docs(diagrams) added some much needed diagrams to this repository (#252)

* add docs folder

* docs(diagrams) upload some draw.io diagrams

* docs(diagrams) updated the diagrams so they're more readable

* docs(diagrams) integrate the diagrams into the README.md

README.md

 # Kong Build Tools
 
-The tools necessary to build Kong
+The tools necessary to build, package and release Kong
 
 ## Prerequisites
 
 - Kong source
 - Docker
+- docker-compose
 - Make
 
-Building non x86_64 architectures additionally requires:
+All examples assume that Kong is a sibling directory of kong-build-tools and run from the kong-build-tools directory
+unless otherwise specified. This behaviour can be adjusted by setting a `KONG_SOURCE_LOCATION` environment variable
+```
+cd ~
+git clone git@github.com:Kong/kong.git
+git clone git@github.com:Kong/kong-build-tools.git
+cd kong-build-tools
+```
+
+Packaging arm64 architectures additionally requires:
 
 - [Docker-machine](https://github.com/docker/machine)
 - [Buildx Docker plugin](https://github.com/docker/buildx)
 - AWS Credentials
 
-## Building a Kong Distribution
+## Packaging a Kong Distribution
 
-The default build task builds an Ubuntu xenial package of Kong where the Kong source is assumed to be
+The default build task builds an Ubuntu bionic package of Kong where the Kong source is assumed to be
 in a sibling directory to where this repository is cloned
 
 ```
-cd ~
-git clone git@github.com:Kong/kong.git
-git clone git@github.com:Kong/kong-build-tools.git
-cd kong-build-tools
 make package-kong
 ls output/
-kong-0.0.0.xenial.all.deb
+kong-0.0.0.bionic.all.deb
 ```
 
-Environment variables:
+**Environment variables:**
 
 You can find all available environment variables at the top of the [Makefile](https://github.com/Kong/kong-build-tools/blob/master/Makefile).
 The most common ones are the following:
 
 ```
-KONG_SOURCE_LOCATION=/src/projects/custom-kong-location
-KONG_PACKAGE_NAME=custom-kong-name
-KONG_VERSION=v1.0.0
 RESTY_IMAGE_BASE=ubuntu|centos|rhel|debian|alpine|amazonlinux
 RESTY_IMAGE_TAG=xenial|bionic|6|7|8|jessie|stretch|latest|latest
 PACKAGE_TYPE=deb|rpm|apk
 ```
 
-For RedHat additionally export:
-```
-export REDHAT_USERNAME=rhuser
-export REDHAT_PASSWORD=password
-```
+### Details
+
+![building kong](/docs/Package%20Kong.png?raw=true)
+
+The Docker files in the dockerfiles directory build on each other in the following manner:
 
-## Building a Container
+- `Dockerfile.package` builds on top of the result of `Dockerfile.kong` to package Kong using `fpm-entrypoint.sh`
+- `Dockerfile.kong` builds on top of the result of `Dockerfile.openresty` to build Kong using `build-kong.sh`
+- `Dockerfile.openresty` builds on top of the result of `Dockerfile.(deb|apk|rpm)` to build the Kong prerequisites using `openresty-build-tools/kong-ngx-build`
+- `Dockerfile.(deb|apk|rpm)` builds the compilation / building prerequisites
 
-Sometimes it's useful to have a docker image with the Kong asset installed that you just built.
+## Running Kong Tests
 
 ```
-export KONG_TEST_IMAGE_NAME=kong:testing
-make build-test-container
+make test-kong
 ```
 
-## Testing
+**Environment variables:**
 
-*Prerequisites:*
-
-- Docker
-- Docker Compose
+Refer to [git://kong/.ci/run_tests.sh](https://github.com/Kong/kong/blob/master/.ci/run_tests.sh) for the authoritative environment variables.
+The most common ones are the following:
 
 ```
-make test
+TEST_DATABASE = "off|postgres|cassandra"
+TEST_SUITE = "dbless|plugins|unit|integration"
 ```
 
-## Functional Tests
+### Details
 
-The Kong functional tests use [Tavern](https://taverntesting.github.io/).
+![testing kong](/docs/Test%20Kong.png?raw=true)
 
-*Prerequisites*
+- `docker-compose.yml` runs the result of `Dockerfile.test` as well as postgres, cassandra, grpc and redis
+- `Dockerfile.test` builds on top of the result of `Dockerfile.openresty` to build Kong for development/testing
+- `Dockerfile.openresty` builds on top of the result of `Dockerfile.(deb|apk|rpm)` to build the Kong prerequisites using `openresty-build-tools/kong-ngx-build`
+- `Dockerfile.(deb|apk|rpm)` builds the compilation / building prerequisites
 
-- Docker
-- A Packaged Kong Release (`make package-kong`)
+### Debugging Tests
+
+If you want to mirror a failed test from CI pull the test image the CI built and retag it:
 
 ```
-make test
+docker pull mashape/kong-build-tools:test-33c8ceb-e2bb1fd54f8d5c12f989a801a44979b610-14
+docker tag mashape/kong-build-tools:test-33c8ceb-e2bb1fd54f8d5c12f989a801a44979b610-14 mashape/kong-build-tools:test
 ```
 
-Will run the functional tests against the defaults specified in the Makefile prefixed with `TEST_`
+If you're trying to test local Kong source code build the test image:
 
-The available ENV's and their defaults are as follows
+```
+make kong-test-container
+```
 
+Now spin up the containers using docker-compose and jump into the Kong image
 ```
-TEST_ADMIN_PROTOCOL?=http://
-TEST_ADMIN_PORT?=8001
-TEST_HOST?=localhost
-TEST_ADMIN_URI?=$(TEST_ADMIN_PROTOCOL)$(TEST_HOST):$(TEST_ADMIN_PORT)
-TEST_PROXY_PROTOCOL?=http://
-TEST_PROXY_PORT?=8000
-TEST_PROXY_URI?=$(TEST_PROXY_PROTOCOL)$(TEST_HOST):$(TEST_PROXY_PORT)
+docker-compose up -d
+docker-compose exec kong /bin/bash
+./ci/run_tests.sh
 ```
 
-### Developing Functional Tests
+## Running Functional Tests
 
-With the same prerequisites as running functional tests
+The Kong Build Tools functional tests suite run a tests on a Kong package which we then integrate
+into our official docker build image dockerfile.
 
 ```
+make package-kong
 make test
-make develop-tests
-py.test test_your_test.tavern.yaml # Expect warnings about https and structure different
 ```
 
-## Releasing a Kong Distribution
+### Details
+
+![releasing kong](/docs/Release%20Kong.png?raw=true)
+
+`test/build_container.sh` clones `git://kong/docker-kong` and provides the Dockerfile with a packaged Kong asset
+
+**01-package**
+
+Validates the version required per `git://kong/.requirements` of our prerequisites is what ended up being installed.
+Also does some rudimentary checks of the systemd and logrotate we include with our packages
+
+**02-api**
+
+Uses the python [tavern](https://taverntesting.github.io/) testing tool to run functional tests against Kong with Postgres by 
+sending REST requests to the Kong admin api and validating the expected responses / behaviour on the proxy ports.
+
+**03-go-plugin**
+
+Builds a go-plugin and sets it up with Kong to verify the go-plugin capabilities
+
+## Releasing Kong
 
 The same defaults that applied when creating a packaged version of Kong apply to releasing said package
 to bintray and can be changed by environment variables. Presumes that the package you want to release
@@ -118,7 +146,7 @@ export BINTRAY_KEY=key
 export RESTY_IMAGE_BASE=seeabove
 export RESTY_IMAGE_TAG=seeabove
 export KONG_PACKAGE_NAME=somename
-export KONG_VERSION=1.2.3
+make package-kong
 make release-kong
 ```
 
@@ -128,14 +156,6 @@ BINTRAY_USR
 BINTRAY_KEY
 ```
 
-Required release ENV variables that have defaults if they are not set:
-```
-RESTY_IMAGE_BASE
-RESTY_IMAGE_TAG
-KONG_PACKAGE_NAME
-KONG_VERSION
-```
-
 Optional release ENV variables:
 ```
 REPOSITORY_TYPE
@@ -155,5 +175,5 @@ bintray.com/kong/$REPOSITORY_NAME/$REPOSITORY_OS_NAME/$KONG_VERSION/$KONG_PACKAG
 Using all defaults one would end up with
 
 ```
-bintray.com/kong/kong-deb/ubuntu/0.0.0/kong-0.0.0.xenial.all.deb
+bintray.com/kong/kong-deb/ubuntu/0.0.0/kong-0.0.0.bionic.all.deb
 ```

docs/README.md

+Sources for the diagrams:
+
+[Test Kong Kong](https://drive.google.com/file/d/18r4hjJBcCIh1UFu3TWxTjUwPEqOg3hM8/view?usp=sharing)
+[Release Kong](https://drive.google.com/file/d/14PjZVcPgJR2_zNbmywiw52IeBdkLjYXE/view?usp=sharing)
+[Package Kong](https://drive.google.com/file/d/1rbEe19MIHYJXdbP18M1vYlxhmvysqc_L/view?usp=sharing)
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