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Lead time

As explained in Platform Engineering on Kubernetes

Lead time for change is the elapsed time from producing a software change to making it available to live customers.

Lead time for change measures the elapsed time between producing a software change and making it available to live customers. It is a DORA delivery-velocity metric, alongside deployment frequency, while change failure rate and time to restore service indicate recovery from failure. section 9.1

Calculating it requires joining source-code version-control events with continuous-deployment events. A standardized event model makes those signals available for metric processing across different delivery systems. section 9.2.1 section 9.2.2

A lead-time measurement pipeline typically performs these steps:

  • Collect events from source-control, deployment, and other delivery systems. section 9.2.1 section 9.2.2
  • Wrap non-CloudEvent data with CloudEvents SDKs before it enters the system. section 9.2.2
  • Map incoming CloudEvents to CDEvents, then process the standardized data to calculate metric values. section 9.2.1 section 9.2.2
  • Persist incoming data and calculations, then expose results through a dashboard. section 9.2.2

Event-based calculation

A source-code version event records when a change is produced, while a deployment event records when that change reaches a live environment. Combining the two event streams supplies the timestamps needed to calculate lead time for change. section 9.2.1

Figure 9.3 Lead time for change data sources

Use the data-source diagram to trace which delivery-system events contribute to lead time for change. section 9.1

How Platform Engineering on Kubernetes covers it

How deep it goes
Defines the interval and outlines event collection, transformation, calculation, storage, and presentation without detailing the formula.
Examples
Uses version-control events, deployment events, CDEvents mappings, PostgreSQL storage, and graphical dashboards.
What it assumes
Assumes access to source-control and deployment events, while requiring nonconforming sources to be adapted to CloudEvents.
What you can do after
Build it from CloudEvents and CDEvents by collecting, standardizing, calculating, storing, and displaying delivery data.
How it connects
Connects deployment frequency, DORA metrics, CloudEvents, CDEvents, continuous delivery, and version control.

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This explainer was generated by Manning's knowledge graph from the text of Platform Engineering on Kubernetes. The section links point to the parts of the book it draws on.