Pull initfs from repository when running ctr-example (#391)

Use the initial filesystem image from a remote repository when brining
up the ctr-example

examples/ctr-example/Makefile

@@ -18,7 +18,7 @@ SWIFT = /usr/bin/swift
 
 .PHONY: all build clean run
 
-all: containerization run
+all: run
 
 build:
 	$(SWIFT) build --configuration release
@@ -39,10 +39,6 @@ debug:
 
 fmt:
 	$(SWIFT) format --in-place --recursive Sources/
-
-containerization: 
-	$(MAKE) -C ../.. all
-
 fetch-default-kernel:
 	$(MAKE) -C ../.. fetch-default-kernel
 	cp -L ../../.local/vmlinux ./vmlinux

examples/ctr-example/README.md

@@ -24,6 +24,7 @@ After the build completes, the example will run. In your terminal you should see
 
 ```
 Starting container example...
+Fetching container initial filesystem...
 Creating container from docker.io/library/alpine:3.16...
 Starting container...
 / #

examples/ctr-example/Sources/ctr-example/main.swift

@@ -28,10 +28,12 @@ struct CtrExample {
         try current.setraw()
         defer { current.tryReset() }
 
+        let initfsReference = "ghcr.io/apple/containerization/vminit:0.13.0"
+        print("Fetching base container filesystem...")
         // Create container manager with file-based initfs
         var manager = try await ContainerManager(
             kernel: Kernel(path: URL(fileURLWithPath: "./vmlinux"), platform: .linuxArm),
-            initfsReference: "vminit:latest",
+            initfsReference: initfsReference,
             network: try ContainerManager.VmnetNetwork()
         )