Image Overview: static

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Base images with the minimum contents needed to run static binaries.

Download this Image

The image is available on cgr.dev:

docker pull cgr.dev/chainguard/static:latest

Upcoming Changes

On July 15, 2024 the static:latest image will move from a Alpine base to a Wolfi base, in-line with all other images in our registry. We do not expect this to cause breakages, but encourage all users to test and verify the new version.

You can test today by migrating to the cgr.dev/chainguard/static:latest-glibc image. From July 15, the :latest and :latest-glibc will point to the same image.

Full details are in this blog post.

Usage

Chainguard’s static Images are meant to be used as a base image only and are not intended to be run directly.

There are two variants of the static Image available: latest, which contains base OS files from Alpine and latest-glibc which contains base OS files from Wolfi. These variants are largely equivalent and can be used to host completely static binaries, such as those generated by gcc, rust, or go. Be aware that there is no libc implementation in either Image, despite the naming convention.

If you need images with the C standard library included, check out Chainguard’s glibc-dynamic Image.

This Image has a single user nonroot with uid 65532, belonging to gid 65532.

Versioning

The static image is not versioned, since there’s hardly any software in it that has a useful version. Most updates to the image are due to routine rebuilds of the packages included in the image, and don’t constitute any functional change.

In general it should be safe to rely on the :latest or :latest-glibc tag, but you may also want to pin the image reference by digest and use a tool like digestabot to automate image digest updates.

Rust Dockerfile Example

This section outlines how to build a Rust static binary with Chainguard’s static Image. First, create a Dockerfile named Dockerfile.rust with your preferred text editor.

nano Dockerfile.rust

Then add the following instructions to the file, which build a Rust static binary and put it into the static Image:

FROM cgr.dev/chainguard/rust as build

RUN echo 'fn main() { println!("Hello Rust users!"); }' > hello.rs
RUN rustc -C target-feature=+crt-static hello.rs

FROM cgr.dev/chainguard/static:latest

COPY --from=build /work/hello /hello
CMD ["/hello"]

Save and close the file. To build the binary, run the following command:

docker build -t rusty-cgr --file Dockerfile.rust .

This command tags the binary with rusty-cgr. You can run this newly-built Image with the following command:

docker run rusty-cgr

Hello Rust users!

If you inspect this image, you’ll find that it has a relatively small size:

docker images rusty-cgr

REPOSITORY   TAG   	IMAGE ID   	CREATED      	SIZE
rusty-cgr	latest	dd789eb1c964   35 seconds ago   3.98MB

C Dockerfile Example

This section is similar to the previous one, but instead outlines how to build a C static binary. This time, create a Dockerfile named Dockerfile.c with your preferred text editor:

nano Dockerfile.c

Add the following instructions to the file:

# syntax=docker/dockerfile:1.4
FROM cgr.dev/chainguard/gcc-glibc as build

COPY <<EOF /hello.c
#include <stdio.h>
int main() { printf("Hello C users!"); }
EOF
RUN cc -static /hello.c -o /hello

FROM cgr.dev/chainguard/static:latest

COPY --from=build /hello /hello
CMD ["/hello"]

After saving and closing the Dockerfile, you can build the binary:

docker build -t c-cgr -f Dockerfile.c .

Then run it by referencing the tag c-cgr:

docker run c-cgr

Hello C users!

Inspect this newly-built image as well.

docker images c-cgr

REPOSITORY   TAG   	IMAGE ID   	CREATED      	SIZE
c-cgr    	latest	fc18c6e71f95   33 seconds ago   3.36MB

This C static binary is even smaller than the Rust one built in the previous section.