Alberto Corrales Garcia

Introduction In AWS, managing your IAM in a centralized account is a good practice, so then you can assume a role to access to other accounts without need of duplicating users. You can find more info about this approach in this article . In addition, for security reasons, it is highly recommended to enable MFA (Multi-factor Authentication), so you need a device to generate a temporary code to get access. In the image below it is showed how assume role with MFA works, but you also have an article about MFA in this link . This approach is really useful and most of the configuration can be automated with pulumi (or other providers like terraform or CloudFormation). And once it is configured, you can switch your role and get access to other accounts with a few clicks.  However, when it comes to external software such us pulumi, getting access assuming a role and using MFA might not be too straightforward. In this article we will see how this can be configured and how we can easily refr...

Introduction to Event Sourcing and CQRS The fundamental idea of Event Sourcing is ensuring that every change to the state of an application is captured in an event object, and that these event objects are themselves stored in the sequence they were applied for the same lifetime as the application state itself. (For more information about Event Sourcing I recommend this post written by Martin Fowler ). Based on my experience working with Event Sourcing, having the sequence of events allows you to perform awesome functionalities, like time travelling or replaying your events into multiple storage technologies. However, it can be tricky for some scenarios. To explain this better, I need to introduce Event Sourcing working together with Command Query Responsibility Segregation (CQRS). If you are not familiar with CQRS, the idea behind it is splitting commands (write operations) from queries (read operations), so they can work independently. (more info about CQRS in this post ). CQRS an...

Introduction Micro-services architecture is becoming trendy since it is a suitable option many projects, specially those that are complex and we want to be able spilt our business logic into different services that can be built and deliver independently. In spite of the fact that micro-services architectures are more complex, they increase the resilience of your system and increase the time-to-market delivery, which can be crucial for many companies. But it is not all about services and backend. With the introduction of single page applications (SPAs), we can build fully-functional user interfaces that can work independently in the browser. And here we should ask ourselves the same questions as for backend applications: Is my SPA becoming a huge monolith? Would I like to deliver functional modules independently? If you using micro-services, is there a relation between my services and your UI? Do we want to have functional teams that can deliver new features (frontend+backend) independe...

Introduction It is awesome to have some useful services like ElasticSearch managed by AWS , so you don't have to care about patching, monitoring, etc.  When it comes to backup management for indexes, Amazon ElasticSearch includes automated snapshots. Automated snapshots are only for cluster recovery. You can use them to restore your domain in the event of red cluster status or other data loss. Amazon ES stores automated snapshots in a preconfigured Amazon S3 bucket at no additional charge. In particular, if you are using a higher version than 5.3, Amazon ElasticSearch takes hourly automated snapshots and retains up to 336 of them for 14 days. However, this policy might not be enough if you need to keep your snapshots for a longer 15 days, or you need to take a snapshot to create a new cluster in another region, subnet, etc. If you have different requirements to manage your snapshots, you will have to work with manual snapshots. For this part, AWS does not offer a good managed exper...

Introduction  EventStoreDB (ESDB) is an industrial-strength database technology used as the central data store for event-sourced systems. It is available open-source to run locally on most platforms or as SaaS through Event Store Cloud. Currently their SaaS version is under development, so if you want to run it on your cloud, you will have to set it up. One option is docker, since ESDB is available as docker image on Docker Hub . However, as Greg Young explains in this issue , it might be not the best option when it comes to performance, due to the extra virtualization layer. For the same reason, we don't usually use docker images for other database engines like SQL Server, MongoDB, etc. Then, if you want to run ESDB on cloud, in particular AWS cloud, EC2 + EBS is the most reasonable option.  In this post, I would like to share how you can configure ESDB on EC2+EBS easily with Pulumi, which will allow you to automate this process following the best practices. Creating EC2 with...

In "Working Effectively with Legacy Code" Michael Feathers introduced a definition of legacy code as code without tests, since a code without tests is difficult to maintain, extend and evolve. It doesn't matter if you are using the latest technologies, if you don't test your code, it will hard to change without breaking anything, which will make it rigid and difficult to maintain. Remember that unit tests are the base in the testing pyramid. In order to ensure that you are covering with unit tests the most important part of our application, code coverage can be helpful to detect where you have lack of tests. Code coverage is a tool offered by products like ReSharper or the Enterprise version of Visual Studio . However, these products are not free and you might not want to pay for this essential feature. But if you are working with dotnet core, it is quite easy to get a code coverage report thanks to ReportGenerator package. In order to generate your tests, first...

  Introduction If you are working with Microservices, you might have noticed that you are repeating over and over the scaffolding for your new microservices. In order to make easier the creation of new microservices, you can build your own custom dotnet core template . Apart from saving time, building a custom template will help to promote good practices, a proper architecture, right dependencies, etc. With this purpose, I have built my custom template, so it can help us to create easily new microservices based on CQRS and DDD, without having to build the same scaffolding each time we have to create a new service. Microservice architecture In microservices architecture, each service can be different, according to the problem it has to solve. However, it is likely that you have a reference architecture that will provide some consistency and it will promote good practices. In our case, the main patterns that drive our microservice architecture are Domain Driven Design (DDD) and Comma...