Project: Flink (App Definition and Development / Streaming & Messaging)
File: s3.md

title: Amazon S3 weight: 3 type: docs aliases: /deployment/filesystems/s3.html /ops/filesystems/s3.html <!-- Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. --> (Amazon S3) provides cloud object storage for a variety of use cases. You can use S3 with Flink for reading and writing data as well in conjunction with the . You can use S3 objects like regular files by specifying paths in the following format: ```plain s3://<your-bucket>/<endpoint> ``` The endpoint can either be a single file or a directory, for example: ```java // Read from S3 bucket env.readTextFile("s3://<bucket>/<endpoint>"); // Write to S3 bucket stream.writeAsText("s3://<bucket>/<endpoint>"); // Use S3 as checkpoint storage Configuration config = new Configuration(); config.set(CheckpointingOptions.CHECKPOINT_STORAGE, "filesystem"); config.set(CheckpointingOptions.CHECKPOINTS_DIRECTORY, "s3://<your-bucket>/<endpoint>"); env.configure(config); ``` Note that these examples are not exhaustive and you can use S3 in other places as well, including your or the ; everywhere that Flink expects a FileSystem URI (unless otherwise stated). For most use cases, you may use one of our `flink-s3-fs-hadoop` and `flink-s3-fs-presto` S3 filesystem plugins which are self-contained and easy to set up. For some cases, however, e.g., for using S3 as YARN's resource storage dir, it may be necessary to set up a specific Hadoop S3 filesystem implementation. {{< hint info >}} You don't have to configure this manually if you are running . {{< /hint >}} Flink provides two file systems to talk to Amazon S3, `flink-s3-fs-presto` and `flink-s3-fs-hadoop`. Both implementations are self-contained with no dependency footprint, so there is no need to add Hadoop to the classpath to use them. `flink-s3-fs-presto`, registered under the scheme s3:// and s3p://, is based on code from the . You can configure it using , by adding the configurations to your . The Presto S3 implementation is the recommended file system for checkpointing to S3. `flink-s3-fs-hadoop`, registered under s3:// and s3a://, based on code from the . The file system can be by adding the configurations to your . For example, Hadoop has a `fs.s3a.connection.maximum` configuration key. If you want to change it, you need to put `s3.connection.maximum: xyz` to the . Flink will internally translate this back to `fs.s3a.connection.maximum`. There is no need to pass configuration parameters using Hadoop's XML configuration files. It is the only S3 file system with support for the . Both `flink-s3-fs-hadoop` and `flink-s3-fs-presto` register default FileSystem wrappers for URIs with the s3:// scheme, `flink-s3-fs-hadoop` also registers for s3a:// and `flink-s3-fs-presto` also registers for s3p://, so you can use this to use both at the same

For example, the job uses the which only supports Hadoop, but uses Presto for checkpointing. In this case, you should explicitly use s3a:// as a scheme for the sink (Hadoop) and s3p:// for checkpointing (Presto). To use `flink-s3-fs-hadoop` or `flink-s3-fs-presto`, copy the respective JAR file from the `opt` directory to the `plugins` directory of your Flink distribution before starting Flink, e.g. ```bash mkdir ./plugins/s3-fs-presto cp ./opt/flink-s3-fs-presto-{{< version >}}.jar ./plugins/s3-fs-presto/ ``` After setting up the S3 FileSystem wrapper, you need to make sure that Flink is allowed to access your S3 buckets. The recommended way of setting up credentials on AWS is via . You can use IAM features to securely give Flink instances the credentials that they need to access S3 buckets. Details about how to do this are beyond the scope of this documentation. Please refer to the AWS user guide. What you are looking for are . If you set this up correctly, you can manage access to S3 within AWS and don't need to distribute any access keys to Flink. Access to S3 can be granted via your access and secret key pair. Please note that this is discouraged since the . You need to configure both `s3.access-key` and `s3.secret-key` in Flink's : ```yaml s3.access-key: your-access-key s3.secret-key: your-secret-key ``` You can limit this configuration to JobManagers by using . ```yaml fs.s3a.aws.credentials.provider: org.apache.flink.fs.s3.common.token.DynamicTemporaryAWSCredentialsProvider presto.s3.credential-provider: org.apache.flink.fs.s3.common.token.DynamicTemporaryAWSCredentialsProvider ``` The S3 Filesystems also support using S3 compliant object stores such as and . To do so, configure your endpoint in . ```yaml s3.endpoint: your-endpoint-hostname ``` Some S3 compliant object stores might not have virtual host style addressing enabled by default, for example when using Standalone MinIO for testing purpose. In such cases, you will have to provide the property to enable path style access in . ```yaml s3.path.style.access: true ``` The bundled S3 file systems (`flink-s3-fs-presto` and `flink-s3-fs-hadoop`) support entropy injection. Entropy injection is a technique to improve the scalability of AWS S3 buckets through adding some random characters near the beginning of the key. If entropy injection is activated, a configured substring in the path is replaced with random characters. For example, path `s3://my-bucket/entropy/checkpoints/dashboard-job/` would be replaced by something like `s3://my-bucket/gf36ikvg/checkpoints/dashboard-job/`. This only happens when the file creation passes the option to inject entropy! Otherwise, the file path removes the entropy key substring entirely. See for details. {{< hint info >}} The Flink runtime currently passes the option to inject entropy only to checkpoint data files. All other files, including checkpoint metadata and external URI, do not inject entropy to keep checkpoint URIs predictable. {{< /hint >}} To enable entropy injection, configure the entropy key and the entropy length parameters. ``` s3.entropy.key: entropy s3.entropy.length: 4 (default) ``` The `s3.entropy.key` defines the string in paths that is replaced by the random characters. Paths that do not contain the entropy key are left unchanged. If a file system operation does not pass the "inject entropy" write option, the entropy key substring is simply removed. The `s3.entropy.length` defines the number of random alphanumeric characters used for entropy. {{< top >}}