Support IRSA for aws-s3 provider

pom.xml

@@ -394,6 +394,11 @@
         </exclusion>
       </exclusions>
     </dependency>
+    <dependency>
+        <groupId>com.amazonaws</groupId>
+        <artifactId>aws-java-sdk-sts</artifactId>
+        <version>1.12.261</version>
+    </dependency>
     <dependency>
       <groupId>args4j</groupId>
       <artifactId>args4j</artifactId>
@@ -510,7 +515,6 @@
       <groupId>org.slf4j</groupId>
       <artifactId>jcl-over-slf4j</artifactId>
       <version>${slf4j.version}</version>
-      <scope>test</scope>
     </dependency>
     <!-- tests dependencies -->
     <dependency>

src/main/java/org/gaul/s3proxy/Main.java

@@ -35,15 +35,21 @@ import java.util.concurrent.Executors;
 import java.util.concurrent.TimeUnit;
 import java.util.regex.Pattern;
 
+import com.amazonaws.auth.AWSCredentials;
+import com.amazonaws.auth.AWSCredentialsProvider;
+import com.amazonaws.auth.AWSSessionCredentials;
+import com.amazonaws.auth.DefaultAWSCredentialsProviderChain;
 import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableBiMap;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.io.MoreFiles;
 import com.google.common.util.concurrent.ThreadFactoryBuilder;
+import com.google.common.base.Supplier;
 
 import org.jclouds.Constants;
 import org.jclouds.ContextBuilder;
 import org.jclouds.JcloudsVersion;
+import org.jclouds.aws.domain.SessionCredentials;
 import org.jclouds.blobstore.BlobStore;
 import org.jclouds.blobstore.BlobStoreContext;
 import org.jclouds.concurrent.DynamicExecutors;
@@ -52,6 +58,7 @@ import org.jclouds.location.reference.LocationConstants;
 import org.jclouds.logging.slf4j.config.SLF4JLoggingModule;
 import org.jclouds.openstack.swift.v1.blobstore.RegionScopedBlobStoreContext;
 import org.jclouds.s3.domain.ObjectMetadata.StorageClass;
+import org.jclouds.domain.Credentials;
 import org.kohsuke.args4j.CmdLineException;
 import org.kohsuke.args4j.CmdLineParser;
 import org.kohsuke.args4j.Option;
@@ -376,7 +383,6 @@ public final class Main {
 
         ContextBuilder builder = ContextBuilder
                 .newBuilder(provider)
-                .credentials(identity, credential)
                 .modules(List.of(
                         new SLF4JLoggingModule(),
                         new ExecutorServiceModule(executorService)))
@@ -385,6 +391,34 @@ public final class Main {
             builder = builder.endpoint(endpoint);
         }
 
+        if ((identity.isEmpty() || credential.isEmpty()) && provider.equals("aws-s3")) {
+            Supplier<Credentials> credentialsSupplier = new Supplier<Credentials>() {
+                @Override
+                public Credentials get() {
+                    AWSCredentialsProvider authChain = DefaultAWSCredentialsProviderChain.getInstance();
+                    AWSCredentials newCreds = authChain.getCredentials();
+                    Credentials jcloudCred = null;
+
+                    if (newCreds instanceof AWSSessionCredentials) {
+                        jcloudCred = SessionCredentials.builder()
+                                .accessKeyId(newCreds.getAWSAccessKeyId())
+                                .secretAccessKey(newCreds.getAWSSecretKey())
+                                .sessionToken(((AWSSessionCredentials) newCreds).getSessionToken())
+                                .build();
+                    } else {
+                        jcloudCred = new Credentials(
+                                newCreds.getAWSAccessKeyId(), newCreds.getAWSSecretKey()
+                        );
+                    }
+
+                    return jcloudCred;
+                }
+            };
+            builder = builder.credentialsSupplier(credentialsSupplier);
+        } else {
+            builder = builder.credentials(identity, credential);
+        }
+
         BlobStoreContext context = builder.build(BlobStoreContext.class);
         BlobStore blobStore;
         if (context instanceof RegionScopedBlobStoreContext &&