title: Druid can not see/read GOOGLE_APPLICATION_CREDENTIALS defined on env path
body: <p>I installed apache-druid-0.22.1 as a cluster (master, data and query nodes) and enabled “druid-google-extensions” by adding it to the array druid.extensions.loadList in common.runtime.properties.
  Finally I defined GOOGLE_APPLICATION_CREDENTIALS ( which has the value of service account json as defined in <a href="https://cloud.google.com/docs/authentication/production" rel="nofollow noreferrer">https://cloud.google.com/docs/authentication/production</a> )as an environment variable of user that run the druid services.
  However, I got the following error when I try to ingest data from GCR buckets:</p>
  <blockquote>
  <p>Error: Cannot construct instance of
  org.apache.druid.data.input.google.GoogleCloudStorageInputSource,
  problem: Unable to provision, see the following errors: 1) Error in
  custom provider, java.io.IOException: The Application Default
  Credentials are not available. They are available if running on Google
  App Engine, Google Compute Engine, or Google Cloud Shell. Otherwise,
  the environment variable GOOGLE_APPLICATION_CREDENTIALS must be
  defined pointing to a file defining the credentials. See
  <a href="https://developers.google.com/accounts/docs/application-default-credentials" rel="nofollow noreferrer">https://developers.google.com/accounts/docs/application-default-credentials</a>
  for more information. at
  org.apache.druid.common.gcp.GcpModule.getHttpRequestInitializer(GcpModule.java:60)
  (via modules: com.google.inject.util.Modules$OverrideModule -&gt;
  org.apache.druid.common.gcp.GcpModule) at
  org.apache.druid.common.gcp.GcpModule.getHttpRequestInitializer(GcpModule.java:60)
  (via modules: com.google.inject.util.Modules$OverrideModule -&gt;
  org.apache.druid.common.gcp.GcpModule) while locating
  com.google.api.client.http.HttpRequestInitializer for the 3rd
  parameter of
  org.apache.druid.storage.google.GoogleStorageDruidModule.getGoogleStorage(GoogleStorageDruidModule.java:114)
  at
  org.apache.druid.storage.google.GoogleStorageDruidModule.getGoogleStorage(GoogleStorageDruidModule.java:114)
  (via modules: com.google.inject.util.Modules$OverrideModule -&gt;
  org.apache.druid.storage.google.GoogleStorageDruidModule) while
  locating org.apache.druid.storage.google.GoogleStorage 1 error at
  [Source: (org.eclipse.jetty.server.HttpInputOverHTTP); line: 1,
  column: 180] (through reference chain:
  org.apache.druid.indexing.overlord.sampler.IndexTaskSamplerSpec[&quot;spec&quot;]-&gt;org.apache.druid.indexing.common.task.IndexTask$IndexIngestionSpec[&quot;ioConfig&quot;]-&gt;org.apache.druid.indexing.common.task.IndexTask$IndexIOConfig[&quot;inputSource&quot;])
  A case reported on this matter caught my attention. But I can not see
  any verified solution to that case. Please help me.</p>
  </blockquote>
  <p>We want to take data from GCP to on prem Druid. We don’t want to take cluster in GCP. So that we want solve this problem.</p>