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Introducing Good Configuration Defaults within the AWS SDK for Java v2

The default configuration within the AWS SDK for Java v2 simply obtained smarter! We’re happy to announce a brand new SDK function —⁠ good configuration defaults within the AWS SDK for Java v2 (model 2.17.102 or later), which vends a set of predefined wise default values tailor-made to frequent utilization patterns. With this new opt-in function, you’ll get an optimized SDK shopper out-of-box with configuration already tuned to stick to AWS SDK finest practices. This function can also be out there within the AWS SDK for .NET, JavaScript v3, Ruby v3, Go v2 , Python and PHP. On this publish, we are going to clarify the function and present you find out how to leverage it within the AWS SDK for Java v2.

What is sensible configuration defaults?

The AWS SDK for Java v2 exposes totally different non-compulsory configuration settings, comparable to retry coverage and join timeout, and it offers default values if they aren’t configured. The good configuration defaults affords enhanced default values for these settings primarily based on the utilization situations. This function will be enabled by way of a setting known as defaults mode, which determines how the default values needs to be resolved.

The SDK helps six defaults modes: legacycommonplace, in-region, cross-region, cell and auto. We’ll clarify every mode intimately in a later part.

To allow good configuration defaults function, you merely want to exchange the default legacy worth with the one that matches your use-case.

How one can configure the defaults mode?

You possibly can configure this function in a number of methods.

Choice 1: Service shopper builder
You possibly can configure the defaults mode on a SDK shopper by way of the service shopper builder instantly. Under is the pattern code to configure auto defaults mode on an S3Client

S3Client s3Client = S3Client.builder()

Choice 2: System property

You possibly can specify defaults mode utilizing the system property aws.defaultsMode. The system property must be set earlier than the SDK shopper initialization to take impact.

System.setProperty("aws.defaultsMode", "auto");

Choice 3: Surroundings variable

You possibly can set the atmosphere variable AWS_DEFAULTS_MODE to the mode you wish to select. Just like the choice above, the atmosphere variable must be set earlier than the SDK shopper initialization to take impact.


Choice 4: AWS config file

Lastly, you’ll be able to add defaults_mode in your AWS config file.

defaults_mode = auto

Which defaults mode to decide on?

Now that we all know find out how to configure the defaults mode, let’s discover out which one to decide on on your software. Listed here are the defaults mode supported within the SDK.

  • commonplace – offers the default values in response to the newest AWS SDK really helpful practices that needs to be protected to run in most situations.
  • in-region – builds on the commonplace mode and additional improves the SDK shopper resilience for in-region API requests. It’s tailor-made for functions that decision AWS companies from throughout the similar AWS area. For instance, in case your software is working in us-east-1 and solely sending requests to an AWS service in us-east-1, then that is the best defaults mode.
  • cross-region – builds on the commonplace mode and additional improves SDK shopper resilience for cross-region API requests. It’s tailor-made for functions which name AWS companies in a special area. For instance, in case your software is working in us-west-2 and making requests to AWS companies in us-east-1, then that is the best defaults mode.
  • cell – builds on the commonplace mode and is additional optimized for cell functions.
  • auto – the SDK first makes an attempt to find the execution atmosphere, e.g. test if the applying is working on cell or if the SDK shopper makes cross-region name, and it then offers default values accordingly. Observe that auto detection is heuristics-based, and thus 100% accuracy isn’t assured.

All of the modes besides auto mode are static defaults modes, which suggests the optimized configuration defaults are decided at compile time. auto mode, alternatively, is dynamic as it can try to examine the execution atmosphere to find out the best static defaults mode to use at runtime. If the runtime atmosphere can’t be decided, the values from commonplace mode will probably be used. The auto detection would possibly question EC2 Occasion metadata and consumer information, which can introduce latency in some situations. In case your software is delicate to startup latency, we suggest selecting one of many static default modes.

To find out which mode to pick out, you need to use the next flowchart as a suggestion.

Smart Configuration Defaults Flowchart

What configuration choices are optimized?

Let’s check out the settings which can be optimized by a given mode. You possibly can try the values for every mode in our AWS SDKs and Instruments Reference Information.

  • retryMode: Specifies how the SDK makes an attempt retries. See RetryMode.
  • s3UsEast1RegionalEndpoints: Specifies how the SDK determines the AWS service endpoint that it makes use of to speak to the Amazon S3 for the us-east-1 area. See AWS_S3_US_EAST_1_REGIONAL_ENDPOINT
  • connectTimeoutInMillis: The period of time after making an preliminary connection try on a socket, the place if the shopper doesn’t obtain a completion of the join handshake, the shopper offers up and fails the operation. See NettyNioAsyncHttpClient.Builder#connectionTimeout 
  • tlsNegotiationTimeoutInMillis: The utmost period of time {that a} TLS handshake is allowed to take from the time the CLIENT HELLO message is distributed to the time the shopper and server have absolutely negotiated ciphers and exchanged keys. See NettyNioAsyncHttpClient.Builder#tlsNegotiationTimeout

Any worth that you just configure explicitly on the SDK shopper will at all times take priority over good configuration default values. For instance, you probably have already set the SDK shopper with join timeout of two seconds , the defaults mode will NOT override it.

Please notice that default values set by this function would possibly change because the SDK finest practices evolve, due to this fact we suggest that you just take a look at your software completely everytime you improve the SDK.


We hope this addition makes configuring the AWS SDK for Java v2 even simpler! You possibly can be taught extra from the AWS SDKs and Instruments Reference Information. We might love your suggestions on this function and in addition to another enhancements you want to see carried out sooner or later. Please tell us by opening a GitHub concern.

Zoe Wang

Zoe Wang

Zoe is a Software program Growth Engineer engaged on the AWS SDK for Java. She is enthusiastic about constructing instruments to enhance the developer expertise. You could find her on GitHub @zoewangg.



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