diff --git a/apt-sync/pre-sync.sh b/apt-sync/pre-sync.sh
new file mode 100755
index 0000000..4171ea6
--- /dev/null
+++ b/apt-sync/pre-sync.sh
@@ -0,0 +1,3 @@
+#!/bin/sh
+
+set_upstream "$APTSYNC_URL"
diff --git a/aptsync/pre-sync.sh b/aptsync/pre-sync.sh
index 8b31b81..efb7494 100755
--- a/aptsync/pre-sync.sh
+++ b/aptsync/pre-sync.sh
@@ -1,5 +1,7 @@
 #!/bin/bash
 
+set_upstream "$APTSYNC_URL"
+
 get_hostname() {
     sed -re 's|[^/]*//([^@]*@)?([^:/]*).*|\2|' <<< "$1"
 }
diff --git a/archvsync/pre-sync.sh b/archvsync/pre-sync.sh
index 85a5c02..69ebfd4 100755
--- a/archvsync/pre-sync.sh
+++ b/archvsync/pre-sync.sh
@@ -1,5 +1,7 @@
 #!/bin/bash
 
+set_upstream "rsync://$RSYNC_HOST/$RSYNC_PATH"
+
 # override the `killer` func in entry.sh
 killer() {
     kill -- "$1"
diff --git a/base/Dockerfile.alpine b/base/Dockerfile.alpine
index ab79a2f..46c8ec1 100644
--- a/base/Dockerfile.alpine
+++ b/base/Dockerfile.alpine
@@ -6,7 +6,7 @@ RUN <<EOF
     apk add --no-cache bash tzdata su-exec
     ln -sf /usr/share/zoneinfo/Asia/Shanghai /etc/localtime
 EOF
-ADD ["entry.sh", "savelog", "/usr/local/bin/"]
+ADD ["entry.sh", "savelog", "set_upstream", "/usr/local/bin/"]
 ADD ["pip.conf", "/etc/"]
 VOLUME ["/data", "/log"]
 CMD ["entry.sh"]
diff --git a/base/Dockerfile.alpine-edge b/base/Dockerfile.alpine-edge
index 7943fd5..8c5e72f 100644
--- a/base/Dockerfile.alpine-edge
+++ b/base/Dockerfile.alpine-edge
@@ -6,6 +6,6 @@ RUN <<EOF
     apk add --no-cache bash tzdata su-exec
     ln -sf /usr/share/zoneinfo/Asia/Shanghai /etc/localtime
 EOF
-ADD ["entry.sh", "savelog", "/usr/local/bin/"]
+ADD ["entry.sh", "savelog", "set_upstream", "/usr/local/bin/"]
 VOLUME ["/data", "/log"]
 CMD ["entry.sh"]
diff --git a/base/Dockerfile.debian b/base/Dockerfile.debian
index a9038d5..8794c00 100644
--- a/base/Dockerfile.debian
+++ b/base/Dockerfile.debian
@@ -14,6 +14,6 @@ chmod +x /usr/local/bin/su-exec
 echo "592f25c51d0e4c90945ece8c4fa35018d20a1091ac109c98b66eb95deef211c7 /usr/local/bin/su-exec" | sha256sum -c -
 apt-get purge -y --auto-remove wget
 EOF
-ADD ["entry.sh", "savelog", "/usr/local/bin/"]
+ADD ["entry.sh", "savelog", "set_upstream", "/usr/local/bin/"]
 VOLUME ["/data", "/log"]
 CMD ["entry.sh"]
diff --git a/base/set_upstream b/base/set_upstream
new file mode 100755
index 0000000..93a52cf
--- /dev/null
+++ b/base/set_upstream
@@ -0,0 +1,23 @@
+#!/bin/sh
+
+set -e
+set -o pipefail
+
+# Write argv[1] (upstream) to $LOGDIR/yuki_upstream.txt
+# This program is expected to be called by pre-sync.sh (recommended) or post-sync.sh
+# in all sync images
+
+if [ -z "$1" ]; then
+    echo "Usage: $0 <upstream>" >&2
+    exit 1
+fi
+
+if [ -z "$LOGDIR" ]; then
+    echo "LOGDIR environment variable is not set" >&2
+    exit 1
+fi
+
+# Avoid leaving empty file in case of being interrupted
+echo "$1" > "$LOGDIR/yuki_upstream.txt.new"
+mv "$LOGDIR/yuki_upstream.txt.new" "$LOGDIR/yuki_upstream.txt"
+echo "Upstream set to: $1"
diff --git a/crates-io-index/pre-sync.sh b/crates-io-index/pre-sync.sh
new file mode 100755
index 0000000..7bbe3dc
--- /dev/null
+++ b/crates-io-index/pre-sync.sh
@@ -0,0 +1,3 @@
+#!/bin/sh
+
+set_upstream "https://github.com/rust-lang/crates.io-index"
diff --git a/debian-cd/pre-sync.sh b/debian-cd/pre-sync.sh
index f939098..d923f3f 100755
--- a/debian-cd/pre-sync.sh
+++ b/debian-cd/pre-sync.sh
@@ -1,5 +1,7 @@
 #!/bin/bash
 
+set_upstream "rsync://$RSYNC_HOST/$RSYNC_MODULE"
+
 # override the `killer` func in entry.sh
 killer() {
     kill -- "$1"
diff --git a/docker-ce/pre-sync.sh b/docker-ce/pre-sync.sh
new file mode 100755
index 0000000..d3b6d3c
--- /dev/null
+++ b/docker-ce/pre-sync.sh
@@ -0,0 +1,3 @@
+#!/bin/sh
+
+set_upstream "https://download.docker.com/"
diff --git a/fedora/pre-sync.sh b/fedora/pre-sync.sh
index bd1f5b1..f0adf45 100755
--- a/fedora/pre-sync.sh
+++ b/fedora/pre-sync.sh
@@ -1,5 +1,11 @@
 #!/bin/bash
 
+if [[ -z "$REMOTE" ]]; then
+    set_upstream "rsync://dl.fedoraproject.org"
+else
+    set_upstream "$REMOTE/$MODULE"
+fi
+
 _CONF_FILE='/etc/quick-fedora-mirror.conf'
 LOGDIR="${LOGDIR%%/}"
 
diff --git a/flatpak/pre-sync.sh b/flatpak/pre-sync.sh
new file mode 100755
index 0000000..42990de
--- /dev/null
+++ b/flatpak/pre-sync.sh
@@ -0,0 +1,3 @@
+#!/bin/sh
+
+set_upstream "https://dl.flathub.org/repo/"
diff --git a/freebsd-pkg/pre-sync.sh b/freebsd-pkg/pre-sync.sh
new file mode 100755
index 0000000..5529519
--- /dev/null
+++ b/freebsd-pkg/pre-sync.sh
@@ -0,0 +1,5 @@
+#!/bin/sh
+
+FBSD_PKG_UPSTREAM=${FBSD_PKG_UPSTREAM:-"http://pkg.freebsd.org"}
+
+set_upstream "$FBSD_PKG_UPSTREAM"
diff --git a/freebsd-ports/pre-sync.sh b/freebsd-ports/pre-sync.sh
new file mode 100755
index 0000000..948589f
--- /dev/null
+++ b/freebsd-ports/pre-sync.sh
@@ -0,0 +1,5 @@
+#!/bin/sh
+
+FBSD_PORTS_DISTFILES_UPSTREAM=${FBSD_PORTS_DISTFILES_UPSTREAM:-"http://distcache.freebsd.org/ports-distfiles"}
+
+set_upstream "$FBSD_PORTS_DISTFILES_UPSTREAM"
diff --git a/ghcup/pre-sync.sh b/ghcup/pre-sync.sh
new file mode 100755
index 0000000..4595539
--- /dev/null
+++ b/ghcup/pre-sync.sh
@@ -0,0 +1,3 @@
+#!/bin/sh
+
+set_upstream "https://www.haskell.org/ghcup/"
diff --git a/github-release/pre-sync.sh b/github-release/pre-sync.sh
new file mode 100755
index 0000000..105f2f4
--- /dev/null
+++ b/github-release/pre-sync.sh
@@ -0,0 +1,3 @@
+#!/bin/sh
+
+set_upstream "https://github.com/"
diff --git a/gitsync/pre-sync.sh b/gitsync/pre-sync.sh
new file mode 100755
index 0000000..1deb377
--- /dev/null
+++ b/gitsync/pre-sync.sh
@@ -0,0 +1,3 @@
+#!/bin/sh
+
+set_upstream "$GITSYNC_URL"
diff --git a/google-repo/pre-sync.sh b/google-repo/pre-sync.sh
index db6c6b6..1e85dc9 100755
--- a/google-repo/pre-sync.sh
+++ b/google-repo/pre-sync.sh
@@ -1,5 +1,9 @@
 #!/bin/sh
 
+UPSTREAM="${UPSTREAM:-https://android.googlesource.com/mirror/manifest}"
+
+set_upstream "$UPSTREAM"
+
 # Alpine's ssh does not seem to like the idea
 # when UID 1000 user is not in /etc/passwd.
 # Otherwise, `ssh -V` will not be executed successfully.
diff --git a/gsutil-rsync/pre-sync.sh b/gsutil-rsync/pre-sync.sh
index 91c0df9..22b26f4 100755
--- a/gsutil-rsync/pre-sync.sh
+++ b/gsutil-rsync/pre-sync.sh
@@ -1,4 +1,6 @@
 #!/bin/bash
 
+set_upstream "$GS_URL"
+
 mkdir -p /.gsutil
 chown -R "$OWNER" /.gsutil
diff --git a/hackage/pre-sync.sh b/hackage/pre-sync.sh
new file mode 100755
index 0000000..fad71e5
--- /dev/null
+++ b/hackage/pre-sync.sh
@@ -0,0 +1,4 @@
+#!/bin/sh
+
+HACKAGE_BASE_URL=${HACKAGE_BASE_URL:-https://hackage.haskell.org/}
+set_upstream "$HACKAGE_BASE_URL"
diff --git a/homebrew-bottles/pre-sync.sh b/homebrew-bottles/pre-sync.sh
new file mode 100755
index 0000000..c74d892
--- /dev/null
+++ b/homebrew-bottles/pre-sync.sh
@@ -0,0 +1,4 @@
+#!/bin/sh
+
+HOMEBREW_BOTTLE_DOMAIN=${HOMEBREW_BOTTLE_DOMAIN:-https://ghcr.io/v2/homebrew/}
+set_upstream "$HOMEBREW_BOTTLE_DOMAIN"
diff --git a/julia-storage/pre-sync.sh b/julia-storage/pre-sync.sh
index fec33a9..da23d3b 100755
--- a/julia-storage/pre-sync.sh
+++ b/julia-storage/pre-sync.sh
@@ -3,6 +3,8 @@
 # But by default, we use 1000:1000 and it has no home folder.
 # This script helps create a user with a home folder corresponding to $OWNER.
 
+set_upstream "https://us-east.storage.juliahub.com, https://kr.storage.juliahub.com"
+
 SYNC_UID=$(echo "$OWNER" | cut -d ':' -f 1)
 SYNC_GID=$(echo "$OWNER" | cut -d ':' -f 2)
 
diff --git a/lftpsync/pre-sync.sh b/lftpsync/pre-sync.sh
new file mode 100755
index 0000000..37420ca
--- /dev/null
+++ b/lftpsync/pre-sync.sh
@@ -0,0 +1,3 @@
+#!/bin/sh
+
+set_upstream "$LFTPSYNC_HOST/$LFTPSYNC_PATH"
diff --git a/nix-channels/pre-sync.sh b/nix-channels/pre-sync.sh
new file mode 100755
index 0000000..cff15d7
--- /dev/null
+++ b/nix-channels/pre-sync.sh
@@ -0,0 +1,5 @@
+#!/bin/sh
+
+NIX_MIRROR_UPSTREAM=${NIX_MIRROR_UPSTREAM:-https://nixos.org/channels/}
+
+set_upstream "$NIX_MIRROR_UPSTREAM"
diff --git a/pypi/pre-sync.sh b/pypi/pre-sync.sh
index 150ec33..383139f 100755
--- a/pypi/pre-sync.sh
+++ b/pypi/pre-sync.sh
@@ -1,5 +1,7 @@
 #!/bin/bash
 
+set_upstream "https://pypi.python.org"
+
 cat << EOF > /etc/bandersnatch.conf
 [mirror]
 directory = $TO
diff --git a/rclone/pre-sync.sh b/rclone/pre-sync.sh
new file mode 100755
index 0000000..58ec9f1
--- /dev/null
+++ b/rclone/pre-sync.sh
@@ -0,0 +1,22 @@
+#!/bin/sh
+
+remote_type="$RCLONE_CONFIG_REMOTE_TYPE"
+path="$RCLONE_PATH"
+domain=""
+
+case "$remote_type" in
+  "swift")
+    domain="$RCLONE_SWIFT_STORAGE_URL/"
+    ;;
+  "http")
+    domain="$RCLONE_CONFIG_REMOTE_URL"
+    ;;
+  "s3")
+    domain="$RCLONE_CONFIG_REMOTE_ENDPOINT"
+    ;;
+  "webdav")
+    domain="$RCLONE_CONFIG_REMOTE_URL"
+    ;;
+esac
+
+set_upstream "${domain}${path}"
diff --git a/rsync/pre-sync.sh b/rsync/pre-sync.sh
new file mode 100755
index 0000000..1efb562
--- /dev/null
+++ b/rsync/pre-sync.sh
@@ -0,0 +1,3 @@
+#!/bin/sh
+
+set_upstream "rsync://$RSYNC_HOST/$RSYNC_PATH"
diff --git a/rubygems-dynamic/pre-sync.sh b/rubygems-dynamic/pre-sync.sh
new file mode 100755
index 0000000..061bc42
--- /dev/null
+++ b/rubygems-dynamic/pre-sync.sh
@@ -0,0 +1,6 @@
+#!/bin/bash
+
+set_upstream "http://rubygems.org/"
+
+mkdir -p "$HOME/.gem"
+chown -R "$OWNER" "$HOME"
diff --git a/rubygems/pre-sync.sh b/rubygems/pre-sync.sh
index c1a0d12..061bc42 100755
--- a/rubygems/pre-sync.sh
+++ b/rubygems/pre-sync.sh
@@ -1,4 +1,6 @@
 #!/bin/bash
 
+set_upstream "http://rubygems.org/"
+
 mkdir -p "$HOME/.gem"
 chown -R "$OWNER" "$HOME"
diff --git a/rustup/pre-sync.sh b/rustup/pre-sync.sh
new file mode 100755
index 0000000..dc07b46
--- /dev/null
+++ b/rustup/pre-sync.sh
@@ -0,0 +1,4 @@
+#!/bin/bash
+
+UPSTREAM="${UPSTREAM:-https://static.rust-lang.org/}"
+set_upstream "$UPSTREAM"
diff --git a/shadowmire/pre-sync.sh b/shadowmire/pre-sync.sh
new file mode 100755
index 0000000..79dca44
--- /dev/null
+++ b/shadowmire/pre-sync.sh
@@ -0,0 +1,4 @@
+#!/bin/bash
+
+UPSTREAM=${UPSTREAM:-"https://pypi.org"}
+set_upstream "$UPSTREAM"
diff --git a/stackage/pre-sync.sh b/stackage/pre-sync.sh
new file mode 100755
index 0000000..b75315b
--- /dev/null
+++ b/stackage/pre-sync.sh
@@ -0,0 +1,3 @@
+#!/bin/bash
+
+set_upstream "https://github.com/commercialhaskell/"
diff --git a/test/pre-sync.sh b/test/pre-sync.sh
new file mode 100755
index 0000000..6bf6d1e
--- /dev/null
+++ b/test/pre-sync.sh
@@ -0,0 +1,3 @@
+#!/bin/bash
+
+set_upstream "https://example.com/ustcmirror-images/"
diff --git a/tsumugu/pre-sync.sh b/tsumugu/pre-sync.sh
new file mode 100755
index 0000000..bc543a5
--- /dev/null
+++ b/tsumugu/pre-sync.sh
@@ -0,0 +1,3 @@
+#!/bin/bash
+
+set_upstream "$UPSTREAM"
diff --git a/winget-source/pre-sync.sh b/winget-source/pre-sync.sh
new file mode 100755
index 0000000..c10e3ba
--- /dev/null
+++ b/winget-source/pre-sync.sh
@@ -0,0 +1,4 @@
+#!/bin/bash
+
+WINGET_REPO_URL=${WINGET_REPO_URL:-"https://cdn.winget.microsoft.com/cache"}
+set_upstream "$WINGET_REPO_URL"
diff --git a/yukina/pre-sync.sh b/yukina/pre-sync.sh
new file mode 100755
index 0000000..bc543a5
--- /dev/null
+++ b/yukina/pre-sync.sh
@@ -0,0 +1,3 @@
+#!/bin/bash
+
+set_upstream "$UPSTREAM"
diff --git a/yum-sync/pre-sync.sh b/yum-sync/pre-sync.sh
new file mode 100755
index 0000000..55a88ce
--- /dev/null
+++ b/yum-sync/pre-sync.sh
@@ -0,0 +1,3 @@
+#!/bin/bash
+
+set_upstream "$YUMSYNC_URL"