The hadoop-aws module provides support for AWS integration. The generated JAR file, hadoop-aws.jar also declares a transitive dependency on all external artifacts which are needed for this support —enabling downstream applications to easily use this support.
Features
The specifics of using these filesystems are documented below.
Amazon S3 is an example of “an object store”. In order to achieve scalability and especially high availability, S3 has —as many other cloud object stores have done— relaxed some of the constraints which classic “POSIX” filesystems promise.
Specifically
For further discussion on these topics, please consult The Hadoop FileSystem API Definition.
Your AWS credentials not only pay for services, they offer read and write access to the data. Anyone with the credentials can not only read your datasets —they can delete them.
Do not inadvertently share these credentials through means such as 1. Checking in Hadoop configuration files containing the credentials. 1. Logging them to a console, as they invariably end up being seen.
If you do any of these: change your credentials immediately!
<property> <name>fs.s3n.awsAccessKeyId</name> <description>AWS access key ID</description> </property> <property> <name>fs.s3n.awsSecretAccessKey</name> <description>AWS secret key</description> </property>
<property> <name>fs.s3n.block.size</name> <value>67108864</value> <description>Block size to use when reading files using the native S3 filesystem (s3n: URIs).</description> </property> <property> <name>fs.s3n.multipart.uploads.enabled</name> <value>false</value> <description>Setting this property to true enables multiple uploads to native S3 filesystem. When uploading a file, it is split into blocks if the size is larger than fs.s3n.multipart.uploads.block.size. </description> </property> <property> <name>fs.s3n.multipart.uploads.block.size</name> <value>67108864</value> <description>The block size for multipart uploads to native S3 filesystem. Default size is 64MB. </description> </property> <property> <name>fs.s3n.multipart.copy.block.size</name> <value>5368709120</value> <description>The block size for multipart copy in native S3 filesystem. Default size is 5GB. </description> </property> <property> <name>fs.s3n.server-side-encryption-algorithm</name> <value></value> <description>Specify a server-side encryption algorithm for S3. The default is NULL, and the only other currently allowable value is AES256. </description> </property>
<property> <name>fs.s3a.access.key</name> <description>AWS access key ID. Omit for Role-based authentication.</description> </property> <property> <name>fs.s3a.secret.key</name> <description>AWS secret key. Omit for Role-based authentication.</description> </property>
<property>
<name>fs.s3a.connection.maximum</name>
<value>15</value>
<description>Controls the maximum number of simultaneous connections to S3.</description>
</property>
<property>
<name>fs.s3a.connection.ssl.enabled</name>
<value>true</value>
<description>Enables or disables SSL connections to S3.</description>
</property>
<property>
<name>fs.s3a.endpoint</name>
<description>AWS S3 endpoint to connect to. An up-to-date list is
provided in the AWS Documentation: regions and endpoints. Without this
property, the standard region (s3.amazonaws.com) is assumed.
</description>
</property>
<property>
<name>fs.s3a.proxy.host</name>
<description>Hostname of the (optional) proxy server for S3 connections.</description>
</property>
<property>
<name>fs.s3a.proxy.port</name>
<description>Proxy server port. If this property is not set
but fs.s3a.proxy.host is, port 80 or 443 is assumed (consistent with
the value of fs.s3a.connection.ssl.enabled).</description>
</property>
<property>
<name>fs.s3a.proxy.username</name>
<description>Username for authenticating with proxy server.</description>
</property>
<property>
<name>fs.s3a.proxy.password</name>
<description>Password for authenticating with proxy server.</description>
</property>
<property>
<name>fs.s3a.proxy.domain</name>
<description>Domain for authenticating with proxy server.</description>
</property>
<property>
<name>fs.s3a.proxy.workstation</name>
<description>Workstation for authenticating with proxy server.</description>
</property>
<property>
<name>fs.s3a.attempts.maximum</name>
<value>10</value>
<description>How many times we should retry commands on transient errors.</description>
</property>
<property>
<name>fs.s3a.connection.establish.timeout</name>
<value>5000</value>
<description>Socket connection setup timeout in milliseconds.</description>
</property>
<property>
<name>fs.s3a.connection.timeout</name>
<value>50000</value>
<description>Socket connection timeout in milliseconds.</description>
</property>
<property>
<name>fs.s3a.paging.maximum</name>
<value>5000</value>
<description>How many keys to request from S3 when doing
directory listings at a time.</description>
</property>
<property>
<name>fs.s3a.threads.max</name>
<value>256</value>
<description> Maximum number of concurrent active (part)uploads,
which each use a thread from the threadpool.</description>
</property>
<property>
<name>fs.s3a.threads.core</name>
<value>15</value>
<description>Number of core threads in the threadpool.</description>
</property>
<property>
<name>fs.s3a.threads.keepalivetime</name>
<value>60</value>
<description>Number of seconds a thread can be idle before being
terminated.</description>
</property>
<property>
<name>fs.s3a.max.total.tasks</name>
<value>1000</value>
<description>Number of (part)uploads allowed to the queue before
blocking additional uploads.</description>
</property>
<property>
<name>fs.s3a.multipart.size</name>
<value>104857600</value>
<description>How big (in bytes) to split upload or copy operations up into.</description>
</property>
<property>
<name>fs.s3a.multipart.threshold</name>
<value>2147483647</value>
<description>Threshold before uploads or copies use parallel multipart operations.</description>
</property>
<property>
<name>fs.s3a.acl.default</name>
<description>Set a canned ACL for newly created and copied objects. Value may be private,
public-read, public-read-write, authenticated-read, log-delivery-write,
bucket-owner-read, or bucket-owner-full-control.</description>
</property>
<property>
<name>fs.s3a.multipart.purge</name>
<value>false</value>
<description>True if you want to purge existing multipart uploads that may not have been
completed/aborted correctly</description>
</property>
<property>
<name>fs.s3a.multipart.purge.age</name>
<value>86400</value>
<description>Minimum age in seconds of multipart uploads to purge</description>
</property>
<property>
<name>fs.s3a.buffer.dir</name>
<value>${hadoop.tmp.dir}/s3a</value>
<description>Comma separated list of directories that will be used to buffer file
uploads to. No effect if fs.s3a.fast.upload is true.</description>
</property>
<property>
<name>fs.s3a.impl</name>
<value>org.apache.hadoop.fs.s3a.S3AFileSystem</value>
<description>The implementation class of the S3A Filesystem</description>
</property>
Warning: NEW in hadoop 2.7. UNSTABLE, EXPERIMENTAL: use at own risk
<property> <name>fs.s3a.fast.upload</name> <value>false</value> <description>Upload directly from memory instead of buffering to disk first. Memory usage and parallelism can be controlled as up to fs.s3a.multipart.size memory is consumed for each (part)upload actively uploading (fs.s3a.threads.max) or queueing (fs.s3a.max.total.tasks)</description> </property> <property> <name>fs.s3a.fast.buffer.size</name> <value>1048576</value> <description>Size (in bytes) of initial memory buffer allocated for an upload. No effect if fs.s3a.fast.upload is false.</description> </property>
Writes are buffered in memory instead of to a file on local disk. This removes the throughput bottleneck of the local disk write and read cycle before starting the actual upload. Furthermore, it allows handling files that are larger than the remaining local disk space.
However, non-trivial memory tuning is needed for optimal results and careless settings could cause memory overflow. Up to fs.s3a.threads.max parallel (part)uploads are active. Furthermore, up to fs.s3a.max.total.tasks additional part(uploads) can be waiting (and thus memory buffers are created). The memory buffer is uploaded as a single upload if it is not larger than fs.s3a.multipart.threshold. Else, a multi-part upload is initiatated and parts of size fs.s3a.multipart.size are used to protect against overflowing the available memory. These settings should be tuned to the envisioned workflow (some large files, many small ones, …) and the physical limitations of the machine and cluster (memory, network bandwidth).
Due to eventual consistency, tests may fail without reason. Transient failures, which no longer occur upon rerunning the test, should thus be ignored.
To test the S3* filesystem clients, you need to provide two files which pass in authentication details to the test runner
These are both Hadoop XML configuration files, which must be placed into hadoop-tools/hadoop-aws/src/test/resources.
The presence of this file triggers the testing of the S3 classes.
Without this file, none of the tests in this module will be executed
The XML file must contain all the ID/key information needed to connect each of the filesystem clients to the object stores, and a URL for each filesystem for its testing.
The contents of each bucket will be destroyed during the test process: do not use the bucket for any purpose other than testing. Furthermore, for s3a, all in-progress multi-part uploads to the bucket will be aborted at the start of a test (by forcing fs.s3a.multipart.purge=true) to clean up the temporary state of previously failed tests.
Example:
<configuration>
<property>
<name>test.fs.s3n.name</name>
<value>s3n://test-aws-s3n/</value>
</property>
<property>
<name>test.fs.s3a.name</name>
<value>s3a://test-aws-s3a/</value>
</property>
<property>
<name>test.fs.s3.name</name>
<value>s3://test-aws-s3/</value>
</property>
<property>
<name>fs.s3.awsAccessKeyId</name>
<value>DONOTPCOMMITTHISKEYTOSCM</value>
</property>
<property>
<name>fs.s3.awsSecretAccessKey</name>
<value>DONOTEVERSHARETHISSECRETKEY!</value>
</property>
<property>
<name>fs.s3n.awsAccessKeyId</name>
<value>DONOTPCOMMITTHISKEYTOSCM</value>
</property>
<property>
<name>fs.s3n.awsSecretAccessKey</name>
<value>DONOTEVERSHARETHISSECRETKEY!</value>
</property>
<property>
<name>fs.s3a.access.key</name>
<description>AWS access key ID. Omit for Role-based authentication.</description>
<value>DONOTCOMMITTHISKEYTOSCM</value>
</property>
<property>
<name>fs.s3a.secret.key</name>
<description>AWS secret key. Omit for Role-based authentication.</description>
<value>DONOTEVERSHARETHISSECRETKEY!</value>
</property>
</configuration>
The file hadoop-tools/hadoop-aws/src/test/resources/contract-test-options.xml must be created and configured for the test filesystems.
If a specific file fs.contract.test.fs.* test path is not defined for any of the filesystems, those tests will be skipped.
The standard S3 authentication details must also be provided. This can be through copy-and-paste of the auth-keys.xml credentials, or it can be through direct XInclude inclusion.
In the file src/test/resources/contract-test-options.xml, the filesystem name must be defined in the property fs.contract.test.fs.s3n. The standard configuration options to define the S3N authentication details must also be provided.
Example:
<property>
<name>fs.contract.test.fs.s3n</name>
<value>s3n://test-aws-s3n/</value>
</property>
In the file src/test/resources/contract-test-options.xml, the filesystem name must be defined in the property fs.contract.test.fs.s3a. The standard configuration options to define the S3N authentication details must also be provided.
Example:
<property> <name>fs.contract.test.fs.s3a</name> <value>s3a://test-aws-s3a/</value> </property>
<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>
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<configuration>
<include xmlns="http://www.w3.org/2001/XInclude"
href="auth-keys.xml"/>
<property>
<name>fs.contract.test.fs.s3</name>
<value>s3://test-aws-s3/</value>
</property>
<property>
<name>fs.contract.test.fs.s3a</name>
<value>s3a://test-aws-s3a/</value>
</property>
<property>
<name>fs.contract.test.fs.s3n</name>
<value>s3n://test-aws-s3n/</value>
</property>
</configuration>
This example pulls in the auth-keys.xml file for the credentials. This provides one single place to keep the keys up to date —and means that the file contract-test-options.xml does not contain any secret credentials itself.