CD: Continuous Delivery

Nowadays, our development teams use Agile methodologies what means that we have accelerate our processes trying to deliver small chunks of functionalities to receive early and real feedback from users to continue iterating our ideas.

Now, we are an organization that follow and use Continuous Integration practices but, we are still missing something. We are not able to receive this feedback if it takes ages between our developers finishing their tasks and the code been deployed in to production where our users can use it. In addition, when a lot of changes or features are delivered at the same time, it makes more difficult to debug bugs on solve possible errors. For a long time, the deployment process has been seen as a risky process that requires a lot of preparation but, this needs to change if we want to be truly Agile.

Here it comes Continuous Delivery (CD). Continuous Delivery is a practice that tries to make tracking and deploying software trivial. The goal is to ship changes to our users early and often, multiple times a day if possible, to help us minimize the risk of releasing, and giving our developers the opportunity to get feedback as soon as possible.

As I have said before, we should have already a Continuous Integration environment to ensure that all changes pushed to the main repository are tested and ready to be deployed. Can it be done without a CI environment? Yes, probably, but more probably we are going to create a machine that it is just going to push our bugs faster to production increasing our risks.

Steps we need to take

Create a continuous delivery pipeline

The continuous delivery pipeline is a list of steps that happen every time our code changes till it finds its way to production. It includes building and testing the application as part of the CI process and extends it with the ability to deploy to and test staging and production environments.

With this we will achieve two things:

  • Our code will be always ready to be deployed to production.
  • Releasing changes will be as simple as clicking a button.

Create a staging environment

All of us, generally, have been writing code in some point in our lives, some of us still do it, some of us have evolve our careers but, something that I am sure all of us remember are these cases of “it worked on my machine…”. Configurations, differences in environments, networks… There are thousands of things that can be different and can go wrong, and probably it will go. No matter how many test we have locally, how many precautions we take, our local conditions are not going to be the same than our production conditions. For this reason we need an intermediate environment, the “staging” environment.

The “staging” environment does not need to support the same scale as our production environment but it should be as close as possible to the production configuration to ensure that the software is tested in similar conditions.

The “staging” environment should allow us to see things before it happen. If something is going to break, it should break in this environment. Using this environment, our release workflow should be similar to:

  1. Developers build and test locally a feature.
  2. Developers push their changes to the main repository where CI tests run automatically against their commits.
  3. If the build is green, the changes are released to the staging environment.
  4. Acceptance tests are run against the staging environments to make sure nothing is broken.
  5. Changes are now ready to be deployed to production.

An additional advantage is that it allows our QA team and product owners to verify the software works as intended before releasing to our users, and without requiring a special deployment or access to a local developer machine.

Automate our deployment

Or, we need to create a “green button” that once it has been pressed, without any other human intervention is going to deploy our code in staging or production.

We can start building some scripts that we run from our development machines and, after that, we can add them to a any CI platform.

There are many ways to deploy software, but there are common rules that maybe we can use as guidance:

  • Version the deployment scripts with our code. That way we will be able to audit changes to our deployment configuration easily if necessary.
  • Do not store passwords in our script. Instead, use environment variables that can be set before launching the deployment script.
  • Use SSH keys when possible to access the deployment servers. They will allow us to connect to our servers without providing a password and will resist a brute force attack.
  • Make sure that any build tools involved in the pipeline does not prompt for user input. Use a non-interactive mode or provide an option to automatically assume yes when installing dependencies.
  • Test it, test it and test it again. Make sure everything deploys as expected, that nothing is missing no matter what kind of changes you are doing.
  • Maybe, it is a good moment to write some smoke test, if you do not have it, to check if your machines are up an running.

Include data structure changes

Let’s face it, when our application changes the code is not the only thing changing. The data structures change too. And, we are not going to have a CD environment if this changes are not added to our automatic deployments.

First, create backups. No matter how good we are, how little is the change, something is going to fail in some point and we want to be able to restore the previous state of the application.

Second, there are multiple tool that can help manage data structure changes as code. Some frameworks bring their own to the table but, if not, we can find tools that fit our technologies and ideas. Just learn them and use them.

All together and the last detail, the CI server

Arriving here, we have set a CI environment with a CI server and we have a “button” to run our deployments, now, why not put everything together?

To do this, we just need to add a manual step in our pipeline to release (press the button) the code to our different environments.

Now, every time our code is merged and ready to production, following business needs, we just need to push the button and release. This give us a great control of our deployments. The only precaution we need to take is not to leave to many commits accumulated.

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CD: Continuous Delivery

CI: Continuous Integration

Continuous integration (CI) is a practice where team members integrate their code early and often to the main branch or code repository. The objective is to reduce the risk, and sometimes pain, generated when we wait till the end of the sprint or project to do it.

One of the biggest benefits of the CI practices is that it allows us to identify and address possible conflicts as soon as possible with the obvious benefit of saving time during our development. In addition, it reduces the amount of time spent in regresion test fixing bugs because it encorages to have a good set of tests. Plus, it gives a better understaning of the features we are developing and the codebase due to the continuous integration of features in our codebase.

What do we need?

Tests, test, tests… Automatic tests

To get the full benefits of CI, we will need to automate our tests to be able to run them for every change that is made to the repository. And when I say repository, I want to say every branch and not just the main branch. Every branch should run the tests and it should not be merged till they are green, all of them. In this way, we will be able to capture issues early and minimise disruptions to our team.

Types of tests

There are many types of tests that can be implemented. We can start small and grow progressibely our coverage. The more meaningfull tests we have the better but, we are running a project, we should find a balance between releasing features and increasing our coverage.

How many should I implement?

To decide about that, we just need to remember two things. The first one is that we want meaninful tests, we should not care about the number of tests we should care about how useful are they. We should write enought tests to be confident that if we introduce a bug (technical or business) we are going to detect it. And second, we should take a look to “The Testing pyramid“, here you can find a link to an artiche of Martin Fowler. Basically, explaing from a cost-efective comparation point of view the amount and type of tests we should write.

Running your tests automatically

One of the things we have discussed we need, it is to run our tests on every change that gets pushed. To do so, we will need to have a service that can monitor our repository and listen to new pushes to the codebase. There are multiple solutions, both, on-premise and in the Cloud.

There are a few considerations we need to think about when we are trying to evaluate a solution like: Platform, resources, access to our repositories, … Some examples are Travis CI, Bamboo or Jenkins.

Immersion in CI

This is not just a technical change, we need to have in mind when we are trying to addopt CI that it is a cultural change too.

We need to start integrating code more often, creating shorter stories or breaking them in short deliverables, we need to keep always the build green, we need to add test in any story, we can use even refactor tasks to add tests and increase our code coverage. We should write test when we fix bugs and so on.

One group of your team that is going to be affected directly by this change is our QA group. They no longer need to test manually trivial capabilities of our application and they can now dedicate more time to providing tools to support developers as well as help them adopt the right testing strategies. Our QA Engineers will be able to focus on facilitating testing with better tooling and datasets as well as help developers grow in their ability to write better code. They will need to test manually some complex stuff but it will not be their main task anymore.

Quick summary

Juts a quick sumarry of the roadmap to addopt CI, we can list the next points:

  1. Start writing code for the critical parts in your system.
  2. Get a CI system to run our tests after every push.
  3. Pay attention to the culture change. Help our team to understand and to achieve.
  4. Keep the build green.
  5. Write tests as part of every story, every bug and every refactor.
  6. Keep doing 4, 5 and 6.

At the beginning, cultural changes are scary and they feel impossible but the rewards sometimes deserve the effort. A new project, if we have one, it is maybe a good option to start changing our minds and taking a CI approach in the development life cycle. If we start with and existing proyect, start slow, step by step but always going forward. And, we should always remember that, this is not just a technological change, it is a cultural change too, explain, share and be patient.

CI: Continuous Integration

CI, CD and CD

When we talk about moder development practices, we often listen some acronyms among we can find CI and CD when we refer the way we build and release software. CI is pretty straightforward and stands for continuous integration. But CD can either mean continuous delivery or continuous deployment. All these practices have things in common but also, they have some significant differences. We are going to explain these similarities and differences.

Continuous integration

In environments where continuous integration is used, developers merge their changes in the main branch as often as the can. These changes are validated by creating a build and running automated tests against the build. Doing this, we avoid the old times painful releases when everything was merged in the last minute.

Continuous integration practice puts a big emphasis on automation testing to keep a healthy build each time the commits are merged in the main branch warning quickly about possible problems.

Continuous delivery

Continuous delivery is the next step towards the release of your changes. This practice make sure you can release to your customers as often and quickly as you want. This means that on top of having automated your testing, you also have automated your release process and you can deploy your application at any point of time by clicking on a button.

With continuous delivery, you can decide to release daily, weekly, fortnightly, or whatever suits your business requirements. However, if you truly want to get the benefits of continuous delivery, you should deploy to production as soon as possible to make sure that you release small batches, that are easy to troubleshoot in case of problems.

Continuous deployment

But, we can go another step farther, and this step is continuous deployment. With this practice, every change that passes all stages of your production pipeline is released to your customers. There is no human intervention (no clicking a button to deploy), and only a fail in test time will prevent a new change to be deployed to production.

Continuous deployment is an excellent way to accelerate the feedback loop with your customers and take pressure off the team as there is not a ‘release day’ anymore. Developers can focus on building software, and they see their work go live minutes after they have finished working on it. Basically, when a developer merges a commit in the main branch, this branch is build, tested and, if everything goes well, deployed to production environments.

Can I use all of them together?

Of course you can, as I have said, each one of them its just a step closer to the production environment. You can set your continuous integration environment, after that, once the team is comfortable, you can add continuous delivery and, finally, continuous deployment can be added to the picture.

PIPELINE
Example of CI, CD and CD pipeline

Is it worth it?

Continuous integration:

What it needs from you:

  • Your team will need to write automated tests for each new feature, improvement or bug fix.
  • You need a continuous integration server that can monitor the main repository and run the tests automatically for every new commits pushed.
  • Developers need to merge their changes as often as possible, at least once a day.

What it gives to you:

  • Less bugs get shipped to production as regressions are captured early by the automated tests.
  • Building the release is easy as all integration issues have been solved early.
  • Less context switching as developers are alerted as soon as they break the build and can work on fixing it before they move to another task.
  • Testing costs are reduced drastically – your CI server can run hundreds of tests in the matter of seconds.
  • Your QA team spend less time testing and can focus on significant improvements to the quality culture.

Continuous delivery

What it needs from you:

  • You need a strong foundation in continuous integration and your test suite needs to cover enough of your codebase.
  • Deployments need to be automated. The trigger is still manual but once a deployment is started there should not be a need for human intervention.
  • Your team will most likely need to embrace feature flags so that incomplete features do not affect customers in production.

What it gives to you:

  • The complexity of deploying software has been taken away. Your team does not have to spend days preparing for a release anymore.
  • You can release more often, thus accelerating the feedback loop with your customers.
  • There is much less pressure on decisions for small changes, hence encouraging iterating faster.

Continuous deployment

What it needs from you:

  • Your testing culture needs to be at its best. The quality of your test suite will determine the quality of your releases.
  • Your documentation process will need to keep up with the pace of deployments.
  • Feature flags become an inherent part of the process of releasing significant changes to make sure you can coordinate with other departments (Support, Marketing, PR…).

What it gives to you:

  • You can develop faster as there is no need to pause development for releases. Deployments pipelines are triggered automatically for every change.
  • Releases are less risky and easier to fix in case of problem as you deploy small batches of changes.
  • Customers see a continuous stream of improvements, and quality increases every day, instead of every month, quarter or year.

As said before, you can adopt continuous integration, continuous delivery and continuous deployment. How you do it depends on your needs and your situation. If you are just starting a project and you do not have customers yet you can go for it and implement the three of them and just iterate on them at the same time you iterate on your project and your needs grow. If you have already a project in production you can just go step by step and adopting the practices first in your staging environments.

CI, CD and CD

Test types

As any developer know or should now, test is an important phase of the SDLC (Software Development Life Cycle) and it is an important step to check if the application matches the requirements, if it works properly and if it is bug free or, at least, it has the less bugs as possible.

To try to achieve these goals, there are some different types of test, each one of them usually associated with one main objective or purpose. In this post, I am going to list six of them. Maybe, someone else knows other types, but those I am going to list are those what I have seen more along the different projects I have been:

Unit test

This kind of tests are focus in a very small unit of functionality. These are the most basic tests we can perform. We try to find if a little piece of code is working as expected, maintaining it isolated from the rest of the pieces of our program. Generally, one unit test is written for each method and usually mock techniques are used to maintain this isolation, especially to avoid things like network, databases or file system influence our tests.

Integration Tests

This should be the next step. Once we are sure the little pieces of our system are working, it is time to put all of them together and to see how the system is working and how the different little pieces are interoperating. In this point, we are going to find network problems, database problems, file system problems and, the most important, if there are some problems with the communication among the little pieces.

Functional Tests

Once we now the system is working properly, we need to check the correctness of the system. That means to test if the system, given the input defined in the specifications, returns the correct output.

Smoke Tests

These are very simple and, generally, basic tests performed after an installation or a new version. They usually are quick and they are designed to check if everything is working after a deploy.

Regression Tests

Sometimes, to correct a bug we need to add a patch to the system that affects the core areas in our system. In this case, we need to be sure that this core functionally is working correctly. In this case, we perform the Regression Tests.

Acceptance Tests

These tests are the last step. They check from the customers perspective the application and the different features are marked as accepted or rejected. They check if everything works fine and it matches customer’s expectations.

More or less, as you can see, I have listed the test in the order that they are going to be executed in any development. Starting from the point of view of the developers and finishing with the customers point of view.

See you.

Test types