* Python Environment: add gevent based WSGI server framework
This supply gevent based WSGI server framework to Python Environment, to
allow customer to run their functions under multi-threads.
* classify the flask based application
This set up the flask based application as individual class, to make
sure the consistent and integrity.
* Add instruction of WSGI server selection applied in Python Environment
* Python Environment starting logger: provide framework name
* Add readiness probe
* Remove builder manager http api interface since we don’t use/need it
* Check environment builder status and block build requests until builder is ready
* Replace deprecated api extension interface
* Add healthy check to python env
Create a container image with the buidler, so we can avoid copying the builder binary into the env container during the env container build.
Gather both stdout and stderr of a build into the logs.
* Add Dockerfile for builder + update release scripts
* Improve logging of buildermgr and builder
* Add support for environment-scoped buildcmd
* Fix fork/exec wd when package is a file
* Update tests to also include builder image
* Add logging to builder's fork/exec
