car is like tar, but for containers!
Mainly, car lets you list or extract files from an OCI (possibly Docker) image, regardless of the platform it was
built for. For example, you can extract files from a windows/amd64 image even if you are running linux/arm64.
$ go build ./cmd/car
# verify a file you think is in an image is really there
$ ./car -tf envoyproxy/envoy-alpine:v1.18.3 'Files/Program Files/envoy/envoy.exe'
error: Files/Program Files/envoy/envoy.exe not found in layer
$ ./car -tf envoyproxy/envoy-windows:v1.18.3 'Files/Program Files/envoy/envoy.exe'
Files/Program Files/envoy/envoy.exe
# extract a file from an image
$ ./car --strip-components 3 --created-by-pattern 'COPY envoy /usr/local/bin/envoy' -xvvf istio/proxyv2:1.10.3 && file envoy
https://index.docker.io/v2/istio/proxyv2/manifests/1.10.3 platform=linux/amd64 totalLayerSize: 95073366
https://index.docker.io/v2/istio/proxyv2/blobs/sha256:5afc65eb63c65ce691cc003c8b26820b7d984181b4871a2735e92cbf69595671 size=26407160
CreatedBy: COPY envoy /usr/local/bin/envoy # buildkit
-rwxr-xr-x 100920696 Jul 15 14:15:57 usr/local/bin/envoy
envoy: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 2.6.32, not stripped
# try a platform you may no usually be able to poke
$ ./car -tvvf chocolateyfest/chocolatey:latest
https://index.docker.io/v2/chocolateyfest/chocolatey/manifests/latest platform=windows/amd64 totalLayerSize: 24102006
https://index.docker.io/v2/chocolateyfest/chocolatey/blobs/sha256:6d2d8da2960b0044c22730be087e6d7b197ab215d78f9090a3dff8cb7c40c241 size=24102006
CreatedBy: cmd /S /C powershell iex(iwr -useb https://chocolatey.org/install.ps1)
-rw-r--r-- 44245 May 5 02:09:14 Files/ProgramData/chocolatey/CREDITS.txt
-rw-r--r-- 670 May 5 02:09:14 Files/ProgramData/chocolatey/LICENSE.txt
-rw-r--r-- 2283 May 5 02:09:14 Files/ProgramData/chocolatey/bin/RefreshEnv.cmd
--snip--
# try a multi-platform image
$ ./car -tvvf alpine:3.14.0
error: choose a platform: linux/386, linux/amd64, linux/arm, linux/arm64, linux/ppc64le, linux/s390x
$ ./car --platform linux/arm64 -tvvf alpine:3.14.0
https://index.docker.io/v2/library/alpine/manifests/sha256:53b74ddfc6225e3c8cc84d7985d0f34666e4e8b0b6892a9b2ad1f7516bc21b54 platform=linux/arm64 totalLayerSize: 2709626
https://index.docker.io/v2/library/alpine/blobs/sha256:58ab47519297212468320b23b8100fc1b2b96e8d342040806ae509a778a0a07a size=2709626
CreatedBy: /bin/sh -c #(nop) ADD file:6797caacbfe41bfe44000b39ed017016c6fcc492b3d6557cdaba88536df6c876 in /
-rwxr-xr-x 878176 Jun 14 18:24:54 bin/busybox
-rw-r--r-- 7 Jun 15 22:32:26 etc/alpine-release
--snip--
# try a wasm image
$ ./car -tvvf ghcr.io/aquasecurity/trivy-module-wordpress:latest
https://ghcr.io/v2/aquasecurity/trivy-module-wordpress/manifests/latest platform= totalLayerSize: 460018
https://ghcr.io/v2/aquasecurity/trivy-module-wordpress/blobs/sha256:3daa3dac086bd443acce56ffceb906993b50c5838b4489af4cd2f1e2f13af03b size=460018
CreatedBy:
-rw-r--r-- 460018 Apr 25 08:22:32 wordpress.wasm
# try a container image that contains a wasm file
$ ./car -tvvf ghcr.io/istio-ecosystem/wasm-extensions/basic_auth:1.12.0
https://ghcr.io/v2/istio-ecosystem/wasm-extensions/basic_auth/manifests/1.12.0 platform=linux/amd64 totalLayerSize: 51012
https://ghcr.io/v2/istio-ecosystem/wasm-extensions/basic_auth/blobs/sha256:c77f41748230039992ddd401681f91238ce2d7149d4d9f28899d389f0ea2692c size=51012
CreatedBy: bazel build ...
-r-xr-xr-x 145568 Jan 1 08:00:00 ./plugin.wasm