How to integrate build output from one git repo into another

Question

I am working on a 2 projects which are stored in 2 git repos Project1 and Project2

Project1 is a javascript project. It has its own repo (for example https://github.com/gandra/project1.git)
Project2 is a java maven project. It has its own repo (for example https://github.com/gandra/project2.git)

Here is a current workflow which I want to improve:

1. Commit changes in a Project1 and push it to origin
2. Run grunt in a Project1. This generates Project1/build directory
3. Manually copy Project1/build contents into Project2/libs/project1-lib directory
4. Commit changes(Project2/libs/project1-lib) in Project2
5. Runk jenkins build and deploy

I want to somehow to avoid step 3 (manual copy of Project1/build contents into Project2/libs/project1-lib directory) I thought about integrate Project1 into Project2 as a subtree but the problem with this approach is beacuse it gets all Project1 directory structure into Project2/libs/project1-lib and I want only to take subdirectory of a Project1 (Project1/build/*)

Some important note: Project1 changes occurs only in its own repo(https://github.com/gandra/project1.git) and this change should be propagated to Project2. So there is no update of Project1 from Project2/libs/project1-lib In other words:
- Commits in Project1 affect Project2
- commits in Project2 not affects Project1

Answer 1

Ok let's recap the most important facts here:

1. Project2 is maven project(with war packaging probably, since you will deploy it ).
2. Project2 depends on Project1 in a way that it expects his output build on a path Project2/libs/project1-lib

In my opinion builds(even partial buils) are not meant to be under any source code management, so I wouldn't reserve any path of Project2 like Project2/libs/project1-lib to be under the git. Maven war plugin has this nice feature maven-war-plugin-overlays. So if Project2 would see Project1 as maven dependency with war type of packaginig e.g.

  <dependencies>
    ...
    <dependency>
      <groupId>your.group.id</groupId>
      <artifactId>project1</artifactId>
      <version>1.0-SNAPSHOT</version>
      <type>war</type>
      <scope>runtime</scope>
    </dependency>
    ...
  </dependencies>

, you wouldn't have to do any coping into Project2/libs/project1-lib location, because that will maven do for you in phase of packaing. But to do this, you have to install war artifact of your Project1 into your nexus. There are couple of solutions here:

Solution 1)

1. Make Project1 to be fully maven project, and make sure output of build finished on a path ./libs/project1-lib in his war. Since Project1 now would be build with maven, you would have to integrate previous building tool of Project1(grunt, gulp or whichever) to be called by maven in some phase before packaging phase.

2. In Project2 add new dependency like this:

   <dependency>
     <groupId>your.group.id</groupId>
     <artifactId>project1</artifactId>
     <version>1.0-SNAPSHOT</version>
     <type>war</type>
     <scope>runtime</scope>
   </dependency>
   

Solution 2).

1. With your current builder of Project1, make sure you package your project into war with following structure ./libs/project1-lib. Using same builder install this as war artifact on your nexus (NOTE: you would have to have pom.xml installed on your nexus so other project can reference Project1) If you are using grunt as a js builder luckily, there is this npm component grunt-nexus-deployer which will do exactly what I described here.
2. same as for Solution 1)...

Explanation:

When you push your changes of Project1 your CI will trigger job which will install project1-1.0-SNAPSHOT.war on your nexus after this is done, CI job for Project2 will be triggered and it will have everything needed for project2 build.

NOTE: In both solutions, delete Project2/libs/project1-lib hierarchy, since it not used anymore...

EDIT:

For solution 2) maybe you should use grunt-maven-tasks instead of grunt-nexus-deployer because it has more options and it is more suitable.