Bump more Dockerfile to go 1.25

Author: stanley-cheung

examples/features/csm_observability/client/Dockerfile

@@ -15,7 +15,7 @@
 # Dockerfile for building the example client. To build the image, run the
 # following command from grpc-go directory:
 # docker build -t <TAG> -f examples/features/csm_observability/client/Dockerfile .
-FROM golang:1.23-alpine as build
+FROM golang:1.25-alpine as build
 
 RUN apk --no-cache add curl
 

examples/features/csm_observability/server/Dockerfile

@@ -16,7 +16,7 @@
 # following command from grpc-go directory:
 # docker build -t <TAG> -f examples/features/csm_observability/server/Dockerfile .
 
-FROM golang:1.23-alpine as build
+FROM golang:1.25-alpine as build
 RUN apk --no-cache add curl
 # Make a grpc-go directory and copy the repo into it.
 WORKDIR /go/src/grpc-go

interop/observability/Dockerfile

@@ -17,7 +17,7 @@
 # Stage 1: Build the interop test client and server
 #
 
-FROM golang:1.24-bullseye as build
+FROM golang:1.25-bullseye as build
 
 WORKDIR /grpc-go
 COPY . .
@@ -36,7 +36,7 @@ RUN go build -o server/ server/server.go && \
 #   with the given parameters.
 #
 
-FROM golang:1.23-bullseye
+FROM golang:1.25-bullseye
 
 ENV GRPC_GO_LOG_SEVERITY_LEVEL info
 ENV GRPC_GO_LOG_VERBOSITY_LEVEL 2

interop/xds/client/Dockerfile

@@ -16,7 +16,7 @@
 # following command from grpc-go directory:
 # docker build -t <TAG> -f interop/xds/client/Dockerfile .
 
-FROM golang:1.23-alpine as build
+FROM golang:1.25-alpine as build
 
 # Make a grpc-go directory and copy the repo into it.
 WORKDIR /go/src/grpc-go

interop/xds/server/Dockerfile

@@ -16,7 +16,7 @@
 # following command from grpc-go directory:
 # docker build -t <TAG> -f interop/xds/server/Dockerfile .
 
-FROM golang:1.23-alpine as build
+FROM golang:1.25-alpine as build
 
 # Make a grpc-go directory and copy the repo into it.
 WORKDIR /go/src/grpc-go

test/kokoro/xds.sh

@@ -9,7 +9,7 @@ export GOPATH="${HOME}/gopath"
 pushd grpc-go/interop/xds/client
 # Install a version of Go supported by gRPC for the new features, e.g.
 # errors.Is()
-gofilename=go1.23.0.linux-amd64.tar.gz
+gofilename=go1.25.0.linux-amd64.tar.gz
 curl --retry 3 -O -L "https://go.dev/dl/${gofilename}"
 sudo tar -C /usr/local -xf "${gofilename}"
 sudo ln -s /usr/local/go/bin/go /usr/bin/go