Sqlite3 about dart-docker

[cpswan]

A few assumptions:

• You're going to start out with the Dart official image (that comes from this repo).
• You're trying to get to a minimal container that has just enough libraries to run your Dart app.
• You're going to use a two stage build to firstly compile your AOT binary within the Dart container then copy it into your FROM scratch container.

The Dart image doesn't have Sqlite3 there by default. So the library needs to be installed. It's that library that will then be used via dart:ffi for packages like drift or sqlite3.

RUN set -eux; \
    apt-get update; \
    apt-get install -y --no-install-recommends libsqlite3-0

The library then needs to be copied into /runtime so that it's there with the other libraries that are needed for an AOT binary to dynamically link to:

RUN set -eux; \
    case "$(dpkg --print-architecture)" in \
        amd64) \
            TRIPLET="x86_64-linux-gnu" ;; \
        armhf) \
            TRIPLET="arm-linux-gnueabihf" ;; \
        arm64) \
            TRIPLET="aarch64-linux-gnu" ;; \
        *) \
            echo "Unsupported architecture" ; \
            exit 5;; \
    esac; \
    FILES="/lib/$TRIPLET/libsqlite3.so.0"; \
    for f in $FILES; do \
        dir=$(dirname "$f"); \
        mkdir -p "/runtime$dir"; \
        cp --archive --link --dereference --no-target-directory "$f" "/runtime$f"; \
    done

The section above copies liberally from the Dockerfile-debian.template in this repo, which is designed for multiple architectures. If you know your target architecture is fixed then things can be simplified quite a bit by simply copying the single libsqlite3.so.0 shared library file.

The second stage of the Dockerfile then proceeds as normal, copying in the /runtime, which will now have the sqlite3 library along with libc and the other AOT dependencies:

FROM scratch
COPY --from=build /runtime/ /

NB I've not tested this, so please excuse any typos. I'm pretty sure that the libraries libsqlite3-0.so.0 links to are already present in runtime:

ldd /lib/x86_64-linux-gnu/libsqlite3.so.0

        linux-vdso.so.1 (0x00007ffdb45f1000)
        libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fa502bd1000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fa5029f0000)
        /lib64/ld-linux-x86-64.so.2 (0x00007fa502e13000)

linux-vdso.so.1 is a virtual shared object rather than a library file on disk.