Fix quickstart Dockerfile warnings

Author: Haihan-Jiang

quickstarts/hello-app-cdn/Dockerfile

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM golang:1.24.3 as builder
+FROM golang:1.24.3 AS builder
 WORKDIR /app
 RUN go mod init hello-app-cdn
 COPY *.go ./
@@ -21,6 +21,6 @@ RUN CGO_ENABLED=0 GOOS=linux go build -o /hello-app-cdn
 FROM gcr.io/distroless/base-debian11
 WORKDIR /
 COPY --from=builder /hello-app-cdn /hello-app-cdn
-ENV PORT 8080
+ENV PORT=8080
 USER nonroot:nonroot
-CMD ["/hello-app-cdn"]
+CMD ["/hello-app-cdn"]

quickstarts/hello-app-redis/Dockerfile

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM golang:1.24.3 as builder
+FROM golang:1.24.3 AS builder
 WORKDIR /app
 RUN go mod init hello-app-redis
 COPY * ./
@@ -21,6 +21,6 @@ RUN CGO_ENABLED=0 GOOS=linux go build -o /hello-app-redis
 FROM gcr.io/distroless/base-debian11
 WORKDIR /
 COPY --from=builder /hello-app-redis /hello-app-redis
-ENV PORT 8080
+ENV PORT=8080
 USER nonroot:nonroot
-CMD ["/hello-app-redis"]
+CMD ["/hello-app-redis"]

quickstarts/hello-app-tls/Dockerfile

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM golang:1.24.3 as builder
+FROM golang:1.24.3 AS builder
 WORKDIR /app
 RUN go mod init hello-app-tls
 COPY *.go ./
@@ -22,4 +22,4 @@ FROM gcr.io/distroless/base-debian11
 WORKDIR /
 COPY --from=builder /hello-app-tls /hello-app-tls
 USER nonroot:nonroot
-CMD ["/hello-app-tls"]
+CMD ["/hello-app-tls"]

quickstarts/languages/go/Dockerfile

@@ -16,7 +16,7 @@
 # Use the offical Go image to create a build artifact.
 # This is based on Debian and sets the GOPATH to /go.
 # https://hub.docker.com/_/golang
-FROM golang:1.24.3 as builder
+FROM golang:1.24.3 AS builder
 WORKDIR /app
 
 # Initialize a new Go module.

quickstarts/languages/java/Dockerfile

@@ -15,7 +15,7 @@
 # [START gke_quickstarts_languages_java_dockerfile]
 # Use the official maven/Java 8 image to create a build artifact.
 # https://hub.docker.com/_/maven
-FROM maven:3.6-jdk-8-alpine as builder
+FROM maven:3.6-jdk-8-alpine AS builder
 
 # Copy local code to the container image.
 WORKDIR /app

quickstarts/languages/python/Dockerfile

@@ -18,7 +18,7 @@
 FROM python:3.13-slim
 
 # Copy local code to the container image.
-ENV APP_HOME /app
+ENV APP_HOME=/app
 WORKDIR $APP_HOME
 COPY . ./