LocalAppDeployer scaling operations causes too many created empty, unnecessary & unused dirs

[Hassen-BENNOUR]

On call to Scale API, every call (in my case with spring-cloud-skipper through Spring Cloud Data Flow & alertmanager) causes a new directories created under the workingDirectoriesRoot

The problem is below, the createWorkingDir is called before checking if deltaCount == 0

So even if there is no scaling needed the directories are created.
With a huge amount of alerts this causes too many empty directories which saturates the files system
Even if i use the tmp dir, the time that the cleaning is done, it creates too many directories

LocalAppDeployer

`

@Override
public void scale(AppScaleRequest appScaleRequest) {
	validateStatus(appScaleRequest.getDeploymentId(), DeploymentState.deployed);
	AppInstancesHolder holder = running.get(appScaleRequest.getDeploymentId());
	List<AppInstance> instances = holder != null ? holder.instances : null;
	if (instances == null) {
		throw new IllegalStateException(
				"Can't find existing instances for deploymentId " + appScaleRequest.getDeploymentId());
	}
	AppDeploymentRequest request = holder.request;

	String group = request.getDeploymentProperties().get(GROUP_PROPERTY_KEY);
	String deploymentId = String.format("%s.%s", group, request.getDefinition().getName());

	try {
		//here is the problem
		Path workDir = createWorkingDir(request.getDeploymentProperties(), deploymentId);
		int deltaCount = appScaleRequest.getCount() - instances.size();
		int targetCount = instances.size() + deltaCount;

		//here we check if scaling is necessary, workDir is created
		if (deltaCount > 0) {
			for (int index = instances.size(); index < targetCount; index++) {
				instances.add(deployApp(request, workDir, group, deploymentId, index, request.getDeploymentProperties()));
			}
		}
		else if (deltaCount < 0) {
		...

`

I use 2.7.4 but this is the case now

Used with Autoscaling with Prometheus, Alertmanager and SCDF Scale API

I propose

`

public void scale(AppScaleRequest appScaleRequest) {
    this.validateStatus(appScaleRequest.getDeploymentId(), DeploymentState.deployed);
    LocalAppDeployer.AppInstancesHolder holder = (LocalAppDeployer.AppInstancesHolder)this.running.get(appScaleRequest.getDeploymentId());
    List<LocalAppDeployer.AppInstance> instances = holder != null ? holder.instances : null;
    if (instances == null) {
        throw new IllegalStateException("Can't find existing instances for deploymentId " + appScaleRequest.getDeploymentId());
    } else {
        int deltaCount = appScaleRequest.getCount() - instances.size();
        if (deltaCount == 0) {
            return;
        }
        AppDeploymentRequest request = holder.request;
        String group = (String)request.getDeploymentProperties().get("spring.cloud.deployer.group");
        String deploymentId = String.format("%s.%s", group, request.getDefinition().getName());

        try {
            Path workDir = this.createWorkingDir(request.getDeploymentProperties(), deploymentId);
            int targetCount = instances.size() + deltaCount;
            if (deltaCount > 0) {
                for(int index = instances.size(); index < targetCount; ++index) {
                    instances.add(this.deployApp(request, workDir, group, deploymentId, index, request.getDeploymentProperties()));
                }
            } else if (deltaCount < 0) {
                List<LocalAppDeployer.AppInstance> processes = new ArrayList();

                for(int index = instances.size() - 1; index >= targetCount; --index) {
                    processes.add(instances.remove(index));
                }

                Iterator var15 = processes.iterator();

                while(var15.hasNext()) {
                    LocalAppDeployer.AppInstance instance = (LocalAppDeployer.AppInstance)var15.next();
                    if (this.isAlive(instance.getProcess())) {
                        logger.info("Un-deploying app with deploymentId {} instance {}.", deploymentId, instance.getInstanceNumber());
                        this.shutdownAndWait(instance);
                    }
                }
            }

        } catch (IOException var13) {
            throw new RuntimeException("Exception trying to deploy " + request, var13);
        }
    }
}
`