some starting point

ubuntu/Dockerfile

@@ -0,0 +1,32 @@
+FROM ubuntu:20.04
+
+VOLUME /etc/portage
+VOLUME /var/db/portajohn-db
+
+RUN apt-get update && apt-get install -y \
+    git \
+    zstd \
+    python3 \
+    python3-distutils \
+    python3-pip \
+    build-essential \
+    rsync
+
+RUN DEBIAN_FRONTEND=noninteractive apt-get install -y tzdata
+
+RUN apt-get install -y mc
+
+RUN useradd -U -r -s /bin/false portage
+
+WORKDIR /portajohn
+
+RUN git clone https://github.com/gentoo/portage.git; \
+    cd portage; \
+    python3 setup.py install; \
+    pip3 install gemato
+
+
+RUN cd /; \
+    emerge --version
+
+CMD ["/bin/bash"]