S3: add support for STS session tokens (AWS STS service)

If the user has set a session token (for AWS Security Token Service)
then use it:
    - https://docs.aws.amazon.com/STS/latest/APIReference/Welcome.html

For testing run: `aws sts get-session-token --duration-seconds 900`. See:
    - https://docs.aws.amazon.com/cli/latest/reference/sts/get-session-token.html

tiledb/sm/c_api/tiledb.h

@@ -1000,6 +1000,9 @@ TILEDB_EXPORT void tiledb_config_free(tiledb_config_t** config);
  * - `vfs.s3.aws_secret_access_key` <br>
  *    Set the AWS_SECRET_ACCESS_KEY <br>
  *    **Default**: ""
+ * - `vfs.s3.aws_access_key_id` <br>
+ *    Set the AWS_SESSION_TOKEN <br>
+ *    **Default**: ""
  * - `vfs.s3.scheme` <br>
  *    The S3 scheme (`http` or `https`), if S3 is enabled. <br>
  *    **Default**: https

tiledb/sm/config/config.cc

@@ -83,6 +83,7 @@ const std::string Config::VFS_FILE_ENABLE_FILELOCKS = "true";
 const std::string Config::VFS_S3_REGION = "us-east-1";
 const std::string Config::VFS_S3_AWS_ACCESS_KEY_ID = "";
 const std::string Config::VFS_S3_AWS_SECRET_ACCESS_KEY = "";
+const std::string Config::VFS_S3_AWS_SESSION_TOKEN = "";
 const std::string Config::VFS_S3_SCHEME = "https";
 const std::string Config::VFS_S3_ENDPOINT_OVERRIDE = "";
 const std::string Config::VFS_S3_USE_VIRTUAL_ADDRESSING = "true";
@@ -117,6 +118,7 @@ const std::set<std::string> Config::unserialized_params_ = {
     "vfs.s3.proxy_password",
     "vfs.s3.aws_access_key_id",
     "vfs.s3.aws_secret_access_key",
+    "vfs.s3.aws_session_token",
     "rest.username",
     "rest.password",
     "rest.token",
@@ -162,6 +164,7 @@ Config::Config() {
   param_values_["vfs.s3.region"] = VFS_S3_REGION;
   param_values_["vfs.s3.aws_access_key_id"] = VFS_S3_AWS_ACCESS_KEY_ID;
   param_values_["vfs.s3.aws_secret_access_key"] = VFS_S3_AWS_SECRET_ACCESS_KEY;
+  param_values_["vfs.s3.aws_session_token"] = VFS_S3_AWS_SESSION_TOKEN;
   param_values_["vfs.s3.scheme"] = VFS_S3_SCHEME;
   param_values_["vfs.s3.endpoint_override"] = VFS_S3_ENDPOINT_OVERRIDE;
   param_values_["vfs.s3.use_virtual_addressing"] =
@@ -373,6 +376,8 @@ Status Config::unset(const std::string& param) {
   } else if (param == "vfs.s3.aws_secret_access_key") {
     param_values_["vfs.s3.aws_secret_access_key"] =
         VFS_S3_AWS_SECRET_ACCESS_KEY;
+  } else if (param == "vfs.s3.aws_session_token") {
+    param_values_["vfs.s3.aws_session_token"] = VFS_S3_AWS_SESSION_TOKEN;
   } else if (param == "vfs.s3.logging_level") {
     param_values_["vfs.s3.logging_level"] = VFS_S3_LOGGING_LEVEL;
   } else if (param == "vfs.s3.scheme") {

tiledb/sm/config/config.h

@@ -173,6 +173,9 @@ class Config {
   /** S3 aws secret access key. */
   static const std::string VFS_S3_AWS_SECRET_ACCESS_KEY;
 
+  /** S3 aws session token. */
+  static const std::string VFS_S3_AWS_SESSION_TOKEN;
+
   /** S3 scheme (http for local minio, https for AWS S3). */
   static const std::string VFS_S3_SCHEME;
 

tiledb/sm/cpp_api/config.h

@@ -335,6 +335,9 @@ class Config {
    * - `vfs.s3.aws_secret_access_key` <br>
    *    Set the AWS_SECRET_ACCESS_KEY <br>
    *    **Default**: ""
+   * - `vfs.s3.aws_session_token` <br>
+   *    Set the AWS_SESSION_TOKEN <br>
+   *    **Default**: ""
    * - `vfs.s3.scheme` <br>
    *    The S3 scheme (`http` or `https`), if S3 is enabled. <br>
    *    **Default**: https

tiledb/sm/filesystem/s3.cc

@@ -224,6 +224,8 @@ Status S3::init(const Config& config, ThreadPool* const thread_pool) {
   auto aws_secret_access_key =
       config.get("vfs.s3.aws_secret_access_key", &found);
   assert(found);
+  auto aws_session_token = config.get("vfs.s3.aws_session_token", &found);
+  assert(found);
   int64_t connect_max_tries = 0;
   RETURN_NOT_OK(config.get<int64_t>(
       "vfs.s3.connect_max_tries", &connect_max_tries, &found));
@@ -265,6 +267,17 @@ Status S3::init(const Config& config, ThreadPool* const thread_pool) {
     Aws::String secret_access_key(aws_secret_access_key.c_str());
     client_creds_ = std::unique_ptr<Aws::Auth::AWSCredentials>(
         new Aws::Auth::AWSCredentials(access_key_id, secret_access_key));
+
+    // If the user has set a session token (for AWS Security Token Service)
+    // then use it:
+    //     - https://docs.aws.amazon.com/STS/latest/APIReference/Welcome.html
+    // For testing run: `aws sts get-session-token --duration-seconds 900`. See:
+    //     -
+    //     https://docs.aws.amazon.com/cli/latest/reference/sts/get-session-token.html
+    if (!aws_session_token.empty()) {
+      Aws::String session_token(aws_session_token.c_str());
+      client_creds_->SetSessionToken(session_token);
+    }
   }
 
   state_ = State::INITIALIZED;