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The (Im)Practical Continuous Delivery

nikoheikkila profile image Niko Heikkilä ・5 min read

This week I participated in a 2-day training session about pragmatic solutions in Continuous Integration, Delivery, and Deployment. I was there because one of our strategic goals at work is to increase the velocity of our product development.

As has been written, implementing a polished development, integration, and testing pipeline as part of your workflow should greatly help you deliver a consistent product passing all the quality gates and striking your customers with constant excitement. If you want to read more about the benefits of Continuous Delivery I warmly suggest you read this post written by @stenpittet .

At first, I thought how hard can implementing a consistent pipeline be? My workflow is already sharpened to the maximum and I'm able to solve multiple problems in a day given the right set of tools. Thanks to our great instructor the reality quickly dawned on me...

Therefore, in this post, I will list methods that I have grown used to in my work but which turn out to be the dreadful anti-patterns of Continuous Integration and Delivery. Naturally, as a disclaimer, there are plenty of articles explaining more anti-patterns so please keep in mind this list is inherently a personal and not a complete one. All of the anti-patterns below reflect my personal experience.

Anti-Pattern #1: Feature Branching

In Continuous Integration model, developers should push their code directly to mainline (eg. the master branch of your Git repository) at least once a day.

What I do instead is that I sit on top of my feature branches for days if not for weeks often rebasing the changes from the parent branch but never pushing back to the mainline. This is so because at work we follow a strict Kanban workflow where for safety and authorization we require both peer review and manual testing before the feature will be merged to mainline.

A downside of the feature branching is that it completely isolates developer from the rest of their team. Despite aggressive rebasing, I still end up with bloody merge conflicts on my hands from time to time. Why is that?

The answer is simple: isolation hinders communication.

I tend to keep the code firmly in my grasp and not discuss it unless I hit a real blocker issue. This effectively leads to two outcomes: a) I end up implementing more than required (YAGNI) slowing me down, or b) implementing the wrong things slowing me down even further as I need to rewrite the code.

To solve this problem and for Continuous Integration to really pick up by the book we should give up feature branching altogether but I'm not convinced that I and my team are prepared for that anytime soon. On the other hand, designing new features as smallest possible increments and merging them rapidly from the feature branches to mainline could work.

Instead, I would like to bump up my communication skills by doing more pair-programming. Lately, I've been practicing it in a real DevOps fashion by pairing up with one of our ops guys – him bashing the server while I'm bashing the code. If you ask me, we have delivered exceptionally well on that front.

Furthermore, when I need a code review I should boldly ask my colleague to review it instead of letting the issue hang on board for ages. I know, I know. It's simple, right? Or not for an introvert type of guy like me. We as developers should start paying more attention to the soft skills of development like communication, cooperation, and empathy to name but a few.

Anti-Pattern #2: Testing Starts Only After the Feature Is Ready

This is something that most quality assurance specialists have probably felt as a rusty nail stuck through their heels. Imagine a couple of huge user stories consisting of 20–30 new increments being developed in parallel. After all of the (painful) merges have been carried out and the code has been merged to mainline in a code freeze ceremony (an anti-pattern itself) it's time to begin testing for regression bugs before releasing to production.

Regression testing will take several days at the minimum even for a professional testing department while developers are either sitting idle waiting for possible bugs to be reported from testing or move on to next features effectively causing unnecessary context-switches between different tasks. I, for one, have a very hard time remembering the code I've written when I'm asked about it a couple of days or weeks later.

The obvious solution here would be to invite your peers to test your code while you're still developing it. Again, pairing up is a favorable method for solving this problem. As a matter of fact, testing specialists should be included in the development sprint from the earliest feasible meetings all the way to the last sprint reviews. Letting them come in as the last step of iteration will only hurt themselves and developers.

Anti-Pattern #3: Junk in the Trunk

Continuous Integration checklists demand that all code will be tested locally before pushing to mainline. Normally when developing code locally I run static code analysis and unit tests waiting for them to pass before creating a new commit. Then how can it be that some of my changes still introduce bugs and breaking changes even though all tests have passed and test coverage is flying high?

Well, if you've been reading this post with the attention I kind of explained it in the Anti-Pattern #1 section. Bugs and breaking changes (junk) in your mainline (trunk) weakens the Continuous Integration and Delivery pipeline making it less reliable and require more manual testing. Furthermore, your version control history will look funky with all those commits that attempt to fix stuff.

Conclusion

For personal projects where you often work in a single branch, it's easy to configure for example Travis CI for building the commit stage of the pipeline and reporting possible errors before packaging the software or shipping it to production.

For both open-source and closed commercial projects involving dozens of people, the transformation to the best practices of Continuous Integration and Delivery will be harder since it's first and foremost a cultural issue. I think any community or company can make the transformation happen if they really want it. I'm committed to starting tackling the mentioned anti-patterns as much as possible wherever I might end up in this career.


Cover image by Nhan Ngo licensed under Creative Commons BY-SA license.

Discussion (10)

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mattkocaj profile image
matt kocaj

Feature Branches are fine, provided you apply discipline and rigour - just like all of your DevOps/agile practises.

The key, like you highlighted is #smallbatches. Feature Branches over one or two days are fine. I’ve worked on teams where every time one pushes a new branch they create a new Pull Request. The convention then is to immediately glance over the other 3-5 PRs in the list. This “give and take” attitude ensures that devs are not left isolated, review happens async, and everyone is encouraged to use Feature Toggles/Flags to get their work into master as soon as they can.

Mainline development is critical in CI/CD but when I say that I don’t exclude Feature Branches. A team more than two pushing direct to master every day only works when everyone is very disciplined or experienced. In my experience, that’s a rare luxury.

As usual, I find the answer is always “it depends”. Please don’t write off Feature Branches. They are most certainly compatible and IMO, a core component, of an agile team and process.

More here leanpub.com/agileforteams/read#lea... and here leanpub.com/agileforteams/read#lea...

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elmuerte profile image
Michiel Hendriks

I dislike features branches. If you think you need this your software is probably too big and/or not properly modularized.

Shippable products should be collections of configured modules of a certain version. Creating a new feature would either result in: a new version of a module, or even a completely new module. If the feature is not ready you can still ship your product with an older version of said module.

Feature branches also have the bad assumption that when it all comes together that it doesn't completely break down. Merging is never free, and hardly ever trivial.

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nikoheikkila profile image
Niko Heikkilä Author

Well said. With poorly designed monolith software continuous delivery is surely to be a rocky path. I've been studying microservices a lot lately and hopefully I can build my next projects to be more modular while dropping the excess branching.

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stenpittet profile image
Sten

Thanks for the mention! I'd love to see more people like you talking about their experience with CI/CD. Quite often we only get to hear about the companies that have mastered their implementation and tell you that all their commits go to production within 10minutes. I think that it benefits everyone to have these stories showing progress towards a great CD workflow.

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nikoheikkila profile image
Niko Heikkilä Author

Thanks! I'll try to write more posts if and when something noteworthy happens on CI/CD journey.

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mykezero profile image
Mykezero

What's been working particularly well for my team is creating a shared sprint branch.

At the beginning of a sprint, we'll create a shared sprint branch off of master.

Features branches are then created off of the sprint branch. Once the work is finished, the feature branch is immediately merged back into the sprint branch.

At the end of a sprint, the sprint branch is merged back into master, and a new sprint branch is created and based off that work.

I think this balances both worlds: one where we can work independently of each other, but also avoids costly merges at the end of sprints.

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nikoheikkila profile image
Niko Heikkilä Author

This sounds like a reasonable solution, and we too have taken a similar approach with story branches. In Continuous Delivery you can deliver multiple times inside a sprint which makes the union of Scrum and CI/CD very interesting.

Do you ever deploy the sprint branch or do you wait for it to be merged to master?

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okolbay profile image
andrew

« Despite aggressive rebasing, I still end up with bloody merge conflicts on my hands from time to time. Why is that?»

there’s another reason why this might happen - you dont have conflicts, if your changes don’t overlap with others. Why are you working on the same code as others? Two reasons - lack of communication, and as a result, two similar so identical features are developed, or your software is coupled and lacks separation of concerns, and virtually any feature requires touching “god classes” here and there.
I mean conflicts can still happen, in config files for example, but I assume if conflicts hurt - its domain code )

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nikoheikkila profile image
Niko Heikkilä Author

Yes, Kent Beck is one author along with Jez Humble and Martin Fowler whose works I've been advised to read more.