Switch base image to Ubuntu

[louischan-oursky]

Ubuntu has more security fixes.

[louischan-oursky]

It is not easy as it seems. We depend on the following system libs libicu, libvips, and libmagic. The official Golang image is based on Debian. So when we build the Go binary, the binary remembers the version of the libs at the time of the build, which are the versions available on Debian.

If we switch the runtime image to Ubuntu, the binary cannot be run because it cannot find the versioned .so files. We will see error message like error while loading shared libraries: libicui18n.so.67: cannot open shared object file: No such file or directory

[kiootic]

Maybe we can use distroless as base image: https://github.com/GoogleContainerTools/distroless/issues/863#issuecomment-949723748

[louischan-oursky]

The main problem is Golang is either debian or alpine based, and our C dependencies and CGO.

[kiootic]

Distroless is debian based (name is misleading), and the linked comment shows how to install Debian packages into the image.

[louischan-oursky]

The official Golang docker image https://github.com/docker-library/golang can be easily customized to become ubuntu based. There is the patch

diff --git a/versions.json b/versions.json
index 179613b..f53e319 100644
--- a/versions.json
+++ b/versions.json
@@ -155,6 +155,7 @@
     "variants": [
       "bullseye",
       "buster",
+      "jammy",
       "alpine3.17",
       "alpine3.16",
       "windows/windowsservercore-ltsc2022",
@@ -320,6 +321,7 @@
     "variants": [
       "bullseye",
       "buster",
+      "jammy",
       "alpine3.17",
       "alpine3.16",
       "windows/windowsservercore-ltsc2022",
diff --git a/versions.sh b/versions.sh
index a26dea4..6121e3c 100755
--- a/versions.sh
+++ b/versions.sh
@@ -145,6 +145,7 @@ for version in "${versions[@]}"; do
                variants: [
                        "bullseye",
                        "buster",
+                       "jammy",
                        (
                                "3.17",
                                "3.16"

Then we can experiment using this base image, and change our runtime image to ubuntu.