ADD with git repository does not reuse cache

[MarekPikula]

Issue Description

When using buildah with (recently added) option to ADD a git repository, the layer cache is not reused (like in BuildKit) even when referencing a specific commit.

Steps to reproduce the issue

Steps to reproduce the issue:

Dockerfile:

FROM debian:stable-slim
RUN apt-get update \
    && apt-get install -y --no-install-recommends ca-certificates git
RUN git clone https://github.com/containers/buildah.git --depth 1 buildah-git
ADD https://github.com/containers/buildah.git#cd2bb6169f2f70794b9276b1ebdb13e891d989b1 buildah-add

Run:

$ buildah bud --layers . | tee bud.1.log
STEP 1/4: FROM debian:stable-slim
STEP 2/4: RUN apt-get update     && apt-get install -y --no-install-recommends ca-certificates git
Get:1 http://deb.debian.org/debian stable InRelease [151 kB]
Get:2 http://deb.debian.org/debian stable-updates InRelease [55.4 kB]
Get:3 http://deb.debian.org/debian-security stable-security InRelease [48.0 kB]
Get:4 http://deb.debian.org/debian stable/main amd64 Packages [8792 kB]
Get:5 http://deb.debian.org/debian stable-updates/main amd64 Packages [512 B]
Get:6 http://deb.debian.org/debian-security stable-security/main amd64 Packages [258 kB]
Fetched 9305 kB in 1s (9057 kB/s)
Reading package lists...
...
done.
--> e24110a734fb
STEP 3/4: RUN git clone https://github.com/containers/buildah.git --depth 1 buildah-git
Cloning into 'buildah-git'...
Updating files: 100% (5800/5800), done.
--> 4464f0894065
STEP 4/4: ADD https://github.com/containers/buildah.git#cd2bb6169f2f70794b9276b1ebdb13e891d989b1 buildah-add
COMMIT
--> 5afb2678c777
5afb2678c77705fc443d9c9e3f55d41dd3c34f848cfc28458228f5c45718a01c
$ buildah bud --layers --no-cache . | tee bud.2.log
STEP 1/4: FROM debian:stable-slim
STEP 2/4: RUN apt-get update     && apt-get install -y --no-install-recommends ca-certificates git
--> Using cache e24110a734fb7b9382378138d077bf4ae16f7d8cdb578622b237f34b4769a573
--> e24110a734fb
STEP 3/4: RUN git clone https://github.com/containers/buildah.git --depth 1 buildah-git
--> Using cache 4464f08940659c8483e1cd0d06d2664fe685bb21efed64fc18ed76db223be8e0
--> 4464f0894065
STEP 4/4: ADD https://github.com/containers/buildah.git#cd2bb6169f2f70794b9276b1ebdb13e891d989b1 buildah-add
COMMIT
--> cd5f19a5f013
cd5f19a5f01339627cbf73fcbf91bda6cec165dd2cca8d2c17757488a4117e15

Describe the results you received

As shown above, the ADD layer produces a different checksum each time it's run.

Describe the results you expected

I would expect the layer to be cached and reused.

buildah version output

Version:         1.40.0
Go Version:      go1.24.2
Image Spec:      1.1.1
Runtime Spec:    1.2.1
CNI Spec:        1.1.0
libcni Version:  
image Version:   5.35.0
Git Commit:      
Built:           Tue Apr 22 12:20:12 2025
OS/Arch:         linux/amd64
BuildPlatform:   linux/amd64

buildah info output

Version:         1.40.0
Go Version:      go1.24.2
Image Spec:      1.1.1
Runtime Spec:    1.2.1
CNI Spec:        1.1.0
libcni Version:  
image Version:   5.35.0
Git Commit:      
Built:           Tue Apr 22 12:20:12 2025
OS/Arch:         linux/amd64
BuildPlatform:   linux/amd64
[root@ca1d8a6e3555 work]# buildah info
{
    "host": {
        "CgroupVersion": "v2",
        "Distribution": {
            "distribution": "fedora",
            "version": "42"
        },
        "MemFree": 2136408064,
        "MemTotal": 67322884096,
        "OCIRuntime": "crun",
        "SwapFree": 0,
        "SwapTotal": 0,
        "arch": "amd64",
        "cpus": 44,
        "hostname": "ca1d8a6e3555",
        "kernel": "6.14.4-arch1-2",
        "os": "linux",
        "rootless": false,
        "uptime": "22h 25m 24.17s (Approximately 0.92 days)",
        "variant": ""
    },
    "store": {
        "ContainerStore": {
            "number": 2
        },
        "GraphDriverName": "overlay",
        "GraphOptions": [
            "overlay.imagestore=/var/lib/shared",
            "overlay.imagestore=/usr/lib/containers/storage",
            "overlay.mount_program=/usr/bin/fuse-overlayfs",
            "overlay.mountopt=nodev,fsync=0"
        ],
        "GraphRoot": "/var/lib/containers/storage",
        "GraphStatus": {
            "Backing Filesystem": "btrfs",
            "Native Overlay Diff": "false",
            "Supports d_type": "true",
            "Supports shifting": "true",
            "Supports volatile": "true",
            "Using metacopy": "false"
        },
        "ImageStore": {
            "number": 6
        },
        "RunRoot": "/run/containers/storage"
    }
}

Provide your storage.conf

Using official quay.io/buildah/testing (e3627d21b5cb)

Upstream Latest Release

Yes

Additional environment details

Using official quay.io/buildah/testing (e3627d21b5cb)

Additional information

No response

[github-actions]

A friendly reminder that this issue had no activity for 30 days.

[arsenalzp]

Hello,
Is this issue suitable for contributors who has previous contribution experience for Podman?