We are using React Native in #SmartHome to share the business logic between Android and iOS team and approach users with a unique brand experience. The drawback is that we require lots of native Android SDK and Objective-C modules, so a good part of the invested time is there. The gain for a app that relies less on native communication, sensors and OS tools should be even higher.

Also it helps us set different testing stages: we use Travis CI for the javascript (business logic), Bitrise to run build tests and @Detox for #end2end automated user tests.

We use a microservices structure on top of Zeit's @now that read from firebase. We use JWT auth to authenticate requests among services and from users, following GitHub philosophy of using the same infrastructure than its API consumers. Firebase is used mainly as a key-value store between services and as a backup database for users. We also use its authentication mechanisms.

You can be super locked-in if you also rely on it's analytics, but we use Amplitude for that, which offers us great insights. Intercom for communications with end-user and Mailjet for marketing.

I initially chose CircleCI for a personal project because I was not satisified with using Travis CI in the past. When it came time to develop my CI/CD config on Circle, I was pleasantly surprised with the fantastic documentation, invaluable collection of example configs and helpful support provided. The free tier they provide is quite robust for most small projects and the platform is updated frequently with nice features.

Areas where CircleCI could improve:

• the UI is a bit slow (you can feel the local machine straining to load all the code) and it is not as intuitive as it could be
• many UI elements receive updates and/or changes that are not always reflected in the current docs

I recommend using Travis CI and/or Appveyor in all projects.

Projects using these tools have given me confidence to know that I don't cause any breaking changes. Travis CI and Appveyor have functionality to test components of a project across multiple installation projects to ensure that modifications don't break a project. These tools integrate easily with GitHub and are useful in open source projects that must review contributions from many different people.

We actually started out on Travis CI, but we've migrated our main builds to CircleCI, and it's been a huge improvement.

The reason it's been a huge improvement is that Travis CI has a fundamentally bad design for their images, where they start with a standard base Linux image containing tons of packages (several versions of postgres, every programming language environment, etc). This is potentially nice for the "get builds for a small project running quickly" use case, but it's a total disaster for a larger project that needs a decent number of dependencies and cares about the performance and reliability of their build.

This issue is exacerbated by their networking infrastructure being unreliable; we usually saw over 1% of builds failing due to transient networking errors in Travis CI, even after we added retries to the most frequently failing operations like apt update or pip install. And they never install Ubuntu's point release updates to their images. So doing an apt update, apt install, or especially apt upgrade would take forever. We ended up writing code to actually uninstall many of their base packages and pin the versions of hundreds of others to get a semi-fast, semi-reliable build. It was infuriating.

The CircleCI v2.0 system has the right design for a CI system: we can customize the base image to start with any expensive-to-install packages we need for our build, and we can update that image if and when we want to. The end result is that when migrating, we were able to delete all the hacky optimizations mentioned above, while still ending up with a 50% faster build latency. And we've also had 5-10x fewer issues with networking-related flakes, which means one doesn't have to constantly check whether a build failure is actually due to an issue with the code under test or "just another networking flake".

I use Google Cloud Build because it's my first foray into the CICD world(loving it so far), and I wanted to work with something GCP native to avoid giving permissions to other SaaS tools like CircleCI and Travis CI.

I really like it because it's free for the first 120 minutes, and it's one of the few CICD tools that enterprises are open to using since it's contained within GCP.

One of the unique things is that it has the Kaniko cache, which speeds up builds by creating intermediate layers within the docker image vs. pushing the full thing from the start. Helpful when you're installing just a few additional dependencies.

Feel free to checkout an example: Cloudbuild Example