Merge pull request moby#47494 from vvoland/devcontainer-golang

devcontainer: Add Golang extension

.devcontainer/devcontainer.json

@@ -3,11 +3,19 @@
   "build": {
     "context": "..",
     "dockerfile": "../Dockerfile",
-    "target": "dev"
+    "target": "devcontainer"
   },
   "workspaceFolder": "/go/src/github.com/docker/docker",
   "workspaceMount": "source=${localWorkspaceFolder},target=/go/src/github.com/docker/docker,type=bind,consistency=cached",
 
   "remoteUser": "root",
-  "runArgs": ["--privileged"]
+  "runArgs": ["--privileged"],
+
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "golang.go"
+      ]
+    }
+  }
 }

Dockerfile

@@ -251,6 +251,12 @@ RUN --mount=type=cache,target=/root/.cache/go-build \
         GOBIN=/build/ GO111MODULE=on go install "mvdan.cc/sh/v3/cmd/shfmt@${SHFMT_VERSION}" \
      && /build/shfmt --version
 
+FROM base AS gopls
+RUN --mount=type=cache,target=/root/.cache/go-build \
+    --mount=type=cache,target=/go/pkg/mod \
+        GOBIN=/build/ GO111MODULE=on go install "golang.org/x/tools/gopls@latest" \
+     && /build/gopls version
+
 FROM base AS dockercli
 WORKDIR /go/src/github.com/docker/cli
 ARG DOCKERCLI_REPOSITORY
@@ -655,6 +661,11 @@ RUN <<EOT
   docker-proxy --version
 EOT
 
+# devcontainer is a stage used by .devcontainer/devcontainer.json
+FROM dev-base AS devcontainer
+COPY --link . .
+COPY --link --from=gopls         /build/ /usr/local/bin/
+
 # usage:
 # > make shell
 # > SYSTEMD=true make shell