Jan Mikoláš
How to install Docker
A simple installation for Windows, macOS, and Linux. At the end, you will check that Docker is really running.
Practical
Guides without the fluff.
Short procedures you can try right away. More guides will be added over time.
How to design a REST API in Symfony
From endpoint addresses through validation to clear JSON responses.
How to connect an online store to an external API
Safe authentication, reliable calls, and what to do when the other side does not respond.
How to automate product imports into an online store
How to turn a feed into a repeatable process that does not confuse prices or stock.
How to process webhooks correctly
Verification, a quick response, and safe processing without duplicates.
How to speed up a slow PHP/Symfony application
Find the real bottleneck before adding cache without a clear reason.
How to use Redis cache in a PHP application
What belongs in cache, how long data should stay there, and when to remove it safely.
How to process background jobs with RabbitMQ
Keep slow work out of web requests and make sure messages are not lost.
How to design an order state system
States, allowed transitions, and clear rules that keep an order under control.
How to prevent duplicate payment or order processing
A practical combination of idempotency, transactions, and safe webhook processing.
How to create a Docker environment for PHP, nginx, and PostgreSQL
A clear three-service baseline for a local PHP project.
How to start a new Symfony project for a real production application
From a clean project to an environment that will not surprise you at the first deployment.
How to use Dependency Injection correctly in Symfony
Pass dependencies clearly, test easily, and keep the container from taking over your design.
How to design the architecture of a larger PHP application
Split responsibilities so the code stays safe to change a year from now.
How to split a monolithic application into modules
A gradual split without a large rewrite or unnecessary coupling between parts.
How to design an internal company system
Start with people and their work. Only then draw screens and integrations.
How to identify what to automate first in a company
Choose a process that saves the most time and can still be verified safely.
How to connect two systems through an API
Agree the data, access, and errors before writing the actual request.
How to synchronize data between two systems
Set a source of truth, capture changes, and expect one system to be unavailable sometimes.
How to handle an external API outage
Do not let another service’s outage block your whole application or overwhelm the other side.
How to implement retry and exponential backoff
Retry only sensible failures, with a delay and a clear limit on attempts.
How to create an API client in PHP
Wrap HTTP communication in a small client with clear requests, responses, and errors.
How to implement API pagination
Choose between offset and cursor pagination and return everything the client needs for the next page.
How to implement API rate limiting
Limit traffic fairly, share counters through Redis, and return a clear HTTP response when rejecting a call.
How to secure an API with tokens
Separate identity verification from permissions and set safe token lifetime, storage, and revocation.
How to design API versioning
Keep routine changes backward compatible and introduce a new version only for a truly incompatible contract.
How to use Doctrine ORM correctly
Keep entities focused on the domain, queries in repositories, and writes within one application operation.
How to solve the N+1 problem in Doctrine
Measure the query count, load the required data deliberately, and avoid pulling the whole object graph into memory.
How to deploy database migrations safely
Split schema changes into compatible steps and prepare verification and recovery before deployment.
How to work with database transactions
Define one atomic operation, confirm it with commit, and safely revert changes with rollback after an error.
How to solve a database deadlock
Find conflicting locks, use a consistent operation order, and retry only the complete safe transaction.
How to create the right indexes in PostgreSQL
Design an index for a real query, verify the query plan, and account for write cost and index size.
How to find a slow SQL query with EXPLAIN ANALYZE
Read the most expensive plan nodes, compare estimates with reality, and fix the cause instead of adding random indexes.
How to store money and prices correctly in a database
Store amounts without floating-point errors, keep currency explicit, and round by one agreed rule.
How to import millions of rows without exhausting memory
Read CSV as a stream, write in batches, and release ORM state continuously instead of loading the whole file.
How to implement full-text search with Elasticsearch
Design documents and language analysis, synchronize data, and test relevance with real queries.
How to create product autocomplete for an online store
Return fast, relevant prefix suggestions without expensive wildcard queries or overwhelming the search cluster.
How a dead-letter queue works and when to use it
Separate permanently failed messages from normal traffic and define controlled inspection, repair, and replay.
How to design a reliable message consumer
Acknowledge only after success, distinguish retryable from permanent failures, and make processing idempotent.
Cron or message queue: which should you use for automation?
Use cron as a time trigger, a queue for individual jobs, and combine both without creating duplicates.
How to reserve stock correctly when placing an order
Reserve stock atomically under a lock, prevent overselling, and safely release expired order reservations.
How to design an online store for multiple countries and currencies
Separate market, language, and currency, preserve historical prices, and define localization, tax, and domain rules.
How to operate multiple online stores from one administration
Share products and workflows while keeping tenant, domain, permissions, and local configuration explicitly scoped.
How to automate order processing
Move orders through an explicit workflow, publish events, and process slow work idempotently through a queue.
How to connect an online store to a warehouse or ERP system
Choose a source of truth for every field, map stable identifiers, and design synchronization for outages and repeats.
How to design a product feed and automate its updates
Define a versioned XML or CSV contract, generate the feed as a stream, and publish it atomically on schedule.
How to write PHPUnit tests that actually matter
Test observable behavior and important rules, mock only real boundaries, and verify integrations with real components.
How to introduce PHPStan into an existing project
Start with reproducible configuration, contain existing debt in a baseline, and fix new errors without growing exceptions.
How to deploy a PHP application with Docker
Build one immutable image, run it consistently across environments, and separate migrations, configuration, and secrets.
How to set up CI checks for a PHP project
Run Composer validation, PHPUnit, PHPStan, and CodeSniffer as separate checks against the same environment version.
How to use AI practically when developing PHP applications
Give AI bounded context and a verifiable task, review changes with tests and humans, and never expose secrets.