Retry wget tasks in Dockerfile (#63615)

Following #52519, our Docker build pulls down curl sources in an
Alpine Linux container using wget. However that version of wget
doesn't support any retry flags. Since network issues can cause build
failures, wrap the wget calls in the same retry construct used for
yum commands elsewhere.

Closes #63600.

Author: pugnascotia

distribution/docker/src/docker/Dockerfile

@@ -61,10 +61,19 @@ RUN apk add gnupg gcc make musl-dev openssl-dev openssl-libs-static file
 RUN mkdir /work
 WORKDIR /work
 
-# Fetch curl sources and files for validation
-RUN wget "https://daniel.haxx.se/mykey.asc" -O "curl-gpg.pub" && \\
-    wget "\${TARBALL_URL}.asc" -O "\${TARBALL_PATH}.asc" && \\
-    wget "\${TARBALL_URL}" -O "\${TARBALL_PATH}"
+# Fetch curl sources and files for validation. Note that alpine's `wget` doesn't have retry options.
+RUN function retry_wget() { \\
+      local URL="\$1" ; \\
+      local DEST="\$2" ; \\
+      for iter in {1..10}; do \\
+        wget "\$URL" -O "\$DEST" && \\
+        exit_code=0 && break || exit_code=\$? && echo "wget error fetching \$URL: retry \$iter in 10s" && sleep 10; \\
+      done; \\
+      return \$exit_code ; \\
+    } ; \\
+    retry_wget "https://daniel.haxx.se/mykey.asc" "curl-gpg.pub" && \\
+    retry_wget "\${TARBALL_URL}.asc" "\${TARBALL_PATH}.asc" && \\
+    retry_wget "\${TARBALL_URL}" "\${TARBALL_PATH}"
 
 # Validate source
 RUN gpg --import --always-trust "curl-gpg.pub" && \\
@@ -216,7 +225,8 @@ RUN for iter in {1..10}; do \\
       ${package_manager} update --setopt=tsflags=nodocs -y && \\
       ${package_manager} install --setopt=tsflags=nodocs -y \\
         nc shadow-utils zip unzip findutils procps-ng && \\
-      ${package_manager} clean all && exit_code=0 && break || exit_code=\$? && echo "${package_manager} error: retry \$iter in 10s" && \\
+      ${package_manager} clean all && \\
+      exit_code=0 && break || exit_code=\$? && echo "${package_manager} error: retry \$iter in 10s" && \\
       sleep 10; \\
     done; \\
     (exit \$exit_code)