Docker ADD does not retain file permissions - bug?

[thernstig]

ADD https://some.url/file.proto /protobuf/test.proto

RUN <<EOF
wget https://some.url/file.proto -P /protobuf/
EOF

Then inside the container:

ls -l /protobuf/
total 16
-rw-r--r-- 1 root root 4951 Jun 27  2023 file.proto 
-rw------- 1 root root 4951 Jun 27  2023 test.proto

Notice how test.proto removed the group and world r flag.

Why is this?

[dvdksn]

Hi, this is expected for ADD with remote files. From the documentation:

In the case where <src> is a remote file URL, the destination will have permissions of 600.

https://docs.docker.com/reference/dockerfile/#add

[thernstig]

@tonistiigi @dvdksn Do you know if this is a limitation that is intentional for very intrinsic reasons? Or that this could potentially be made into a proper issue to solve?

wget and curl both retain file permissions when fetching remote files. That ADD does not do this is not intuitive, and is the odd duck.

[tonistiigi]

wget and curl both retain file permissions when fetching remote files.

wdym? There are no "file permissions" when you are downloading bytes from a URL through HTTP. wget/curl could have a different default(that usually depends on your current umask while you invoke these commands).

There is ADD --chmod if you wish to change the permissions of a file to something different than the default.