Measures are useful for making decisions about infrastructure delivery workflows and practices, as well as about design and team organization. The four key metrics identified by the DORA group are a good base set of measures. The performance of software delivery processes on these metrics, although also affected by other factors, is an indicator of how well environments, platforms, and infrastructure for delivery and production hosting enable delivery effectiveness.
As a refresher, the four key metrics are:
Delivery lead time: The elapsed time it takes to implement, test, and deliver changes to the production system
Deployment frequency: How often changes are deployed to production systems Change fail percentage: What percentage of changes either cause an impaired service or need immediate correction, such as a rollback or emergency fix Mean Time to Restore (MTTR): How long it takes to restore service when there is an unplanned outage or impairment
The four key metrics can also be measured for changes to infrastructure and platform services, giving an idea of the effectiveness of infrastructure delivery systems and processes. Other metrics that may be useful for infrastructure delivery include:
Effort: How much expert time is needed to complete a change? Self-service systems and other automation can reduce this number.
Toil: How much of your infrastructure and platform team members’ time is spent on work that could potentially be removed, typically repetitive, manual, tactical work. See Eliminating Toil](https://sre.google/sre-book/eliminating-toil/) from the book Site Reliability Engineering.
Version Spread: How many different versions of a given software, infrastructure, and systems are currently deployed to systems in the estate. Keeping systems patched and upgraded reduces the time needed to maintain them and avoids the potential number of vulnerabilities.
Utilization: How often environments and other infrastructure is actually in use. Replacing static, long-running environments with dynamically provisioned “Environments as a Service” can reduce waste.
