How does Docker scratch image support musl?
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I've created a simple Docker image which is completely raw with single binary copied and run:
FROM scratch
COPY ./target/release/hello_docker /
CMD ["/hello_docker"]
My compiler (Rust) by default creates binaries which dynamically load glibc and use it as their libc library. There is also a special flag, which makes binaries use musl.
On my Ubuntu 18.04 both binaries run flawlessly. I assume, that it provides support for both libc implementations, but I couldn't find a definitive confirmation.
But when I run these binaries in a scratch Docker image, only the musl version works. Glibc is not installed, so obviously it can't be loaded in runtime and crashes the application. But why does the musl version work?
I've read that most of musl is in the statically linked part, but there is also a tiny dynamically loaded part, which provides code for the specific kernel version. But there is nothing installed, where does this dynamic shim come from?
docker glibc
asked 6 hours ago
CodeSandwich
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up vote
0
down vote
favorite
I've created a simple Docker image which is completely raw with single binary copied and run:
FROM scratch
COPY ./target/release/hello_docker /
CMD ["/hello_docker"]
My compiler (Rust) by default creates binaries which dynamically load glibc and use it as their libc library. There is also a special flag, which makes binaries use musl.
On my Ubuntu 18.04 both binaries run flawlessly. I assume, that it provides support for both libc implementations, but I couldn't find a definitive confirmation.
But when I run these binaries in a scratch Docker image, only the musl version works. Glibc is not installed, so obviously it can't be loaded in runtime and crashes the application. But why does the musl version work?
I've read that most of musl is in the statically linked part, but there is also a tiny dynamically loaded part, which provides code for the specific kernel version. But there is nothing installed, where does this dynamic shim come from?
docker glibc
asked 6 hours ago
CodeSandwich
82
add a comment |Â
up vote
0
down vote
favorite
up vote
0
down vote
favorite
I've created a simple Docker image which is completely raw with single binary copied and run:
FROM scratch
COPY ./target/release/hello_docker /
CMD ["/hello_docker"]
My compiler (Rust) by default creates binaries which dynamically load glibc and use it as their libc library. There is also a special flag, which makes binaries use musl.
On my Ubuntu 18.04 both binaries run flawlessly. I assume, that it provides support for both libc implementations, but I couldn't find a definitive confirmation.
But when I run these binaries in a scratch Docker image, only the musl version works. Glibc is not installed, so obviously it can't be loaded in runtime and crashes the application. But why does the musl version work?
I've read that most of musl is in the statically linked part, but there is also a tiny dynamically loaded part, which provides code for the specific kernel version. But there is nothing installed, where does this dynamic shim come from?
docker glibc
asked 6 hours ago
CodeSandwich
82
I've created a simple Docker image which is completely raw with single binary copied and run:
FROM scratch
COPY ./target/release/hello_docker /
CMD ["/hello_docker"]
My compiler (Rust) by default creates binaries which dynamically load glibc and use it as their libc library. There is also a special flag, which makes binaries use musl.
On my Ubuntu 18.04 both binaries run flawlessly. I assume, that it provides support for both libc implementations, but I couldn't find a definitive confirmation.
But when I run these binaries in a scratch Docker image, only the musl version works. Glibc is not installed, so obviously it can't be loaded in runtime and crashes the application. But why does the musl version work?
I've read that most of musl is in the statically linked part, but there is also a tiny dynamically loaded part, which provides code for the specific kernel version. But there is nothing installed, where does this dynamic shim come from?
docker glibc
docker glibc
asked 6 hours ago
CodeSandwich
82
asked 6 hours ago
CodeSandwich
82
asked 6 hours ago
CodeSandwich
82
asked 6 hours ago
CodeSandwich
82
asked 6 hours ago
CodeSandwich
82
82
add a comment |Â
add a comment |Â
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