OK, so we all know continuous integration CI, right?
It's pretty much the bedrock of how modern software gets built.
Merging, building basic tests. Absolutely.
CI is table stakes now. It solves that classic developer
headache. Merge conflicts, broken builds,
you know, right? But it often stops there,
doesn't it? The code gets built, maybe
passes some unit tests, but there's still this this gap.
It's not actually out there with users.
Exactly. CI often leaves the code, well,
in a kind of limbo. It's technically OK, maybe, but
not fully vetted for production. Or it's just sitting there
waiting for someone to manually push the big red button.
In that gap, that space between code merged and code live,
that's what we're diving into today.
We're moving past CI and into the deep end with continuous
deployment. Our goal here is to really
unpack continuous deployment or CD.
What is it? How does it radically change
things? And crucially, how is it
different from continuous delivery?
Because those terms get mixed up a lot.
They really do. And that core your idea of CD
is, well, it's pretty radical. It's total automation.
When you commit the CD, you're saying every single commit that
makes it to the main branch and passes tests go straight to
production automatically. No human gatekeeper, no final
sign off. Nope.
Typically within hours, sometimes minutes that.
Kind of speed is. It's almost scary.
It really begs the question, how can you possibly trust a system
moving that fast? If you take out the manual
checks, the automation has to be absolutely bulletproof.
It does, and that's why the workflow is key.
OK, let's get into that right? How does a piece of code
actually travel from a developer's laptop to the
customer screen in this fully automated CD world?
It's a very structured, automated 4 step process.
It has to be much more rigorous than just basic CI.
Think of it like the automation demands complete accountability
at every single stage. OK, walk us through it step by
step. All right, step one is still
local. The developer writes their code,
tests it thoroughly on their own machine.
You know, make sure it works before it even goes anywhere
else. Standard practice.
Right then, Step 2, they commit the code, the CI server
immediately picks it up, reruns those basic unit tests just like
normal CI. OK, still sounds like CI.
So where does it diverge? What makes this a deployment
pipeline, not just integration? The divergent is really in Step
3, the sheer magnitude of the automated validation.
This is where it gets serious. Several times a day the pipeline
grabs commits that pass the initial checks and throws a
whole battery of additional non negotiable tests at them.
What kind of tests are we talking about?
We're talking heavy duty stuff, rigorous integration tests,
making sure different parts work together, full end to end test
that simulate real user journeys, performance and load
testing, maybe simulating thousands of users or running
against a production like staging environment.
So it's not just does the code work in isolation, it's does it
work under pressure with everything else.
Exactly. It's testing against a simulated
reality. The system has to earn its trust
through this intense validation. OK, makes sense.
And then Step 4 is the payoff if and only if all those
comprehensive tests pass. Only if everything is green.
Then the commits are automatically deployed into
production. Customers get access almost
immediately, and crucially this usually includes things like
automated production health checks, 0 downtime deployment
strategies, and importantly, automatic rollback capabilities
if anything looks off post deployment.
So there are safety Nets built into the automation.
Absolutely. That's how you build trust in a
system like this. OK, so assuming you have this
incredibly robust, trustworthy automation, what's the big win?
What is this actually by the organization?
Let's talk advantages like the feature funnel idea.
Right, the traditional way is often batching features, right?
You wait for feature F1F2F3 and maybe all the way to F and then
do one big risky, stressful release.
We've all lived through those weekends.
Oh yeah, continuous deployment flips that entirely.
Features don't get batched, they get released the moment they are
ready and pass the test. More releases, but smaller ones.
Exactly. Way more frequent releases, but
each one contains far fewer changes.
This dramatically reduces the time between a feature being
done and a customer actually using it.
And that ties into making releases boring, right?
And not event it gets rid of that huge deadline pressure.
Precisely. Those big release deadlines are
a massive source of stress. Missing 1 can push a critical
feature back by weeks, even months.
CD basically eliminates that specific type of deadline
pressure. The code goes out when it's
ready. Period.
That must be huge for developer morale too.
It really is. Imagine you finish a piece of
work and within hours, potentially real customers are
using it. You're not just coding into a
void for months on end. You get that feedback loop
incredibly quickly. Yeah, that immediate connection
to impact must be powerful. Definitely, and it fuels another
big advantage, data-driven development and experimentation.
When you can deploy small changes so quickly, you can
start treating deployment as a learning opportunity.
How so? Like AB testing.
Exactly like AB testing or using feature flags.
You don't have to launch a big new feature to everyone at once.
You can deploy it behind a flag, turn it on for maybe 1% of
users. See how they react.
Collect real world data. And then decide whether to roll
it out further, tweak it, or even scrap it based on actual
usage, not just guesswork. Precisely.
Deployment becomes part of the product discovery process, not
just the endpoint you ship to learn.
OK, this all sounds great philosophically, but let's
ground it. Our sources mentioned some
concrete data from Facebook back in 2016, a place known for
massive scale CD. It really shows how small these
changes need to be. Yeah, that data is pretty eye
opening. It really highlights the
discipline required. On average at Facebook then,
each developer was deploying about 3.5 updates into
production per week. 3 1/2 * a week per developer.
Wow. And the size.
This is the kicker. Those updates added or modified
on average only 92 lines of code. 92 lines.
That's tiny. Almost nothing.
It's incredibly small. It means developers just cannot
work on huge, sprawling changes that touch everything.
The whole model relies on atomic commits.
So what's the skill shift there? What is that demand from
engineers? It demands a very specific
skill, the ability to break down complex problems, even big new
features, into tiny, independent, safely deployable
chunks. Each chunk has to be testable on
its own and releasable on its own.
Because if you have a massive pull request touching thousands
of lines. The automated pipeline grinds to
a halt, the risk skyrockets, and the whole CD advantage just
evaporates. It forces an architecture and a
mindset focused on small, incremental steps.
Right, it sounds like it really favors architectures designed
for isolation and independent deployment, like micro services
maybe. It certainly aligns very well
with those kinds of architectures, yes, but the core
principle is decomposition, regardless of the specific
architecture. Even and large refactorings have
to be done incrementally, often using techniques like parallel
runs or feature flags to avoid breaking anything.
So discipline and decomposition are key.
Absolutely fundamental. OK, this makes a ton of sense
for say a web application or a back end service where updates
can happen behind the scenes transparently to the user.
But it can't be the right answer for everything, can it?
No, definitely not. And that's where we need to draw
that crucial distinction we mentioned earlier, continuous
deployment. This fully automated model isn't
really suitable for certain types of systems because the
update process itself isn't transparent or server
controlled. Think about desktop
applications, your IDE maybe, or a web browser or embedded
software like firmware for your printer.
Things you actually have to install on your local machine.
Exactly. These rely on client resources,
user permissions. You can't just push an update
silently from a server. The user usually has to actively
download and install it, and users frankly don't want
mandatory installs popping up multiple times a day.
Yeah, that would be incredibly annoying.
So for those kinds of systems where there's a manual client
sidestep involved, what's the alternative?
The alternative, and the term that often gets confused with
CD, is Continuous delivery. We sometimes call it CDEL for
short. OK.
Continuous delivery. How is it different?
The core idea is smaller in the preparation phase.
With continuous delivery, every code push is still automatically
built, tested, and prepared for immediate deployment.
The delivery part is still continuous and automated.
The code is ready to go at any time.
OK, so the automation handles everything up to the release.
Precisely. The crucial difference is that
final step, the actual deployment to production,
requires manual authorization. Someone, an external authority,
has to give the green light. Who's that authority typically?
Could be a project manager, could be someone in marketing,
maybe a dedicated release manager.
It depends on the organization. The point is, the code is
technically ready, verified, probably sitting in a staging
environment, but a human makes the call on when to push it
live. And why hold back if the code is
ready and tested? What drives that manual
decision? It's.
Usually business or strategic reasons, not technical ones.
Marketing campaigns, maybe coordinating with a big
announcement or a trade show, perhaps seasonal timing or other
corporate strategic initiatives. They want to control the exact
moment the feature becomes available, even if engineering
finished it weeks ago. Got it.
So the when is driven by strategy, not just readiness.
Exactly. OK, so let's really nail down
these definitions then. It sounds like they hinge on the
difference between getting ready and actually releasing.
That's a great way to put it. The source material defines it
clearly. Deployment is the actual act of
releasing new software versions to customers.
Putting it out there, right? Whereas delivery is the process
of preparing those new patients for potential deployment,
getting them ready, fully tested, lined up on the
launchpad. OK, so summarizing in continuous
deployment CD, both the preparation delivery and the
release deployment are automatic and continuous full end to end
automation. Correct, it's a completely hands
off pipeline once the code is committed.
Whereas in continuous delivery sidelo, the preparation delivery
is frequent and automated, ensuring the code is always
release ready, but the final deployment step requires that
explicit manual go ahead. That's the key difference, the
human authorization for the final release.
It seems like regardless of whether a company fully embraces
CD or OPS for C Dell, the overall trend is clear, isn't
it? Everyone is trying to shorten
those release cycles. Absolutely.
Whether it's fully automated deployment or just continuously
delivering release candidates, the whole industry is moving
towards faster, more frequent releases.
It's about staying competitive, getting feedback faster, keeping
users engaged, and frankly, keeping development teams
motivated. Yeah, the days of the massive
once a year release seem numbered for most software.
Definitely, the pressure for speed and responsiveness is just
too high. So the big take away here, maybe
the thing to really chew on isn't just about the tools or
the automation pipelines. It's how adopting something like
continuous deployment forces a fundamental shift in
organizational culture. It changes how you think about
risk, how you handle failure, because small failures happen
more often but are less catastrophic, and critically,
how you train engineers to breakdown work.
Not just features, but the smallest possible safest
component of a feature. It really does demand a
different mindset, a mental restructuring almost focused on
constant incremental progress and immediate accountability.
Constant immediate accountability.
That sums it up well. Well, thank you for joining us
for this deep dive into the world of continuous deployment
and continuous delivery.