Investigate improving Apicast dependency builds

Context

Apicast build depends on the following RPM packages:

• openresty
• openresty-resty (same spec as openresty)
• openresty-opentracing (same spec as openresty)
• luarocks
• gateway-rockspecs
• opentracing-cpp
• opentracing-cpp-devel (same spec as opentracing-cpp)
• jaegertracing-cpp-client
   

Those packages are generated from source code from https://code.engineering.redhat.com

Some examples:

• http://pkgs.devel.redhat.com/cgit/rpms/openresty/tree/source-repos?h=3scale-2.12-rhel-8
•  http://pkgs.devel.redhat.com/cgit/rpms/jaegertracing-cpp-client/tree/source-repos?h=3scale-2.12-rhel-8

 WHAT

The main goal is to reduce complexity of the apicast productization pipeline. The idea is to remove all RPM dependencies and have multistage docker build that ends up with the final apicast runtime image.

HOW

Some packages like  openresty and lua rocks (in gateway-rockspec rpm) are being built in productization pipelines. The source code is hosted in gerrit. Some of the components, include custom 3scale patches in a `_product` branch. For example, nginx patch at release-1.19.3-product-3 branch

Those 3scale patched modules in RPMs are used in upstream to build the runtime image by uploading the RPM packages to a public repo: packages.dev.3scale.net

yum config-manager --add-repo http://packages.dev.3sca.net/dev_packages_3sca_net.repo 

The main idea would be to public all patches in public repos. Have them mirrored in gerrit and write a multistage docker build file for the apicast runtime image. No more RPMs.

Upstream build can also benefit a lot from this change. Upstream build no longer will depend on some RPMs built only for productization purposes.

Related links:

* APICast productization details