Starting LocalDatastoreHelper stalls if `beta` gcloud component is not installed

[pomu0325]

Environment details

• OS type and version: Debian GNU/Linux 10 (buster) (on Docker)
• Java version: openjdk version "1.8.0_275"
• datastore version(s): com.google.cloud:google-cloud-datastore:jar:1.105.0

Steps to reproduce

1. Remove beta component: gcloud components remove beta
2. Run the code which uses LocalDatastoreHelper

Code example

import com.google.cloud.datastore.testing.LocalDatastoreHelper;

public class Test {
  public static void main(String[] args) throws Exception {
    LocalDatastoreHelper emulator = LocalDatastoreHelper.create();
    emulator.start();

    System.out.println("Started!");
  }
}

How I found this

• Removed beta component

  root@17224e8a6010:/app# gcloud components remove beta --quiet
  ┌──────────────────────────────────────────┐
  │    These components will be removed.     │
  ├──────────────────────┬────────────┬──────┤
  │         Name         │  Version   │ Size │
  ├──────────────────────┼────────────┼──────┤
  │ gcloud Beta Commands │ 2019.05.17 │      │
  └──────────────────────┴────────────┴──────┘
  ...
  Uninstall done!

• Run code example, then it stalls.

  root@17224e8a6010:/app# mvn exec:java -Dexec.mainClass=Test

• Ctrl+Z and run ps to find out what command is executed via LocalDatastoreHelper

  ^Z
  [1]+  Stopped                 mvn exec:java -Dexec.mainClass=Test
  root@17224e8a6010:/app# ps -ef 
  ...
  root      1840  1795  0 17:40 pts/1    00:00:00 python2 -S /root/google-cloud-sdk/lib/gcloud.py beta emulators datastore start --host-port=localhost:40079 --consistency=0.9

• Execute the same command at the terminal, then it prompts whether continue to install beta component

  
  root@17224e8a6010:/app# python2 -S /root/google-cloud-sdk/lib/gcloud.py beta emulators datastore start --host-port=localhost:40079 --consistency=0.9
  You do not currently have this command group installed.  Using it 
  requires the installation of components: [beta]

Your current Cloud SDK version is: 322.0.0 Installing components from version: 322.0.0

┌─────────────────────────────────────────────┐ │ These components will be installed. │ ├──────────────────────┬────────────┬─────────┤ │ Name │ Version │ Size │ ├──────────────────────┼────────────┼─────────┤ │ gcloud Beta Commands │ 2019.05.17 │ < 1 MiB │ └──────────────────────┴────────────┴─────────┘

For the latest full release notes, please visit: https://cloud.google.com/sdk/release_notes

Do you want to continue (Y/n)?

#### Possible solution

Add `--quiet` option to run emulator, so as to silently install `beta` component.
https://github.com/pomu0325/java-datastore/commit/e2cb8f26e977c6c220ba047fe28f4ca1c3da7d40

[crwilcox]

It seems the issue here is likely that the process is blocking on https://github.com/googleapis/java-datastore/blob/master/google-cloud-datastore/src/main/java/com/google/cloud/datastore/testing/LocalDatastoreHelper.java#L273 which never occurs as the components aren't present.

Perhaps this method https://github.com/googleapis/java-core/blob/375983090b3700b3fb6a1953626db7efca49cc51/google-cloud-core/src/main/java/com/google/cloud/testing/BaseEmulatorHelper.java#L94 needs a timeout?

[meredithslota]

@prash-mi Can you or @jainsahab take a look?