Add VMR sync functionality into dotnet/dotnet's Codespaces (#15750)

.devcontainer/vmr-source-build/README.md

@@ -12,14 +12,14 @@ This Codespace can help you debug the source build of .NET. In case you have run
 `dotnet/installer` PR branch, it will contain the VMR (`dotnet/dotnet`) checked out into
 `/workspaces/dotnet` with the PR changes pulled into it. You can then attempt to source-build
 the VMR which is what the VMR leg in the installer PR build doing. This build takes about 45
-minutes and, after completion, produces an archived .NET SDK in `/workspaces/artifacts/x64/Release`.
+minutes and, after completion, produces an archived .NET SDK located in
+`/workspaces/dotnet/artifacts/x64/Release`.
 
 ## Build the SDK
 
 To build the VMR, run following:
 ```bash
 cd /workspaces/dotnet
-unset RepositoryName
 ./build.sh --online
 ```
 
@@ -37,22 +37,16 @@ When debugging the build, you have two options how to test your changes in this
 You can make the changes directly to the local checkout of the VMR at `/workspaces/dotnet`. You
 can then try to build the VMR and see if the change works for you.
 
-### Pull changes into the local VMR
+### Pull changes into the Codespace from your fork
 
 You can also make a fix in the individual source repository (e.g. `dotnet/runtime`) and push the
-fix into a branch (can be in your fork too). Once you have the commit pushed, you can pull this
-version of the repository into the VMR locally.
+fix into a branch; can be in your fork too. Once you have the commit pushed, you can pull this
+version of the repository into the Codespace by running:
 
-Let's consider you pushed a commit with SHA `abcdef` into your fork at `github.com/yourfork/runtime`.
-You can now bring this version of runtime into the local VMR in this Codespace by running:
-
-```bash
-cd /workspaces/installer
-./eng/vmr-sync.sh             \
-  --vmr /workspaces/dotnet    \
-  --tmp /workspaces/tmp       \
-  --repository runtime:abcdef \
-  --remote runtime:https://github.com/yourfork/runtime
+```
+/workspaces/synchronize-vmr.sh                \
+  --repository <repo>:<commit, tag or branch> \
+  --remote <repo>:<fork URI>
 ```
 
 You can now proceed building the VMR in the Codespace using instructions above. You can repeat

.devcontainer/vmr-source-build/init.sh

@@ -10,6 +10,8 @@ workspace_dir=$(realpath "$installer_dir/../")
 tmp_dir=$(realpath "$workspace_dir/tmp")
 vmr_dir=$(realpath "$workspace_dir/dotnet")
 
+cp "$installer_dir/.devcontainer/vmr-source-build/synchronize-vmr.sh" "$workspace_dir"
+
 mkdir -p "$tmp_dir"
 
 # Codespaces performs a shallow fetch only
@@ -18,21 +20,16 @@ git -C "$installer_dir" fetch --all --unshallow
 # We will try to figure out, which branch is the current (PR) branch based off of
 # We need this to figure out, which VMR branch to use
 vmr_branch=$(git -C "$installer_dir" log --pretty=format:'%D' HEAD^ \
-  | grep 'origin/' \
-  | head -n1 \
+  | grep 'origin/'    \
+  | head -n1          \
   | sed 's@origin/@@' \
   | sed 's@,.*@@')
 
-pushd "$installer_dir"
-  "./eng/vmr-sync.sh"      \
-    --vmr "$vmr_dir"       \
-    --tmp "$tmp_dir"       \
-    --branch "$vmr_branch" \
-    --debug
-popd
+"$workspace_dir/synchronize-vmr.sh" \
+  --repository "installer:$(git -C "$installer_dir" rev-parse HEAD)" \
+  --recursive                         \
+  --branch "$vmr_branch"              \
+  --remote "installer:$installer_dir" \
+  --debug
 
-# Run prep.sh
-unset RepositoryName
-pushd "$vmr_dir"
-./prep.sh
-popd
+(cd "$vmr_dir" && ./prep.sh)

.devcontainer/vmr-source-build/synchronize-vmr.sh

@@ -0,0 +1,4 @@
+#!/bin/bash
+
+(cd /workspaces/installer \
+    && ./eng/vmr-sync.sh --vmr /workspaces/dotnet --tmp /workspaces/tmp $*)