Articles on AWS, backend architecture and AI in production. From projects, not from slides.https://timrutte.de/enhttps://timrutte.de/en/blog/coding-agents-eight-steps/https://timrutte.de/en/blog/coding-agents-eight-steps/The agent works in one of eight steps. How specification, architecture rules, CI and review turn speed into software rather than just more code.Sun, 11 Oct 2026 12:00:00 GMThttps://timrutte.de/en/blog/taking-over-a-go-project/https://timrutte.de/en/blog/taking-over-a-go-project/Go code tells you almost everything about itself, except whether it runs. What I check in the first week: operation, build, reachable vulnerabilities, load.Wed, 30 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/code-too-old-for-coding-agents/https://timrutte.de/en/blog/code-too-old-for-coding-agents/Whether a coding agent works safely in a codebase is not decided by its age but by whether a command can say no. Four questions that settle it.Tue, 29 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/php-8-2-end-of-life/https://timrutte.de/en/blog/php-8-2-end-of-life/PHP 8.2 gets no more security updates from January. Who is affected, which target version is worth it and what the move from 8.2 costs.Tue, 29 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/terraform-or-aws-cdk/https://timrutte.de/en/blog/terraform-or-aws-cdk/Terraform or AWS CDK? Why I usually describe AWS infrastructure with Terraform, and when CDK really earns its extra programming layer.Thu, 24 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/api-gateway-or-alb/https://timrutte.de/en/blog/api-gateway-or-alb/API Gateway or Application Load Balancer on AWS? When an ALB is enough, and when API Gateway actually justifies its extra layer.Thu, 24 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/ecs-fargate-or-kubernetes/https://timrutte.de/en/blog/ecs-fargate-or-kubernetes/ECS Fargate or Kubernetes on AWS? Why I start normal applications on Fargate, and at what point Kubernetes actually pays back its overhead.Wed, 23 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/rest-or-grpc/https://timrutte.de/en/blog/rest-or-grpc/REST or gRPC? Why I decide public APIs differently from internal service communication, and which criteria actually matter.Wed, 23 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/synchronous-or-event-driven/https://timrutte.de/en/blog/synchronous-or-event-driven/Synchronous or event-driven? Why I do not decouple backend services by default, and when a call, a queue or an event is the right fit.Tue, 22 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/strangler-fig-pattern-in-practice/https://timrutte.de/en/blog/strangler-fig-pattern-in-practice/The switch is an afternoon, the data is the project: cut by ownership, shadow runs, switching in steps, and the five places where it tears.Sun, 13 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/monolith-to-microservices/https://timrutte.de/en/blog/monolith-to-microservices/Three of the four reasons for splitting are delivery problems. What a service costs, what a module already does, and the four cases where a service really is one.Sun, 13 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/legacy-application-on-kubernetes/https://timrutte.de/en/blog/legacy-application-on-kubernetes/The groundwork costs weeks, swapping the platform costs days. Three conditions under which a cluster pays, and what sits in between.Sun, 13 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/nis2-legacy-systems/https://timrutte.de/en/blog/nis2-legacy-systems/Four of the ten areas are a question of construction for a grown system, not of intent. The findings, the evidence, and the order that is worth the money.Sun, 13 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/getting-source-code-from-an-agency/https://timrutte.de/en/blog/getting-source-code-from-an-agency/An archive is not software. What belongs on the list, in which order to ask for it, what to do on day one afterwards, and what helps when it stalls.Sun, 13 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/legacy-modernization-five-sentences/https://timrutte.de/en/blog/legacy-modernization-five-sentences/Five sentences that ran through forty-four articles, two assessments that shifted, and four entry points depending on your situation.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/rector-in-a-legacy-project/https://timrutte.de/en/blog/rector-in-a-legacy-project/One rule set, one directory, one pull request: why the first attempt fails, which sets are mechanics and which are opinion, and how to review four hundred files.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/handing-over-a-software-project/https://timrutte.de/en/blog/handing-over-a-software-project/A handover is a state, not an appointment. The one test that says anything, the access inventory before it, and a deadline instead of an open door.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/blue-green-canary-without-kubernetes/https://timrutte.de/en/blog/blue-green-canary-without-kubernetes/Two machines and a switch are enough. The condition sits in the database, not the tooling, and without an abort rule a canary is just a slower release.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/retrofitting-multi-tenancy/https://timrutte.de/en/blog/retrofitting-multi-tenancy/Three models and what they suit, the filter one level down, the test that finds leaks, and the half of the effort that is not in the database.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/what-does-a-legacy-modernization-cost/https://timrutte.de/en/blog/what-does-a-legacy-modernization-cost/The price is not driven by the amount of code but by five quantities you can establish in a week. Plus the items missing from every quote.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/removing-unused-features/https://timrutte.de/en/blog/removing-unused-features/Measure instead of guessing, set the waiting period by the rhythm of the thing, and know what goes with it. Half-deleted is worse than not deleted.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/end-of-life-calendar-for-a-stack/https://timrutte.de/en/blog/end-of-life-calendar-for-a-stack/What carries an expiry date, how to build the list in a day, why end of life minus lead time is the only number that counts, and the sentence that gets the budget.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/distributed-monolith/https://timrutte.de/en/blog/distributed-monolith/Five sentences to diagnose it, why the cuts follow the nouns, what helps immediately without a rebuild, and why merging back is not a step backwards.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/cleaning-up-iam-aws-account/https://timrutte.de/en/blog/cleaning-up-iam-aws-account/See first, then the keys, then the permissions: credential report and last-accessed data, OIDC instead of key pairs, one boundary instead of many rules.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/test-data-from-production/https://timrutte.de/en/blog/test-data-from-production/Not the dump but the shaped slice: pick an anchor, find the silent references, mask deterministically, and close the outbound paths in the environment.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/coding-agent-in-a-legacy-codebase/https://timrutte.de/en/blog/coding-agent-in-a-legacy-codebase/What an agent is good for in legacy code, where it predictably fails, and the precondition without which it multiplies risk rather than speed.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/introducing-opentelemetry-php-go/https://timrutte.de/en/blog/introducing-opentelemetry-php-go/Traces first, one path instead of all: the PHP export quirk, the context in Go, the seam across the queue, and what drives the invoice.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/cache-invalidation-legacy-system/https://timrutte.de/en/blog/cache-invalidation-legacy-system/Three kinds of cache, why an expiry time usually wins, what goes wrong with cached permissions, and how the debt gets paid back.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/modernizing-a-frontend-without-a-spa/https://timrutte.de/en/blog/modernizing-a-frontend-without-a-spa/Partial updates instead of a framework switch: the three problems that actually annoy users, twenty lines of JavaScript, and where this route ends.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/modernization-in-twelve-weeks/https://timrutte.de/en/blog/modernization-in-twelve-weeks/A shape that fits a quarter: six blocks, a result after each, a decision at the end, and the place where every plan tears.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/testing-backup-restores/https://timrutte.de/en/blog/testing-backup-restores/Three ways backups fail silently, what a rehearsal actually measures, how it runs, and what rhythm can be sustained.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/configuration-and-secrets-in-go/https://timrutte.de/en/blog/configuration-and-secrets-in-go/Three layers with three origins, a start that fails on missing values, secrets without environment variables, and rotation without a restart.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/security-holes-in-old-php-code/https://timrutte.de/en/blog/security-holes-in-old-php-code/The ten holes I find most often in grown PHP systems, the command that finds each one, and an order sorted by risk rather than by effort.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/api-in-front-of-a-monolith/https://timrutte.de/en/blog/api-in-front-of-a-monolith/Why the interface comes before the new front end, where it gets cut, how authentication is solved, and what the layer must not do.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/mysql-5-7-to-8-0-migration/https://timrutte.de/en/blog/mysql-5-7-to-8-0-migration/Four classes of breakage, two of which stay silent, how to find them in advance, and what the managed service additionally does differently.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/introducing-phpstan-into-legacy-code/https://timrutte.de/en/blog/introducing-phpstan-into-legacy-code/Eight thousand messages become zero in a day: the baseline, what actually gets found at which level, and where further levels deliver nothing.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/modernizing-with-an-external-freelancer/https://timrutte.de/en/blog/modernizing-with-an-external-freelancer/Why the team often changes nothing after the project, four testable criteria for handover readiness, and the role split that shifts over time.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/php-monolith-on-ecs-fargate/https://timrutte.de/en/blog/php-monolith-on-ecs-fargate/Containers without cluster administration: what belongs in the image, how configuration and secrets are separated, and what the health check has to check.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/replacing-cron-jobs-with-a-queue/https://timrutte.de/en/blog/replacing-cron-jobs-with-a-queue/When a schedule is no longer enough, how a job becomes a task with state, and why a job table is often enough instead of a dedicated queue.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/legacy-system-in-maintenance-mode/https://timrutte.de/en/blog/legacy-system-in-maintenance-mode/Not modernizing does not mean doing nothing. Five things that keep running, three that stop, and the two facts without which it is neglect.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/learning-go-as-a-php-developer/https://timrutte.de/en/blog/learning-go-as-a-php-developer/Five places where Go means something different from what it looks like: errors, concurrency, packages, interfaces and the missing framework.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/shopware-5-plugins-migration/https://timrutte.de/en/blog/shopware-5-plugins-migration/The cost driver is not the data, it is the plugins. Three lists instead of one, four categories with four answers, and the order that pays off.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/dual-write-and-backfill/https://timrutte.de/en/blog/dual-write-and-backfill/The five phases of a data migration on a running system, the code for the trickiest one, and the four places where it tears in practice.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/developer-knowledge-monopoly/https://timrutte.de/en/blog/developer-knowledge-monopoly/Knowledge does not pile up because somebody hoards it but because the system forces it. Five properties, three useless measures, and what works instead.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/detecting-terraform-drift/https://timrutte.de/en/blog/detecting-terraform-drift/Drift is not an exception in grown environments. How to make it visible, the three possible answers, and where codification stops.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/laravel-upgrade-pitfalls/https://timrutte.de/en/blog/laravel-upgrade-pitfalls/Why the tools from a Symfony upgrade do not bite here, and four places where Laravel upgrades have pitfalls of their own.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/building-an-anti-corruption-layer/https://timrutte.de/en/blog/building-an-anti-corruption-layer/So the old data model does not travel into the new service: where the layer sits, what it translates, what it handles alongside, and when it goes.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/baseline-before-refactoring/https://timrutte.de/en/blog/baseline-before-refactoring/Which three measurements have to exist before the first rebuild, how to get them without specialist tooling, and why the average is the wrong number.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/reconstructing-composer-dependencies/https://timrutte.de/en/blog/reconstructing-composer-dependencies/No lock file, vendor in the repository, patched packages: how to reconstruct the dependency tree of an old PHP project before raising it.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/making-a-php-application-stateless/https://timrutte.de/en/blog/making-a-php-application-stateless/What stops an application running on more than one machine: sessions, uploaded files and state inside the process, and how to undo those chains.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/feature-flags-in-a-monolith/https://timrutte.de/en/blog/feature-flags-in-a-monolith/An implementation that stands up in a day: table, switch class, stable assignment. Where the switch sits, how it fits the database, and how it disappears again.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/lift-and-shift-or-replatforming/https://timrutte.de/en/blog/lift-and-shift-or-replatforming/Moving and rebuilding are two projects. What changes even in a pure move, when replatforming pays off, and why the first bill goes up.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/first-service-out-of-the-monolith/https://timrutte.de/en/blog/first-service-out-of-the-monolith/The first cut decides whether there is a second. Four criteria, three candidates that almost always fit, and three places you never touch first.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/business-case-for-modernization/https://timrutte.de/en/blog/business-case-for-modernization/Four kinds of cost you can put a number on, lead time as a measurement instead of an estimate, a risk table with expected values, and the one slide.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/working-through-symfony-deprecations/https://timrutte.de/en/blog/working-through-symfony-deprecations/Turning twelve thousand messages into an order of work: three kinds of deprecation, the bottom-up route, and the rebuilds that never announce themselves.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/legacy-database-schema/https://timrutte.de/en/blog/legacy-database-schema/The schema outlives every modernization of the code. The four legacy traits that are almost always there, what to measure first, and in what order to change.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/replacing-ftp-deployment/https://timrutte.de/en/blog/replacing-ftp-deployment/From "somebody uploads it" to a rollout with a way back: artefact, atomic switch, rollback, and where the database draws the line.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/testing-legacy-code-without-tests/https://timrutte.de/en/blog/testing-legacy-code-without-tests/How to pin down the behaviour of a legacy system before you change it: characterization tests, golden master, seams, and when to stop.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/technical-due-diligence-legacy-system/https://timrutte.de/en/blog/technical-due-diligence-legacy-system/How I assess a legacy system in five days before somebody buys or inherits it: the order of work, the commands, and what ends up in the report.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/when-modernization-is-the-wrong-answer/https://timrutte.de/en/blog/when-modernization-is-the-wrong-answer/Modernization is not always the right answer to a legacy system. When freezing, standard software or retirement is the better call, and how to tell.Sat, 12 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/developer-gone-first-week/https://timrutte.de/en/blog/developer-gone-first-week/When the developer of a running system is gone, the first week decides the cost. What to secure before touching the code, in the right order.Fri, 11 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/german-e-invoicing-mandate-2027/https://timrutte.de/en/blog/german-e-invoicing-mandate-2027/Whether you must issue e-invoices from January 2027 depends on your 2026 revenue. What counts, what is exempt, and why receiving them is not enough.Wed, 09 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/second-brain-for-ai-agents/https://timrutte.de/en/blog/second-brain-for-ai-agents/How I moved my knowledge into a Git repository so agents can work with it. What held up after nine days, what did not, and what a team can take from it.Wed, 09 Sep 2026 12:00:00 GMThttps://timrutte.de/en/blog/php-7-4-to-php-8-4/https://timrutte.de/en/blog/php-7-4-to-php-8-4/PHP 7.4 has been without security updates since late 2022. What the jump to 8.4 involves: hard breaks, silent behaviour changes, real cost drivers.Sat, 29 Aug 2026 12:00:00 GMThttps://timrutte.de/en/blog/zend-framework-1-end-of-life/https://timrutte.de/en/blog/zend-framework-1-end-of-life/Zend Framework 1 has been without support since 2016 and still runs in production. What that means, what forks can do and the three ways out.Mon, 24 Aug 2026 12:00:00 GMThttps://timrutte.de/en/blog/aws-cost-reduction-case-report/https://timrutte.de/en/blog/aws-cost-reduction-case-report/Twelve months of FinOps across two AWS accounts: where the large amounts were and why commitments come last.Wed, 19 Aug 2026 12:00:00 GMThttps://timrutte.de/en/blog/ai-in-production-on-zero-budget/https://timrutte.de/en/blog/ai-in-production-on-zero-budget/Six architectural decisions and three mistakes from an AI side project that must cost nothing. With real code and the places where it went wrong.Tue, 18 Aug 2026 12:00:00 GMThttps://timrutte.de/en/blog/finops-aws-hidden-architecture-costs/https://timrutte.de/en/blog/finops-aws-hidden-architecture-costs/Where four- and five-figure amounts quietly disappear in grown AWS setups, and how to get them back without changing a single line of code.Thu, 11 Jun 2026 12:00:00 GMThttps://timrutte.de/en/blog/aws-region-outage-multi-region/https://timrutte.de/en/blog/aws-region-outage-multi-region/What actually matters when an AWS region goes down: multi-region strategies, realistic failover concepts and the costs nobody plans for.Thu, 09 Apr 2026 12:00:00 GMThttps://timrutte.de/en/blog/agentic-coding-spec-driven-development/https://timrutte.de/en/blog/agentic-coding-spec-driven-development/Why your AI agent needs structure before it writes code. Spec-driven development as a method for predictable, consistent quality with AI tools.Mon, 30 Mar 2026 12:00:00 GMThttps://timrutte.de/en/blog/golang-in-a-php-world/https://timrutte.de/en/blog/golang-in-a-php-world/How I add new high-performance Go services to existing PHP systems without rebuilding everything. Strangler fig in practice instead of a big-bang rewrite.Tue, 03 Feb 2026 12:00:00 GMThttps://timrutte.de/en/blog/why-full-rewrites-fail/https://timrutte.de/en/blog/why-full-rewrites-fail/Rewrites fail, and so does standing still. Why the complete rebuild almost never works and how incremental modernization delivers measurable results.Sun, 11 Jan 2026 12:00:00 GMThttps://timrutte.de/en/blog/from-sphinx-to-manticore-search/https://timrutte.de/en/blog/from-sphinx-to-manticore-search/A search migration from Sphinx to Manticore about latency, relevance and operational discipline. From 5 seconds to under 100 ms in practice.Thu, 10 Jul 2025 12:00:00 GMThttps://timrutte.de/en/blog/technical-debt-as-business-risk/https://timrutte.de/en/blog/technical-debt-as-business-risk/Technical debt is not a developer problem. It is a business risk, and it grows quietly until it becomes visible exactly when there is no room for it.Thu, 03 Apr 2025 12:00:00 GMT