Bring examples back into the monorepo

[virkt25]

There is a growing list of examples that need to be maintained and kept up to date with the latest version of LoopBack especially as there are breaking changes that might be made during the development of MVP.

The example repos are kept in their own repository right now so it's easy for users to be able to clone the examples and play around with working code and this won't be possible if we move the examples to the monorepo but it would make maintenance a lot easier.

The purpose of this task is to explore options for doing this in a user friendly manner. Some avenues of exploration are:

• A CLI command that can get the relevant example from the monorepo, update package.json and stand up the example without the monorepo dependencies. Ex commands: lb4 example getting-started or lb4 example log-extension, etc.

• A new monorepo just for examples. Not as clean but users will be able to clone the entire repo and run the individual examples by going to the appropriate section. NOTE: When I say monorepo here, I mean more a big folder of example repos and not a lerna monorepo since different examples shouldn't have dependencies on each other.

Tasks

• Implement lb4 example CLI command - see feat(cli): lb4 example [<example-name>] #848
• Move https://github.com/strongloop/loopback4-example-getting-started to monorepo - see feat(getting-started): migrate into monorepo #869 and Add a deprecation message pointing to our monorepo strongloop-archive/loopback4-example-getting-started#19
• Move https://github.com/strongloop/loopback4-example-log-extension to monorepo - see Bring in loopback4-example-log-extension #908
• Move https://github.com/strongloop/loopback4-example-rpc-server to monorepo - see Bring in loopback4-example-rpc-server #915
• Remove example-codehub - docs: remove outdated example-codehub project #900
• https://github.com/strongloop/loopback4-example-hello-world: Move it into monorepo as even simpler version than loopback4-example-getting-started. See docs: add example-hello-world #924
• https://github.com/strongloop/loopback-next-example: Rename it to reflect it's advanced example of how multiple micro services work together. It will be great that we can evolve it with gRPC and OpenAPI based assembly. See docs: add example-microservices #933
• https://github.com/strongloop/loopback4-extension-starter: DEPRECATE. Move sample controller/provider/etc. source files from to lb4 extension templates See strongloop-archive/loopback4-extension-starter@8e869c0
• DEPRECATE https://github.com/strongloop/loopback4-extension-typeorm - see doc: Add deprecation notice strongloop-archive/loopback4-extension-typeorm#6
• DEPRECATE https://github.com/strongloop/loopback-next-hello-world - see README: Add a deprecation notice strongloop-archive/loopback-next-hello-world#26
• Update the docs: http://loopback.io/doc/en/lb4/Examples-and-tutorials.html - see lb4: update and improve Examples-and-tutorials loopback.io#595
• Write a blog post - see https://github.com/strongloop/strongloop.com/pull/110

Things to change as part of migration:

• run slt license and slt copyright
• mark the package as private
• review package.json scripts - make them consistent with other monorepo packages
• add an entry to CODEOWNERS
• add an entry to the list of examples used by lb4 example
• update README with instructions mentioning lb4 example
• move the original repo to strongloop-archive
• remove all files from the original repo, keep README pointing to our monorepo only
• archive the original repo (make it read-only)

See also #855

[bajtos]

I personally prefer to bring all examples to the main monorepo, so that we run their tests as part of our CI for any changes we are making in loopback core.

Here are my thoughts how the CLI command could be implemented, preferably with no dependency on git:

1. Start with a prompt asking the user what example to obtain. (There should be a CLI argument to skip this prompt and run in a non-iteractive mode.) The list of examples can be hard-coded for now, to keep things simple. Later, we may implement some automated solution that would fetch the list of examples from GitHub.

2. Download a ZIP archive of loopback-next's master branch: https://github.com/strongloop/loopback-next/archive/master.zip

3. Use extract-zip to open the archive and extract only the files from packages/<selected-example>.

4. AFAICT, there are only few things we need to fix when extracting a package from a monorepo:

   • add some of the shared dev-dependencies from monorepo's top-level package.json
   • add test/mocha.opts from monorepo to the example package
   • fix the npm script for running mocha - remove the reference to mocha.opts, since test/mocha.opts is loaded by default

This looks pretty doable to me :)

I am proposing the following approach:

• Start with implementing lb4 example using the existing example-codehub package to seed the initial list of examples
• Once lb4 example is landed, start moving individual example repositories to our monorepo

[bajtos]

The kick-off: #848

[raymondfeng]

@bajtos Here is my view:

• https://github.com/strongloop/loopback4-example-hello-world (Move it into monorepo as even simpler version than loopback4-example-getting-started)
• https://github.com/strongloop/loopback-next-example (Rename it to reflect it's advanced example of how multiple micro services work together. It will be great that we can evolve it with gRPC and OpenAPI based assembly)
• https://github.com/strongloop/loopback-next-hello-world (Deprecate)

[bajtos]

https://github.com/strongloop/loopback4-extension-starter

@raymondfeng @kjdelisle @virkt25 I am proposing to deprecate this repository and tell our users to run lb4 extension instead. Any objections? Are you aware of any specific content in the extension starter that is not part of our current extension template and that should be copied over?