The Runtime Theory
medium · 5h · 18 steps

Build and Operate Reliable Systems

Connect architecture choices to deployment control loops, security boundaries, performance evidence, and safe software delivery.

Curriculum (18 steps)

1

Use cohesion, coupling, and dependency direction to choose software boundaries that make likely changes easier to contain.

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2

Follow a request from a stable caller through an injected policy interface to one selected implementation.

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3

Refactor a checkout calculation so rate rules can vary without spreading carrier-specific branches through the order workflow.

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4

Turn user requirements into a data flow, capacity model, and failure-aware architecture before drawing infrastructure boxes.

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5

Visualize a client request, routing, cache hit or miss, database access, and the chosen freshness policy.

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6

Follow the cloud control plane that compares declared configuration with live resources and works toward the requested state.

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7

Follow a desired replica count through the API server, controllers, scheduler, node agent, runtime, and readiness checks.

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8

Deploy a small stateless workload, scale it, change its image, and inspect how desired and ready state differ over time.

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9

Threat-model a request by tracing sensitive data, user authority, trust boundaries, and the controls that limit abuse.

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10

Follow a login attempt through rate limits, password-hash verification, authorization context, and a protected session cookie.

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11

Trace untrusted input into a web page, identify the output context, and choose encoding or sanitization at the correct boundary.

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12

Use workload shape, latency distributions, profiling, and controlled experiments to find the cause of slow software.

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13

Follow a request through a saturated connection pool and distinguish queue delay from database execution time.

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14

Use a repeatable matrix workload to compare loop order, profile cache behavior, and report what the measurement can support.

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15

Follow a change from Git objects and review through tests, build artifacts, deployment, rollback, and production feedback.

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16

Visualize review, automated checks, immutable artifacts, staged rollout, observability, and rollback decisions.

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17

Follow a reviewed commit through repeatable checks, an immutable artifact, staged deployment, health signals, and promotion.

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18

Use a visual Git sandbox to create branches, merge histories, resolve a conflict, and recover a commit by following references.

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