diff --git a/deploy_checkit_tiff/centos6/Dockerfile b/deploy_checkit_tiff/centos6/Dockerfile
deleted file mode 100644
index 349f3650b3a406452b7f660f8e167f7a82a4f854..0000000000000000000000000000000000000000
--- a/deploy_checkit_tiff/centos6/Dockerfile
+++ /dev/null
@@ -1,153 +0,0 @@
-###############################################################################
-# Building checkit_tiff 0.6.0 as a dynamically linked binary on RHEL 6 is not
-# possible, because the cmake3 version even from EPEL is not sufficiently
-# recent to build it. This is why we build a statically linked binary of
-# checkit_tiff 0.6.0 on RHEL 7 that can then be run on RHEL 6.
-#
-# Use this Dockerfile as follows:
-# docker build --tag checkit-tiff --rm=true --file Dockerfile ./
-###############################################################################
-
-FROM centos:centos7.8.2003
-MAINTAINER Andreas Romeyke <romeyke@slub-dresden.de>
-# current could be 0.3.1 or 0.4.0, because 0.4.0 is bugfixed version of
-# checkit_tiff with rules compatible to 0.3.1 based on Handreichung TIFF v1.2
-# in checkit_tiff 0.4.1 the rules are adapted to Handreichung TIFF v1.3
-ENV checkit_tiff_current_version=v0.6.0
-ENV checkit_tiff_upcoming_version=v0.6.0
-# ENV checkit_tiff_gitrepository=https://github.com/SLUB-digitalpreservation/checkit_tiff.git
-ENV checkit_tiff_gitrepository=http://art1pirat.spdns.org/art1/checkit_tiff.git
-ENV pcre_version=8.41
-ENV PATCH="\
---- a/src/CMakeLists.txt\n\
-+++ b/src/CMakeLists.txt\n\
-@@ -28,9 +28,6 @@\n\
- # Make a version file containing the current version from git.\n\
- #\n\
- execute_process( COMMAND git rev-list HEAD --count OUTPUT_VARIABLE REPO_REVISION OUTPUT_STRIP_TRAILING_WHITESPACE )\n\
--execute_process( COMMAND git rev-parse --abbrev-ref HEAD OUTPUT_VARIABLE BUILD_BRANCH OUTPUT_STRIP_TRAILING_WHITESPACE)\n\
--execute_process( COMMAND git rev-parse HEAD OUTPUT_VARIABLE BUILD_REV_ID OUTPUT_STRIP_TRAILING_WHITESPACE)\n\
--execute_process( COMMAND git describe --long --tags --dirty --always OUTPUT_VARIABLE BUILD_REV_ID_SHORT OUTPUT_STRIP_TRAILING_WHITESPACE)\n\
- add_definitions(-DVERSION=\"\${BUILD_BRANCH}\")\n\
- add_definitions(-DREPO_REVISION=\"\${REPO_REVISION}\")\n"
-
-# THIS IS A BAD IDEA!!! ONLY SKIP CERTIFICATE VALIDATION IF THERE'S NO OTHER
-# ALTERNATIVE!!!
-ENV GIT_SSL_NO_VERIFY=true
-
-#RUN yum install -y ca-certificates wget git
-#RUN mkdir -p /usr/local/share/ca-certificates/cacert.org
-#RUN wget -P /usr/local/share/ca-certificates/cacert.org http://www.cacert.org/certs/root.crt http://www.cacert.org/certs/class3.crt
-#RUN update-ca-trust
-#RUN git config --global http.sslCAinfo /etc/ssl/certs/ca-certificates.crt
-
-# based on https://hub.docker.com/r/rpmbuild/centos6/
-## install base environment
-RUN yum install -y https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
-RUN yum install -y \
-                   git \
-                   libtool libtool-ltdl \
-                   glibc-static \
-                   make cmake3 \
-                   pkgconfig \
-                   sudo \
-                   automake autoconf \
-                   wget \
-                   yum-utils rpm-build && \
-    yum clean all
-#RUN wget http://people.centos.org/tru/devtools-2/devtools-2.repo -O /etc/yum.repos.d/devtools-2.repo
-# git [devtools-2] (1.8.4) for "rev-list --count" feature, git [centos6] (1.7.1) too old
-#RUN yum install -y devtoolset-2-git
-#RUN ln -s /opt/rh/devtoolset-2/root/usr/bin/git /usr/bin/git
-
-# Doku: https://wiki.centos.org/AdditionalResources/Repositories/SCL#head-9c6aea9c13b921d5258446c4c5e5886571bdb741
-RUN yum --enablerepo=extras install -y centos-release-scl
-RUN yum install -y \
-                   devtoolset-8-gcc \
-                   devtoolset-8-binutils \
-                   devtoolset-8-gcc-c++ \
-                   devtoolset-8-libstdc++-devel \
-                   devtoolset-8-toolchain
-RUN scl enable devtoolset-8 bash
-
-## add user environment
-RUN useradd builder -u 1000 -m -G users,wheel && \
-    echo "builder ALL=(ALL:ALL) NOPASSWD:ALL" >> /etc/sudoers && \
-    echo "# macros"                      >  /home/builder/.rpmmacros && \
-    echo "%_topdir    /home/builder/rpm" >> /home/builder/.rpmmacros && \
-    echo "%_sourcedir %{_topdir}"        >> /home/builder/.rpmmacros && \
-    echo "%_builddir  %{_topdir}"        >> /home/builder/.rpmmacros && \
-    echo "%_specdir   %{_topdir}"        >> /home/builder/.rpmmacros && \
-    echo "%_rpmdir    %{_topdir}"        >> /home/builder/.rpmmacros && \
-    echo "%_srcrpmdir %{_topdir}"        >> /home/builder/.rpmmacros && \
-    mkdir /home/builder/rpm && \
-    chown -R builder /home/builder
-USER builder
-RUN scl enable devtoolset-8 bash
-ENV FLAVOR=rpmbuild OS=centos DIST=el7 CC=/opt/rh/devtoolset-8/root/usr/bin/gcc CXX=/opt/rh/devtoolset-8/root/usr/bin/g++
-CMD /srv/pkg
-
-WORKDIR /home/builder/
-
-# get and compile libpcre (v8)
-RUN wget -np https://ftp.pcre.org/pub/pcre/pcre-${pcre_version}.tar.bz2
-RUN tar xfj pcre-${pcre_version}.tar.bz2
-WORKDIR /home/builder/pcre-${pcre_version}/
-RUN ./configure --disable-shared -enable-static && /usr/bin/make -j
-USER root
-RUN /usr/bin/make install
-USER builder
-WORKDIR /home/builder/
-
-# get checkit_tiff
-RUN git clone ${checkit_tiff_gitrepository}
-RUN rm -Rf /home/builder/checkit_tiff/build_*
-## compile checkit_tiff stable
-#WORKDIR /home/builder/checkit_tiff
-#RUN git checkout ${checkit_tiff_current_version}
-#RUN git checkout -- src/CMakeLists.txt
-## add patches to workaround outdated git
-#RUN cat src/CMakeLists.txt | \
-#sed -e "s/execute_process( COMMAND git rev-parse --abbrev-ref HEADOUTPUT_VARIABLE BUILD_BRANCH OUTPUT_STRIP_TRAILING_WHITESPACE)//g" \
-# -e "s/execute_process( COMMAND git rev-parse HEAD OUTPUT_VARIABLE BUILD_REV_ID OUTPUT_STRIP_TRAILING_WHITESPACE)//g" \
-# -e "s/\(add_definitions(-DVERSION=\"\)\([^\"]*\)/\1${checkit_tiff_current_version}/"  \
-# -e "s/execute_process( COMMAND git describe --long --tags --dirty --always OUTPUT_VARIABLE BUILD_REV_ID_SHORT OUTPUT_STRIP_TRAILING_WHITESPACE)//g" > src/CMakeLists.txt.patched
-#RUN mv src/CMakeLists.txt.patched src/CMakeLists.txt
-#RUN cat -n src/CMakeLists.txt
-#RUN mkdir build_stable
-#WORKDIR /home/builder/checkit_tiff/build_stable
-#RUN cmake3 -DCMAKE_INSTALL_PREFIX=/tmp/checkit_tiff_stable/ \
-#  -DBUILD_BRANCH=${checkit_tiff_current_version} \
-#  -DPCRE_LIBRARY=../../pcre-${pcre_version}/.libs/libpcre.a \
-#  -DSTATIC=1 -DCMAKE_C_FLAGS="-O3 -s -Wno-unused-function -fstack-check -fstack-protector-strong -Wformat -Werror=format-security" \
-#  -DPCRE_INCLUDE_DIR=../../pcre-${pcre_version}/ ../src
-#RUN make && make install
-##RUN make && make package
-
-# compile checkit_tiff development
-WORKDIR /home/builder/checkit_tiff
-RUN git checkout -- src/CMakeLists.txt
-RUN git checkout ${checkit_tiff_upcoming_version}
-RUN git checkout -- src/CMakeLists.txt
-# add patch to workaround outdated git
-RUN cat src/CMakeLists.txt | \
-sed -e "s/execute_process( COMMAND git rev-parse --abbrev-ref HEADOUTPUT_VARIABLE BUILD_BRANCH OUTPUT_STRIP_TRAILING_WHITESPACE)//g" \
- -e "s/execute_process( COMMAND git rev-parse HEAD OUTPUT_VARIABLE BUILD_REV_ID OUTPUT_STRIP_TRAILING_WHITESPACE)//g" \
- -e "s/\(add_definitions(-DVERSION=\"\)\([^\"]*\)/\1${checkit_tiff_upcoming_version}/"  \
- -e "s/execute_process( COMMAND git describe --long --tags --dirty --always OUTPUT_VARIABLE BUILD_REV_ID_SHORT OUTPUT_STRIP_TRAILING_WHITESPACE)//g" > src/CMakeLists.txt.patched
-RUN mv src/CMakeLists.txt.patched src/CMakeLists.txt
-RUN cat -n src/CMakeLists.txt
-RUN mkdir build_development
-WORKDIR /home/builder/checkit_tiff/build_development
-RUN cmake3 -DCMAKE_INSTALL_PREFIX=/tmp/checkit_tiff_development/ \
-  -DBUILD_BRANCH=${checkit_tiff_upcoming_version} \
-  -DPCRE_LIBRARY=../../pcre-${pcre_version}/.libs/libpcre.a \
-  -DSTATIC=1 -DCMAKE_C_FLAGS="-O3 -s -Wno-unused-function -fstack-check -fstack-protector-strong -Wformat -Werror=format-security" \
-  -DPCRE_INCLUDE_DIR=../../pcre-${pcre_version}/ ../src
-RUN make && make install
-#RUN make && make package
-
-# create tar-balls
-WORKDIR /tmp/
-#RUN tar cfz checkit_tiff_current.tgz checkit_tiff_stable/
-RUN tar cfz checkit_tiff_upcoming.tgz checkit_tiff_development/
diff --git a/deploy_checkit_tiff/centos6/Dockerfile_dynlink b/deploy_checkit_tiff/centos6/Dockerfile_dynlink
deleted file mode 100644
index df2f535db2bec473f3cebbffe9bbde41dfb5f9fa..0000000000000000000000000000000000000000
--- a/deploy_checkit_tiff/centos6/Dockerfile_dynlink
+++ /dev/null
@@ -1,125 +0,0 @@
-###############################################################################
-# This Dockerfile is deprecated and will no longer be used when checkit_tiff
-# version 0.5.3 becomes outdated, because starting with version 0.6.0, 
-# checkit_tiff can be compiled into a statically linked binary that can run on
-# RHEL 6 using newer RHEL versions.
-#
-# Building checkit_tiff 0.6.0 on RHEL 6 is not possible, because the cmake3
-# version even from EPEL is not sufficiently recent to build it.
-#
-# Use this Dockerfile as follows:
-# docker build --tag checkit-tiff --rm=true --file Dockerfile_dynlink ./
-###############################################################################
-
-FROM centos:6.10
-MAINTAINER Andreas Romeyke <romeyke@slub-dresden.de>
-# current could be 0.3.1 or 0.4.0, because 0.4.0 is bugfixed version of
-# checkit_tiff with rules compatible to 0.3.1 based on Handreichung TIFF v1.2
-# in checkit_tiff 0.4.1 the rules are adapted to Handreichung TIFF v1.3
-ENV checkit_tiff_current_version=v0.5.3
-# ENV checkit_tiff_gitrepository=https://github.com/SLUB-digitalpreservation/checkit_tiff.git
-ENV checkit_tiff_gitrepository=http://art1pirat.spdns.org/art1/checkit_tiff.git
-ENV pcre_version=8.41
-ENV PATCH="\
---- a/src/CMakeLists.txt\n\
-+++ b/src/CMakeLists.txt\n\
-@@ -28,9 +28,6 @@\n\
- # Make a version file containing the current version from git.\n\
- #\n\
- execute_process( COMMAND git rev-list HEAD --count OUTPUT_VARIABLE REPO_REVISION OUTPUT_STRIP_TRAILING_WHITESPACE )\n\
--execute_process( COMMAND git rev-parse --abbrev-ref HEAD OUTPUT_VARIABLE BUILD_BRANCH OUTPUT_STRIP_TRAILING_WHITESPACE)\n\
--execute_process( COMMAND git rev-parse HEAD OUTPUT_VARIABLE BUILD_REV_ID OUTPUT_STRIP_TRAILING_WHITESPACE)\n\
--execute_process( COMMAND git describe --long --tags --dirty --always OUTPUT_VARIABLE BUILD_REV_ID_SHORT OUTPUT_STRIP_TRAILING_WHITESPACE)\n\
- add_definitions(-DVERSION=\"\${BUILD_BRANCH}\")\n\
- add_definitions(-DREPO_REVISION=\"\${REPO_REVISION}\")\n"
-
-# THIS IS A BAD IDEA!!! ONLY SKIP CERTIFICATE VALIDATION IF THERE'S NO OTHER
-# ALTERNATIVE!!!
-ENV GIT_SSL_NO_VERIFY=true
-
-#RUN yum install -y ca-certificates wget git
-#RUN mkdir -p /usr/local/share/ca-certificates/cacert.org
-#RUN wget -P /usr/local/share/ca-certificates/cacert.org http://www.cacert.org/certs/root.crt http://www.cacert.org/certs/class3.crt
-#RUN update-ca-trust
-#RUN git config --global http.sslCAinfo /etc/ssl/certs/ca-certificates.crt
-
-# based on https://hub.docker.com/r/rpmbuild/centos6/
-## install base environment
-RUN yum install -y https://dl.fedoraproject.org/pub/epel/epel-release-latest-6.noarch.rpm
-RUN yum install -v -y \
-                      libtool \
-                      libtool-ltdl \
-                      make cmake3 \
-                      pkgconfig \
-                      sudo \
-                      automake autoconf \
-                      wget \
-                      yum-utils rpm-build && \
-    yum clean all
-RUN wget http://people.centos.org/tru/devtools-2/devtools-2.repo -O /etc/yum.repos.d/devtools-2.repo
-# git [devtools-2] (1.8.4) for "rev-list --count" feature, git [centos6] (1.7.1) too old
-RUN yum install -y devtoolset-2-git
-RUN ln -s /opt/rh/devtoolset-2/root/usr/bin/git /usr/bin/git
-RUN yum install -y \
-                   devtoolset-2-gcc \
-                   devtoolset-2-binutils \
-                   devtoolset-2-gcc-c++ \
-                   devtoolset-2-libstdc++-devel \
-                   devtoolset-2-toolchain
-RUN scl enable devtoolset-2 bash
-
-## add user environment
-RUN useradd builder -u 1000 -m -G users,wheel && \
-    echo "builder ALL=(ALL:ALL) NOPASSWD:ALL" >> /etc/sudoers && \
-    echo "# macros"                      >  /home/builder/.rpmmacros && \
-    echo "%_topdir    /home/builder/rpm" >> /home/builder/.rpmmacros && \
-    echo "%_sourcedir %{_topdir}"        >> /home/builder/.rpmmacros && \
-    echo "%_builddir  %{_topdir}"        >> /home/builder/.rpmmacros && \
-    echo "%_specdir   %{_topdir}"        >> /home/builder/.rpmmacros && \
-    echo "%_rpmdir    %{_topdir}"        >> /home/builder/.rpmmacros && \
-    echo "%_srcrpmdir %{_topdir}"        >> /home/builder/.rpmmacros && \
-    mkdir /home/builder/rpm && \
-    chown -R builder /home/builder
-USER builder
-RUN scl enable devtoolset-2 bash
-ENV FLAVOR=rpmbuild OS=centos DIST=el6 CC=/opt/rh/devtoolset-2/root/usr/bin/gcc CXX=/opt/rh/devtoolset-2/root/usr/bin/g++
-CMD /srv/pkg
-
-WORKDIR /home/builder/
-
-# get and compile libpcre (v8)
-RUN wget -np https://ftp.pcre.org/pub/pcre/pcre-${pcre_version}.tar.bz2
-RUN tar xfj pcre-${pcre_version}.tar.bz2
-WORKDIR /home/builder/pcre-${pcre_version}/
-RUN ./configure --disable-shared -enable-static && /usr/bin/make -j
-USER root
-RUN /usr/bin/make install
-USER builder
-WORKDIR /home/builder/
-
-# get checkit_tiff
-RUN git clone ${checkit_tiff_gitrepository}
-RUN rm -Rf /home/builder/checkit_tiff/build_*
-# compile checkit_tiff stable
-WORKDIR /home/builder/checkit_tiff
-RUN git checkout ${checkit_tiff_current_version}
-RUN git checkout -- src/CMakeLists.txt
-# add patches to workaround outdated git
-RUN cat src/CMakeLists.txt | \
-sed -e "s/execute_process( COMMAND git rev-parse --abbrev-ref HEADOUTPUT_VARIABLE BUILD_BRANCH OUTPUT_STRIP_TRAILING_WHITESPACE)//g" \
- -e "s/execute_process( COMMAND git rev-parse HEAD OUTPUT_VARIABLE BUILD_REV_ID OUTPUT_STRIP_TRAILING_WHITESPACE)//g" \
- -e "s/\(add_definitions(-DVERSION=\"\)\([^\"]*\)/\1${checkit_tiff_current_version}/"  \
- -e "s/execute_process( COMMAND git describe --long --tags --dirty --always OUTPUT_VARIABLE BUILD_REV_ID_SHORT OUTPUT_STRIP_TRAILING_WHITESPACE)//g" > src/CMakeLists.txt.patched
-RUN mv src/CMakeLists.txt.patched src/CMakeLists.txt
-RUN cat -n src/CMakeLists.txt
-RUN mkdir build_stable
-WORKDIR /home/builder/checkit_tiff/build_stable
-RUN cmake3 -DCMAKE_INSTALL_PREFIX=/tmp/checkit_tiff_stable/ \
-  -DBUILD_BRANCH=${checkit_tiff_current_version} \
-  -DPCRE_LIBRARY=../../pcre-${pcre_version}/.libs/libpcre.a \
-  -DPCRE_INCLUDE_DIR=../../pcre-${pcre_version}/ ../src
-RUN make && make install
-
-# create tar-balls
-WORKDIR /tmp/
-RUN tar cfz checkit_tiff_current.tgz checkit_tiff_stable/
diff --git a/deploy_checkit_tiff/centos6/README.txt b/deploy_checkit_tiff/centos6/README.txt
deleted file mode 100644
index 5bef8c9c26b6605b8f08f8f627fd6f080d876e8c..0000000000000000000000000000000000000000
--- a/deploy_checkit_tiff/centos6/README.txt
+++ /dev/null
@@ -1,42 +0,0 @@
-How to build checkit-tiff variants for Redhat 6 system used by Rosetta
-======================================================================
-
-:lang: en
-:encoding: utf-8
-:author: Andreas Romeyke
-
-== Prerequisites
-
-* you need 'docker'
-* If using Debian buster or higher, you must(!) add "vsyscall=emulate" option
-to the Linux kernel boot option, because CentOS 6.xx triggers syscalls in an
-outdated way.
-
-== How to build
-
-# If something was built, delete all containers for specific image:
-docker ps -a | awk '{ print $1,$2 }' | grep checkit-tiff | awk '{print $1 }' | xargs -I {} docker rm {}
-
-# build stuff
-docker build -t checkit-tiff --rm=true ./
-
-== find out which image
-
-docker images
-
-lists:
-REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
-checkit-tiff        latest              acc13d4a83d9        3 minutes ago       827 MB     # <==== that's it!
-<none>              <none>              e3be26e603f0        5 minutes ago       824 MB
-centos              6.10                0cd976dc0a98        10 months ago       195 MB
-
-
-== How to copy already built binaries
-
-id=$(docker create checkit-tiff)
-
-docker cp $id:/tmp/checkit_tiff_current.tgz ./
-docker cp $id:/tmp/checkit_tiff_upcoming.tgz ./
-
-docker rm -v $id
-