Glossary

Prune

Deleting resources absent from the desired declaration. Understand dependencies, finalizers and data policies before enabling automatic deletion.

Pull request / merge request

PR

Pull Request

A proposal to integrate changes with review and verification results. Describe the problem, changed behaviour, tests and limitations, not merely changed files.

Pure function

Produces the same result for the same arguments without observable side effects. Supplying time, randomness and I/O results as data helps test the rule.

Pydantic AI

A Python AI application/agent framework with typed interfaces. A valid response type does not prove factual accuracy or tool authorization.

Pydantic Settings

A library for reading and validating Python configuration from explicitly selected sources. It is a separate dependency, not automatically added to every FastAPI project.

pytest

A Python test framework with assertions, fixtures and discovery. Fixture scope controls lifetime; shared state can affect ordering.

Python

A dynamically typed language also used for backends. Type hints support tooling but do not replace runtime validation; concurrency depends on the execution model.

Python module name

A variable identifying a module. An ordinary import uses its package name; execution as the entry point normally uses __main__. A guard checking it protects only its block; import still executes other module-level statements.

Python namespace package

A Python package with portions across directories without a regular __init__.py. It is unrelated to a Kubernetes namespace. Learn regular packages and installation in one directory first.

Python None

The sole NoneType instance, often representing no result. It is neither zero nor empty text. The application contract defines its input meaning; test it with is None.

Python package entry point

The file executed by python -m package_name. A package need not have it. It differs from a conventional main() function, which requires a call; running a package does not execute all its files.

Python Protocol

A structural contract for Python typing tools. A class can satisfy it without inheritance; it is not runtime input validation.

Python slots

A mechanism declaring storage for selected instance attributes; dataclass(slots=True) can generate it. It can reduce memory and restrict dynamic attributes, with inheritance-dependent exceptions. It does not validate domain rules or provide deep immutability.

Python virtual environment

A project-specific interpreter and dependencies. Select it in the IDE too; .venv does not isolate network or permissions like a separate host.

Quarkus

A JVM framework emphasizing build-time application preparation. Compare concrete features and execution modes; one measurement does not establish superiority for every project.

Race condition

The outcome depends on the ordering of concurrent operations. Checking availability before a write does not protect against another request; enforce the guarantee at the write boundary.

RAM

RAM

Random Access Memory

Working memory used by processes and the system. Account for buffers, caches, runtime overhead and container limits as well as objects; exhaustion may terminate a process.

RDS

RDS

Relational Database Service

AWS’s managed relational database service. Schema, queries, permissions and recovery procedures remain necessary; managed does not mean maintenance-free.

An application-to-RDS connection separately needs routing, network rules, TLS and database permissions.

Reactive Relational Database Connectivity

R2DBC

Reactive Relational Database Connectivity

An interface for reactive relational database access. Do not assume JDBC-equivalent transaction, driver and diagnostic behavior without checking.

Readiness

A signal indicating whether an instance should receive traffic. It is not a restart instruction. A dependency failure does not necessarily mean restarting the application helps.

Readonly field

A restriction on field assignment. It need not prevent mutation of the referenced object; details depend on the language.

Reconciliation

Check the actual state after an ambiguous outcome, such as querying a payment provider after a timeout. Then decide whether to retry, finish or compensate.

Record data carrier

A Java data carrier with generated construction, access and component equality. Immutable field references do not make contained lists immutable.

Redis

A data-structure store used for caches and queues. Durability and consistency depend on configuration and usage protocol; Redis alone does not provide exactly-once.

Refactoring

Changing internal structure while preserving agreed behaviour. Tests and small diffs help distinguish structural changes from business-rule changes.

Regular expression

A pattern describing allowed characters and their arrangement in text. A substring match does not establish validity of the entire input. Define full-string matching, allowed characters and length limits; a pattern does not replace business rules.

Release Candidate

RC

Release Candidate

A version proposed for stable release after final checks. It may still require changes; RC is not automatically a production release.

Release promotion

Moving an approved artifact to another environment through declaration changes. Reusing a digest limits differences; rebuilding may produce a different artifact.

ReplicaSet

Maintains a desired number of matching Pods. Usually managed by a Deployment; manual child changes may be reverted by its parent controller.

Repository

Exposes domain-object operations while hiding mapping and storage details. It need not wrap every ORM and should not independently commit half a use case.