build: install latest gosu from published image (#3717)

Author: itzg

Dockerfile

@@ -15,6 +15,7 @@ ARG FORCE_INSTALL_PACKAGES=1
 RUN --mount=target=/build,source=build \
     TARGET=${TARGETARCH}${TARGETVARIANT} \
     /build/run.sh install-packages
+COPY --from=tianon/gosu /gosu /usr/local/bin/
 
 RUN --mount=target=/build,source=build \
     /build/run.sh setup-user

build/alpine/install-packages.sh

@@ -10,7 +10,6 @@ apk add --no-cache -U \
     imagemagick \
     file \
     lsof \
-    su-exec \
     coreutils \
     findutils \
     procps \

build/ol/install-gosu.sh

@@ -59,9 +59,6 @@ dnf install -y git-lfs
 # Clean up DNF when done
 dnf clean all
 
-# Install gosu (assuming the script /build/ol/install-gosu.sh exists and is executable)
-bash /build/ol/install-gosu.sh
-
 # Download and install patched knockd
 curl -fsSL -o /tmp/knock.tar.gz https://github.com/Metalcape/knock/releases/download/0.8.1/knock-0.8.1-$TARGET.tar.gz
 tar -xf /tmp/knock.tar.gz -C /usr/local/ && rm /tmp/knock.tar.gz

build/ol/install-packages.sh

@@ -11,7 +11,6 @@ DEBIAN_FRONTEND=noninteractive \
 apt-get install -y \
   imagemagick \
   file \
-  gosu \
   sudo \
   net-tools \
   iputils-ping \

build/ubuntu/install-packages.sh

@@ -48,7 +48,7 @@ if ! isTrue "${SKIP_SUDO:-false}" && [ "$(id -u)" = 0 ]; then
     echo 'hosts: files dns' > /etc/nsswitch.conf
   fi
 
-  exec $(getSudoFromDistro) ${runAsUser}:${runAsGroup} "$(dirname "$0")/start-configuration" "$@"
+  exec gosu ${runAsUser}:${runAsGroup} "$(dirname "$0")/start-configuration" "$@"
 else
   exec "$(dirname "$0")/start-configuration" "$@"
 fi

scripts/start

@@ -121,17 +121,6 @@ function log() {
   eval "$oldState"
 }
 
-function getSudoFromDistro(){
-  distro=$(getDistro)
-  command=
-  if [[ $distro == alpine ]]; then
-    command="su-exec"
-  else
-    command="gosu"
-  fi
-  echo $command
-}
-
 # Refer to https://unix.stackexchange.com/a/10065/102376
 function isTerminal() {
   if test -t 1; then