People create great applications in the Google Cloud. Popular tools for development, deployment and monitoring just work in GCP. You also have options for tools that are tightly integrated with GCP and in this module, I'll explain them. Let's start with talking about development. Lots of GCP customers use Git to store and manage their source code trees. That means, running their own Git instances or using a hosted Git provider. Running your own is great because you have total control. Using a hosted Git provider is great because it's less work. What if there were a third way? Maybe a way to keep code private to a GCP project and use IAM permissions to protect it, but not have to maintain the Git instance yourself. That's what Cloud Source Repositories is. It provides Git version control to support your team's development of any application or service, including those that run on App Engine, Compute Engine, and Kubernetes Engine. With Cloud Source Repositories, you can have any number of private Git repositories, which allows you to organize the code associated with your cloud project in whatever way works best for you. Cloud Source Repositories also contains a source viewer so that you can browse and view repository files from within the GCP console. Many applications contain event-driven parts. For example, maybe you have an application that lets users upload images. Whenever that happens, you need to process that image in various ways: convert it to a standard image format, thumbnail into various sizes, and store each in a repository. You could always integrate this function into your application, but then you have to worry about providing compute resources for it, no matter whether it happens once a day or once a millisecond. What if you could just make that provisioning problem go away? It would be great if you could write a single purpose function that did the necessary image manipulations and then arrange for it to automatically run whenever a new image gets uploaded. That's exactly what Cloud Functions lets you do. You don't have to worry about servers or runtime binaries. You just write your code in JavaScript for a Node.js environment that GCP provides and then configure when it should fire. There's no need for you to pay for servers either. You just pay whenever your functions run, in 100 millisecond intervals. Cloud Functions can trigger on events in Cloud Storage, Cloud Pub/Sub, or in HTTP call. Here's how setting up a Cloud Function works. You choose which events you care about. For each event type, you tell Cloud Functions you're interested in it. These declarations are called triggers. Then you attach JavaScript functions to your triggers. From now on, your functions will respond whenever the events happen. Some applications, especially those that have microservices architecture, can be implemented entirely in Cloud Functions. People also use Cloud Functions to enhance existing applications without having to worry about scaling.
