enable autoindexing for ubuntu mirror

Dockerfile

@@ -6,8 +6,9 @@ ENV MIRROR_UPDATE_INTERVAL_SECONDS 43200
 ENV UBUNTU_MIRROR_ARCHITECTURES amd64
 # set to anything but 'false' to mirror source code as well
 ENV UBUNTU_ENABLE_SOURCE_MIRRORING false
-ENV UBUNTU_MIRROR_CATEGORIES main,universe,restricted,multiverse
+ENV UBUNTU_MIRROR_CATEGORIES main,universe,restricted,multiverse,main/debian-installer
 ENV UBUNTU_MIRROR_UPSTREAM archive.ubuntu.com
+ENV UBUNTU_MIRROR_UPSTREAM_PATH /ubuntu
 ENV UBUNTU_MIRROR_PROJECTS bionic,bionic-updates,bionic-security,bionic-backports,focal,focal-updates,focal-security,focal-backports
 
 # The following is the URL populated in /mirrors.txt as used by mirror://

mirror/syncubuntu.sh

@@ -18,6 +18,10 @@ fi
 
 DONE=0
 
+DIDIST="$(
+    echo -n "$UBUNTU_MIRROR_PROJECTS" | tr "," "\n" | grep -v "\-" | tr "\n" ","
+)"
+
 while [[ $DONE -eq 0 ]]; do
     debmirror \
         -a ${UBUNTU_MIRROR_ARCHITECTURES} \
@@ -25,10 +29,10 @@ while [[ $DONE -eq 0 ]]; do
         -h ${UBUNTU_MIRROR_UPSTREAM} \
         -d ${UBUNTU_MIRROR_PROJECTS} \
         $SOURCEOPT \
-        --di-dist=dists \
+        --di-dist="$DIDIST" \
         --di-arch=arches \
         --ignore-small-errors \
-        -r /ubuntu \
+        -r "$UBUNTU_MIRROR_UPSTREAM_PATH" \
         --getcontents \
         --progress \
         --method=http \

nginx.conf

@@ -33,12 +33,12 @@ http {
 
         index index.html index.htm;
 
-        #location /ubuntu/ {
+        location /ubuntu/ {
         #    # alias, not root!
         #    # trailing slash important!
         #    alias /var/mirror/ubuntu/;
-        #    autoindex on;
+            autoindex on;
-        #}
+        }
 
     }
 }