Add DOCKERFILE_VERSION variable to all CI dockerfiles

ci/alpine/Dockerfile

@@ -1,5 +1,9 @@
 FROM alpine:latest
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 RUN apk add --no-cache \
   ccache \
   cmake \

ci/centos-7/Dockerfile

@@ -1,5 +1,9 @@
 FROM centos:7
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 ENV FLEX_VERSION=2.6.4
 ENV FLEX_DIR=/opt/flex
 

ci/centos-stream-8/Dockerfile

@@ -1,5 +1,9 @@
 FROM quay.io/centos/centos:stream8
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 RUN dnf -y install https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm
 RUN dnf config-manager --set-enabled powertools
 

ci/centos-stream-9/Dockerfile

@@ -1,5 +1,9 @@
 FROM quay.io/centos/centos:stream9
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 # dnf config-manager isn't available at first, and
 # we need it to install the CRB repo below.
 RUN dnf -y install 'dnf-command(config-manager)'

ci/debian-10/Dockerfile

@@ -2,6 +2,10 @@ FROM debian:10
 
 ENV DEBIAN_FRONTEND="noninteractive" TZ="America/Los_Angeles"
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 ENV CMAKE_DIR "/opt/cmake"
 ENV CMAKE_VERSION "3.19.1"
 

ci/debian-11/Dockerfile

@@ -2,6 +2,10 @@ FROM debian:11
 
 ENV DEBIAN_FRONTEND="noninteractive" TZ="America/Los_Angeles"
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 RUN apt-get update && apt-get -y install \
     ccache \
     git \

ci/debian-9-32bit/Dockerfile

@@ -4,7 +4,7 @@ ENV DEBIAN_FRONTEND="noninteractive" TZ="America/Los_Angeles"
 
 # A version field to invalide Cirrus's build cache when needed, as suggested in
 # https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
-ENV DOCKERFILE_VERSION 221001
+ENV DOCKERFILE_VERSION 20220519
 
 ENV CMAKE_DIR "/opt/cmake"
 ENV CMAKE_VERSION "3.19.1"

ci/debian-9/Dockerfile

@@ -4,7 +4,7 @@ ENV DEBIAN_FRONTEND="noninteractive" TZ="America/Los_Angeles"
 
 # A version field to invalide Cirrus's build cache when needed, as suggested in
 # https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
-ENV DOCKERFILE_VERSION 221001
+ENV DOCKERFILE_VERSION 20220519
 
 ENV CMAKE_DIR "/opt/cmake"
 ENV CMAKE_VERSION "3.19.1"

ci/fedora-34/Dockerfile

@@ -1,5 +1,9 @@
 FROM fedora:34
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 RUN dnf -y install \
     ccache \
     bison \

ci/fedora-35/Dockerfile

@@ -1,5 +1,9 @@
 FROM fedora:35
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 RUN dnf -y install \
     ccache \
     bison \

ci/openssl-3.0/Dockerfile

@@ -2,6 +2,10 @@ FROM ubuntu:20.04
 
 ENV DEBIAN_FRONTEND="noninteractive" TZ="America/Los_Angeles"
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 RUN apt-get update && apt-get -y install \
     ccache \
     git \

ci/opensuse-leap-15.3/Dockerfile

@@ -1,5 +1,9 @@
 FROM opensuse/leap:15.3
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 RUN zypper addrepo https://download.opensuse.org/repositories/openSUSE:Leap:15.2:Update/standard/openSUSE:Leap:15.2:Update.repo \
  && zypper refresh \
  && zypper in -y \

ci/ubuntu-18.04/Dockerfile

@@ -2,6 +2,10 @@ FROM ubuntu:18.04
 
 ENV DEBIAN_FRONTEND="noninteractive" TZ="America/Los_Angeles"
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 ENV CMAKE_DIR "/opt/cmake"
 ENV CMAKE_VERSION "3.19.1"
 ENV PATH "${CMAKE_DIR}/bin:${PATH}"

ci/ubuntu-20.04/Dockerfile

@@ -2,6 +2,10 @@ FROM ubuntu:20.04
 
 ENV DEBIAN_FRONTEND="noninteractive" TZ="America/Los_Angeles"
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 RUN apt-get update && apt-get -y install \
     ccache \
     git \

ci/ubuntu-21.10/Dockerfile

@@ -2,6 +2,10 @@ FROM ubuntu:21.10
 
 ENV DEBIAN_FRONTEND="noninteractive" TZ="America/Los_Angeles"
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 RUN apt-get update && apt-get -y install \
     git \
     ccache \