Persist builder caches outside container

iso/builder/build.sh

@@ -16,6 +16,7 @@ DIST_DIR="${REPO_ROOT}/dist"
 VENDOR_DIR="${REPO_ROOT}/iso/vendor"
 BUILD_WORK_DIR="${DIST_DIR}/live-build-work"
 OVERLAY_STAGE_DIR="${DIST_DIR}/overlay-stage"
+CACHE_ROOT="${BEE_CACHE_DIR:-${DIST_DIR}/cache}"
 AUTH_KEYS=""
 
 # parse args
@@ -29,6 +30,10 @@ done
 . "${BUILDER_DIR}/VERSIONS"
 export PATH="$PATH:/usr/local/go/bin"
 mkdir -p "${DIST_DIR}"
+mkdir -p "${CACHE_ROOT}"
+: "${GOCACHE:=${CACHE_ROOT}/go-build}"
+: "${GOMODCACHE:=${CACHE_ROOT}/go-mod}"
+export GOCACHE GOMODCACHE
 
 echo "=== bee ISO build ==="
 echo "Debian: ${DEBIAN_VERSION}, Kernel ABI: ${DEBIAN_KERNEL_ABI}, Go: ${GO_VERSION}"
@@ -51,7 +56,16 @@ if [ "$NEED_BUILD" = "1" ]; then
         -o "$BEE_BIN" \
         ./cmd/bee
     echo "binary: $BEE_BIN"
-    echo "size:   $(du -sh "$BEE_BIN" | cut -f1)"
+    if command -v stat >/dev/null 2>&1; then
+        BEE_SIZE_BYTES="$(stat -c '%s' "$BEE_BIN" 2>/dev/null || stat -f '%z' "$BEE_BIN")"
+    else
+        BEE_SIZE_BYTES="$(wc -c < "$BEE_BIN" | tr -d ' ')"
+    fi
+    if command -v numfmt >/dev/null 2>&1; then
+        echo "size:   $(numfmt --to=iec --suffix=B "$BEE_SIZE_BYTES")"
+    else
+        echo "size:   ${BEE_SIZE_BYTES} bytes"
+    fi
 else
     echo "=== bee binary up to date, skipping build ==="
 fi
@@ -201,7 +215,16 @@ if [ -f "$ISO_RAW" ]; then
     echo ""
     echo "=== done ==="
     echo "ISO: $ISO_OUT"
-    echo "Size: $(du -sh "$ISO_OUT" | cut -f1)"
+    if command -v stat >/dev/null 2>&1; then
+        ISO_SIZE_BYTES="$(stat -c '%s' "$ISO_OUT" 2>/dev/null || stat -f '%z' "$ISO_OUT")"
+    else
+        ISO_SIZE_BYTES="$(wc -c < "$ISO_OUT" | tr -d ' ')"
+    fi
+    if command -v numfmt >/dev/null 2>&1; then
+        echo "Size: $(numfmt --to=iec --suffix=B "$ISO_SIZE_BYTES")"
+    else
+        echo "Size: ${ISO_SIZE_BYTES} bytes"
+    fi
 else
     echo "ERROR: ISO not found at $ISO_RAW"
     exit 1