How do you tag docker images?

An interesting question came up at work today: how do you tag your Docker images? In previous projects, I’ve always used a short git sha, or sometimes a semver, but with no great consistency. As luck would have it, I had pushed for a change in tagging format at a client not so long ago as the method we were using didn’t make a lot of sense and, worst of all, it was a manual process....

November 10, 2021 · 6 min

Architecture Decision Records

This is a text version of a short talk (affectionately known as a “Coffee Bag”) I gave at work this week, on Architecture Design Records. You can see the slides here, but there isn’t a recording available, unfortunately. It should be noted; these are not to replace full architecture diagrams; you should definitely still write C4 Models to cover the overall architecture. ADRs are for the details, such as serializer formats, convention-over-configuration details, number precisions for timings, or which metrics library is used and why....

June 29, 2019 · 8 min

Microservices or Components

One of the reasons people list for using MicroServices is that it helps enforce separation of concerns. This is usually achieved by adding a network boundary between the services. While this is useful, it’s not without costs; namely that you’ve added a set of new failure modes: the network. We can achieve the same separation of concerns within the same codebase if we put our minds to it. In fact, this is what Simon Brown calls a Modular Monolith, and DHH calls the Majestic Monolith....

October 28, 2018 · 6 min

Feature Toggles with Consul

Feature Toggles are a great way of helping to deliver working software, although there are a few things which could go wrong. See my talk Feature Toggles: The Good, The Bad and The Ugly for some interesting stories and insights on it! I was talking with a colleague the other day about how you could go about implementing Feature Toggles in a centralised manner into an existing system, preferably with a little overhead as possible....

September 6, 2018 · 4 min

Evolutionary Development

Having recently finished reading the Building Evolutionary Architectures: Support Constant Change book, I got to thinking about a system which was fairly representative of an architecture which was fine for it’s initial version, but it’s usage had outgrown the architecture. Example System: Document Storage The system in question was a file store for a multi user, internal, desktop based CRM system. The number of users was very small, and the first implementation was just a network file share....

November 17, 2017 · 4 min

Strong Configuration Composition

It’s no secret I am a fan of strong typing - not only do I talk and blog about it a lot, but I also have a library called Stronk which provides strong typed configuration for non dotnet core projects. The problem I come across often is large configurations. For example, given the following project structure (3 applications, all reference the Domain project): DemoService `-- src |-- Domain | |-- Domain....

November 9, 2017 · 5 min

Repositories Revisited (and why CQRS is better)

TLDR: I still don’t like Repositories! Recently I had a discussion with a commenter on my The problems with, and solutions to Repositories post, and felt it was worth expanding on how I don’t use repositories. My applications tend to use the mediator pattern to keep things decoupled (using the Mediatr library), and this means that I end up with “handler” classes which process messages; they load something from storage, call domain methods, and then write it back to storage, possibly returning some or all the data....

September 9, 2017 · 2 min

Don't write Frameworks, write Libraries

Programmers have a fascination with writing frameworks for some reason. There are many problems with writing frameworks: Opinions Frameworks are opinionated, and will follow their author’s opinions on how things should be done, such as application structure, configuration, and methodology. The problem this gives is that not everyone will agree with the author, or their framework’s opinions. Even if they really like part of how the framework works, they might not like another part, or might not be able to rewrite their application to take advantage of the framework....

April 16, 2017 · 3 min

Don't Let The Database Dictate Your Design

I have been thinking recently about how the database can influence our design decisions, and perhaps makes them harder than they need to be in some cases. An example of this is the design of a system which stores data about people, specifically for this, their email addresses. A cut down version of the structure is this: table people id serial primary key firstname varchar(50) lastname varchar(50) table emails id serial primary key person_id int => people....

April 1, 2015 · 5 min

The problems with and solutions to Repositories

Repositories are a design pattern which I have never been a huge fan of. I can see the use of them as a good layer boundary, but too often I see them being used all over the place instead of at an infrastructure level in a code base. A particularly prevalent version of this misuse I see is self populating collections. These generally inherit List<TEntity> or Dictionary<TID, TEntity>, and provide a set of methods such as ....

March 28, 2015 · 3 min