diff --git a/3.10-rc/bullseye/Dockerfile b/3.10-rc/bullseye/Dockerfile
new file mode 100644
index 000000000..6cda10523
--- /dev/null
+++ b/3.10-rc/bullseye/Dockerfile
@@ -0,0 +1,97 @@
+#
+# NOTE: THIS DOCKERFILE IS GENERATED VIA "update.sh"
+#
+# PLEASE DO NOT EDIT IT DIRECTLY.
+#
+
+FROM buildpack-deps:bullseye
+
+# ensure local python is preferred over distribution python
+ENV PATH /usr/local/bin:$PATH
+
+# http://bugs.python.org/issue19846
+# > At the moment, setting "LANG=C" on a Linux system *fundamentally breaks Python 3*, and that's not OK.
+ENV LANG C.UTF-8
+
+# extra dependencies (over what buildpack-deps already includes)
+RUN apt-get update && apt-get install -y --no-install-recommends \
+		libbluetooth-dev \
+		tk-dev \
+		uuid-dev \
+	&& rm -rf /var/lib/apt/lists/*
+
+ENV GPG_KEY A035C8C19219BA821ECEA86B64E628F8D684696D
+ENV PYTHON_VERSION 3.10.0rc1
+
+RUN set -ex \
+	\
+	&& wget -O python.tar.xz "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz" \
+	&& wget -O python.tar.xz.asc "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz.asc" \
+	&& export GNUPGHOME="$(mktemp -d)" \
+	&& gpg --batch --keyserver hkps://keys.openpgp.org --recv-keys "$GPG_KEY" \
+	&& gpg --batch --verify python.tar.xz.asc python.tar.xz \
+	&& { command -v gpgconf > /dev/null && gpgconf --kill all || :; } \
+	&& rm -rf "$GNUPGHOME" python.tar.xz.asc \
+	&& mkdir -p /usr/src/python \
+	&& tar -xJC /usr/src/python --strip-components=1 -f python.tar.xz \
+	&& rm python.tar.xz \
+	\
+	&& cd /usr/src/python \
+	&& gnuArch="$(dpkg-architecture --query DEB_BUILD_GNU_TYPE)" \
+	&& ./configure \
+		--build="$gnuArch" \
+		--enable-loadable-sqlite-extensions \
+		--enable-optimizations \
+		--enable-option-checking=fatal \
+		--enable-shared \
+		--with-system-expat \
+		--with-system-ffi \
+		--without-ensurepip \
+	&& make -j "$(nproc)" \
+	&& make install \
+	&& rm -rf /usr/src/python \
+	\
+	&& find /usr/local -depth \
+		\( \
+			\( -type d -a \( -name test -o -name tests -o -name idle_test \) \) \
+			-o \( -type f -a \( -name '*.pyc' -o -name '*.pyo' -o -name '*.a' \) \) \
+		\) -exec rm -rf '{}' + \
+	\
+	&& ldconfig \
+	\
+	&& python3 --version
+
+# make some useful symlinks that are expected to exist
+RUN cd /usr/local/bin \
+	&& ln -s idle3 idle \
+	&& ln -s pydoc3 pydoc \
+	&& ln -s python3 python \
+	&& ln -s python3-config python-config
+
+# if this is called "PIP_VERSION", pip explodes with "ValueError: invalid truth value '<VERSION>'"
+ENV PYTHON_PIP_VERSION 21.2.4
+# https://github.com/pypa/get-pip
+ENV PYTHON_GET_PIP_URL https://github.com/pypa/get-pip/raw/c20b0cfd643cd4a19246ccf204e2997af70f6b21/public/get-pip.py
+ENV PYTHON_GET_PIP_SHA256 fa6f3fb93cce234cd4e8dd2beb54a51ab9c247653b52855a48dd44e6b21ff28b
+
+RUN set -ex; \
+	\
+	wget -O get-pip.py "$PYTHON_GET_PIP_URL"; \
+	echo "$PYTHON_GET_PIP_SHA256 *get-pip.py" | sha256sum --check --strict -; \
+	\
+	python get-pip.py \
+		--disable-pip-version-check \
+		--no-cache-dir \
+		"pip==$PYTHON_PIP_VERSION" \
+	; \
+	pip --version; \
+	\
+	find /usr/local -depth \
+		\( \
+			\( -type d -a \( -name test -o -name tests -o -name idle_test \) \) \
+			-o \
+			\( -type f -a \( -name '*.pyc' -o -name '*.pyo' \) \) \
+		\) -exec rm -rf '{}' +; \
+	rm -f get-pip.py
+
+CMD ["python3"]
diff --git a/3.10-rc/bullseye/slim/Dockerfile b/3.10-rc/bullseye/slim/Dockerfile
new file mode 100644
index 000000000..13f34b4b9
--- /dev/null
+++ b/3.10-rc/bullseye/slim/Dockerfile
@@ -0,0 +1,146 @@
+#
+# NOTE: THIS DOCKERFILE IS GENERATED VIA "update.sh"
+#
+# PLEASE DO NOT EDIT IT DIRECTLY.
+#
+
+FROM debian:bullseye-slim
+
+# ensure local python is preferred over distribution python
+ENV PATH /usr/local/bin:$PATH
+
+# http://bugs.python.org/issue19846
+# > At the moment, setting "LANG=C" on a Linux system *fundamentally breaks Python 3*, and that's not OK.
+ENV LANG C.UTF-8
+
+# runtime dependencies
+RUN set -eux; \
+	apt-get update; \
+	apt-get install -y --no-install-recommends \
+		ca-certificates \
+		netbase \
+		tzdata \
+	; \
+	rm -rf /var/lib/apt/lists/*
+
+ENV GPG_KEY A035C8C19219BA821ECEA86B64E628F8D684696D
+ENV PYTHON_VERSION 3.10.0rc1
+
+RUN set -ex \
+	\
+	&& savedAptMark="$(apt-mark showmanual)" \
+	&& apt-get update && apt-get install -y --no-install-recommends \
+		dpkg-dev \
+		gcc \
+		libbluetooth-dev \
+		libbz2-dev \
+		libc6-dev \
+		libexpat1-dev \
+		libffi-dev \
+		libgdbm-dev \
+		liblzma-dev \
+		libncursesw5-dev \
+		libreadline-dev \
+		libsqlite3-dev \
+		libssl-dev \
+		make \
+		tk-dev \
+		uuid-dev \
+		wget \
+		xz-utils \
+		zlib1g-dev \
+# as of Stretch, "gpg" is no longer included by default
+		$(command -v gpg > /dev/null || echo 'gnupg dirmngr') \
+	\
+	&& wget -O python.tar.xz "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz" \
+	&& wget -O python.tar.xz.asc "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz.asc" \
+	&& export GNUPGHOME="$(mktemp -d)" \
+	&& gpg --batch --keyserver hkps://keys.openpgp.org --recv-keys "$GPG_KEY" \
+	&& gpg --batch --verify python.tar.xz.asc python.tar.xz \
+	&& { command -v gpgconf > /dev/null && gpgconf --kill all || :; } \
+	&& rm -rf "$GNUPGHOME" python.tar.xz.asc \
+	&& mkdir -p /usr/src/python \
+	&& tar -xJC /usr/src/python --strip-components=1 -f python.tar.xz \
+	&& rm python.tar.xz \
+	\
+	&& cd /usr/src/python \
+	&& gnuArch="$(dpkg-architecture --query DEB_BUILD_GNU_TYPE)" \
+	&& ./configure \
+		--build="$gnuArch" \
+		--enable-loadable-sqlite-extensions \
+		--enable-optimizations \
+		--enable-option-checking=fatal \
+		--enable-shared \
+		--with-system-expat \
+		--with-system-ffi \
+		--without-ensurepip \
+	&& make -j "$(nproc)" \
+		LDFLAGS="-Wl,--strip-all" \
+	&& make install \
+	&& rm -rf /usr/src/python \
+	\
+	&& find /usr/local -depth \
+		\( \
+			\( -type d -a \( -name test -o -name tests -o -name idle_test \) \) \
+			-o \( -type f -a \( -name '*.pyc' -o -name '*.pyo' -o -name '*.a' \) \) \
+		\) -exec rm -rf '{}' + \
+	\
+	&& ldconfig \
+	\
+	&& apt-mark auto '.*' > /dev/null \
+	&& apt-mark manual $savedAptMark \
+	&& find /usr/local -type f -executable -not \( -name '*tkinter*' \) -exec ldd '{}' ';' \
+		| awk '/=>/ { print $(NF-1) }' \
+		| sort -u \
+		| xargs -r dpkg-query --search \
+		| cut -d: -f1 \
+		| sort -u \
+		| xargs -r apt-mark manual \
+	&& apt-get purge -y --auto-remove -o APT::AutoRemove::RecommendsImportant=false \
+	&& rm -rf /var/lib/apt/lists/* \
+	\
+	&& python3 --version
+
+# make some useful symlinks that are expected to exist
+RUN cd /usr/local/bin \
+	&& ln -s idle3 idle \
+	&& ln -s pydoc3 pydoc \
+	&& ln -s python3 python \
+	&& ln -s python3-config python-config
+
+# if this is called "PIP_VERSION", pip explodes with "ValueError: invalid truth value '<VERSION>'"
+ENV PYTHON_PIP_VERSION 21.2.4
+# https://github.com/pypa/get-pip
+ENV PYTHON_GET_PIP_URL https://github.com/pypa/get-pip/raw/c20b0cfd643cd4a19246ccf204e2997af70f6b21/public/get-pip.py
+ENV PYTHON_GET_PIP_SHA256 fa6f3fb93cce234cd4e8dd2beb54a51ab9c247653b52855a48dd44e6b21ff28b
+
+RUN set -ex; \
+	\
+	savedAptMark="$(apt-mark showmanual)"; \
+	apt-get update; \
+	apt-get install -y --no-install-recommends wget; \
+	\
+	wget -O get-pip.py "$PYTHON_GET_PIP_URL"; \
+	echo "$PYTHON_GET_PIP_SHA256 *get-pip.py" | sha256sum --check --strict -; \
+	\
+	apt-mark auto '.*' > /dev/null; \
+	[ -z "$savedAptMark" ] || apt-mark manual $savedAptMark; \
+	apt-get purge -y --auto-remove -o APT::AutoRemove::RecommendsImportant=false; \
+	rm -rf /var/lib/apt/lists/*; \
+	\
+	python get-pip.py \
+		--disable-pip-version-check \
+		--no-cache-dir \
+		"pip==$PYTHON_PIP_VERSION" \
+	; \
+	pip --version; \
+	\
+	find /usr/local -depth \
+		\( \
+			\( -type d -a \( -name test -o -name tests -o -name idle_test \) \) \
+			-o \
+			\( -type f -a \( -name '*.pyc' -o -name '*.pyo' \) \) \
+		\) -exec rm -rf '{}' +; \
+	rm -f get-pip.py
+
+CMD ["python3"]
diff --git a/3.6/stretch/Dockerfile b/3.6/bullseye/Dockerfile
similarity index 99%
rename from 3.6/stretch/Dockerfile
rename to 3.6/bullseye/Dockerfile
index a016369ce..a93ad2f94 100644
--- a/3.6/stretch/Dockerfile
+++ b/3.6/bullseye/Dockerfile
@@ -4,7 +4,7 @@
 # PLEASE DO NOT EDIT IT DIRECTLY.
 #
 
-FROM buildpack-deps:stretch
+FROM buildpack-deps:bullseye
 
 # ensure local python is preferred over distribution python
 ENV PATH /usr/local/bin:$PATH
diff --git a/3.6/stretch/slim/Dockerfile b/3.6/bullseye/slim/Dockerfile
similarity index 99%
rename from 3.6/stretch/slim/Dockerfile
rename to 3.6/bullseye/slim/Dockerfile
index 32a80f5d8..3e1710f81 100644
--- a/3.6/stretch/slim/Dockerfile
+++ b/3.6/bullseye/slim/Dockerfile
@@ -4,7 +4,7 @@
 # PLEASE DO NOT EDIT IT DIRECTLY.
 #
 
-FROM debian:stretch-slim
+FROM debian:bullseye-slim
 
 # ensure local python is preferred over distribution python
 ENV PATH /usr/local/bin:$PATH
diff --git a/3.7/stretch/Dockerfile b/3.7/bullseye/Dockerfile
similarity index 99%
rename from 3.7/stretch/Dockerfile
rename to 3.7/bullseye/Dockerfile
index f6baebca8..20a1046da 100644
--- a/3.7/stretch/Dockerfile
+++ b/3.7/bullseye/Dockerfile
@@ -4,7 +4,7 @@
 # PLEASE DO NOT EDIT IT DIRECTLY.
 #
 
-FROM buildpack-deps:stretch
+FROM buildpack-deps:bullseye
 
 # ensure local python is preferred over distribution python
 ENV PATH /usr/local/bin:$PATH
diff --git a/3.7/stretch/slim/Dockerfile b/3.7/bullseye/slim/Dockerfile
similarity index 99%
rename from 3.7/stretch/slim/Dockerfile
rename to 3.7/bullseye/slim/Dockerfile
index 25645138f..028e23d7f 100644
--- a/3.7/stretch/slim/Dockerfile
+++ b/3.7/bullseye/slim/Dockerfile
@@ -4,7 +4,7 @@
 # PLEASE DO NOT EDIT IT DIRECTLY.
 #
 
-FROM debian:stretch-slim
+FROM debian:bullseye-slim
 
 # ensure local python is preferred over distribution python
 ENV PATH /usr/local/bin:$PATH
diff --git a/3.8/bullseye/Dockerfile b/3.8/bullseye/Dockerfile
new file mode 100644
index 000000000..dfacc4005
--- /dev/null
+++ b/3.8/bullseye/Dockerfile
@@ -0,0 +1,98 @@
+#
+# NOTE: THIS DOCKERFILE IS GENERATED VIA "update.sh"
+#
+# PLEASE DO NOT EDIT IT DIRECTLY.
+#
+
+FROM buildpack-deps:bullseye
+
+# ensure local python is preferred over distribution python
+ENV PATH /usr/local/bin:$PATH
+
+# http://bugs.python.org/issue19846
+# > At the moment, setting "LANG=C" on a Linux system *fundamentally breaks Python 3*, and that's not OK.
+ENV LANG C.UTF-8
+
+# extra dependencies (over what buildpack-deps already includes)
+RUN apt-get update && apt-get install -y --no-install-recommends \
+		libbluetooth-dev \
+		tk-dev \
+		uuid-dev \
+	&& rm -rf /var/lib/apt/lists/*
+
+ENV GPG_KEY E3FF2839C048B25C084DEBE9B26995E310250568
+ENV PYTHON_VERSION 3.8.11
+
+RUN set -ex \
+	\
+	&& wget -O python.tar.xz "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz" \
+	&& wget -O python.tar.xz.asc "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz.asc" \
+	&& export GNUPGHOME="$(mktemp -d)" \
+	&& gpg --batch --keyserver hkps://keys.openpgp.org --recv-keys "$GPG_KEY" \
+	&& gpg --batch --verify python.tar.xz.asc python.tar.xz \
+	&& { command -v gpgconf > /dev/null && gpgconf --kill all || :; } \
+	&& rm -rf "$GNUPGHOME" python.tar.xz.asc \
+	&& mkdir -p /usr/src/python \
+	&& tar -xJC /usr/src/python --strip-components=1 -f python.tar.xz \
+	&& rm python.tar.xz \
+	\
+	&& cd /usr/src/python \
+	&& gnuArch="$(dpkg-architecture --query DEB_BUILD_GNU_TYPE)" \
+	&& ./configure \
+		--build="$gnuArch" \
+		--enable-loadable-sqlite-extensions \
+		--enable-optimizations \
+		--enable-option-checking=fatal \
+		--enable-shared \
+		--with-system-expat \
+		--with-system-ffi \
+		--without-ensurepip \
+	&& make -j "$(nproc)" \
+	&& make install \
+	&& rm -rf /usr/src/python \
+	\
+	&& find /usr/local -depth \
+		\( \
+			\( -type d -a \( -name test -o -name tests -o -name idle_test \) \) \
+			-o \( -type f -a \( -name '*.pyc' -o -name '*.pyo' -o -name '*.a' \) \) \
+			-o \( -type f -a -name 'wininst-*.exe' \) \
+		\) -exec rm -rf '{}' + \
+	\
+	&& ldconfig \
+	\
+	&& python3 --version
+
+# make some useful symlinks that are expected to exist
+RUN cd /usr/local/bin \
+	&& ln -s idle3 idle \
+	&& ln -s pydoc3 pydoc \
+	&& ln -s python3 python \
+	&& ln -s python3-config python-config
+
+# if this is called "PIP_VERSION", pip explodes with "ValueError: invalid truth value '<VERSION>'"
+ENV PYTHON_PIP_VERSION 21.2.4
+# https://github.com/pypa/get-pip
+ENV PYTHON_GET_PIP_URL https://github.com/pypa/get-pip/raw/c20b0cfd643cd4a19246ccf204e2997af70f6b21/public/get-pip.py
+ENV PYTHON_GET_PIP_SHA256 fa6f3fb93cce234cd4e8dd2beb54a51ab9c247653b52855a48dd44e6b21ff28b
+
+RUN set -ex; \
+	\
+	wget -O get-pip.py "$PYTHON_GET_PIP_URL"; \
+	echo "$PYTHON_GET_PIP_SHA256 *get-pip.py" | sha256sum --check --strict -; \
+	\
+	python get-pip.py \
+		--disable-pip-version-check \
+		--no-cache-dir \
+		"pip==$PYTHON_PIP_VERSION" \
+	; \
+	pip --version; \
+	\
+	find /usr/local -depth \
+		\( \
+			\( -type d -a \( -name test -o -name tests -o -name idle_test \) \) \
+			-o \
+			\( -type f -a \( -name '*.pyc' -o -name '*.pyo' \) \) \
+		\) -exec rm -rf '{}' +; \
+	rm -f get-pip.py
+
+CMD ["python3"]
diff --git a/3.8/bullseye/slim/Dockerfile b/3.8/bullseye/slim/Dockerfile
new file mode 100644
index 000000000..5dc739aa0
--- /dev/null
+++ b/3.8/bullseye/slim/Dockerfile
@@ -0,0 +1,146 @@
+#
+# NOTE: THIS DOCKERFILE IS GENERATED VIA "update.sh"
+#
+# PLEASE DO NOT EDIT IT DIRECTLY.
+#
+
+FROM debian:bullseye-slim
+
+# ensure local python is preferred over distribution python
+ENV PATH /usr/local/bin:$PATH
+
+# http://bugs.python.org/issue19846
+# > At the moment, setting "LANG=C" on a Linux system *fundamentally breaks Python 3*, and that's not OK.
+ENV LANG C.UTF-8
+
+# runtime dependencies
+RUN set -eux; \
+	apt-get update; \
+	apt-get install -y --no-install-recommends \
+		ca-certificates \
+		netbase \
+	; \
+	rm -rf /var/lib/apt/lists/*
+
+ENV GPG_KEY E3FF2839C048B25C084DEBE9B26995E310250568
+ENV PYTHON_VERSION 3.8.11
+
+RUN set -ex \
+	\
+	&& savedAptMark="$(apt-mark showmanual)" \
+	&& apt-get update && apt-get install -y --no-install-recommends \
+		dpkg-dev \
+		gcc \
+		libbluetooth-dev \
+		libbz2-dev \
+		libc6-dev \
+		libexpat1-dev \
+		libffi-dev \
+		libgdbm-dev \
+		liblzma-dev \
+		libncursesw5-dev \
+		libreadline-dev \
+		libsqlite3-dev \
+		libssl-dev \
+		make \
+		tk-dev \
+		uuid-dev \
+		wget \
+		xz-utils \
+		zlib1g-dev \
+# as of Stretch, "gpg" is no longer included by default
+		$(command -v gpg > /dev/null || echo 'gnupg dirmngr') \
+	\
+	&& wget -O python.tar.xz "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz" \
+	&& wget -O python.tar.xz.asc "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz.asc" \
+	&& export GNUPGHOME="$(mktemp -d)" \
+	&& gpg --batch --keyserver hkps://keys.openpgp.org --recv-keys "$GPG_KEY" \
+	&& gpg --batch --verify python.tar.xz.asc python.tar.xz \
+	&& { command -v gpgconf > /dev/null && gpgconf --kill all || :; } \
+	&& rm -rf "$GNUPGHOME" python.tar.xz.asc \
+	&& mkdir -p /usr/src/python \
+	&& tar -xJC /usr/src/python --strip-components=1 -f python.tar.xz \
+	&& rm python.tar.xz \
+	\
+	&& cd /usr/src/python \
+	&& gnuArch="$(dpkg-architecture --query DEB_BUILD_GNU_TYPE)" \
+	&& ./configure \
+		--build="$gnuArch" \
+		--enable-loadable-sqlite-extensions \
+		--enable-optimizations \
+		--enable-option-checking=fatal \
+		--enable-shared \
+		--with-system-expat \
+		--with-system-ffi \
+		--without-ensurepip \
+	&& make -j "$(nproc)" \
+		LDFLAGS="-Wl,--strip-all" \
+	&& make install \
+	&& rm -rf /usr/src/python \
+	\
+	&& find /usr/local -depth \
+		\( \
+			\( -type d -a \( -name test -o -name tests -o -name idle_test \) \) \
+			-o \( -type f -a \( -name '*.pyc' -o -name '*.pyo' -o -name '*.a' \) \) \
+			-o \( -type f -a -name 'wininst-*.exe' \) \
+		\) -exec rm -rf '{}' + \
+	\
+	&& ldconfig \
+	\
+	&& apt-mark auto '.*' > /dev/null \
+	&& apt-mark manual $savedAptMark \
+	&& find /usr/local -type f -executable -not \( -name '*tkinter*' \) -exec ldd '{}' ';' \
+		| awk '/=>/ { print $(NF-1) }' \
+		| sort -u \
+		| xargs -r dpkg-query --search \
+		| cut -d: -f1 \
+		| sort -u \
+		| xargs -r apt-mark manual \
+	&& apt-get purge -y --auto-remove -o APT::AutoRemove::RecommendsImportant=false \
+	&& rm -rf /var/lib/apt/lists/* \
+	\
+	&& python3 --version
+
+# make some useful symlinks that are expected to exist
+RUN cd /usr/local/bin \
+	&& ln -s idle3 idle \
+	&& ln -s pydoc3 pydoc \
+	&& ln -s python3 python \
+	&& ln -s python3-config python-config
+
+# if this is called "PIP_VERSION", pip explodes with "ValueError: invalid truth value '<VERSION>'"
+ENV PYTHON_PIP_VERSION 21.2.4
+# https://github.com/pypa/get-pip
+ENV PYTHON_GET_PIP_URL https://github.com/pypa/get-pip/raw/c20b0cfd643cd4a19246ccf204e2997af70f6b21/public/get-pip.py
+ENV PYTHON_GET_PIP_SHA256 fa6f3fb93cce234cd4e8dd2beb54a51ab9c247653b52855a48dd44e6b21ff28b
+
+RUN set -ex; \
+	\
+	savedAptMark="$(apt-mark showmanual)"; \
+	apt-get update; \
+	apt-get install -y --no-install-recommends wget; \
+	\
+	wget -O get-pip.py "$PYTHON_GET_PIP_URL"; \
+	echo "$PYTHON_GET_PIP_SHA256 *get-pip.py" | sha256sum --check --strict -; \
+	\
+	apt-mark auto '.*' > /dev/null; \
+	[ -z "$savedAptMark" ] || apt-mark manual $savedAptMark; \
+	apt-get purge -y --auto-remove -o APT::AutoRemove::RecommendsImportant=false; \
+	rm -rf /var/lib/apt/lists/*; \
+	\
+	python get-pip.py \
+		--disable-pip-version-check \
+		--no-cache-dir \
+		"pip==$PYTHON_PIP_VERSION" \
+	; \
+	pip --version; \
+	\
+	find /usr/local -depth \
+		\( \
+			\( -type d -a \( -name test -o -name tests -o -name idle_test \) \) \
+			-o \
+			\( -type f -a \( -name '*.pyc' -o -name '*.pyo' \) \) \
+		\) -exec rm -rf '{}' +; \
+	rm -f get-pip.py
+
+CMD ["python3"]
diff --git a/3.9/bullseye/Dockerfile b/3.9/bullseye/Dockerfile
new file mode 100644
index 000000000..847cf1117
--- /dev/null
+++ b/3.9/bullseye/Dockerfile
@@ -0,0 +1,97 @@
+#
+# NOTE: THIS DOCKERFILE IS GENERATED VIA "update.sh"
+#
+# PLEASE DO NOT EDIT IT DIRECTLY.
+#
+
+FROM buildpack-deps:bullseye
+
+# ensure local python is preferred over distribution python
+ENV PATH /usr/local/bin:$PATH
+
+# http://bugs.python.org/issue19846
+# > At the moment, setting "LANG=C" on a Linux system *fundamentally breaks Python 3*, and that's not OK.
+ENV LANG C.UTF-8
+
+# extra dependencies (over what buildpack-deps already includes)
+RUN apt-get update && apt-get install -y --no-install-recommends \
+		libbluetooth-dev \
+		tk-dev \
+		uuid-dev \
+	&& rm -rf /var/lib/apt/lists/*
+
+ENV GPG_KEY E3FF2839C048B25C084DEBE9B26995E310250568
+ENV PYTHON_VERSION 3.9.6
+
+RUN set -ex \
+	\
+	&& wget -O python.tar.xz "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz" \
+	&& wget -O python.tar.xz.asc "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz.asc" \
+	&& export GNUPGHOME="$(mktemp -d)" \
+	&& gpg --batch --keyserver hkps://keys.openpgp.org --recv-keys "$GPG_KEY" \
+	&& gpg --batch --verify python.tar.xz.asc python.tar.xz \
+	&& { command -v gpgconf > /dev/null && gpgconf --kill all || :; } \
+	&& rm -rf "$GNUPGHOME" python.tar.xz.asc \
+	&& mkdir -p /usr/src/python \
+	&& tar -xJC /usr/src/python --strip-components=1 -f python.tar.xz \
+	&& rm python.tar.xz \
+	\
+	&& cd /usr/src/python \
+	&& gnuArch="$(dpkg-architecture --query DEB_BUILD_GNU_TYPE)" \
+	&& ./configure \
+		--build="$gnuArch" \
+		--enable-loadable-sqlite-extensions \
+		--enable-optimizations \
+		--enable-option-checking=fatal \
+		--enable-shared \
+		--with-system-expat \
+		--with-system-ffi \
+		--without-ensurepip \
+	&& make -j "$(nproc)" \
+	&& make install \
+	&& rm -rf /usr/src/python \
+	\
+	&& find /usr/local -depth \
+		\( \
+			\( -type d -a \( -name test -o -name tests -o -name idle_test \) \) \
+			-o \( -type f -a \( -name '*.pyc' -o -name '*.pyo' -o -name '*.a' \) \) \
+		\) -exec rm -rf '{}' + \
+	\
+	&& ldconfig \
+	\
+	&& python3 --version
+
+# make some useful symlinks that are expected to exist
+RUN cd /usr/local/bin \
+	&& ln -s idle3 idle \
+	&& ln -s pydoc3 pydoc \
+	&& ln -s python3 python \
+	&& ln -s python3-config python-config
+
+# if this is called "PIP_VERSION", pip explodes with "ValueError: invalid truth value '<VERSION>'"
+ENV PYTHON_PIP_VERSION 21.2.4
+# https://github.com/pypa/get-pip
+ENV PYTHON_GET_PIP_URL https://github.com/pypa/get-pip/raw/c20b0cfd643cd4a19246ccf204e2997af70f6b21/public/get-pip.py
+ENV PYTHON_GET_PIP_SHA256 fa6f3fb93cce234cd4e8dd2beb54a51ab9c247653b52855a48dd44e6b21ff28b
+
+RUN set -ex; \
+	\
+	wget -O get-pip.py "$PYTHON_GET_PIP_URL"; \
+	echo "$PYTHON_GET_PIP_SHA256 *get-pip.py" | sha256sum --check --strict -; \
+	\
+	python get-pip.py \
+		--disable-pip-version-check \
+		--no-cache-dir \
+		"pip==$PYTHON_PIP_VERSION" \
+	; \
+	pip --version; \
+	\
+	find /usr/local -depth \
+		\( \
+			\( -type d -a \( -name test -o -name tests -o -name idle_test \) \) \
+			-o \
+			\( -type f -a \( -name '*.pyc' -o -name '*.pyo' \) \) \
+		\) -exec rm -rf '{}' +; \
+	rm -f get-pip.py
+
+CMD ["python3"]
diff --git a/3.9/bullseye/slim/Dockerfile b/3.9/bullseye/slim/Dockerfile
new file mode 100644
index 000000000..ecd15dc28
--- /dev/null
+++ b/3.9/bullseye/slim/Dockerfile
@@ -0,0 +1,146 @@
+#
+# NOTE: THIS DOCKERFILE IS GENERATED VIA "update.sh"
+#
+# PLEASE DO NOT EDIT IT DIRECTLY.
+#
+
+FROM debian:bullseye-slim
+
+# ensure local python is preferred over distribution python
+ENV PATH /usr/local/bin:$PATH
+
+# http://bugs.python.org/issue19846
+# > At the moment, setting "LANG=C" on a Linux system *fundamentally breaks Python 3*, and that's not OK.
+ENV LANG C.UTF-8
+
+# runtime dependencies
+RUN set -eux; \
+	apt-get update; \
+	apt-get install -y --no-install-recommends \
+		ca-certificates \
+		netbase \
+		tzdata \
+	; \
+	rm -rf /var/lib/apt/lists/*
+
+ENV GPG_KEY E3FF2839C048B25C084DEBE9B26995E310250568
+ENV PYTHON_VERSION 3.9.6
+
+RUN set -ex \
+	\
+	&& savedAptMark="$(apt-mark showmanual)" \
+	&& apt-get update && apt-get install -y --no-install-recommends \
+		dpkg-dev \
+		gcc \
+		libbluetooth-dev \
+		libbz2-dev \
+		libc6-dev \
+		libexpat1-dev \
+		libffi-dev \
+		libgdbm-dev \
+		liblzma-dev \
+		libncursesw5-dev \
+		libreadline-dev \
+		libsqlite3-dev \
+		libssl-dev \
+		make \
+		tk-dev \
+		uuid-dev \
+		wget \
+		xz-utils \
+		zlib1g-dev \
+# as of Stretch, "gpg" is no longer included by default
+		$(command -v gpg > /dev/null || echo 'gnupg dirmngr') \
+	\
+	&& wget -O python.tar.xz "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz" \
+	&& wget -O python.tar.xz.asc "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz.asc" \
+	&& export GNUPGHOME="$(mktemp -d)" \
+	&& gpg --batch --keyserver hkps://keys.openpgp.org --recv-keys "$GPG_KEY" \
+	&& gpg --batch --verify python.tar.xz.asc python.tar.xz \
+	&& { command -v gpgconf > /dev/null && gpgconf --kill all || :; } \
+	&& rm -rf "$GNUPGHOME" python.tar.xz.asc \
+	&& mkdir -p /usr/src/python \
+	&& tar -xJC /usr/src/python --strip-components=1 -f python.tar.xz \
+	&& rm python.tar.xz \
+	\
+	&& cd /usr/src/python \
+	&& gnuArch="$(dpkg-architecture --query DEB_BUILD_GNU_TYPE)" \
+	&& ./configure \
+		--build="$gnuArch" \
+		--enable-loadable-sqlite-extensions \
+		--enable-optimizations \
+		--enable-option-checking=fatal \
+		--enable-shared \
+		--with-system-expat \
+		--with-system-ffi \
+		--without-ensurepip \
+	&& make -j "$(nproc)" \
+		LDFLAGS="-Wl,--strip-all" \
+	&& make install \
+	&& rm -rf /usr/src/python \
+	\
+	&& find /usr/local -depth \
+		\( \
+			\( -type d -a \( -name test -o -name tests -o -name idle_test \) \) \
+			-o \( -type f -a \( -name '*.pyc' -o -name '*.pyo' -o -name '*.a' \) \) \
+		\) -exec rm -rf '{}' + \
+	\
+	&& ldconfig \
+	\
+	&& apt-mark auto '.*' > /dev/null \
+	&& apt-mark manual $savedAptMark \
+	&& find /usr/local -type f -executable -not \( -name '*tkinter*' \) -exec ldd '{}' ';' \
+		| awk '/=>/ { print $(NF-1) }' \
+		| sort -u \
+		| xargs -r dpkg-query --search \
+		| cut -d: -f1 \
+		| sort -u \
+		| xargs -r apt-mark manual \
+	&& apt-get purge -y --auto-remove -o APT::AutoRemove::RecommendsImportant=false \
+	&& rm -rf /var/lib/apt/lists/* \
+	\
+	&& python3 --version
+
+# make some useful symlinks that are expected to exist
+RUN cd /usr/local/bin \
+	&& ln -s idle3 idle \
+	&& ln -s pydoc3 pydoc \
+	&& ln -s python3 python \
+	&& ln -s python3-config python-config
+
+# if this is called "PIP_VERSION", pip explodes with "ValueError: invalid truth value '<VERSION>'"
+ENV PYTHON_PIP_VERSION 21.2.4
+# https://github.com/pypa/get-pip
+ENV PYTHON_GET_PIP_URL https://github.com/pypa/get-pip/raw/c20b0cfd643cd4a19246ccf204e2997af70f6b21/public/get-pip.py
+ENV PYTHON_GET_PIP_SHA256 fa6f3fb93cce234cd4e8dd2beb54a51ab9c247653b52855a48dd44e6b21ff28b
+
+RUN set -ex; \
+	\
+	savedAptMark="$(apt-mark showmanual)"; \
+	apt-get update; \
+	apt-get install -y --no-install-recommends wget; \
+	\
+	wget -O get-pip.py "$PYTHON_GET_PIP_URL"; \
+	echo "$PYTHON_GET_PIP_SHA256 *get-pip.py" | sha256sum --check --strict -; \
+	\
+	apt-mark auto '.*' > /dev/null; \
+	[ -z "$savedAptMark" ] || apt-mark manual $savedAptMark; \
+	apt-get purge -y --auto-remove -o APT::AutoRemove::RecommendsImportant=false; \
+	rm -rf /var/lib/apt/lists/*; \
+	\
+	python get-pip.py \
+		--disable-pip-version-check \
+		--no-cache-dir \
+		"pip==$PYTHON_PIP_VERSION" \
+	; \
+	pip --version; \
+	\
+	find /usr/local -depth \
+		\( \
+			\( -type d -a \( -name test -o -name tests -o -name idle_test \) \) \
+			-o \
+			\( -type f -a \( -name '*.pyc' -o -name '*.pyo' \) \) \
+		\) -exec rm -rf '{}' +; \
+	rm -f get-pip.py
+
+CMD ["python3"]
diff --git a/generate-stackbrew-library.sh b/generate-stackbrew-library.sh
index 67c87209a..01e367282 100755
--- a/generate-stackbrew-library.sh
+++ b/generate-stackbrew-library.sh
@@ -6,9 +6,9 @@ declare -A aliases=(
 	[3.9]='3 latest'
 )
 
-defaultDebianSuite='buster' # TODO buster
+defaultDebianSuite='bullseye'
 declare -A debianSuites=(
-	#[3.8-rc]='buster'
+	#[3.10-rc]='bullseye'
 )
 defaultAlpineVersion='3.14'
 
@@ -78,7 +78,7 @@ for version in "${versions[@]}"; do
 	rcVersion="${version%-rc}"
 
 	for v in \
-		{buster,stretch}{,/slim} \
+		{bullseye,buster}{,/slim} \
 		alpine{3.14,3.13} \
 		windows/windowsservercore-{1809,ltsc2016} \
 	; do
@@ -106,7 +106,7 @@ for version in "${versions[@]}"; do
 		variantAliases=( "${versionAliases[@]/%/-$variant}" )
 		debianSuite="${debianSuites[$version]:-$defaultDebianSuite}"
 		case "$variant" in
-			*-"$debianSuite") # "slim-stretch", etc need "slim"
+			*-"$debianSuite") # "slim-bullseye", etc need "slim"
 				variantAliases+=( "${versionAliases[@]/%/-${variant%-$debianSuite}}" )
 				;;
 			"alpine${defaultAlpineVersion}")
diff --git a/update.sh b/update.sh
index 228161c4a..591eb945f 100755
--- a/update.sh
+++ b/update.sh
@@ -133,7 +133,7 @@ for version in "${versions[@]}"; do
 
 	for v in \
 		alpine{3.14,3.13} \
-		{stretch,buster}{/slim,} \
+		{buster,bullseye}{/slim,} \
 		windows/windowsservercore-{1809,ltsc2016} \
 	; do
 		dir="$version/$v"