AWS Lambda standardizes billing for INIT Phase | Amazon Web Services
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Effective August 1, 2025, AWS will standardize billing for the initialization (INIT) phase across all AWS Lambda function configurations. This change specifically affects on-demand invocations of Lambda functions packaged as ZIP files that use managed runtimes, for which the INIT phase duration was previously unbilled. This update standardizes billing of the INIT phase across all runtime types, deployment packages, and invocation modes. In this post, we discuss the Lambda Function Lifecycle and upcoming changes to INIT phase billing. You will learn what happens in the INIT phase and when it occurs, how to monitor your INIT phase duration, and strategies to optimize this phase and minimize costs.

Effective August 1, 2025, AWS will start billing for compute used during INIT phases. No more doing lots of work in your init phase for free

  • deegeese@sopuli.xyz
    81·
    15 hours ago

    Since AWS controls when the function is expired from warm start to cold start, it’s a guarantee they’re going to become extra aggressive about terminating idle functions.

    Why leave customer code loaded for free when you can charge for startup again?

    • chaospatterns@lemmy.worldOPEnglish
      5·
      15 hours ago

      That’s an inherent problem with serverless/functions as a service. There’s no guarantee at all on it staying warm for a given amount of time and any system that depended on it without paying for provisioned concurrency was just depending on hopes and dreams.

  • fubarx@lemmy.world
    91·
    1 day ago

    This just means more people will set up Eventbridge rules to call lambdas regularly and keep them running. You avoid having to pay the time penalty and now, actual financial cost of a cold start.

    • kensand@sopuli.xyz
      5·
      20 hours ago

      Ah yes, keeping your Lambda functions running, rendering the main benefit of them pointless 🙃

      People really should just set up a Fargate task instead…

      • chaospatterns@lemmy.worldOPEnglish
        5·
        15 hours ago

        Yeah I often see devs come up with complex architectures to just work around Lambda’s limitations. Things to keep them warm (but then fail because they don’t account for concurrent requests still hitting cold starts), multiple levels of Lambda functions to work around 15 minute time outs, and more. Just use the right tool for the job and look at Fargate or Batch.