds/${BUILD_TYPE} && ./ci_build.sh