Docker build: docs, and Jessie support

Dockerfile.build

@@ -22,8 +22,9 @@ ARG PYVERSION
 ARG PKGNAME
 ARG DEB_POOL
 
-# Install build tools and package build deps including nodejs
-RUN env LANG=C apt-get update -qq -o Acquire::Languages=none \
+# Install build tools and package build deps
+RUN sed -i,orig 's/^\(.*jessie-updates\)/#\1/' /etc/apt/sources.list \
+    && env LANG=C apt-get update -qq -o Acquire::Languages=none \
     && env LANG=C DEBIAN_FRONTEND=noninteractive apt-get install \
         -yqq --no-install-recommends -o Dpkg::Options::=--force-unsafe-io \
         \
@@ -43,7 +44,7 @@ RUN env LANG=C apt-get update -qq -o Acquire::Languages=none \
         python${PYVERSION}-pkg-resources \
         python${PYVERSION}-setuptools \
         python-virtualenv \
-        sphinx-rtd-theme-common \
+        $(apt-cache search sphinx-rtd-theme-common | cut -f1 -d' ') \
         tar \
         \
         libcurl4-openssl-dev \
@@ -63,6 +64,13 @@ RUN env LANG=C apt-get update -qq -o Acquire::Languages=none \
         libldap2-dev \
         libpq-dev \
         libsasl2-dev \
+    && if grep -q VERSION.*jessie /etc/os-release ; then \
+            echo "deb http://archive.debian.org/debian jessie-backports main" >/etc/apt/sources.list.d/backports.list \
+            && apt-get update -o Acquire::Check-Valid-Until=false \
+            && env LANG=C DEBIAN_FRONTEND=noninteractive apt-get install \
+                -yqq --no-install-recommends -o Dpkg::Options::=--force-unsafe-io \
+                -t jessie-backports cmake ; \
+       fi \
     && apt-get clean && rm -rf "/var/lib/apt/lists"/*
 
 # Uncomment and adapt these ENV instructions to use a local PyPI mirror

README.md

@@ -58,7 +58,26 @@ This is also the place where you can put in your own
 
 ## How to build and install the package
 
-You need a build machine with all build dependencies installed, specifically
+### Building in a Docker container
+
+The easiest way to build the package is using the provided ``Dockerfile.build``.
+Then you do not need to install tooling and build dependencies on your machine,
+and the package gets built in a pristine environment.
+The only thing you need on your workstatioon is a ``docker-ce`` installation of version 17.06 or higher
+(either on [Debian](https://docs.docker.com/install/linux/docker-ce/debian/)
+or on [Ubuntu](https://docs.docker.com/install/linux/docker-ce/ubuntu/)).
+
+Call ``./build.sh debian:stretch`` to build the package for *Debian Stretch*
+– building for *Debian Jessie* and *Ubuntu Bionic* (with ``./build.sh ubuntu:bionic``) is also supported.
+See [Building Debian Packages in Docker](https://dockyard.readthedocs.io/en/latest/packaging-howto.html#dpkg-in-docker)
+for more details.
+
+The resulting package files are placed in the ``dist/`` directory.
+
+
+### Building directly on your workstation
+
+Otherwise, you need a build machine with all build dependencies installed, specifically
 [dh-virtualenv](https://github.com/spotify/dh-virtualenv) in addition to the normal Debian packaging tools.
 You can get it from [this PPA](https://launchpad.net/~spotify-jyrki/+archive/ubuntu/dh-virtualenv),
 the [official Ubuntu repositories](http://packages.ubuntu.com/search?keywords=dh-virtualenv),