Add support for excluding files/directories from mounted source

[rkgrep]

When local agent mounts source path, it includes all sub-directories including .git, node_modules, etc.
This either makes DOWNLOAD_SOURCE step very long or breaks local development environment most of the time, there must be some way to control which files are being mounted.

[adanemayer]

I also struggled with the 'DOWNLOAD_SOURCE' times but then re-read the flags and added '-m' so that the CodeBuild image mounts the specified source directory directly instead of creating a temporary copy.

./codebuild_build.sh -i <image> -s <path_to_repo> -m

[kevin-brotcke]

Another workaround is to mount an empty folder with a compressed version of your code using git archive or tar then extract it in your buildspec.

[jeremyj563]

It feels like -m should be the default behavior honestly considering this is used for local testing.

[hermanho]

Mount the source directory directly might be created unexpected side effect. For example, npm install will be one of the steps in pre_build. The working directory will be polluted with mounting approach since node_modules are existed when development. Also, developers would expect the build is running is an isolated environment.

[dangeReis]

So I see 4 years later this is still not done. From what I understand we don't have the source for the local_builder so we can't do this ourselves, what have people been doing to avoid having the node_modules in the build?