GCP Pub/Sub throws "The Application Default Credentials are not available" - eclipse

Question

I am trying to publish to Google Pub/Sub topic using the following:
ProjectTopicName topicName = ProjectTopicName.of("my-project-id", "my-topic-id");
Publisher publisher = null;
try {
// Create a publisher instance with default settings bound to the topic
publisher = Publisher.newBuilder(topicName).build();
List<String> messages = Arrays.asList("first message", "second message");
for (final String message : messages) {
ByteString data = ByteString.copyFromUtf8(message);
PubsubMessage pubsubMessage = PubsubMessage.newBuilder().setData(data).build();
// Once published, returns a server-assigned message id (unique within the topic)
ApiFuture<String> future = publisher.publish(pubsubMessage);
// Add an asynchronous callback to handle success / failure
ApiFutures.addCallback(
future,
new ApiFutureCallback<String>() {
#Override
public void onFailure(Throwable throwable) {
if (throwable instanceof ApiException) {
ApiException apiException = ((ApiException) throwable);
// details on the API exception
System.out.println(apiException.getStatusCode().getCode());
System.out.println(apiException.isRetryable());
}
System.out.println("Error publishing message : " + message);
}
#Override
public void onSuccess(String messageId) {
// Once published, returns server-assigned message ids (unique within the topic)
System.out.println(messageId);
}
},
MoreExecutors.directExecutor());
}
} finally {
if (publisher != null) {
// When finished with the publisher, shutdown to free up resources.
publisher.shutdown();
publisher.awaitTermination(1, TimeUnit.MINUTES);
}
}
I have changed the default values you see here to the particulars of the account I am hitting.
The environment variable points to the JSON file containing the pub/sub authentication credentials:
GOOGLE_APPLICATION_CREDENTIALS
was set using:
export GOOGLE_APPLICATION_CREDENTIALS=path/to/file.json
and verified with echo $GOOGLE_APPLICATION_CREDENTIALS - after a reboot.
But I am still encountering:
The Application Default Credentials are not available. They are available
if running in Google Compute Engine. Otherwise, the environment variable
GOOGLE_APPLICATION_CREDENTIALS must be defined pointing to a file defining
the credentials. See https://developers.google.com/accounts/docs/application-
default-credentials for more information.
I believe this is related to the default environment that the application is running in, or rather what GCP object thinks the context is -runningOnComputeEngine:
com.google.auth.oauth2.ComputeEngineCredentials runningOnComputeEngine
INFO: Failed to detect whether we are running on Google Compute Engine.
also, a dialog displayed:
Unable to launch App Engine Server
Cannot determine server execution context
and there are no Google Cloud Platform settings in project (Eclipse 2019-3):
This is not an App Engine application.
How to set the environment that GCP objects point to -> Non App Engine.
For reference:
Server to Server (link in error message)
Publish
Google Cloud Tools for Eclipse
Java 7 application
Mac OS (Sierra)
The file permissions are set that app can read the file.

Answer 1

Google's documentation on this is terrible - it does not mention this anywhere.
The answer is to use:
// create a credentials provider
CredentialsProvider credentialsProvider = FixedCredentialsProvider.create(ServiceAccountCredentials.fromStream(new FileInputStream(Constants.PUB_SUB_KEY)));
// apply credentials provider when creating publisher
publisher = Publisher.newBuilder(topicName).setCredentialsProvider(credentialsProvider).build();
The Environment variable usage is either deprecated or the documentation is flat out wrong, or I'm missing something,... which is entirely possible given the poor documentation.