Unable to load AWS credentials from any provider in the chain

Start with the Java snippets using DefaultAWSCredentialsProviderChain.getCredentials(), the DynamoDB builder, and ClientConfiguration proxy settings. Reproduce the credential-chain failure on EC2 and determine whether the missing behavior is in instance-role access, proxy configuration, or client setup; done means documenting a confirmed cause and a reproducible resolution.

I have my application running on EC2. Trying to access dynamoDB from my Java application. But for every operation, I get "Unable to load AWS credentials from any provider in the chain".

• I have added dynamoDB permissions in the IAM role that gets attached to EC2 instance
• And also configured EC2 to assume that role in trust relationship.

Code:

            AWSCredentialsProvider provider = new DefaultAWSCredentialsProviderChain();
            AWSCredentials credentials = provider.getCredentials();
            if(credentials != null) {
                LOG.info("Credentials Key: " + credentials.getAWSAccessKeyId());
                LOG.info("Credentials secret: " + credentials.getAWSSecretKey());
            }
        } catch (Exception e) {
            LOG.info("Exception in credentials cause:" + e.getCause() +";message: " + e.getMessage() +";stack: " +e.getStackTrace());
        }

The getCredentials() line itself throws an Exception with message: "Unable to load AWS credentials from any provider in the chain".
If I do not try to get credentials here and pass it to the DynamoDB client:

                .withClientConfiguration(clientConfig)
                .build();```

Then it throws the same exception when I try to do any operation.

I tried setting up the proxy too: 

```ClientConfiguration clientConfig = new ClientConfiguration();
        clientConfig.setProxyHost("yyy");
        clientConfig.setProxyPort(port);
        clientConfig.setNonProxyHosts("xxx");
        clientConfig.setProtocol(Protocol.HTTP);```

and then passing it while creating the client:

```        dynamoDBClient = builder.withEndpointConfiguration(new AwsClientBuilder.EndpointConfiguration(url, region.getName()))
                .withCredentials(credentialProvider())
                .withClientConfiguration(clientConfig)
                .build();

But no success.

Can someone @here guide me what am I missing here?