Docker config for testing python-build (#1548)

* Dockerfile for testing python builds

* README: document docker usage

* Finish docker

dockerignore file, specify ephemeral nature of containers.

* Move docs for docker usage to python-build README

.dockerignore

@@ -0,0 +1,4 @@
+.git/
+.python-version
+.vscode/
+.idea/

Dockerfile

@@ -0,0 +1,35 @@
+FROM ubuntu:18.04
+
+LABEL maintainer="Chris L. Barnes <chrislloydbarnes@gmail.com>"
+
+ENV DEBIAN_FRONTEND=noninteractive
+
+RUN apt-get update -y \
+    && apt-get install -y \
+        make \
+        build-essential \
+        libssl-dev \
+        zlib1g-dev \
+        libbz2-dev \
+        libreadline-dev \
+        libsqlite3-dev \
+        wget \
+        curl \
+        llvm \
+        libncurses5-dev \
+        libncursesw5-dev \
+        xz-utils \
+        tk-dev \
+        libffi-dev \
+        liblzma-dev \
+        python-openssl \
+        git \
+    && rm -rf /var/lib/apt/lists/*
+
+ENV PYENV_ROOT "/pyenv"
+ENV PATH "$PYENV_ROOT/bin:$PATH"
+
+COPY . /pyenv
+
+RUN eval "$(pyenv init -)"
+

plugins/python-build/README.md

@@ -226,3 +226,51 @@ Please see the [pyenv wiki](https://github.com/pyenv/pyenv/wiki) for solutions t
 If you can't find an answer on the wiki, open an issue on the [issue
 tracker](https://github.com/pyenv/pyenv/issues). Be sure to include
 the full build log for build failures.
+
+## Contributing
+
+### Testing new python versions
+
+If you are contributing a new python version for python-build, 
+you can test the build in a [docker](https://www.docker.com/) container based on Ubuntu 18.04.
+
+With docker installed:
+
+```sh
+docker build -t my_container .
+docker run my_container pyenv install <my_version>
+```
+
+To enter a shell which will allow you to build and then test a python version,
+replace the second line with
+
+```sh
+docker run -it my_container
+```
+
+The container will need to be rebuilt whenever you change the repo,
+but after the first build, this will be very fast, 
+as the layer including the build dependencies will be cached.
+
+Changes made inside the container will not be persisted.
+
+To test *all* new versions since a particular revision (e.g. `master`), `cd` to the root of your `pyenv` repo, and run this script:
+
+```sh
+set -e
+set -x
+
+docker build -t pyenv-test-container .
+
+git diff --name-only master \
+  | grep '^plugins/python-build/share/python-build/' \
+  | awk -F '/' '{print $NF}' \
+  | xargs -I _ docker run pyenv-test-container pyenv install _
+```
+
+- Build the docker image with the **t**ag pyenv-test-container
+- Look for the names files changed since revision `master`
+- Filter out any which don't live where python-build keeps its build scripts
+- Look only at the file name (i.e. the python version name)
+- Run a new docker container for each, building that version
+