Extending Deployment Manager with Type Providers

It’s been just s few weeks since I complained that Google’s Deployment Manager (DM) doesn’t support its own latest Cloud Functions API, when I accidentally found an alternative way to use it. Thing is that if you have a RESTful CRUD-like API and OpenAPI specification for it, you can register it as DM’s type provider and use it almost like any other type from inside of a YAML configuration. Cloud Functions API v1 does have such specification, so in fact I could use it with DM.

Using default type providers

There’s whole bunch of type providers available by default. Surprisingly, they provide way more functionality than regular resource types do. For instance, running gcloud beta deployment-manager types list will show me that among the other things, I have access to gcp-types/compute-v1 type provider. There’s bunch of regular compute resource types, sure, but this type provider also have, for example, diskTypes. I can’t create a new disk type, but diskTypes has list method, which I can call right from Deployment Manager’s config:

I also added outputs section with the reference to first found result, so when configuration gets deployed, there’s something to see in the output:

This might look useless (and it is), but instead of compute-v1 we could’ve used another default type provider: cloudresourcemanager-v1. Among many other things it knows how to get and set IAM policies, and that is very, very powerful.

Adding a new type provider

As I said before, if you have a RESTful CRUD API with OpenAPI specification, it can be used as a type provider. Dataflow API is just like that, and that’s a perfect candidate for becoming a new provider, because out of the box DM can’t do anything about Dataflow at all. API specification is available right at the home page, so just in one command:

Ta-daaam! Let’s check what types does it have:

Lots of them. One of them will even let you to launch Dataflow templates directly from Deployment Manager. Something that DM can’t do any other way.

Creating type provider by type provider

Even though Dataflow type provider is available for my GCP project now, unless I repeat installation steps elsewhere, I can’t expect it will be available anywhere else. This means that in order to create a deployment configuration that uses Dataflow, someone must manually register the type first. And it goes without saying that this is not the Jedi way.

How about that: let’s register a type provider from Deployment Manager itself, and then delete it once we finished using its types. Wouldn’t that be cool?

One of default DM type providers is a DM itself, so that deployment-manager deployments create actually can be turned into action: gcp-types/deploymentmanager...insert and delete:

If we try to run this:

Cool, isn’t it? This deployment leaves no traces, but if you comment out the deletion step, you could easily see that the Dataflow type provider indeed was there.

Conclusion

Among the all Deployment Manager features I saw so far, the ability to use and to add new type providers is probably the coolest one. If I can register a new type from inside of DM and use that type afterwards, I hardly can see what DM couldn’t do. I could create and configure custom resources, call external APIs, implement complex setup logic – I could do lots of things. The only and probably the main downside of type providers is that unlike regular types, deleting the deployment won’t always undo the side effects it introduced. There might be some hooks to use for custom cleanup, but I haven’t came across any of them yet. Other than that it’s incredibly powerful feature.