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IntermediateDistributed Systems

By Mozilla Automation Team engineers · Mozilla Automation Team · Added 2026-10-12

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Learn this article

About 37 min left. Your work is saved as you go.

What you are about to study

Mozilla Automation Team wrote this to explain how they thought about a problem. You should know the basics: caching, queues and replication.

Ideas you will meet

Distributed Systems
Consensus, time, failure and the fundamentals of scale-out.

What we already know about this

Our own lessons on these ideas. Read them here before you start, so it makes sense.

  • Core Concepts: How Things Actually Work · 9 minDevOps in practice, and where to learn moreWhat DevOps really means, the practices behind it, how to measure delivery performance, and a short reading list.Read here

    It is a culture first

    DevOps removes the wall between people who build software and people who run it. The old model threw code "over the wall" to operations, who feared change; developers wanted change. DevOps aligns both on the same goal: deliver value quickly and reliably. Tools help, but the core is shared ownership, automation and fast feedback.

    The pipeline

    Figure SDA-CORE-23-1 · The pipeline · © forcsguy.com

    Core practices

    1. Version control for everything: code, configuration and infrastructure definitions.
    2. Continuous integration (CI): merge small changes frequently; each triggers an automated build and tests.
    3. Continuous delivery and deployment (CD): automated, repeatable release to staging and production, with safe rollout (see the deployment strategies lesson).
    4. Infrastructure as code (IaC): define servers, networks and permissions in code (Terraform, CloudFormation, Pulumi, Ansible). Review, version and recreate environments on demand.
    5. Containers and orchestration: package software consistently (Docker) and run it on a platform such as Kubernetes.
    6. Observability: metrics, logs and traces, with alerts on user-visible symptoms.
    7. Security in the pipeline ("DevSecOps"): dependency scanning, secret detection, image scanning, least privilege.
    8. Blameless learning: postmortems and improvement of the system, not of blame.
    9. GitOps: Git is the source of truth for desired state; automation reconciles the real environment with it.

    Measuring delivery performance: the DORA metrics

    Research by the DevOps Research and Assessment (DORA) team found four measures that predict both delivery and business performance:

    MetricQuestion
    Deployment frequencyHow often do we deploy to production?
    Lead time for changesHow long from commit to running in production?
    Change failure rateWhat share of deployments cause a failure needing remediation?
    Time to restore serviceHow quickly do we recover from a failure?

    The finding that surprised many: high performers are both faster and more stable. Speed and stability reinforce each other when you work in small batches with strong automation.

    Common mistakes

    • Renaming the operations team "DevOps" without changing responsibilities.
    • Buying tools without changing habits.
    • Automating a broken process instead of fixing it.
    • Measuring individuals (lines of code, tickets closed) instead of flow and outcomes.
    • Ignoring security and cost until the end.

    Where to learn more

    These books are widely recommended (buy or borrow them; this course summarises ideas in its own words):

    • Accelerate by Nicole Forsgren, Jez Humble and Gene Kim: the research behind the DORA metrics.
    • The DevOps Handbook by Gene Kim, Jez Humble, Patrick Debois and John Willis: practices and case studies.
    • The Phoenix Project by Gene Kim, Kevin Behr and George Spafford: a novel that explains the ideas through a story.
    • Site Reliability Engineering by Google's SRE team (free online): reliability, monitoring and incidents.
    • Continuous Delivery by Jez Humble and David Farley: pipelines and release engineering.
    • Release It! by Michael Nygard: designing for production failure.
    • Infrastructure as Code by Kief Morris: managing infrastructure with software practices.

    Real-world reading

    Related reading

    Show 6 more

    Open this lesson with its quiz and exercise

Continue to Mozilla Automation Team

Go deeper on this

A path through videos, articles, other case studies and code on the same ideas as Mozilla Automation Team Engineering Blog.

  1. Warm upGet the vocabulary first.

  2. WatchHow others solve the same problem, on video.

    Videos belong to their creators and play from YouTube. More on YouTube (opens in a new tab)

  3. ReadEngineers explain it in their own words.

  4. See it in another companyThe same ideas, a different system.

  5. Read the codeSee how it looks when it is real.

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