Split Codespaces configuration based on development scenarios

.devcontainer/libraries/Dockerfile

@@ -0,0 +1,29 @@
+# See here for image contents: https://github.com/microsoft/vscode-dev-containers/tree/v0.192.0/containers/dotnet/.devcontainer/base.Dockerfile
+# For details on dotnet specific container, see: https://github.com/microsoft/vscode-dev-containers/tree/main/containers/dotnet
+
+# [Choice] .NET version: 6.0, 3.1
+ARG VARIANT="6.0-focal"
+FROM mcr.microsoft.com/devcontainers/dotnet:0-${VARIANT}
+
+# Set up machine requirements to build the repo and the gh CLI
+RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \
+    && apt-get -y install --no-install-recommends \
+        cmake \
+        llvm-10 \
+        clang-10 \
+        build-essential \
+        python \
+        curl \
+        git \
+        lldb-6.0 \
+        liblldb-6.0-dev \
+        libunwind8 \
+        libunwind8-dev \
+        gettext \
+        libicu-dev \
+        liblttng-ust-dev \
+        libssl-dev \
+        libnuma-dev \
+        libkrb5-dev \
+        zlib1g-dev \
+        ninja-build

.devcontainer/libraries/devcontainer.json

@@ -0,0 +1,51 @@
+// For format details, see https://aka.ms/devcontainer.json.
+{
+	"name": "C# (.NET)",
+	"build": {
+		"dockerfile": "Dockerfile",
+		"args": {
+			// Update 'VARIANT' to pick a .NET Core version: 3.1, 6.0
+			// Append -bullseye or -focal to pin to an OS version.
+			"VARIANT": "6.0-focal"
+		}
+	},
+
+	"features": {
+		"ghcr.io/devcontainers/features/github-cli:1": {}
+	},
+
+	// Configure tool-specific properties.
+	"customizations": {
+		// Configure properties specific to VS Code.
+		"vscode": {
+			// Add the IDs of extensions you want installed when the container is created.
+			"extensions": [
+				"ms-dotnettools.csharp"
+			],
+			"settings": {
+				// Loading projects on demand is better for larger codebases
+				"omnisharp.enableMsBuildLoadProjectsOnDemand": true,
+				"omnisharp.enableRoslynAnalyzers": true,
+				"omnisharp.enableEditorConfigSupport": true,
+				"omnisharp.enableAsyncCompletion": true,
+				"omnisharp.testRunSettings": "${containerWorkspaceFolder}/artifacts/obj/vscode/.runsettings"
+			}
+		}
+	},
+
+	// Use 'onCreateCommand' to run pre-build commands inside the codespace
+	"onCreateCommand": "${containerWorkspaceFolder}/.devcontainer/scripts/onCreateCommand.sh libraries",
+
+	// Use 'postCreateCommand' to run commands after the container is created.
+	"postCreateCommand": "${containerWorkspaceFolder}/.devcontainer/scripts/postCreateCommand.sh",
+
+	// Add the locally installed dotnet to the path to ensure that it is activated
+	// This allows developers to just use 'dotnet build' on the command-line, and the local dotnet version will be used.
+	"remoteEnv": {
+		"PATH": "${containerWorkspaceFolder}/.dotnet:${containerEnv:PATH}",
+		"DOTNET_MULTILEVEL_LOOKUP": "0"
+	},
+
+	// Comment out connect as root instead. More info: https://aka.ms/vscode-remote/containers/non-root.
+	"remoteUser": "vscode"
+}

.devcontainer/scripts/onCreateCommand.sh

@@ -2,18 +2,26 @@
 
 set -e
 
-# prebuild the repo, so it is ready for development
-./build.sh libs+clr -rc Release
-# restore libs tests so that the project is ready to be loaded by OmniSharp
-./build.sh libs.tests -restore
+opt=$1
+case "$opt" in
 
-# prebuild for WASM, so it is ready for wasm development
-make -C src/mono/wasm provision-wasm
-export EMSDK_PATH=$PWD/src/mono/wasm/emsdk
-./build.sh mono+libs -os Browser -c release
+    libraries)
+        # prebuild the repo, so it is ready for development
+        ./build.sh libs+clr -rc Release
+        # restore libs tests so that the project is ready to be loaded by OmniSharp
+        ./build.sh libs.tests -restore
+    ;;
 
-# install dotnet-serve for running wasm samples
-./dotnet.sh tool install dotnet-serve --tool-path ./.dotnet-tools-global
+    wasm)
+        # prebuild for WASM, so it is ready for wasm development
+        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
+    ;;
+esac
 
 # save the commit hash of the currently built assemblies, so developers know which version was built
 git rev-parse HEAD > ./artifacts/prebuild.sha

.devcontainer/Dockerfile → .devcontainer/wasm/Dockerfile

@@ -1,22 +1,32 @@
 # See here for image contents: https://github.com/microsoft/vscode-dev-containers/tree/v0.192.0/containers/dotnet/.devcontainer/base.Dockerfile
 # For details on dotnet specific container, see: https://github.com/microsoft/vscode-dev-containers/tree/main/containers/dotnet
 
-# [Choice] .NET version: 6.0, 5.0, 3.1, 2.1
+# [Choice] .NET version: 6.0, 3.1
 ARG VARIANT="6.0-focal"
-FROM mcr.microsoft.com/vscode/devcontainers/dotnet:0-${VARIANT}
-
-# Setup the gh (GitHub) CLI signing key.
-RUN curl -fsSL https://cli.github.com/packages/githubcli-archive-keyring.gpg | dd of=/usr/share/keyrings/githubcli-archive-keyring.gpg && \
-    chmod go+r /usr/share/keyrings/githubcli-archive-keyring.gpg && \
-    echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/githubcli-archive-keyring.gpg] https://cli.github.com/packages stable main" | tee /etc/apt/sources.list.d/github-cli.list > /dev/null
+FROM mcr.microsoft.com/devcontainers/dotnet:0-${VARIANT}
 
 # Set up machine requirements to build the repo and the gh CLI
 RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \
-    && apt-get -y install --no-install-recommends cmake llvm-10 clang-10 \
-        build-essential python curl git lldb-6.0 liblldb-6.0-dev \
-        libunwind8 libunwind8-dev gettext libicu-dev liblttng-ust-dev \
-        libssl-dev libnuma-dev libkrb5-dev zlib1g-dev ninja-build \
-        gh
+    && apt-get -y install --no-install-recommends \
+        cmake \
+        llvm-10 \
+        clang-10 \
+        build-essential \
+        python \
+        curl \
+        git \
+        lldb-6.0 \
+        liblldb-6.0-dev \
+        libunwind8 \
+        libunwind8-dev \
+        gettext \
+        libicu-dev \
+        liblttng-ust-dev \
+        libssl-dev \
+        libnuma-dev \
+        libkrb5-dev \
+        zlib1g-dev \
+        ninja-build
 
 # Install V8 Engine
 SHELL ["/bin/bash", "-c"]

.devcontainer/devcontainer.json → .devcontainer/wasm/devcontainer.json

@@ -1,31 +1,40 @@
-// For format details, see https://aka.ms/devcontainer.json. For config options, see the README at:
-// https://github.com/microsoft/vscode-dev-containers/tree/v0.192.0/containers/dotnet
+// For format details, see https://aka.ms/devcontainer.json.
 {
 	"name": "C# (.NET)",
 	"build": {
 		"dockerfile": "Dockerfile",
 		"args": {
-			// Update 'VARIANT' to pick a .NET Core version: 2.1, 3.1, 5.0
-			"VARIANT": "5.0",
+			// Update 'VARIANT' to pick a .NET Core version: 3.1, 6.0
+			// Append -bullseye or -focal to pin to an OS version.
+			"VARIANT": "6.0-focal"
 		}
 	},
 
-	"settings": {
-		// Loading projects on demand is better for larger codebases
-		"omnisharp.enableMsBuildLoadProjectsOnDemand": true,
-		"omnisharp.enableRoslynAnalyzers": true,
-		"omnisharp.enableEditorConfigSupport": true,
-		"omnisharp.enableAsyncCompletion": true,
-		"omnisharp.testRunSettings": "${containerWorkspaceFolder}/artifacts/obj/vscode/.runsettings"
+	"features": {
+		"ghcr.io/devcontainers/features/github-cli:1": {}
 	},
 
-	// Add the IDs of extensions you want installed when the container is created.
-	"extensions": [
-		"ms-dotnettools.csharp"
-	],
+	// Configure tool-specific properties.
+	"customizations": {
+		// Configure properties specific to VS Code.
+		"vscode": {
+			// Add the IDs of extensions you want installed when the container is created.
+			"extensions": [
+				"ms-dotnettools.csharp"
+			],
+			"settings": {
+				// Loading projects on demand is better for larger codebases
+				"omnisharp.enableMsBuildLoadProjectsOnDemand": true,
+				"omnisharp.enableRoslynAnalyzers": true,
+				"omnisharp.enableEditorConfigSupport": true,
+				"omnisharp.enableAsyncCompletion": true,
+				"omnisharp.testRunSettings": "${containerWorkspaceFolder}/artifacts/obj/vscode/.runsettings"
+			}
+		}
+	},
 
 	// Use 'onCreateCommand' to run pre-build commands inside the codespace
-	"onCreateCommand": "${containerWorkspaceFolder}/.devcontainer/scripts/onCreateCommand.sh",
+	"onCreateCommand": "${containerWorkspaceFolder}/.devcontainer/scripts/onCreateCommand.sh wasm",
 
 	// Use 'postCreateCommand' to run commands after the container is created.
 	"postCreateCommand": "${containerWorkspaceFolder}/.devcontainer/scripts/postCreateCommand.sh",

docs/workflow/Codespaces.md

@@ -7,9 +7,20 @@ dotnet/runtime runs a nightly GitHub Action to build the latest code in the repo
 
 1. From https://github.com/dotnet/runtime, drop-down the `Code` button and select the `Codespaces` tab.
 
-![New codespace button](https://docs.github.com/assets/images/help/codespaces/new-codespace-button.png)
+![New codespace button](https://docs.github.com/assets/cb-138303/images/help/codespaces/new-codespace-button.png)
 
-2. Select the Machine type. For dotnet/runtime, it is recommended to select at least a `4-core` machine. You can also verify that a "Prebuild" is ready.
+2. Click the drop-down at the side of the `Create codespace on main` button and select `Configure and create codespace`
+
+![Configure and create codespace](https://docs.github.com/assets/cb-49317/images/help/codespaces/default-machine-type.png)
+
+3. Select which Dev container configuration you want to use.
+
+![Dev container configuration](./codespace-dev-container-configuration.png)
+
+    - For `libraries` work, pick `.devcontainer/libraries/devcontainer.json`.
+    - For `WASM` work, pick `.devcontainer/wasm/devcontainer.json`.
+
+4. Select the Machine type. For `dotnet/runtime`, it is recommended to select at least a `4-core` machine. You can also verify that a `Prebuild` is ready.
 
 ![Codespace machine size](./codespace-machine-size.png)
 
@@ -20,21 +31,15 @@ dotnet/runtime runs a nightly GitHub Action to build the latest code in the repo
 
 The Codespaces configuration is spread across the following places:
 
-1. The [.devcontainer](../../.devcontainer) folder contains:
-    - `devcontainer.json` file configures the codespace and mostly has VS Code settings
-    - The Dockerfile used to create the image
+1. The [.devcontainer](../../.devcontainer) folder contains folders for each "development scenario":
+    - `libraries` - Used by developers working in `src/libraries`
+    - `wasm` - Used by developers working on the browser-wasm workload
     - The `scripts` folder contains any scripts that are executed during the creation of the codespace. This has the build command that builds the entire repo for prebuilds.
-2. The GitHub Action can be configured by following the instructions at https://docs.github.com/codespaces/prebuilding-your-codespaces/configuring-prebuilds.
+2. Each development scenario folder contains:
+    - `devcontainer.json` file configures the codespace and has VS Code / Environment settings
+    - The Dockerfile used to create the Docker image
+3. The GitHub Action can be configured by following the instructions at https://docs.github.com/codespaces/prebuilding-your-codespaces/configuring-prebuilds.
 
 To test out changes to the `.devcontainer` files, you can follow the process in [Applying changes to your configuration](https://docs.github.com/codespaces/customizing-your-codespace/configuring-codespaces-for-your-project#applying-changes-to-your-configuration) docs. This allows you to rebuild the Codespace privately before creating a PR.
 
-To test out your `.yml` changes, here is the process:
-
-**Note**: *Executing these steps will overwrite the current prebuilt container for the entire repo. Afterwards, anyone creating a new codespace will get a prebuilt machine with your test changes until the Action in `main` is executed again.*
-
-1. Edit and commit the files to a branch.
-2. Push that to a branch on dotnet/runtime. Be careful that you aren't pushing to `main` or some other important branch. Prefix your branch name with your GitHub account name, so others know it is a dev branch. ex. `username/FixCodespaces`.
-3. In the "Actions" tab at the top of dotnet/runtime:
-    - Select "Create Codespaces Prebuild" action on the left
-    - On the right click "Run workflow" and pick your branch
-    - After it runs, try to create a codespace
+To test out your changes you can run the [Codespaces Prebuilds Action](https://github.com/dotnet/runtime/actions/workflows/codespaces/create_codespaces_prebuilds) in your fork against a branch with your changes.