File copy modification timestamp is off

[orishuss]

What went wrong?

When copying files, the files stats don't change as expected. The specific important stat is the date modified of the file, which is always 2020-04-16 12:00:00.000000000 +0000.

I encountered this error when go build inside a container failed due to cache problems: it thought that a file hasn't changed when in fact it has. This usually doesn't break go's build - go usually understands that the file has changed, but apparently in some cases it relies on the file's modification date.

Adding a RUN touch * line right after the copy solves the problem (and go builds successfully), as the modification & access stats change.

In the log below I ran the simple Earthfile:

VERSION --try 0.8

test:
    FROM ubuntu:22.04
    COPY file file
    RUN cat file
    RUN stat file

When running earthly -i +test twice, when changing the content of file in the middle, I'd expect that the file's modify date stat would change, but it doesn't. The "change" date changes, and I'd expect the modify date to be the same.

[I] > earthly -i +test
 Init 🚀
————————————————————————————————————————————————————————————————————————————————

           buildkitd | Found buildkit daemon as docker container (earthly-buildkitd)

 Build 🔧
————————————————————————————————————————————————————————————————————————————————

              logbus | Setting organization "" and project ""
               +test | --> FROM +base
        ubuntu:22.04 | --> Load metadata ubuntu:22.04 linux/amd64
               +test | --> FROM ubuntu:22.04
               +test | [----------] 100% FROM ubuntu:22.04
               +test | *cached* --> COPY file file
               +test | --> RUN cat file
               +test | file3
               +test | --> RUN stat file
               +test |   File: file
               +test |   Size: 6                Blocks: 8          IO Block: 4096   regular file
               +test | Device: 7ah/122d Inode: 116654190   Links: 1
               +test | Access: (0664/-rw-rw-r--)  Uid: (    0/    root)   Gid: (    0/    root)
               +test | Access: 2020-04-16 12:00:00.000000000 +0000
               +test | Modify: 2020-04-16 12:00:00.000000000 +0000
               +test | Change: 2024-04-24 07:47:14.669475735 +0000
               +test |  Birth: 2024-04-24 07:47:14.669475735 +0000
              output | --> exporting outputs

 Push Summary ⏫ (disabled)
————————————————————————————————————————————————————————————————————————————————

To enable pushing use earthly --push

 Local Output Summary 🎁
————————————————————————————————————————————————————————————————————————————————



========================== 🌍 Earthly Build  ✅ SUCCESS ==========================

🛰️ Reuse cache between CI runs with Earthly Satellites! 2-20X faster than without cache. Generous free tier https://cloud.earthly.dev
[I] > earthly -i +test
 Init 🚀
————————————————————————————————————————————————————————————————————————————————

           buildkitd | Found buildkit daemon as docker container (earthly-buildkitd)

 Build 🔧
————————————————————————————————————————————————————————————————————————————————

              logbus | Setting organization "" and project ""
               +test | --> FROM +base
        ubuntu:22.04 | --> Load metadata ubuntu:22.04 linux/amd64
               +test | --> FROM ubuntu:22.04
               +test | [----------] 100% FROM ubuntu:22.04
               +test | --> COPY file file
               +test | --> RUN cat file
               +test | file4
               +test | --> RUN stat file
               +test |   File: file
               +test |   Size: 6                Blocks: 8          IO Block: 4096   regular file
               +test | Device: 7ah/122d Inode: 116654235   Links: 1
               +test | Access: (0664/-rw-rw-r--)  Uid: (    0/    root)   Gid: (    0/    root)
               +test | Access: 2020-04-16 12:00:00.000000000 +0000
               +test | Modify: 2020-04-16 12:00:00.000000000 +0000
               +test | Change: 2024-04-24 07:48:44.893795412 +0000
               +test |  Birth: 2024-04-24 07:48:44.893795412 +0000
              output | --> exporting outputs

 Push Summary ⏫ (disabled)
————————————————————————————————————————————————————————————————————————————————

To enable pushing use earthly --push

 Local Output Summary 🎁
————————————————————————————————————————————————————————————————————————————————



========================== 🌍 Earthly Build  ✅ SUCCESS ==========================

🛰️ Reuse cache between CI runs with Earthly Satellites! 2-20X faster than without cache. Generous free tier https://cloud.earthly.dev

What earthly version?

earthly version v0.8.8

[ingwarsw]

Did you tried COPY --keep-ts

See docs.
Maybe that should resolve the issue?

[orishuss]

Yes this does the trick, thanks!
Any reason for this not to be the default behaviour? It is the default in docker.