add readme from master

Author: hjwp

README.md

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+# Example application code for the python architecture book
+
+## Chapters
+
+Each chapter has its own branch which contains all the commits for that chapter,
+so it has the state that corresponds to the _end_ of that chapter.  If you want
+to try and code along with a chapter, you'll want to check out the branch for the
+previous chapter.
+
+https://github.com/python-leap/code/branches/all
+
+
+## Exercises
+
+Branches for the exercises follow the convention `{chatper_name}_exercise`, eg 
+https://github.com/python-leap/code/tree/chapter_04_service_layer_exercise
+
+
+## Requirements
+
+* docker with docker-compose
+* for chapters 1 and 2, and optionally for the rest: a local python3.7 virtualenv
+
+
+## Building the containers
+
+_(this is only required from chapter 3 onwards)_
+
+```sh
+make build
+make up
+# or
+make all # builds, brings containers up, runs tests
+```
+
+## Creating a local virtualenv (optional)
+
+```sh
+python3.8 -m venv .venv && source ./venv/bin/activate # or however you like to create virtualenvs
+
+# for chapter 1
+pip install pytest 
+
+# for chapter 2
+pip install pytest sqlalchemy
+
+# for chapter 4+5
+pip install requirements.txt
+
+# for chapter 6+
+pip install requirements.txt
+pip install -e src/
+```
+
+<!-- TODO: use a make pipinstall command -->
+
+
+## Running the tests
+
+```sh
+make test
+# or, to run individual test types
+make unit
+make integration
+make e2e
+# or, if you have a local virtualenv
+make up
+pytest tests/unit
+pytest tests/integration
+pytest tests/e2e
+```
+
+## Makefile
+
+There are more useful commands in the makefile, have a look and try them out.
+