Roles · Backend Developer (Rust) · Principal

What a Principal } should know

44 core skills, 66 in total. Expectations per skill, and what changes at the next level.

This page lists what a Principal } is expected to know and do, skill by skill. Core skills are the ones a manager and peers assess in a review cycle; the rest count only in self-assessment. Main areas: Programming Fundamentals, Backend Development, Database Management.

44core skills
22additional skills
13skill areas
100%at Advanced or Expert
Assess myself as Principal Full role matrix

Core skills for a Principal

Grouped by area. The label on the right is the expected depth: Awareness, Working, Advanced or Expert.

Programming Fundamentals · 11

Defines algorithmic strategy for the entire Rust platform, implementing custom allocators and SIMD optimizations for critical paths. Develops internal libraries with O(1) allocation guarantees using arena allocators and zero-copy approaches through Cow and Bytes.

Defines asynchronous architecture for the entire platform: choosing between Tokio and async-std, executor pool strategies for CPU-bound and IO-bound tasks. Develops futures abstractions with custom combinators, implements backpressure protocols and cancellation guarantees through CancellationToken at organizational level.

Shapes Rust code quality culture in the organization: custom clippy lints through dylint, mandatory cargo-vet for supply chain security, documentation standards through rustdoc. Defines unsafe code review policies, MSRV strategy and dependency audit processes through cargo-crev.

Creates platform-wide data architecture, designing custom concurrent structures with unsafe blocks and formal correctness proofs. Defines standards for using Pin, PhantomData and interior mutability patterns (Cell, RefCell, RwLock) at organizational level.

Defines architectural patterns for the organizational Rust service ecosystem: tower middleware stacks, typed configurations through serde, plugin systems through dynamic dispatch. Develops proc macros for code generation of repetitive patterns.

Defines organizational generics strategy: higher-kinded type emulations, const generics for compile-time computations, specialization through marker traits. Develops proc macros for automating derive implementations and creates internal DSLs through Rust's type system.

Develops architectural memory management principles for the organization: custom allocators through GlobalAlloc trait, zero-copy deserialization through rkyv/zerocopy, fragmentation prevention strategies. Establishes unsafe usage policies for raw pointers with mandatory verification through Miri and cargo-careful.

Defines platform-wide memory management strategy: global allocator selection (jemalloc, mimalloc), arena allocators for hot paths, memory-mapped I/O through memmap2. Implements continuous profiling in production through pprof-rs and automated alerts on RSS/heap growth.

Develops platform-wide concurrency strategy: lock-free algorithms through atomics, actor models through Actix, shared-nothing architectures. Defines standards for using unsafe for FFI and low-level synchronization primitives with formal verification through Miri.

Shapes architectural philosophy for domain modeling in Rust, combining algebraic data types, typestate patterns and sealed traits. Defines when to use trait objects (dyn Trait), generics (impl Trait) and enum dispatch for optimal balance of performance and flexibility.

Shapes type safety strategy for the entire codebase: session types for protocols, refinement types through const generics, branded types for preventing ID mixing. Defines 'making invalid states unrepresentable' standards and develops type-level state machines for critical business logic.

Backend Development · 4

Apache Kafka Expert

Defines event-driven architecture strategy in Rust: choosing between rdkafka and kafka-rust, designing event sourcing with CQRS patterns. Develops organizational standards for schema evolution, partition strategies and consumer lag monitoring through Prometheus metrics from Rust services.

Defines platform-wide Rust caching strategy: CDN integrations, distributed cache coherence protocols, predictive caching based on ML models. Establishes architectural principles for cache budgeting, consistency guarantees and automated capacity planning for cache layers.

Redis Expert

Defines Redis strategy for organizational Rust ecosystem: choosing between redis-rs and fred, multi-tier caching architecture with in-process (moka) and distributed layers. Establishes memory budgeting standards, eviction policies and monitoring through redis-exporter with Grafana integration.

Defines Rust Web Frameworks strategy at company level. Evaluates new technologies and approaches. Shapes enterprise standards and reference architectures.

Database Management · 5

Defines organizational data modeling strategy: DDD approaches with aggregate roots as Rust structs, CQRS with projection tables, multi-model storage. Establishes data governance standards, event schema registry and master data management architecture.

Shapes organizational database indexing policy: automated auditing through Rust tools, ML-driven index recommendations, strategies for sharded databases. Defines index bloat monitoring standards, reindex procedures and capacity planning for index storage.

Defines organizational database schema management policy: naming standards, mandatory review process for migrations, automated rollback strategies. Shapes multi-tenant migration architecture, schema-per-service isolation and disaster recovery procedures for migration failures.

PostgreSQL Expert

Defines PostgreSQL strategy for Rust ecosystem: ORM standards (SeaORM vs Diesel vs SQLx), read-replica and partitioning architecture. Establishes connection management policies, prepared statement caching and monitoring through pg_stat_statements with Prometheus integration.

Defines organizational SQL optimization standards: automated pg_stat_statements monitoring through Rust agents, continuous query profiling in production. Shapes query routing architecture between primary and read replicas considering service consistency requirements.

API & Integration · 4

Shapes organizational API documentation strategy: developer experience portal with automated aggregation from all Rust services, SDK generation for clients. Defines API governance processes, mandatory specification review and documentation quality metrics.

Shapes organizational API lifecycle management policy: sunset/deprecation strategies, automated client migration, multi-version support matrix. Defines API gateway architecture for version routing and decision-making processes for breaking changes.

Shapes organizational gRPC strategy: service mesh integration (Linkerd) with Rust services, backward compatibility protocols, multi-language code generation. Defines gRPC gateway architecture for REST clients and performance tuning standards (HTTP/2 settings, message size limits).

Shapes organizational API strategy on Rust: design standards with API-first approach, code generation from OpenAPI specifications, API gateway patterns. Defines versioning, deprecation policies and automated contract testing between Rust microservices.

Cloud & Infrastructure · 3

AWS Expert

Shapes organizational cloud strategy for Rust workloads: multi-region resilience, disaster recovery with RPO/RTO guarantees, compliance frameworks (SOC2, HIPAA). Defines landing zone architecture, account vending machine and platform-as-a-service abstractions for teams.

Docker Expert

Shapes organizational container strategy for Rust: base image standards, supply chain security through cosign/in-toto, automated CVE patching. Defines container registry architecture, image promotion pipelines and retention policies for production images.

Shapes organizational Kubernetes strategy: multi-cluster architecture, federation, cross-region disaster recovery. Defines platform engineering approach with internal developer platform, service mesh standards, network policies and compliance automation for Rust workloads.

DevOps & CI/CD · 1

Shapes organizational DevOps strategy for Rust: platform engineering with golden paths, release trains, feature flags through LaunchDarkly. Defines deployment pipeline architecture with progressive delivery, chaos engineering integration and automated rollback based on SLO metrics.

Testing & QA · 3

Shapes organizational integration testing strategy: continuous testing in production through synthetic monitoring, canary deployments with automated rollback. Defines test environment architecture, test data management standards and SLA for test execution time.

Shapes organizational formal verification and property testing strategy: combining proptest, cargo-fuzz and Kani (bounded model checking) for critical components. Defines continuous fuzzing processes through OSS-Fuzz, correctness proof standards and coverage metrics.

Unit Testing Expert

Shapes organizational testing strategy for Rust: test pyramid with emphasis on compile-time guarantees, mutation testing through cargo-mutants, benchmark regression through criterion. Defines test quality metrics, test review processes and unsafe code testing standards.

Security · 3

Shapes organizational identity strategy: zero-trust architecture with mTLS and JWT, federated identity management, passwordless authentication. Defines token governance standards, regulatory compliance (GDPR, SOX) and centralized audit logging architecture.

Shapes organizational security strategy for Rust: memory safety advantages at architectural level, supply chain security (cargo-vet, crev), compliance frameworks. Defines security incident response processes, bug bounty programs and unsafe code audit standards.

Shapes secure development culture on Rust in the organization: security champions program, mandatory training on unsafe code and cryptography. Defines secure SDLC processes, threat modeling standards for new services and zero-trust architecture between Rust microservices.

AI-Assisted Development · 1

Shapes AI strategy for Rust development in the organization: AI tool ROI evaluation, integration with internal code generation pipelines. Defines architecture for custom AI models trained on internal Rust codebase and intellectual property policies for AI-generated code.

Architecture & System Design · 1

Shapes organizational technology strategy and architectural vision: domain-driven design at organizational level, evolutionary architecture principles. Defines platform architecture considering Rust specifics (zero-cost abstractions, memory safety), scaling standards and resilience.

Observability & Monitoring · 3

OpenTelemetry Expert

Shapes organizational observability strategy based on OpenTelemetry: vendor-agnostic architecture, eBPF instrumentation for zero-code observability. Defines telemetry data governance standards, cost management through intelligent sampling and observability platform architecture.

Shapes organizational metrics strategy: Prometheus architecture for multi-cluster monitoring, Thanos/Cortex for long-term storage. Defines SLO framework based on Rust metrics, automated capacity planning and metric storage cost optimization.

Shapes organizational observability strategy through logging: unified collection and analysis platform, ML-driven anomaly detection on logs. Defines log pipeline architecture (Vector/Fluentd), PII compliance standards in logs and cost optimization for log storage.

Version Control & Collaboration · 2

Code Review Expert

Shapes code review culture in the organization: standards for cross-team Rust code review, architectural review for significant changes. Defines processes for unsafe code audit committee, dependency approval workflow and knowledge sharing through exemplary review comments.

Git Advanced Expert

Shapes organizational source code management strategy: monorepo vs polyrepo for Rust ecosystem, inner source practices. Defines code ownership architecture, contribution guidelines standards and cross-team collaboration processes for shared Rust libraries.

Performance Engineering · 3

CPU Profiling Expert

Shapes performance engineering culture in the organization: production profiling through eBPF, automated performance regression detection. Defines performance observability architecture, hardware-aware optimization standards (SIMD, cache-oblivious algorithms) and performance review processes.

Shapes organizational latency minimization strategy: kernel bypass through DPDK/io_uring, hardware-software co-design for ultra-low-latency. Defines real-time system architecture on Rust (no_std for critical paths), tail latency management standards and capacity planning.

Shapes organizational throughput scaling strategy: data-intensive system architecture on Rust, LMAX Disruptor patterns. Defines capacity management standards, automated auto-scaling and architecture for processing millions of RPS through sharding and partitioning.

Additional skills

Not assessed by the team, but part of the self-assessment and the development plan.

ChatGPT / ClaudeClean ArchitectureConnection PoolingCQRSDatabase ShardingDocumentation as CodeE2E TestingELK StackEvent-Driven ArchitectureGraphQL DesigngRPC & Protocol BuffersMemory ProfilingMessage Broker PatternsPerformance BudgetsPrompt Engineering for CodePython Web FrameworksRate Limiting & ThrottlingSecrets ManagementSLI / SLO / SLATDD & BDDTerraformWebSocket API Design
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} in the open competency matrix: 66 skills across 5 levels. The matrix is free for individuals and stays free.