jib:build is not reproducible due to directory timestamps not being set

[eisig]

Description of the issue:
When I build the code in container, it will rebuild all the layer every time.

Expected behavior:
I don’t have to wait for Docker to rebuild your entire Java application - just deploy the layers that changed.
Steps to reproduce:

1. clone https://github.com/GoogleContainerTools/jib.git , cd to examples/spring-boot
2. build with:

docker run -v `pwd`:/tmp/build -w /tmp/build -v $HOME/.m2:/root/.m2 maven:3-jdk-8 mvn clean compile jib:build -Djib.from.image=openjdk:8-alpine -Dimage=<myimage>

3. docker pull the new image. I have to pull all the 3 layers, include the 14.38MB dependency layer every time .

Environment:
macos 10.14.3, docker Version 2.0.0.3

[loosebazooka]

Can you run docker history on the image to see if the digests are actually different?

[chanseokoh]

Seems like a critical bug. Timestamps of directories are not set to the epoch+1 sec.

examples/spring-boot$ tar tvf target/jib-cache/layers/01*/f8*
drwxr-xr-x 0/0               0 2019-04-19 13:28 app/
drwxr-xr-x 0/0               0 2019-04-19 13:28 app/classes/
drwxr-xr-x 0/0               0 1969-12-31 19:00 app/classes/hello/
-rw-r--r-- 0/0             699 1969-12-31 19:00 app/classes/hello/Application.class
-rw-r--r-- 0/0             594 1969-12-31 19:00 app/classes/hello/HelloController.class

We need to track down since when this started to happen.

[chanseokoh]

It doesn't have to run inside the container to reproduce.

[loosebazooka]

I think #1571 added this regression: https://github.com/GoogleContainerTools/jib/pull/1571/files#diff-9f3ce3d4c2254dbe95c91624e7b434d9R110

[loosebazooka]

Moving the time code in the link above doesn't account for parent directories added with uniqueTarArchiveEntries.add(entry);

[chanseokoh]

Gosh. That explains it. That is in 1.1.0.

[loosebazooka]

okay, fix is coming, behavior:

• By default timestamp will be epoch+1.second
• Order matters in layerEntries: to correctly configure a directory it must come before any file that exists in it, otherwise it will get default properties.

[loosebazooka]

@eisig thanks again for reporting this. We just released 1.1.2 with the fix.

[eisig]

Great 👍