fix(ci): Resolve CTAN mirror outside of Docker build

Can't seem to resolve mirrors.ctan.org from within `docker build`.
For reasons. (?)

Credits: https://github.com/zauguin/install-texlive via @koppor

.github/scripts/build-image.sh

@@ -7,6 +7,10 @@ set -eu
 installer_image=${TEXLIVE_INSTALLER_IMAGE:-'texlive-installer:latest'}
 image_tag_list="${IMAGE_TAG_LIST:-/dev/stdout}"
 
+# NB: Can't seem to resolve mirrors.ctan.org from within `docker build`, so do it here:
+ctan_mirror="$(curl -Ls -o /dev/null -w '%{url_effective}' https://mirrors.ctan.org)"
+echo "Will use CTAN mirror ${ctan_mirror}"
+
 ref="${1}"
 profile="${2:-minimal}"
 commit_time="$(date --date="@$(git show -s --format=%ct HEAD)" --rfc-3339=seconds)"
@@ -32,6 +36,7 @@ case "${ref}" in
             --cache-from "${installer_image}" \
             --tag "$(make_docker_tag "${profile}" "${version}")" \
             --tag "$(make_docker_tag "${profile}" latest)" \
+            --build-arg "ctan_mirror=${ctan_mirror}" \
             --build-arg "profile=${profile}" \
             --build-arg "label_created=${commit_time}" \
             --build-arg "label_version=${version}" \
@@ -46,6 +51,7 @@ case "${ref}" in
         docker build \
             --cache-from "${installer_image}" \
             --tag "$(make_docker_tag "${profile}" "${version}")" \
+            --build-arg "ctan_mirror=${ctan_mirror}" \
             --build-arg "profile=${profile}" \
             --build-arg "label_created=${commit_time}" \
             --build-arg "label_version=${version}" \
@@ -61,6 +67,7 @@ case "${ref}" in
         docker build \
             --cache-from "${installer_image}" \
             --tag "$(make_docker_tag "${profile}" "${version}")" \
+            --build-arg "ctan_mirror=${ctan_mirror}" \
             --build-arg "profile=${profile}" \
             .
         make_docker_tag "${profile}" "${version}" >> "${image_tag_list}"

.github/scripts/build-installer-image.sh

@@ -4,7 +4,12 @@ set -e
 
 installer_image=${TEXLIVE_INSTALLER_IMAGE:-'texlive-installer:latest'}
 
+# NB: Can't seem to resolve mirrors.ctan.org from within `docker build`, so do it here:
+ctan_mirror="$(curl -Ls -o /dev/null -w '%{url_effective}' https://mirrors.ctan.org)"
+echo "Will use CTAN mirror ${ctan_mirror}"
+
 docker build --no-cache \
+    --build-arg "ctan_mirror=${ctan_mirror}" \
     --target "texlive-installer" \
     --tag "${installer_image}" \
     .

Dockerfile

@@ -44,7 +44,10 @@ RUN apk --no-cache add \
     xz=${XZ_VERSION} \
     zlib=${ZLIB_VERSION}
 
-RUN wget https://mirrors.ctan.org/systems/texlive/tlnet/install-tl-unx.tar.gz \
+ARG ctan_mirror="https://mirrors.ctan.org"
+ENV CTAN_MIRROR=$ctan_mirror
+
+RUN wget "${CTAN_MIRROR}/systems/texlive/tlnet/install-tl-unx.tar.gz" \
  && tar -xzf install-tl-unx.tar.gz \
  && rm install-tl-unx.tar.gz \
  && mv install-tl-* install-tl
@@ -66,14 +69,20 @@ RUN tlversion=$(cat install-tl/release-texlive.txt | head -n 1 | awk '{ print $5
  && ln -s /usr/local/texlive/${tlversion}/bin/x86_64-linuxmusl /usr/local/texlive/${tlversion}/bin/x86_64-linux \
  && ln -s /usr/local/texlive/${tlversion}/bin/x86_64-linuxmusl/mktexlsr /usr/local/bin/mktexlsr
 
+ARG ctan_mirror="https://mirrors.ctan.org"
+ENV CTAN_MIRROR=$ctan_mirror
+
 RUN (  cd install-tl \
     && tlversion=$(cat release-texlive.txt | head -n 1 | awk '{ print $5 }') \
     && sed -i "s/\${tlversion}/${tlversion}/g" ${profile}.profile \
-    && ./install-tl -profile ${profile}.profile \
+    && ./install-tl -repository="${CTAN_MIRROR}/systems/texlive/tlnet" -profile ${profile}.profile \
  ) \
  && rm -rf install-tl \
  && tlmgr version | tail -n 1 > version \
  && echo "Installed on $(date)" >> version
+ # && tlmgr option repository "${CTAN_MIRROR}"
+ # TODO: Determine if this is necessary -- shouldn't be, and
+ #       we don't want to hammer the same mirror whenever the image is used!
 
 ARG src_dir="/work/src"
 ARG tmp_dir="/work/tmp"