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**Gerhard Lazu:** I think that worked out really well, because what you did manage to do was spend a bit more time on those videos that I've alluded to in the past... And that is actually how I came across, like "Oh, Dave Farley? I've heard that name. Continuous Delivery? Okay, I haven't read it, but I've heard of that... |
The second step is you were able to capture some concepts in very simple terms, in very good terms, and these concepts stood the test of time. So that's out there, it's super-valuable, and it will continue being valuable for many years to come, I'm sure of it. |
If someone's listening to this and wants to do this, that would be really interesting... Like, what would a GitHub Actions pipeline look like, for example, that resembles Dave's ideal pipeline? I think in your videos you even have -- like, that graphic keeps coming up. Do you have a specific course or book that talks m... |
**Dave Farley:** I do. So the Continuous Delivery book that we've been discussing talks in broad principles about continuous delivery, and the deployment pipeline is kind of the core of the book, but it's not all the book's about. I have another book that was released this year on Leanpub, which is more of a focus manu... |
\[48:06\] It's a pattern, so you would expect it to evolve over time and to morph into different shapes, so you take it parallel, and so on. But it seems to me there are some fundamental things, is that your fast feedback on the technical quality of your work as a development team, and then you need confidence to know ... |
So you need to think about this as kind of a machine, a parallel computing algorithm, if you like, so that you can kind of trade-off - getting the fast feedback, and then moving ahead in confidence that you're likely to get good feedback from later stages. So if thinking in those sorts of terms helps you model it... I ... |
**Gerhard Lazu:** It's almost like a template for pipelines. |
**Dave Farley:** Yes. |
**Gerhard Lazu:** If there was a template that captured these important elements that need to be present, and then from that, it's almost like an RFC, and then from that you have a specific implementation which is for maybe a specific CI, and then you have variations of that implementation in whichever CI it is. |
**Dave Farley:** Yes. And there are key stages that I would a system of any complexity would probably want to parallelize and grow, to get fast feedback... What people took from the idea of continuous delivery was -- when people think about deployment pipelines, I think what most people probably interpret that to mean ... |
If at the end of a deployment pipeline you've got more work to do, it's not finished. It's not a deployment pipeline. The objective of a deployment pipeline is go commit to a releasable outcome. It doesn't mean you have to necessarily push the thing into production. That depends on the business, whether that makes sens... |
So that's what we're trying to get to... And if you're thinking about that - so what does that then take? Well, it depends on your system. But at a minimum, you want to know that the software works, it does what you think it does as a developer, and is deployable and does what the users want. As an absolute minimum, yo... |
So part of this is really to address the problem of how do you get organizations to start buying into this, and what you wanna do is that you wanna make it really easy to do the right things, or what you think are the right things, and possible to do other things. That's my approach. So I would like it to be absolutely... |
And now, as a developer, I'm gonna press the button, get my template out, start building my project against that template, and my deployment pipeline just starts functioning. Instead, at the moment, with all of the technologies that I've tried so far, I pretty much have to go through that exercise every time to set som... |
**Break:** \[52:35\] |
**Gerhard Lazu:** Okay, let's do this... My assumption is that the pipeline that we use to push Changelog.com updates out is wrong. So my assumption is wrong. This is what the pipeline is, and I would like you to tell me what your thoughts are on the pipeline. |
**Dave Farley:** Okay. |
**Gerhard Lazu:** The pipeline, whenever there's a commit to the GitHub repository, it pulls down the code, it runs a build... By the way, it's an Erlang-based project, Elixir-based project, so it has to fetch some dependencies, compile the code... So that's the first step. And then it fans out into two other steps. On... |
All those things put together, it takes maybe up to ten minutes to run. it can be a bit slow, but we won't get into that. The point is that the pipeline ends at publishing this artifact to a repository. And this is like an artifact repository. |
In production, we receive notifications, "Oh, there's a new artifact." And the production system - in this case it's Kubernetes - knows how to pull the latest version down, how to do blue-green deploy, and there are checks which make sure that the new version actually works. It connects to the database, the health chec... |
All this happens within 15 minutes. A lot of it is just like slow workers... Anyways, it's a lot of free infrastructure there, especially on the build side. But within 10-15 minutes every commit goes out into production. What are your thoughts about this pipeline. I'm assuming it's the wrong one based on your descripti... |
**Dave Farley:** \[laughs\] I think all of the things that you've said - I can't be too critical of it, because it's working. So I'm nothing if not a pragmatist. Let me critique it, nevertheless. |
**Gerhard Lazu:** \[56:10\] Yes, please. |
**Dave Farley:** So I think what you've said - I think the implications of what you've said is as a developer I don't know that I'm ready to move on to something new until after about ten minutes, when you've run all of your tests. That seems a little bit slow to me. I suppose it depends how big or complicated the code... |
**Gerhard Lazu:** Okay. |
**Dave Farley:** So when I say a pipeline, I don't mean a straight line. What I mean is an instruction pipeline. And an instruction pipeline in a Pentium processor was a branch prediction algorithm. So at a point in which you come to a branch in the code, a Pentium processor will start three threads of executions, thre... |
At the point at which a developer commits a change, my recommendation for a way of working is that you sit and you wait for the results of the tests. And at that point, what I'm looking for is a high level of confidence that if all of those tests pass in the commit stage, then everything else is gonna be fine. If my te... |
So I'm gonna run very fast, very efficient tests in the first stage, in the commit stage. It's gonna be focused on a really technical evaluation of what we're doing. Then I'm looking for the deployability of that. One of the things that you said was that the first time that you actually deploy the software is in produc... |
**Gerhard Lazu:** Yes. It goes straight into production, yes. |
**Dave Farley:** Yeah. So how often is that a problem? Does it ever cause a problem, or does it always work? |
**Gerhard Lazu:** It always works. |
**Dave Farley:** Then I can't critique it. For other kinds of software though, I wanna test the deployment of the system. I want to test that that works... Because it changes over time. If you introduce a new service, or something that's different, then you're gonna be evolving that over time, so I'd like to be able to... |
These days I make a living as a consultant, advising usually large companies on how to improve their software engineering practices... And one of the companies that I worked with was Siemens Healthcare. They're building machines that can kill you if they get the wrong -- you know, these medical devices in hospitals. Th... |
\[01:00:07.16\] So I must say, I can't really critique your project very well, because it sounds very good. It's light years ahead of probably whatever average means in our industry. |
**Gerhard Lazu:** This was really good, because even talking to you about how it works, I realized why certain layers are so slow. Why this takes 15 minutes. And it's not the tests. The tests run in maybe 15 seconds. The tests are really fast. But it's all the caches, of dependencies, of pulling things down, of running... |
When we run this in the CI, there's a queue. So your jobs may be queued for maybe 30 seconds or a minute. And you have multiple jobs, you have containers, you have to pull down images that may or may not be on the node or on the host where they run. And all those things, like the cache misses, can mean 30-45 seconds...... |
What is the impact of something not working? Well, when we deploy into production, the reason why it's slightly slower is because the first thing that we do is we back up the database before we're running the migration, so there's a full database backup every single time a new version starts. We backup all the assets t... |
**Dave Farley:** I have a good video on that topic. |
**Gerhard Lazu:** I know you do. We will definitely discuss that next. And in front of the website there's a CDN which serves all the content cached. So if the origin is down, if the app is down, that's okay. Everything is cached worldwide. So we serve the cached content. So the impact on end users is none. They see th... |
But anyways, I would love to talk more about this, but we're running out of time, and this just shows how much we have to talk about... I would really like to talk about your YouTube channel next. So what made you start your YouTube channel? By the way, for those that don't know about this amazing -- it's my favorite Y... |
**Dave Farley:** The simple answer is it was Coronavirus. |
**Gerhard Lazu:** Finally, there's a positive... \[laughter\] |
**Dave Farley:** So it's something that I kind of had in the back of my mind for a long time. I am approaching the end of my career. I've done a lot of interesting things... I am opinionated, as you can probably tell from my conversation, about software... And I think that the teams that I've worked on, I've found some... |
\[01:03:59.00\] I think that if people just did that, then they would find a dramatic, experience-changing improvement in their experience of building and delivering software. You genuinely can build better software, faster, doing these techniques. |
Sometimes I err on the side of being too prescriptive about some of these things, possibly, but I wanted to start talking about those things. And I've been talking at conferences for some years, working as a consultant for some years, helping people to do this kind of thing. And I had in the back of my mind it'd be nic... |
Sometimes some of the comments are not quite so delightful, but usually they are. Mostly they're lovely. And I've had a fantastic time. I think it helped to keep me, my wife and my son saner than we would have been otherwise through the process. |
We have released a video every week at 7 PM on Wednesday since the start of the pandemic, and we haven't missed one yet. |
**Gerhard Lazu:** Now, I have to thank you again... I find myself thanking you so much, because those videos - they are like a breath of fresh air. There's so many videos obviously on YouTube; it's massive. For me at least, and for our family, it's like the new TV. We use YouTube way more than anything else. Netflix is... |
I'm sure that some of the information that you convey - it will not hit home until a few months later, or maybe even a few years later. It's simple, but there's so much there. And my favorite one - you keep mentioning Elon Musk, by the way... If you know him, or if someone that knows him is listening, I really want to ... |
Now, I try to limit myself to three. This was my top. The other one is "How to build quality software fast." That shipped yesterday. I mean, if you're paying attention, there are videos that you're just publishing which are top, so they are getting better, in my mind... "Why CI is BETTER than feature branching" - I wou... |
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