Spring Cloud GCP Cloud Spanner Example For ReadWriteTransaction issues

This code sample demonstrates that you are forced to use SpannerRepository base methods in case of you open a read-write transaction. In case you don’t use the provided parameter, and use the actual repository instead, then the already opened transaction is not recognized and the result is a nested transaction that is not supported.

Anyhow, the target should be to create a single transaction using the custom repository methods of an application. This should be easy and is one of the most use cases for spanner data.

Running the example

Simplest solution is the setup the emulator like using for example this script:

#!/usr/bin/env bash

set -e

# check if gcloud is installed
if ! command -v gcloud &> /dev/null
then
    echo "Please install gcloud to run this script"
    exit
fi

#
# create gcloud dev profile
#

# check if the profile already exists
configListResult=$(gcloud config configurations list)
if [[ ! $configListResult == *"emualtor"* ]]; then
  echo "'emualtor' profile not found, creating..."

  gcloud config configurations create emualtor
  gcloud auth login
  gcloud config set project emualtor
  gcloud auth application-default login

fi


# start emulator when not running
imageName='gcr.io/cloud-spanner-emulator/emulator'
emulatorImageRunningResult=$(docker ps | awk '{split($2,image,":"); print $1, image[1]}')

if [[ ! $emulatorImageRunningResult == *$imageName* ]]; then
  echo "Emulator not running, starting..."

  # check if image is stopped
  emulatorAllImagesResult=$(docker ps -a | awk '{split($2,image,":"); print $1, image[1]}')

  # start new container
  if [[ ! $emulatorAllImagesResult == *$imageName* ]]; then
    echo "No stopped containers found, starting new container..."
    docker run -d -p 9010:9010 -p 9020:9020 gcr.io/cloud-spanner-emulator/emulator
  fi

  # start existing container
  if [[ $emulatorAllImagesResult == *$imageName* ]]; then
    echo "Stopped container found, starting existing container..."
    docker start $(docker ps -a | awk '{split($2,image,":"); print $1, image[1]}' | awk -v image=$imageName '$2 == image {print $1}')
  fi
fi

gcloud config configurations activate emualtor
gcloud config set project emualtor
gcloud config set auth/disable_credentials true
gcloud config set api_endpoint_overrides/spanner http://localhost:9020/

# create spanner instance if not exists
spannerInstanceResult=$(gcloud spanner instances list)
if [[ ! $spannerInstanceResult == *"spring-demo"* ]]; then
  echo "No local spanner instance found, creating..."

  gcloud spanner instances create spring-demo \
   --config=emualtor --description="Local spanner instance for spring-demo" --nodes=1

   gcloud spanner databases create trades --instance spring-demo
fi

You can also connect to a real spanner. In this case, make sure to enable authentication by removing the NoCredentialsProvider bean from SpannerExampleDriver.java and updating the application.properties to your needs.