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Airbnb Shares Architecture Behind Sitar-Agent Dynamic Configuration Sidecar for Kubernetes Services
Airbnb engineers detailed Sitar-agent, a Kubernetes sidecar for dynamic configuration delivery across tens of thousands of pods, processing updates several times per minute. The system was redesigned with Java, Amazon S3 snapshot bootstrapping, and a migration from Sparkey to SQLite to improve reliability, startup performance, and configuration availability at scale. By Leela Kumili
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Terraform LifeCycle Rules
Day 9 of the 30 Days of AWS Terraform series focuses on Terraform Lifecycle Rules — powerful controls that decide how Terraform creates, updates, replaces, and destroys resources. What Terraform LifeCycle meta arguments are Lifecycle meta arguments allow us to control how Terraform behaves when it creates, updates, or destroys resources. They help us: Avoid downtime Protect important resources Handle changes made outside Terraform Validate configurations before and after deployment Enforcing compliance Controlling replacement behavior Lifecycle rules allow us to override default behavior safely. Lifecycle rules are Terraform-native controls applied inside a resource block: lifecycle { ... } Lifecycle Rules Covered 1️⃣ create_before_destroy — Zero Downtime Updates Problem: Terraform destroys the old resource before creating the new one → downtime. Solution: lifecycle { create_before_destroy = true } Behavior: New resource is created first Old resource is destroyed only after Ensures zero downtime 2️⃣ prevent_destroy — Protect Critical Resources This setting prevents Terraform from deleting a resource. Example If Terraform tries to destroy this resource, it will fail with an error. This is useful for: Production databases State storage buckets Important data resources 3️⃣ ignore_changes — Allow External Modifications Problem: Terraform overwrites manual or automated external changes. Solution: lifecycle { ignore_changes = [desired_capacity] } Demo: Auto Scaling Group desired capacity modified manually in AWS Console terraform apply did not revert the change Behavior: Terraform ignores changes for specified attributes. ✅ Use for: Auto Scaling Groups Resources modified by external systems Ops-driven configurations 4️⃣ replace_triggered_by — Replace When Dependency Changes Problem: Changing a dependency doesn’t always recreate dependent resources. Solution: lifecycle { replace_triggered_by = [aws_security_group.main] } Behavior: When security group changes EC2 instance i
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دليل عملي لاختبار التحميل لواجهات API باستخدام أرتيلري
Artillery هي مجموعة أدوات مفتوحة المصدر لاختبار التحميل مبنية على Node.js. تتيح لك توليد حركة مرور عالية التزامن على واجهة برمجة التطبيقات (API) من خلال ملف YAML بسيط: تحدد مراحل التحميل، تصف تدفقات الطلبات، تشغل artillery run script.yml ، ثم تقرأ نسب زمن الاستجابة المئوية، معدلات الطلبات، وعدد الأخطاء. يشرح هذا الدليل طريقة تثبيت Artillery v2، كتابة اختبار عملي، تشغيله، استخراج النتائج بالطريقة الصحيحة في v2، وربطه بمسار CI. جرّب Apidog اليوم ما هو Artillery ومتى تستخدمه؟ ينشئ Artillery مستخدمين افتراضيين (VUs) يرسلون طلبات إلى نقاط النهاية لديك ويقيسون قدرة النظام على تحمل الحمل المستمر. المستخدم الافتراضي هو عميل مُحاكى ينفذ سيناريو خطوة بخطوة، كما يفعل مستخدم أو خدمة حقيقية. استخدم Artillery عندما تريد إجابات عملية على أسئلة الأداء مثل: كيف يتغير زمن الاستجابة p95 عند 50 طلبًا في الثانية؟ عند أي معدل وصول تبدأ الأخطاء بالظهور؟ هل تبقى واجهة API مستقرة لمدة 5 دقائق من الحمل المستمر؟ هل يتدهور الأداء تدريجيًا مع استمرار الضغط؟ الميزة الأساسية في Artillery أن الاختبار تصريحي. بدل كتابة حلقات تزامن يدويًا، تصف شكل الحمل في YAML. وبما أنه يعمل فوق Node.js، يمكنك تشغيل نفس الاختبار محليًا وفي CI. إذا كنت تقارن الأدوات، راجع ملخص أفضل أدوات اختبار التحميل و مقارنة برامج اختبار التحميل لفهم الفروقات بين k6 وJMeter وGatling وغيرها. تثبيت Artillery v2 اسم الحزمة هو artillery ، والإصدار الرئيسي الحالي هو v2. ثبته عالميًا عبر npm: npm install -g artillery@latest artillery version تحتاج إلى إصدار LTS حديث من Node.js. يعمل Artillery على Windows وmacOS وLinux. إذا كنت لا تريد تثبيت الحزمة عالميًا، استخدم npx : npx artillery@latest run script.yml كتابة اختبار Artillery يتكون ملف الاختبار من قسمين أساسيين: config : يحدد الهدف ومراحل الحمل والمتغيرات. scenarios : يحدد ما يفعله كل مستخدم افتراضي. مثال كامل: config : target : " https://api.example.com" phases : - name : " Warm up" duration : 60 arrivalRate : 5 - name : " Ramp to peak" duration : 120 arrivalRate : 5 rampTo : 50 - name : " Sustained load" duration : 300 arrivalRate : 50 maxVusers : 500 variables : productId : - " 100
科技前沿
How to align columnar output in the terminal
In bioinformatics we are handling a lot of tabular data. Be it VCF files, tabular Blast output, or just creating a CSV or TSV samplesheet. Actually, one of my favorite tabular formats is by using SeqKit to convert Fasta or FastQ files to tabular format, as this allows to do various filtering operations by row , using standard unix tools if so wished. Scrolling through this type of data in the terminal can be messy to say the least though. Although CSVs can of course be imported into a spreadsheet software for viewing, it would be very powerful to be able to view them comfortably right from the terminal, isn't it? To take one example that fits within the code window of a blog post, let's take a selected set of columns from the CSV output from the Mykrobe tool. And to make it emulate another common problem with many csv formats, let's also use tr to convert the _ :s in the headers into real spaces (Mykrobe does not do this, but many other tools do): $ cat SOME_SAMPLE.csv | cut -d , -f 2,3,10,14,15,17,18 | tr '_' ' ' > selection.csv $ cat selection.csv "drug" , "susceptibility" , "kmer size" , "phylo group per covg" , "species per covg" , "phylo group depth" , "species depth" "Amikacin" , "S" , "21" , "99.672" , "98.428" , "372" , "347" "Capreomycin" , "S" , "21" , "99.672" , "98.428" , "372" , "347" "Ciprofloxacin" , "S" , "21" , "99.672" , "98.428" , "372" , "347" "Delamanid" , "S" , "21" , "99.672" , "98.428" , "372" , "347" "Ethambutol" , "S" , "21" , "99.672" , "98.428" , "372" , "347" "Ethionamide" , "S" , "21" , "99.672" , "98.428" , "372" , "347" "Isoniazid" , "R" , "21" , "99.672" , "98.428" , "372" , "347" "Kanamycin" , "S" , "21" , "99.672" , "98.428" , "372" , "347" "Levofloxacin" , "S" , "21" , "99.672" , "98.428" , "372" , "347" "Linezolid" , "S" , "21" , "99.672" , "98.428" , "372" , "347" "Moxifloxacin" , "S" , "21" , "99.672" , "98.428" , "372" , "347" "Ofloxacin" , "S" , "21" , "99.672" , "98.428" , "372" , "347" "Pyrazinamide" , "S" , "21" , "99.672"
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AWS Is Not Simpler. Agents Just Got Better at Reading It.
I optimized my architecture for the wrong model. I used to think black-box infrastructure was the right abstraction for AI-driven development. Vercel, Supabase, Cloudflare Workers — a sharp contract in front, a managed backend behind — felt like the obvious fit. The less an agent had to reason about, the fewer places it could get lost. Give it a clean interface, hide the messy backend, move fast. I still think that was right for the agents we had last year. I don't think it's right for the agents we're starting to use now. The shift is not that AWS got simpler. It didn't. Setup still takes longer, CI/CD takes more work to wire, and cost control has real limits. The shift is that agents got better at reading complexity — and once an agent can actually use a large structured context, the things I treated as overhead (resources, provider schemas, IAM policies, explicit queues, explicit alarms, explicit networks) become the highest-signal context I can hand it. To keep this concrete, I'm holding the tool constant. This is HCL/Terraform on AWS vs HCL/Terraform on Cloudflare — same language, same workflow, two providers. The inversion Agents are… Best served by… Context-poor (last year's loops) Black boxes — shrink the surface, hide the backend Context-rich (now) Inspectable systems — describe everything as code The one-line version: The better agents get at reading, the more valuable explicit infrastructure becomes. I didn't become more pro-AWS because AWS got easier. I became more pro-AWS because agents got better at reading it. Same Terraform, two providers The interesting comparison isn't AWS-elegance vs Cloudflare-elegance. It's how much of the infrastructure topology and operational contract an agent can reconstruct from the HCL plus the provider schema alone. Terraform × AWS Terraform × Cloudflare Provider maturity AWS provider is about as battle-tested as IaC gets; enormous public corpus of modules/examples v5 is a ground-up, OpenAPI-generated rewrite — improving
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Chrome for Developers a Berlino: cosa aspettarsi dall’ecosistema web nel 2026
Tra performance, piattaforma e toolchain: i temi che contano davvero per chi costruisce frontend oggi. Il frontend nel 2026 è diventato una disciplina sempre più “di prodotto”: non basta far funzionare l’interfaccia, serve che sia veloce, stabile, accessibile e misurabile in produzione. E quando l’ecosistema Chrome parla di “connessione” tra developer e piattaforma, il messaggio utile per chi lavora sul web è semplice: capire dove investire tempo per ottenere impatto reale sugli utenti . Di seguito, una lettura pratica dei temi che continuano a emergere come prioritari per chi costruisce applicazioni e siti moderni. 1) Performance: meno benchmark, più realtà La performance non è più un esercizio di ottimizzazione a fine progetto. È un requisito continuo che va gestito con strumenti, metriche e processi. Cosa significa “misurabile” oggi Metriche di campo (real user monitoring) : le prestazioni che contano sono quelle che arrivano dai dispositivi reali, su reti reali. Metriche di laboratorio : restano utili per regressioni e CI, ma vanno interpretate come “segnali” e non come verità assolute. Implicazione pratica Imposta una pipeline dove: le metriche sintetiche bloccano regressioni evidenti (build/PR), le metriche reali guidano le priorità (release e backlog). 2) DevTools: dal debug al controllo qualità Gli strumenti di sviluppo non servono più solo a “trovare il bug”, ma a ridurre il rischio : regressioni di layout, memory leak, risorse inutili, dipendenze pesanti. Abitudini che fanno differenza Profilare prima di ottimizzare: CPU, rete e rendering hanno colli di bottiglia diversi. Isolare i cambiamenti: una variazione di bundling o di immagini può ribaltare il profilo prestazionale più di una micro-ottimizzazione in JS. 3) La piattaforma web continua a crescere (e chiede scelte più consapevoli) La Web Platform oggi offre API potenti, ma la parte difficile non è “usarle”: è scegliere quando usarle. Un criterio utile Se una feature riduce complessità (meno librerie,
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Left of the Loop: The PO is Dead, Long Live the PO
When I wrote about shifting the engineering process left — spec sessions, autonomous agents, humans reviewing output rather than writing code — a question kept coming up. Where does the Product Owner fit in all of this? It’s the right question. And I think the answer is more interesting than “the PO disappears.” Let’s start with acceptance criteria. We invented them to bridge a gap. The team needed to know when something was done. The PO needed confidence that what got built matched the intent. Acceptance criteria were the contract between the two. But if the Spec Session is where intent gets defined — by the whole team, together, before the agent runs — that gap closes. What the team agreed on in the room is the definition of done. The spec is the acceptance criteria. You don’t need a separate validation step because the planning and the agreement happened at the same time. The tighter the loop, the less ceremony you need around it. There’s a caveat though. The spec is a necessary contract. It’s not a sufficient one. Simon Martinelli’s work on the AI Unified Process validates the spec-driven approach technically. But his model is about the artifact — requirements at the center, AI generating everything else from them. How the team actually builds shared understanding before the spec exists isn’t something it addresses. That’s not a criticism. It’s just a different question. A spec written after a real Spec Session — where the team worked through edge cases together, disagreed, got to resolution — is different from a spec written by one person and signed off asynchronously. Same artifact. Different quality of shared understanding. That distinction matters when the agent hits an edge case the spec didn’t anticipate. So what’s actually left for a dedicated PO? Two things. And they’re very different. The first is product thinking — challenging intent, representing user needs, asking why before the agent runs with something. That’s valuable. But it doesn’t require a ded
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Performance Testing RAG Applications: Complete Engineering Guide
In this blog post, we will see how to performance test a RAG (Retrieval-Augmented Generation) application properly, covering both speed and correctness, and how to wire both into a CI/CD pipeline so regressions get caught before they reach production. Performance testing a RAG application requires two separate testing gates: one for speed and one for answer quality. Traditional load testing tools measure response times but cannot detect hallucinations, where a model returns fast but factually incorrect answers grounded in fabricated context rather than retrieved documents. The guide demonstrates using k6 for load testing end-to-end latency and DeepEval for evaluating faithfulness and answer relevancy using an LLM-as-judge approach. Both gates are integrated into a GitHub Actions CI/CD pipeline so regressions in either performance or output quality are caught automatically on every pull request before reaching production. If you've come from a JMeter or k6 background like I have, your first instinct with a RAG endpoint is probably to point a load test at it and check response times. That gets you halfway there. A RAG app can return a fast, confident, completely wrong answer, and a plain load test will never tell you that. You need two testing surfaces, not one: performance and quality. This guide covers both, using a single running example throughout: a documentation assistant that answers "How do I run JMeter in non-GUI mode?" against a small knowledge base. Why RAG breaks traditional load testing assumptions A conventional API returns a complete response and you measure the round trip. A RAG endpoint does two expensive things before it answers: it retrieves context from a vector store or search index, then it streams a generated response token by token. That second part matters a lot. A single request can stream hundreds of tokens over several seconds, so "request duration" as a single number hides two very different problems: how long the model took to start answe
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F1 in Britain: Automated software to blame for crushing expectations
Sometimes races finish behind a safety car, but it's not always satisfying.
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Scaling Terraform Infrastructure Beyond a Single Team
When a single engineer manages all the Terraform in an organisation, everything is simple. One repo, one state, one pipeline, one set of credentials. There's no coordination overhead because there's no one to coordinate with. That stops working the moment a second team needs to deploy infrastructure. And by the time you have three or four teams — networking, platform, application, security — the single-team model is actively slowing everyone down. This guide covers what breaks, how teams typically work around it, and how to set up a structure where each team owns their slice of infrastructure independently. What breaks State lock contention Terraform's state locking is per-state. When the networking team is running terraform plan , the application team's pipeline is blocked — even though they're changing completely unrelated resources. The more teams share a state, the more time everyone spends waiting. Blast radius A junior engineer deploying a new application service shouldn't be able to accidentally destroy the VPC. But if application resources and networking resources share a state, a single misconfigured terraform apply can touch anything. Code review catches some of this. Not all of it. Credential sprawl A shared pipeline needs credentials for everything — the networking team's Azure subscription, the application team's AWS account, the security team's DNS provider. Every team's secrets end up in one CI environment, accessible to anyone who can trigger a run. This fails most compliance audits. Approval bottlenecks In many organisations, one person or a small group gatekeeps all infrastructure changes. Every PR needs their review. Every apply needs their approval. The gatekeeper becomes a bottleneck not because they're slow, but because they're a single point of serialisation for all infrastructure work. Backend access as implicit access control Terraform has no built-in concept of per-team or per-workspace permissions. All workspaces in a backend share the sam
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Managing Terraform Across Multiple Cloud Providers
Most organisations don't live in a single cloud. You might run compute in AWS, DNS in Cloudflare, identity in Azure AD, and logging in GCP. Terraform handles each provider fine on its own, but the moment you need to coordinate across providers the tooling fights you. This guide walks through the common pain points of multi-cloud Terraform setups and the approaches teams use to cope — then shows how Snap CD makes cross-cloud dependency management a solved problem. Where it gets difficult Credential sprawl Each cloud provider has its own authentication mechanism. AWS uses IAM roles and access keys. Azure uses service principals and managed identities. GCP uses service accounts and workload identity federation. A single Terraform state that spans providers needs credentials for all of them — which means your CI runner or developer workstation holds keys to everything. That's a security problem. A compromised CI pipeline with AWS and Azure credentials exposes both clouds simultaneously. And it's an operational problem — rotating credentials means updating every pipeline that touches that state. This problem compounds at scale: Terraform couples provider processes tightly to credentials , so managing hundreds of accounts across clouds means spawning thousands of provider processes, which quickly becomes unmanageable. Provider version conflicts Terraform providers are versioned independently. Upgrading the AWS provider to fix a bug in aws_eks_cluster shouldn't require you to also test a new version of the Azure provider. But when they share a state, a terraform init -upgrade pulls new versions for everything, and a regression in one provider blocks all deployments. Terraform also lacks built-in support for instantiating multiple providers with a loop and passing providers to modules in for_each , making multi-cloud configurations especially verbose and repetitive. Blast radius across clouds A misconfigured terraform apply in a single-cloud state damages resources in one c
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Como servir os 68 milhões de CNPJs da Receita com ~10ms de latência em Go
Todo dev brasileiro que já precisou consultar CNPJ conhece o dilema: ou você usa uma API que faz proxy da Receita (3 a 10 segundos por consulta, quando não cai), ou baixa o dump de dados abertos e monta a própria base — e descobre que "baixar um CSV" era a parte fácil. Eu montei a própria base. Este post é o diário honesto do que funcionou, do que quebrou e dos números reais — 217 milhões de linhas servidas em ~10ms de p50 dentro do datacenter, num Postgres de 1 vCPU. A arquitetura em uma frase Não consulte a Receita em tempo real. Ingira o dump mensal e sirva da sua infra. O resto é decorrência. Receita (dump mensal, ~6GB zip) ──▶ ingestão Go (COPY) ──▶ Postgres ──▶ API (chi) CGU (CEIS/CNEP, zip diário) ──▶ job diário ──┘ O dump da Receita: as pegadinhas que ninguém documenta O layout oficial existe, mas o que quebra parser de verdade é o que está fora dele: Encoding latin1 (ISO-8859-1) — acento vira lixo se você ler como UTF-8. Em Go: charmap.ISO8859_1.NewDecoder() num transform.Reader streaming. Decimal com vírgula ( "1000000,00" ) e datas YYYYMMDD onde 0 e 00000000 significam nulo. CNPJ quebrado em 3 colunas (básico 8 + ordem 4 + DV 2). A chave de junção entre empresas, estabelecimentos e sócios é o básico — errar isso custa um dia. As partições 0–9 não se alinham entre arquivos. O estabelecimento da partição 3 pode ser de uma empresa da partição 7. Foreign key rígida entre as tabelas = COPY quebrando no meio da carga. A solução: sem FK; a integridade vem da fonte. Bytes NUL ( 0x00 ) no meio dos dados. O Postgres rejeita NUL em text . Um strings.ReplaceAll(s, "\x00", "") no parser economizou três recargas. Desde jan/2026 o repositório é um Nextcloud do SERPRO+ com WebDAV público — dá pra listar meses com PROPFIND e baixar com o token do share como usuário. Adeus, scraping. COPY ou morte A diferença entre INSERT em lote e o protocolo COPY não é incremental — é outra categoria. Com pgx.CopyFrom e lotes de 50k: 28,1 milhões de empresas em 1m28s (~320k linhas/s) num
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You Can't Review an Agent. You Can Review a Plan.
A harness for AI-era Terraform. I'm building one. For a while now I've been developing a harness for infrastructure-as-code as a private SDK and compiler — the layer that sits between whoever proposes a change (a person, an agent, CI) and whatever actually reaches production. This post isn't the tool. It's the thinking underneath it, and the few pieces I've become most convinced by while building it. (Notes from inside the work — where I've landed so far, not advice.) The problem that sent me down this road is easy to state and easy to underrate. A version of it happened recently. An agent fixed some Terraform; the PR read clean — tidy diff, sensible resource names, a plan output that looked exactly like what I'd asked for. It got approved. And then, at apply time, a different plan ran than the one that was reviewed: apply had re-planned against state that moved in between, and the diff that touched production wasn't quite the diff anyone had read. Nothing broke, that time. But that near-miss is the whole reason the harness exists. Because the danger was never "the agent writes bad HCL." Agents write perfectly good HCL; I let them. The danger is the distance between the plan a human reviewed and the plan that actually runs — and once agents are the ones proposing changes at volume, that distance is the thing I most want to nail shut. Where I've landed for now (and expect to keep revising): What AI-era IaC needs isn't AI that can apply . It's a structure where every change — human or agent — is evaluated at the same boundary , and only a reviewed plan ships. The unit of trust isn't the agent. It's a specific, reviewed plan , bound byte for byte. You can't review an agent. You can only review a plan. Instructions to an agent can be broken. A CI gate can't be talked out of it. Put guidance in the prompt; put the guarantee in the gate. Terraform/OpenTofu don't go away. You wrap them in a harness; you don't replace them. Your repo has non-human authors now For years IaC
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PostgreSQL query planner parameters and prepared statements
PostgreSQL provides several planner configuration parameters, such as enable_seqscan and enable_indexscan , that influence how execution plans are generated. These settings affect planning, not the execution of an already-generated plan. With prepared statements, this raises an interesting question. Should planner settings be applied before PREPARE, before EXECUTE, or both? Let's look at a simple example: a "tasks" table with a due date and a "done" status: \ c drop table if exists tasks ; -- a table of tasks with status (done or not) and due date create table tasks ( id bigint generated always as identity primary key , due timestamptz , done boolean ); -- insert 500 tasks, with 1% not done insert into tasks ( due , done ) select now () + interval '1 day' * n , 42 != n % 100 from generate_series ( 1 , 500 ) n ; -- index the todo (partial index) create index on tasks ( due , id ) where done = false ; vacuum analyze tasks ; With a partial index, I indexed only the tasks that are not yet done ( done = false ) because that's my most frequent query pattern: postgres =# explain select id , due , done from tasks where done = false and id > 0 order by due limit 1 ; QUERY PLAN --------------------------------------------------------------------------------------- Limit ( cost = 0 . 13 .. 3 . 60 rows = 1 width = 17 ) -> Index Scan using tasks_due_id_idx1 on tasks ( cost = 0 . 13 .. 17 . 47 rows = 5 width = 17 ) Index Cond : ( id > 0 ) ( 3 rows ) With partial indexes, the condition covered by the index is not even visible in the execution plan because the index itself enforces the condition. Prepared statement I decided to use a prepared statement with all values as parameters. It is probably not a good idea in this case. When a parameter can have only a few different values and you expect different cardinalities for each, you should probably define one query per value, using literals. I'm doing this to illustrate what can happen, with a simple, extreme example: postgres =# pr
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Prompt Caching and Cost Control in Java
Introduction We already covered picking the right model tier for the task and caching a large shared prefix in https://pg-blogs.netlify.app/posts/11-building-reliable-llm-apps-in-java/ . Those two lines were the tip of a bigger discipline: LLM cost is not a fixed line item, it's an engineering variable — one you can measure and shrink with the same rigor you'd apply to database query time or container memory. This post goes deeper: how input/output pricing actually works, the exact cache_control shape and how to prove a cache hit rather than assume one, the Batches API for work that isn't latency-sensitive, and model routing — using a cheap model to triage, escalating only the hard cases to a stronger one. The honest framing throughout: measure before you optimize. Every technique here has a cost of its own; applied to the wrong workload, "optimization" makes things slower or more expensive. Token Economics: Why the Prefix Is the Bill Anthropic (like every hosted LLM provider) prices input and output tokens separately, and output is always pricier — the model has to generate output autoregressively, one token informed by all the ones before it, while input can be processed in parallel. Representative pricing from the current model catalog: Model Input Output Claude Opus 4.8 $5.00 / MTok $25.00 / MTok Claude Sonnet 5 $3.00 / MTok $15.00 / MTok Claude Haiku 4.5 $1.00 / MTok $5.00 / MTok Two consequences follow directly: Long system prompts, tool definitions, and RAG context are read on every request , not written once. A 20K-token system prompt sent on every one of 10,000 requests is 200M input tokens — at Opus 4.8 rates, $1,000 before a single output token is generated. The shared prefix , not the user's question, is usually where the money goes. A verbose model wastes money twice — once on the extra output tokens themselves, and again because the next turn's messages history now carries that verbosity forward as input on every subsequent call. Trimming max_tokens an
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Prompt Caching and Cost Control in Python
Introduction https://pg-blogs.netlify.app/posts/10-building-reliable-llm-apps-in-python/ closed with a section on picking the right model per task and caching a shared prefix. That was the entry point into a bigger discipline: LLM spend is an engineering variable, not a fixed bill — one you can measure and reduce with the same rigor you'd apply to query latency or memory footprint. This post goes deeper on four levers: how input/output pricing actually works and why the prefix is usually where the money goes, the exact cache_control shape and how to prove a cache hit instead of assuming one, the Batches API for work that isn't latency-sensitive, and model routing — a cheap model triaging requests and escalating only the hard ones. The throughline is honest: measure before you optimize. Every lever here has its own cost; misapplied, it makes things slower or pricier, not cheaper. Token Economics: Why the Prefix Is the Bill LLM providers price input and output tokens separately, and output always costs more — generation is autoregressive (each token depends on every one before it), while input can be processed in parallel. Representative pricing from the current model catalog: Model Input Output Claude Opus 4.8 $5.00 / MTok $25.00 / MTok Claude Sonnet 5 $3.00 / MTok $15.00 / MTok Claude Haiku 4.5 $1.00 / MTok $5.00 / MTok Two things follow: A long system prompt, tool list, or RAG context is billed as input on every request , not written once. Send a 20K-token system prompt on 10,000 requests and that's 200M input tokens — at Opus 4.8 rates, $1,000 before the model has generated a single output token. The shared prefix , not the user's actual question, is usually the dominant cost. Verbose output costs twice — once directly (more output tokens billed at the higher rate), and again because the next turn's history carries that verbosity forward as input. Asking for concise output and setting a sane max_tokens is a cost control, not just a style choice. This is why the tw
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Securing Your Terraform Infrastructure with Checkov and GitHub Actions
Infrastructure as Code (IaC) has revolutionized how we provision and manage cloud resources. Tools like Terraform, Pulumi, and OpenTofu allow us to define infrastructure using code, making it versionable, repeatable, and scalable. However, with great power comes great responsibility. Misconfigurations in IaC can lead to massive security breaches, such as publicly exposed data storage or overly permissive access roles. This is where Static Application Security Testing (SAST) comes in. SAST tools analyze your source code to find security vulnerabilities before the code is deployed. In this article, we'll explore how to apply SAST to a Terraform project using Checkov , a popular open-source static analysis tool for IaC, and how to automate this process using GitHub Actions. (Note: We are intentionally avoiding tfsec for this demonstration to explore other powerful alternatives). Why Checkov? Checkov, created by Bridgecrew (now part of Prisma Cloud), is a static code analysis tool for IaC. It scans cloud infrastructure provisioned using Terraform, Terraform plan, Cloudformation, Kubernetes, Dockerfile, Serverless, or ARM Templates and detects security and compliance misconfigurations. It includes hundreds of built-in policies covering security and compliance best practices for AWS, Azure, and Google Cloud. The Demo Scenario: A Vulnerable S3 Bucket Let's start by creating a simple Terraform configuration for an AWS S3 bucket. We will intentionally introduce a security misconfiguration: making the bucket public without encryption. Create a file named main.tf : # main.tf provider "aws" { region = "us-east-1" } resource "aws_s3_bucket" "my_vulnerable_bucket" { bucket = "my-company-public-data-bucket-12345" } # Misconfiguration 1: Public Read Access resource "aws_s3_bucket_acl" "example" { bucket = aws_s3_bucket . my_vulnerable_bucket . id acl = "public-read" } If we were to deploy this, anyone on the internet could read the contents of this bucket. Let's see how Checkov can
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NodeLLM 1.17: MCP Sampling, Concurrent Tool Execution, and Smarter ORM Control
Back when we introduced MCP support , we ended on a teaser: Phase 3 would tackle Sampling —letting servers request completions from the host instead of only exposing tools and resources to it. NodeLLM 1.17 delivers on that, and pairs it with a second, unrelated but overdue improvement: precise control over how tool calls execute, now available consistently in both core and the ORM persistence layer. 🔄 MCP Sampling: Closing the Loop Sampling inverts the usual MCP direction. Instead of the client asking the server for tools, the server asks the client to run an LLM completion on its behalf. This lets an MCP server offer LLM-powered capabilities—summarization, classification, drafting—without needing its own API key or provider integration. createLLMSamplingHandler answers those requests using a real NodeLLM instance, so a server's tool ends up powered by whatever model you configure client-side: import { createLLM } from " @node-llm/core " ; import { MCP , createLLMSamplingHandler } from " @node-llm/mcp " ; const llm = createLLM ({ provider : " openai " }); const mcp = await MCP . connect ( { command : " node " , args : [ " ./sampling-server.mjs " ] }, { sampling : createLLMSamplingHandler ( llm , " gpt-4o-mini " ) } ); const tools = await mcp . discoverTools (); // The server only advertises sampling-backed tools once it sees // the client declared sampling support during the handshake. If you need full control over how a sampling request is answered—routing by model hint, injecting your own guardrails—pass a plain handler function instead of { llm, model } . It receives the raw sampling/createMessage params and returns a CreateMessageResult , so you decide exactly how (or whether) to answer. ⚡ Concurrent Tool Execution When a model returns several independent tool calls in the same turn, NodeLLM has always executed them one at a time. That's safe by default, but wastes time when the calls don't depend on each other—three weather lookups for three different cities, s
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Database Indexing and Query Optimization for Python Developers
Introduction Fixing N+1 queries with select_related / prefetch_related or selectinload (see the previous post ) gets you down to a small, sane number of queries per request. The next bottleneck is what each query costs once the table has millions of rows — and that is almost always about indexing. An index turns "scan every row" into "look it up directly." Skip it, and a query that's instant in development takes seconds once real data volume shows up in production. How Indexes Work: The B-Tree Intuition Without an index, a WHERE clause forces a sequential scan : the database reads every row and checks the condition — O(n) , cost grows linearly with table size. An index is a separate, sorted structure (almost always a B-tree ) mapping column values to row locations. Because it's sorted and balanced, finding a value is a tree walk: O(log n) . On a 10-million-row table, that's the difference between reading 10 million rows and roughly 23 tree nodes. This isn't free: Writes get slower — every INSERT / UPDATE / DELETE on an indexed column also updates the index. Storage grows — each index is a sorted copy of (part of) the data. An index trades write cost and storage for read speed. Indexing a column you rarely filter or sort on is pure cost, no benefit. Reading Query Plans: EXPLAIN ANALYZE Postgres' EXPLAIN ANALYZE shows what the planner actually did, not an estimate. Before an index , filtering orders by customer_id : EXPLAIN ANALYZE SELECT * FROM orders WHERE customer_id = 48291 ; Seq Scan on orders (cost=0.00..21453.00 rows=42 width=96) (actual time=0.021..118.442 rows=41 loops=1) Filter: (customer_id = 48291) Rows Removed by Filter: 1199959 Planning Time: 0.112 ms Execution Time: 118.471 ms Seq Scan means Postgres read all ~1.2 million rows and discarded all but 41. actual time is real elapsed time — 118ms for one lookup. After CREATE INDEX idx_orders_customer_id ON orders (customer_id); : Index Scan using idx_orders_customer_id on orders (cost=0.42..8.53 rows=42 wid
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Database Indexing and Query Optimization for Java Developers
Introduction Fixing N+1 queries (see the previous post ) gets your Hibernate app down to a handful of queries per request. The next bottleneck is what each of those queries costs once your tables have millions of rows — and that is almost always a question of indexing. An index turns "scan every row" into "look it up directly." Get the index wrong — or skip it — and a query that took 2ms in development takes 4 seconds in production once real data volume shows up. How Indexes Work: The B-Tree Intuition Without an index, a WHERE clause forces a sequential scan : the database reads every row and checks the condition. That's O(n) — cost grows linearly with table size. An index is a separate, sorted data structure (almost always a B-tree ) that maps column values to row locations. Because it's sorted and balanced, finding a value is a tree walk: O(log n) . On a 10-million-row table, that's the difference between reading 10 million rows and reading roughly 23 tree nodes. The cost is not free: Writes get slower. Every INSERT / UPDATE / DELETE on an indexed column must also update the index structure. Storage grows. Each index is a copy of (part of) the data, sorted differently. An index is a trade: you pay on every write so that specific reads become fast. Indexing a column you rarely filter or sort on is pure cost with no benefit. Reading Query Plans: EXPLAIN ANALYZE Postgres' EXPLAIN ANALYZE shows what the planner actually did — not what you hope it did. Before an index , filtering orders by customer_id : EXPLAIN ANALYZE SELECT * FROM orders WHERE customer_id = 48291 ; Seq Scan on orders (cost=0.00..21453.00 rows=42 width=96) (actual time=0.021..118.442 rows=41 loops=1) Filter: (customer_id = 48291) Rows Removed by Filter: 1199959 Planning Time: 0.112 ms Execution Time: 118.471 ms Seq Scan means Postgres read all ~1.2 million rows and threw away all but 41 of them. actual time is the real elapsed time, not an estimate — 118ms for one lookup. After CREATE INDEX idx_orders