Prevent duplicate app dir paths

[jromero]

Changes

• Make app dir absolute
  • In regards to discussions with @ekcasey: it's unexpected to think that -app ./some/path/ and -app /my-app/some/path/ would place the application source in different directories within the final image
• Clean src path to tar to prevent duplicate entries eg. some/dir/ vs some/dir vs some/dir/.
• Update tool dependency golangci - I did this in an attempt to solve issues with scopelint.
• Update Makefile to support incoming GOFLAGS - IntelliJ/Goland's built-in terminal provides this flag that then collides with -mod=vendor and we get an error stating the it can only be specified once.

Resolves #222

Sidenote

A concern that come up with the current implementation is that the app dir isn't configurable and is based directly off of the -app argument. For example, in theory -app=/home/jromero/my-app would yield with that directory location in the final image as /home/jromero/my-app/. My initial thought would be that there would be a standard app path location. Seems like this might have existed in PR #35 but has since been removed.

• After discussing this with @ekcasey, it appears that this is intended for now due to the fact that it's intended to run in a container in which case paths could be modified to suit the need. Some concerns over specific CI systems still exist by chose to defer until such case arises.

Related to:

• Consider making $HOME = /app #123
• As a CNB user, the default layers directory should be /layers and the default app directory should be /workspace #77
• Add support for custom app directory with cmd arg #35

[ekcasey]

Cleaning the app dir path seems like a good thing to do. However, I feel that we should address the issue in the archive package (in our layer creation logic) that results in duplicate entries in these cases. If the path is valid that archive package should handle it correctly. I also think we should test edge cases (.e.g a path with .) in tar_test.go.

[sclevine]

Also may be a good idea to clean the layer directory, like we do for builder:

lifecycle/builder.go

Lines 58 to 69 in 5a1ef31

	platformDir, err := filepath.Abs(b.PlatformDir)
	if err != nil {
	return nil, err
	}
	layersDir, err := filepath.Abs(b.LayersDir)
	if err != nil {
	return nil, err
	}
	appDir, err := filepath.Abs(b.AppDir)
	if err != nil {
	return nil, err
	}

[jromero]

RE: @ekcasey
Although I agree with the sentiment as a whole I find it cumbersome to think about maintaining two robust implementations of archiving functionality. In practice, we've resolved these issues already in pack and have a different solution for how this occurs. I wonder if a better approach wouldn't be to instead move (or centralize) archiving functionality so that pack and lifecycle share the same solution.

[ekcasey]

@jromero One could make a case for moving some of this logic to imgutil I suppose, given that the package in question provides utilities for creating layers. I'm fairly ambivalent on that question. With less duplication we won't have to fix bugs in two places. However, the logic is not completely identical due to the differing contexts (e.g lifecycle adds parent dirs) and moving it to imgutil adds a bit more friction to the process of making changes.

Whether we extract this package to a shared location or not, I do believe we should fix the core issue in the archive package rather than, or in addition to, working around it.

Updated

[natalieparellano]

Accepting - on 5b9f575 (without the fix) invoking the exporter with -app /workspace/. produces the following error:

[exporter] ERROR: failed to export: failed to write image to the following tags: [index.docker.io/library/fake-app-new:latest: save image 'index.docker.io/library/fake-app-new:latest': Error: No such image: 471f8ab89748b6e40135612e8ef4c89715df0e661b7c9eed8f93cfefa4293248]

On master, we were able to successfully build the app image with the same invocation.

Note, our acceptance steps used pack as the platform. We did the following:

• make build the lifecycle binaries
• cp out/lifecycle/exporter /tmp/fake-app/real-exporter
• wrote a shell script saved to out/lifecycle/exporter to run real-exporter from /workspace in the build container
• make package && pack create-builder test-builder --builder-config ./builder.toml
• pack build test-app --path /tmp/fake-app --builder test-builder --buildpack /tmp/fake-buildpack <- observe the build fail or succeed