Fix credential reloading by default + gracefully handle missing files

.changes/next-release/bugfix-AWSSDKforJavav2-1c5bd30.json

@@ -0,0 +1,6 @@
+{
+    "type": "bugfix",
+    "category": "AWS SDK for Java v2",
+    "contributor": "",
+    "description": "Fix credential reloading in defaults when shared credential/config files are modified."
+}

.changes/next-release/bugfix-AWSSDKforJavav2-b3c8f2c.json

@@ -0,0 +1,6 @@
+{
+    "type": "bugfix",
+    "category": "AWS SDK for Java v2",
+    "contributor": "",
+    "description": "Gracefully handle missing file in ProfileFileSupplier.reloadWhenModified."
+}

core/auth/src/main/java/software/amazon/awssdk/auth/credentials/InstanceProfileCredentialsProvider.java

@@ -105,7 +105,7 @@ private InstanceProfileCredentialsProvider(BuilderImpl builder) {
         this.asyncCredentialUpdateEnabled = builder.asyncCredentialUpdateEnabled;
         this.asyncThreadName = builder.asyncThreadName;
         this.profileFile = Optional.ofNullable(builder.profileFile)
-                                   .orElseGet(() -> ProfileFileSupplier.fixedProfileFile(ProfileFile.defaultProfileFile()));
+                                   .orElseGet(ProfileFileSupplier::defaultSupplier);
         this.profileName = Optional.ofNullable(builder.profileName)
                                    .orElseGet(ProfileFileSystemSetting.AWS_PROFILE::getStringValueOrThrow);
         this.sourceChain = builder.sourceChain;

core/auth/src/main/java/software/amazon/awssdk/auth/credentials/ProfileCredentialsProvider.java

@@ -73,7 +73,7 @@ private ProfileCredentialsProvider(BuilderImpl builder) {
                                           .orElseGet(ProfileFileSystemSetting.AWS_PROFILE::getStringValueOrThrow);
             selectedProfileSupplier =
                 Optional.ofNullable(builder.profileFile)
-                        .orElseGet(() -> ProfileFileSupplier.fixedProfileFile(builder.defaultProfileFileLoader.get()));
+                        .orElse(defaultProfileFileLoader);
 
         } catch (RuntimeException e) {
             // If we couldn't load the credentials provider for some reason, save an exception describing why. This exception
@@ -216,7 +216,7 @@ public interface Builder extends CopyableBuilder<Builder, ProfileCredentialsProv
     static final class BuilderImpl implements Builder {
         private Supplier<ProfileFile> profileFile;
         private String profileName;
-        private Supplier<ProfileFile> defaultProfileFileLoader = ProfileFile::defaultProfileFile;
+        private Supplier<ProfileFile> defaultProfileFileLoader = ProfileFileSupplier.defaultSupplier();
 
         BuilderImpl() {
         }

core/auth/src/test/java/software/amazon/awssdk/auth/credentials/ProfileCredentialsProviderTest.java

@@ -25,6 +25,7 @@
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.Optional;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.function.Supplier;
 import org.junit.jupiter.api.AfterAll;
 import org.junit.jupiter.api.BeforeAll;
@@ -33,6 +34,7 @@
 import software.amazon.awssdk.profiles.ProfileFile;
 import software.amazon.awssdk.profiles.ProfileFileSupplier;
 import software.amazon.awssdk.profiles.ProfileProperty;
+import software.amazon.awssdk.testutils.Waiter;
 import software.amazon.awssdk.utils.StringInputStream;
 
 /**
@@ -243,6 +245,32 @@ void resolveCredentials_presentSupplierProfileFile_returnsCredentials() {
         });
     }
 
+    @Test
+    void resolveCredentials_defaultProfileFileSupplier_refreshesCredentials() {
+        AtomicBoolean firstCall = new AtomicBoolean(true);
+        ProfileFile file1 = profileFile("[default]\naws_access_key_id = akid1\n"
+                                        + "aws_secret_access_key = sak1\n");
+        ProfileFile file2 = profileFile("[default]\naws_access_key_id = akid2\n"
+                                        + "aws_secret_access_key = sak2\n");
+        Supplier<ProfileFile> refreshingSupplier = () ->  firstCall.getAndSet(false) ? file1 : file2;
+
+        ProfileCredentialsProvider provider =  new ProfileCredentialsProvider
+            .BuilderImpl()
+            .defaultProfileFileLoader(refreshingSupplier)
+                                      .profileName("default")
+                                      .build();
+
+        assertThat(provider.resolveCredentials()).satisfies(credentials -> {
+            assertThat(credentials.accessKeyId()).isEqualTo("akid1");
+            assertThat(credentials.secretAccessKey()).isEqualTo("sak1");
+        });
+
+        assertThat(provider.resolveCredentials()).satisfies(credentials -> {
+            assertThat(credentials.accessKeyId()).isEqualTo("akid2");
+            assertThat(credentials.secretAccessKey()).isEqualTo("sak2");
+        });
+    }
+
     @Test
     void create_noProfileName_returnsProfileCredentialsProviderToResolveWithDefaults() {
         ProfileCredentialsProvider provider = ProfileCredentialsProvider.create();

core/profiles/src/main/java/software/amazon/awssdk/profiles/ProfileFileSupplier.java

@@ -15,6 +15,7 @@
 
 package software.amazon.awssdk.profiles;
 
+import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.Collections;
 import java.util.LinkedHashMap;
@@ -38,7 +39,7 @@ public interface ProfileFileSupplier extends Supplier<ProfileFile> {
 
     /**
      * Creates a {@link ProfileFileSupplier} capable of producing multiple profile objects by aggregating the default
-     * credentials and configuration files as determined by {@link ProfileFileLocation#credentialsFileLocation()} abd
+     * credentials and configuration files as determined by {@link ProfileFileLocation#credentialsFileLocation()} and
      * {@link ProfileFileLocation#configurationFileLocation()}. This supplier will return a new ProfileFile instance only once
      * either disk file has been modified. Multiple calls to the supplier while both disk files are unchanged will return the
      * same object.
@@ -81,13 +82,17 @@ static ProfileFileSupplier defaultSupplier() {
      */
     static ProfileFileSupplier reloadWhenModified(Path path, ProfileFile.Type type) {
         return new ProfileFileSupplier() {
-
-            final ProfileFile.Builder builder = ProfileFile.builder()
-                                                           .content(path)
-                                                           .type(type);
+            Supplier<ProfileFile> profileFileSupplier = () -> {
+                if (Files.isRegularFile(path) && Files.isReadable(path)) {
+                    return ProfileFile.builder()
+                                      .content(path)
+                                      .type(type).build();
+                }
+                return ProfileFile.empty();
+            };
 
             final ProfileFileRefresher refresher = ProfileFileRefresher.builder()
-                                                                       .profileFile(builder::build)
+                                                                       .profileFile(profileFileSupplier)
                                                                        .profileFilePath(path)
                                                                        .build();
 

core/profiles/src/main/java/software/amazon/awssdk/profiles/ProfileFileSupplierBuilder.java

@@ -15,6 +15,7 @@
 
 package software.amazon.awssdk.profiles;
 
+import java.nio.file.Files;
 import java.nio.file.Path;
 import java.time.Clock;
 import java.util.Objects;
@@ -33,10 +34,14 @@ final class ProfileFileSupplierBuilder {
     private Consumer<ProfileFile> onProfileFileLoad;
 
     public ProfileFileSupplierBuilder reloadWhenModified(Path path, ProfileFile.Type type) {
-        ProfileFile.Builder builder = ProfileFile.builder()
-                                                 .content(path)
-                                                 .type(type);
-        this.profileFile = builder::build;
+        this.profileFile = () -> {
+            if (Files.isRegularFile(path) && Files.isReadable(path)) {
+                return ProfileFile.builder()
+                                  .content(path)
+                                  .type(type).build();
+            }
+            return ProfileFile.empty();
+        };
         this.profileFilePath = path;
         this.reloadingSupplier = true;
         return this;

core/profiles/src/main/java/software/amazon/awssdk/profiles/internal/ProfileFileRefresher.java

@@ -122,7 +122,7 @@ private boolean isNewProfileFile(ProfileFile profileFile) {
     }
 
     private boolean canReloadProfileFile() {
-        if (Objects.isNull(profileFilePath)) {
+        if (Objects.isNull(profileFilePath) || !Files.exists(profileFilePath)) {
             return false;
         }
 

core/profiles/src/test/java/software/amazon/awssdk/profiles/ProfileFileSupplierTest.java

@@ -592,6 +592,28 @@ public void defaultSupplier_noCredentialsFiles_returnsEmptyProvider() {
         });
     }
 
+    @Test
+    public void reloadWhenModified_noCredentialsFiles_returnsEmptyProvider_andRefreshes() throws IOException {
+        Path credentialsFilePath = getTestCredentialsFilePath();
+        Files.deleteIfExists(credentialsFilePath);
+
+        AdjustableClock clock = new AdjustableClock();
+        ProfileFileSupplier supplier = builderWithClock(clock)
+            .reloadWhenModified(credentialsFilePath, ProfileFile.Type.CREDENTIALS)
+            .build();
+
+        assertThat(supplier.get().profiles()).isEmpty();
+
+        generateTestCredentialsFile("modifiedAccessKey", "modifiedSecretAccessKey", "modifiedAccountId");
+        updateModificationTime(credentialsFilePath, clock.instant().plusMillis(1));
+
+        clock.tickForward(Duration.ofSeconds(10));
+
+        // supplied ProfileFile should refreshed and now have data under the `default` profile
+        Optional<Profile> fileOptional = supplier.get().profile("default");
+        assertThat(fileOptional).isPresent();
+    }
+
     private Path writeTestFile(String contents, Path path) {
         try {
             Files.createDirectories(testDirectory);

core/sdk-core/src/main/java/software/amazon/awssdk/core/client/builder/SdkDefaultClientBuilder.java

@@ -105,13 +105,13 @@
 import software.amazon.awssdk.identity.spi.IdentityProviders;
 import software.amazon.awssdk.metrics.MetricPublisher;
 import software.amazon.awssdk.profiles.ProfileFile;
+import software.amazon.awssdk.profiles.ProfileFileSupplier;
 import software.amazon.awssdk.profiles.ProfileFileSystemSetting;
 import software.amazon.awssdk.profiles.ProfileProperty;
 import software.amazon.awssdk.retries.api.RetryStrategy;
 import software.amazon.awssdk.utils.AttributeMap;
 import software.amazon.awssdk.utils.AttributeMap.LazyValueSource;
 import software.amazon.awssdk.utils.Either;
-import software.amazon.awssdk.utils.Lazy;
 import software.amazon.awssdk.utils.OptionalUtils;
 import software.amazon.awssdk.utils.StringUtils;
 import software.amazon.awssdk.utils.ThreadFactoryBuilder;
@@ -280,7 +280,7 @@ protected SdkClientConfiguration mergeChildDefaults(SdkClientConfiguration confi
      * Apply global default configuration
      */
     private SdkClientConfiguration mergeGlobalDefaults(SdkClientConfiguration configuration) {
-        Supplier<ProfileFile> defaultProfileFileSupplier = new Lazy<>(ProfileFile::defaultProfileFile)::getValue;
+        Supplier<ProfileFile> defaultProfileFileSupplier = ProfileFileSupplier.defaultSupplier();
 
         configuration = configuration.merge(c -> c.option(EXECUTION_INTERCEPTORS, new ArrayList<>())
                                                   .option(METRIC_PUBLISHERS, new ArrayList<>())

core/sdk-core/src/test/java/software/amazon/awssdk/core/client/builder/DefaultClientBuilderTest.java

@@ -44,8 +44,12 @@
 import java.beans.BeanInfo;
 import java.beans.Introspector;
 import java.beans.PropertyDescriptor;
+import java.io.File;
+import java.io.IOException;
 import java.lang.reflect.Method;
 import java.net.URI;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
 import java.time.Duration;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -59,7 +63,9 @@
 import java.util.function.Supplier;
 import org.assertj.core.api.Assertions;
 import org.junit.Before;
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
 import org.junit.runner.RunWith;
 import org.mockito.Mock;
 import org.mockito.Mockito;
@@ -81,6 +87,8 @@
 import software.amazon.awssdk.metrics.MetricCollection;
 import software.amazon.awssdk.metrics.MetricPublisher;
 import software.amazon.awssdk.profiles.ProfileFile;
+import software.amazon.awssdk.testutils.EnvironmentVariableHelper;
+import software.amazon.awssdk.testutils.Waiter;
 import software.amazon.awssdk.utils.AttributeMap;
 import software.amazon.awssdk.utils.StringInputStream;
 
@@ -100,6 +108,9 @@ public class DefaultClientBuilderTest {
     private static final URI ENDPOINT = URI.create("https://example.com");
     private static final NoOpSigner TEST_SIGNER = new NoOpSigner();
 
+    @Rule
+    public TemporaryFolder tempFolder = new TemporaryFolder();
+
     @Mock
     private SdkHttpClient.Builder defaultHttpClientFactory;
 
@@ -437,6 +448,13 @@ private SdkDefaultClientBuilder<TestAsyncClientBuilder, TestAsyncClient> testAsy
         return new TestAsyncClientBuilder().overrideConfiguration(overrideConfig);
     }
 
+    private void writeTestCredentialsFile(File file, String accessKeyId, String secretAccessKey)
+            throws IOException {
+        String contents = String.format("[default]\naws_access_key_id = %s\naws_secret_access_key = %s\n",
+                                        accessKeyId, secretAccessKey);
+        Files.write(file.toPath(), contents.getBytes(StandardCharsets.UTF_8));
+    }
+
     private static class TestClient {
         private final SdkClientConfiguration clientConfiguration;
 

services/s3/src/main/java/software/amazon/awssdk/services/s3/S3Utilities.java

@@ -121,7 +121,7 @@ private S3Utilities(Builder builder) {
         this.region = Validate.paramNotNull(builder.region, "Region");
         this.endpoint = builder.endpoint;
         this.profileFile = Optional.ofNullable(builder.profileFile)
-                                   .orElseGet(() -> ProfileFileSupplier.fixedProfileFile(ProfileFile.defaultProfileFile()));
+                                   .orElseGet(ProfileFileSupplier::defaultSupplier);
         this.profileName = builder.profileName;
 
         if (builder.s3Configuration == null) {