[Codespaces] Make it possible to run wasm samples in the browser (#64277)

With these changes, running the following in the Codespace will open the local browser to a page served from the codespace hosting the WASM sample:

```console
cd src/mono/sample/wasm/browser
make
make run-browser
```


* Set EMSDK_PATH in .devcontainer.json

   We provision Emscripten as part of the devcontainer prebuild.

   Set EMSDK_PATH to allow rebuilding the wasm runtime to work without any additional ceremony

* Install dotnet-serve into .dotnet-tools-global

* [wasm] Don't try to open browser if running in Codespaces

* .devcontainer: add global tools dir to PATH

* .devcontainer: forward port 8000

   This enables running the mono wasm samples in the local browser:

* [wasm] samples: also check for dotnet-serve on the path

   On Codespaces we install dotnet-serve on the PATH but not where `dotnet tool list` can see it

* remove onAutoForward: notify - it's the default

* Adjust the path of v8 depends if running in a dev container

* Check if we're running in any Docker container, not just Codespaces

Co-authored-by: Fan Yang <52458914+fanyang-mono@users.noreply.github.com>

.devcontainer/devcontainer.json

@@ -4,7 +4,7 @@
 	"name": "C# (.NET)",
 	"build": {
 		"dockerfile": "Dockerfile",
-		"args": { 
+		"args": {
 			// Update 'VARIANT' to pick a .NET Core version: 2.1, 3.1, 5.0
 			"VARIANT": "5.0",
 		}
@@ -32,11 +32,22 @@
 
 	// Add the locally installed dotnet to the path to ensure that it is activated
 	// This allows developers to just use 'dotnet build' on the command-line, and the local dotnet version will be used.
+	// Add the global tools dir to the PATH so that globally installed tools will work
 	"remoteEnv": {
-		"PATH": "${containerWorkspaceFolder}/.dotnet:${containerEnv:PATH}",
+		"PATH": "${containerWorkspaceFolder}/.dotnet:${containerWorkspaceFolder}/.dotnet-tools-global:${containerEnv:PATH}",
-		"DOTNET_MULTILEVEL_LOOKUP": "0"
+		"DOTNET_MULTILEVEL_LOOKUP": "0",
+		// Path to provisioned Emscripten SDK, for rebuilding the wasm runtime
+		"EMSDK_PATH": "${containerWorkspaceFolder}/src/mono/wasm/emsdk",
 	},
 
 	// Comment out connect as root instead. More info: https://aka.ms/vscode-remote/containers/non-root.
-	"remoteUser": "vscode"
+	"remoteUser": "vscode",
+
+	// Forward mono samples port
+	"forwardPorts": [8000],
+	"portsAttributes": {
+		"8000": {
+			"label": "mono wasm samples (8000)",
+		}
+	}
 }

.devcontainer/scripts/onCreateCommand.sh

@@ -12,5 +12,8 @@ make -C src/mono/wasm provision-wasm
 export EMSDK_PATH=$PWD/src/mono/wasm/emsdk
 ./build.sh mono+libs -os Browser -c release
 
+# install dotnet-serve for running wasm samples
+./dotnet.sh tool install dotnet-serve --tool-path ./.dotnet-tools-global
+
 # save the commit hash of the currently built assemblies, so developers know which version was built
 git rev-parse HEAD > ./artifacts/prebuild.sha

.gitignore

@@ -7,6 +7,7 @@ syntax: glob
 #       instead of directories), git will still ignore them.
 .dotnet
 .dotnet-mono
+.dotnet-tools-global
 .packages
 .tools
 

src/mono/sample/wasm/wasm.mk

@@ -10,6 +10,15 @@ CONFIG?=Release
 
 WASM_DEFAULT_BUILD_ARGS?=/p:TargetArchitecture=wasm /p:TargetOS=Browser /p:Configuration=$(CONFIG)
 
+# if we're in a container, don't try to open the browser
+ifneq ("$(wildcard /.dockerenv)", "")
+  OPEN_BROWSER=
+  V8_PATH=v8
+else
+  OPEN_BROWSER=-o
+  V8_PATH=~/.jsvu/v8
+endif
+
 all: publish
 
 build:
@@ -22,15 +31,15 @@ clean:
 	rm -rf bin $(TOP)/artifacts/obj/mono/$(PROJECT_NAME:%.csproj=%)
 
 run-browser:
-	if ! $(DOTNET) tool list --global | grep dotnet-serve; then \
+	if ! $(DOTNET) tool list --global | grep dotnet-serve && ! which dotnet-serve ; then \
 		echo "The tool dotnet-serve could not be found. Install with: $(DOTNET) tool install --global dotnet-serve"; \
 		exit 1; \
 	else  \
-		$(DOTNET) serve -d:bin/$(CONFIG)/AppBundle -o -p:8000; \
+		$(DOTNET) serve -d:bin/$(CONFIG)/AppBundle $(OPEN_BROWSER) -p:8000; \
 	fi
 
 run-console:
-	cd bin/$(CONFIG)/AppBundle && ~/.jsvu/v8 --stack-trace-limit=1000 --single-threaded --expose_wasm $(MAIN_JS) -- $(DOTNET_MONO_LOG_LEVEL) --run $(CONSOLE_DLL) $(ARGS)
+	cd bin/$(CONFIG)/AppBundle && $(V8_PATH) --stack-trace-limit=1000 --single-threaded --expose_wasm $(MAIN_JS) -- $(DOTNET_MONO_LOG_LEVEL) --run $(CONSOLE_DLL) $(ARGS)
 
 run-console-node:
 	cd bin/$(CONFIG)/AppBundle && node --stack-trace-limit=1000 --single-threaded --expose_wasm $(MAIN_JS) -- $(DOTNET_MONO_LOG_LEVEL) --run $(CONSOLE_DLL) $(ARGS)