ProfileCredentialsProvider can now reload credentials when profile files change

.changes/next-release/feature-AWSSDKforJavav2-688d30e.json

@@ -0,0 +1,6 @@
+{
+    "category": "AWS SDK for Java v2", 
+    "contributor": "", 
+    "type": "feature", 
+    "description": "Created ReloadingProfileCredentialsProvider to reload credentials due to disk changes"
+}

core/auth/pom.xml

@@ -152,6 +152,12 @@
             <artifactId>commons-lang3</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>com.google.jimfs</groupId>
+            <artifactId>jimfs</artifactId>
+            <version>${jimfs.version}</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
     <build>
         <plugins>

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

@@ -30,7 +30,7 @@
 public interface AwsCredentialsProvider {
     /**
      * Returns {@link AwsCredentials} that can be used to authorize an AWS request. Each implementation of AWSCredentialsProvider
-     * can chose its own strategy for loading credentials. For example, an implementation might load credentials from an existing
+     * can choose its own strategy for loading credentials. For example, an implementation might load credentials from an existing
      * key management system, or load new credentials when credentials are rotated.
      *
      * <p>If an error occurs during the loading of credentials or credentials could not be found, a runtime exception will be

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

@@ -15,6 +15,7 @@
 
 package software.amazon.awssdk.auth.credentials;
 
+import java.util.Objects;
 import java.util.Optional;
 import java.util.function.Consumer;
 import java.util.function.Supplier;
@@ -23,6 +24,7 @@
 import software.amazon.awssdk.auth.credentials.internal.ProfileCredentialsUtils;
 import software.amazon.awssdk.core.exception.SdkClientException;
 import software.amazon.awssdk.profiles.ProfileFile;
+import software.amazon.awssdk.profiles.ProfileFileSupplier;
 import software.amazon.awssdk.profiles.ProfileFileSystemSetting;
 import software.amazon.awssdk.utils.IoUtils;
 import software.amazon.awssdk.utils.SdkAutoCloseable;
@@ -46,55 +48,42 @@ public final class ProfileCredentialsProvider
     implements AwsCredentialsProvider,
                SdkAutoCloseable,
                ToCopyableBuilder<ProfileCredentialsProvider.Builder, ProfileCredentialsProvider> {
-    private final AwsCredentialsProvider credentialsProvider;
-    private final RuntimeException loadException;
 
-    private final ProfileFile profileFile;
+    private AwsCredentialsProvider credentialsProvider;
+    private final RuntimeException loadException;
+    private final ProfileFileSupplier profileFileSupplier;
+    private volatile ProfileFile currentProfileFile;
     private final String profileName;
-
     private final Supplier<ProfileFile> defaultProfileFileLoader;
 
     /**
      * @see #builder()
      */
     private ProfileCredentialsProvider(BuilderImpl builder) {
-        AwsCredentialsProvider credentialsProvider = null;
-        RuntimeException loadException = null;
-        ProfileFile profileFile = null;
-        String profileName = null;
+        this.defaultProfileFileLoader = builder.defaultProfileFileLoader;
+
+        RuntimeException thrownException = null;
+        String selectedProfileName = null;
+        ProfileFileSupplier selectedProfileSupplier = null;
 
         try {
-            profileName = builder.profileName != null ? builder.profileName
-                                                      : ProfileFileSystemSetting.AWS_PROFILE.getStringValueOrThrow();
-
-            // Load the profiles file
-            profileFile = Optional.ofNullable(builder.profileFile)
-                                  .orElseGet(builder.defaultProfileFileLoader);
-
-            // Load the profile and credentials provider
-            String finalProfileName = profileName;
-            ProfileFile finalProfileFile = profileFile;
-            credentialsProvider =
-                    profileFile.profile(profileName)
-                               .flatMap(p -> new ProfileCredentialsUtils(finalProfileFile, p, finalProfileFile::profile)
-                                       .credentialsProvider())
-                               .orElseThrow(() -> {
-                                   String errorMessage = String.format("Profile file contained no credentials for " +
-                                                                       "profile '%s': %s", finalProfileName, finalProfileFile);
-                                   return SdkClientException.builder().message(errorMessage).build();
-                               });
+            selectedProfileName = Optional.ofNullable(builder.profileName)
+                                          .orElseGet(ProfileFileSystemSetting.AWS_PROFILE::getStringValueOrThrow);
+
+            selectedProfileSupplier = Optional.ofNullable(builder.profileFileSupplier)
+                                              .orElseGet(() -> ProfileFileSupplier
+                                                  .fixedProfileFile(builder.defaultProfileFileLoader.get()));
+
         } catch (RuntimeException e) {
             // If we couldn't load the credentials provider for some reason, save an exception describing why. This exception
-            // will only be raised on calls to getCredentials. We don't want to raise an exception here because it may be
+            // will only be raised on calls to resolveCredentials. We don't want to raise an exception here because it may be
             // expected (eg. in the default credential chain).
-            loadException = e;
+            thrownException = e;
         }
 
-        this.loadException = loadException;
-        this.credentialsProvider = credentialsProvider;
-        this.profileFile = profileFile;
-        this.profileName = profileName;
-        this.defaultProfileFileLoader = builder.defaultProfileFileLoader;
+        this.loadException = thrownException;
+        this.profileName = selectedProfileName;
+        this.profileFileSupplier = selectedProfileSupplier;
     }
 
     /**
@@ -127,19 +116,39 @@ public AwsCredentials resolveCredentials() {
         if (loadException != null) {
             throw loadException;
         }
+
+        ProfileFile cachedOrRefreshedProfileFile = refreshProfileFile();
+        if (isNewProfileFile(cachedOrRefreshedProfileFile)) {
+            currentProfileFile = cachedOrRefreshedProfileFile;
+            handleProfileFileReload(cachedOrRefreshedProfileFile);
+        }
+
         return credentialsProvider.resolveCredentials();
     }
 
+    private void handleProfileFileReload(ProfileFile profileFile) {
+        credentialsProvider = createCredentialsProvider(profileFile, profileName);
+    }
+
+    private ProfileFile refreshProfileFile() {
+        return profileFileSupplier.get();
+    }
+
+    private boolean isNewProfileFile(ProfileFile profileFile) {
+        return !Objects.equals(currentProfileFile, profileFile);
+    }
+
     @Override
     public String toString() {
         return ToString.builder("ProfileCredentialsProvider")
                        .add("profileName", profileName)
-                       .add("profileFile", profileFile)
+                       .add("profileFile", currentProfileFile)
                        .build();
     }
 
     @Override
     public void close() {
+        profileFileSupplier.close();
         // The delegate credentials provider may be closeable (eg. if it's an STS credentials provider). In this case, we should
         // clean it up when this credentials provider is closed.
         IoUtils.closeIfCloseable(credentialsProvider, null);
@@ -150,6 +159,17 @@ public Builder toBuilder() {
         return new BuilderImpl(this);
     }
 
+    private AwsCredentialsProvider createCredentialsProvider(ProfileFile profileFile, String profileName) {
+        // Load the profile and credentials provider
+        return profileFile.profile(profileName)
+                          .flatMap(p -> new ProfileCredentialsUtils(profileFile, p, profileFile::profile).credentialsProvider())
+                          .orElseThrow(() -> {
+                              String errorMessage = String.format("Profile file contained no credentials for " +
+                                                                  "profile '%s': %s", profileName, profileFile);
+                              return SdkClientException.builder().message(errorMessage).build();
+                          });
+    }
+
     /**
      * A builder for creating a custom {@link ProfileCredentialsProvider}.
      */
@@ -158,6 +178,7 @@ public interface Builder extends CopyableBuilder<Builder, ProfileCredentialsProv
         /**
          * Define the profile file that should be used by this credentials provider. By default, the
          * {@link ProfileFile#defaultProfileFile()} is used.
+         * @see #profileFile(ProfileFileSupplier) 
          */
         Builder profileFile(ProfileFile profileFile);
 
@@ -167,6 +188,14 @@ public interface Builder extends CopyableBuilder<Builder, ProfileCredentialsProv
          */
         Builder profileFile(Consumer<ProfileFile.Builder> profileFile);
 
+        /**
+         * Define the mechanism for loading profile files.
+         *
+         * @param profileFileSupplier Supplier interface for generating a ProfileFile instance.
+         * @see #profileFile(ProfileFile) 
+         */
+        Builder profileFile(ProfileFileSupplier profileFileSupplier);
+
         /**
          * Define the name of the profile that should be used by this credentials provider. By default, the value in
          * {@link ProfileFileSystemSetting#AWS_PROFILE} is used.
@@ -176,27 +205,27 @@ public interface Builder extends CopyableBuilder<Builder, ProfileCredentialsProv
         /**
          * Create a {@link ProfileCredentialsProvider} using the configuration applied to this builder.
          */
+        @Override
         ProfileCredentialsProvider build();
     }
 
     static final class BuilderImpl implements Builder {
-        private ProfileFile profileFile;
+        private ProfileFileSupplier profileFileSupplier;
         private String profileName;
         private Supplier<ProfileFile> defaultProfileFileLoader = ProfileFile::defaultProfileFile;
 
         BuilderImpl() {
         }
 
         BuilderImpl(ProfileCredentialsProvider provider) {
-            this.profileFile = provider.profileFile;
             this.profileName = provider.profileName;
             this.defaultProfileFileLoader = provider.defaultProfileFileLoader;
+            this.profileFileSupplier = provider.profileFileSupplier;
         }
 
         @Override
         public Builder profileFile(ProfileFile profileFile) {
-            this.profileFile = profileFile;
-            return this;
+            return profileFile(ProfileFileSupplier.wrapIntoNullableSupplier(profileFile));
         }
 
         public void setProfileFile(ProfileFile profileFile) {
@@ -208,6 +237,16 @@ public Builder profileFile(Consumer<ProfileFile.Builder> profileFile) {
             return profileFile(ProfileFile.builder().applyMutation(profileFile).build());
         }
 
+        @Override
+        public Builder profileFile(ProfileFileSupplier profileFileSupplier) {
+            this.profileFileSupplier = profileFileSupplier;
+            return this;
+        }
+
+        public void setProfileFile(ProfileFileSupplier supplier) {
+            profileFile(supplier);
+        }
+
         @Override
         public Builder profileName(String profileName) {
             this.profileName = profileName;
@@ -225,13 +264,15 @@ public ProfileCredentialsProvider build() {
 
         /**
          * Override the default configuration file to be used when the customer does not explicitly set
-         * profileName(profileName);
-         * {@link #profileFile(ProfileFile)}. Use of this method is only useful for testing the default behavior.
+         * profileFile(ProfileFile) or profileFileSupplier(supplier);
+         * {@link #profileFile(ProfileFile)}. Use of this method is
+         * only useful for testing the default behavior.
          */
         @SdkTestInternalApi
         Builder defaultProfileFileLoader(Supplier<ProfileFile> defaultProfileFileLoader) {
             this.defaultProfileFileLoader = defaultProfileFileLoader;
             return this;
         }
     }
+
 }