fix: skip port deletion when instances have no port (#779)

diff --git a/images/Earthfile b/images/Earthfile
new file mode 100644
index 0000000..c87a870
--- /dev/null
+++ b/images/Earthfile
@@ -0,0 +1,10 @@
+VERSION 0.7
+
+APT_INSTALL:
+  COMMAND
+  ARG packages
+  RUN \
+    apt-get update && \
+    apt-get install --no-install-recommends -y ${packages} && \
+    apt-get clean && \
+    rm -rf /var/lib/apt/lists/*