# Polyn Schemas Repository This repository contains all of the schemas and terraform resources for the Polyn services environment. 1. Install [Ruby](https://github.com/asdf-vm/asdf-ruby) 2. Install bundler `gem install bundler` 3. Install dependencies `bundle install` 4. Install Terraform. For M1 Macs, [download the AMD64 version](https://www.terraform.io/downloads) rather than using Homebrew to install Terraform. 5. Ensure Docker & Docker Compose is installed 6. Call `bundle exec polyn tf_init` if this is the first time using terraform in the codebase. 7. Call `bundle exec polyn up`. By default this will run in `development` mode, which will start the NATS server, configure it via Terraform, and update the Polyn Schema Registry. ### Running NATS locally `bundle exec polyn up` will use run a Docker container for you if one is not already running. Alternatively, you can run `nats-server` yourself locally if you prefer. ## Naming Conventions See the Protocol Documentation for [Naming Conventions](https://github.com/SpiffInc/polyn/blob/main/polyn_protocol/README.md) ## Streams Each stream should have its own configuration file under `./tf`. Run `bundle exec polyn gen:stream ` to generate a new configuration file for a stream ## Consumers Run `bundle exec polyn gen:consumer ` to generate new configuration for a consumer of a stream. It will be included in the same file as the stream configuration. ## Message Schemas Run `bundle exec polyn gen:schema ` to generate a new JSON Schema for a message All the schemas for your messages should live in the `./schemas` directory. The name of your schema file should be the same as your message, but with `.json` at the end. So if you have an message called `widgets.created.v1` you would create a schema file called `widgets.created.v1.json` in the `./schemas` directory. Every schema should be a valid [JSON Schema](https://json-schema.org/) document. The Polyn CLI tool will combine your message schema with the [Cloud Events Schema](https://cloudevents.io/) when it adds it to the Polyn Schema Registry. This means you only need to include the JSON Schema for the `data` portion of the Cloud Event and not the entire Cloud Event schema. ### Subdirectories If you'd like to organize your messages by team ownership or some other convention, you can use subdirectories to do so. The full message name should still be part of the file name. You should also ensure there are not duplicate schema names in different directories as only one schema can be defined per message name. You can generate a schema in a subdirectory like this: `bundle exec polyn gen:schema some/nested/dir/widgets.created.v1` ## Schema Versioning ### New Message A new message schema file should be a lower-case, dot-separated, name with a `v1` suffix ### Existing Message Existing message schemas can be changed without updating the file name if the change is backwards-compatible. Backwards-compatibile meaning that any services Producing or Consuming the message will not break or be invalid when the Polyn Schema Registry is updated with the change. There are many ways to make breaking change and so you should be careful when you do this. Making a change to a message schema that is not backwards-compatible will require you to create a brand new json file. The new file should have the same name as your old file, but with the version number increased. Your Producers will need to continue producing both message versions until you are sure there are no more consumers using the old message. ## Terraform State Terraform generates and maintains a [`terraform.tfstate`](https://www.terraform.io/language/state) file that is used to map terraform configuration to real production server instances. Polyn needs to interact with this file differently based on whether we are developing locally or in a production environment. ### Local Development For local development Polyn expects the `terraform.tfstate` file to exist in the local file system. However, it should not be checked in to version control. We don't want experiments and updates made on a local developer machines to end up as the "source of truth" for our production infrastucture. ### Production In production Terraform recommends keeping `terraform.tfstate` in a [remote storage location](https://www.terraform.io/language/state). The remote state file should be the "source of truth" for your infrastucture and shouldn't be getting accessed during development. Depending on the size of your organization and security policies, not all developers will have access to the remote storage source and you don't want that to prohibit them from adding schemas, streams, or consumers. Polyn expects you to keep a `./remote_state_config/backend.tf` file that configures a Terraform [backend](https://www.terraform.io/language/settings/backends/configuration). This will only be used when `POLYN_ENV=production`. ## Deployment The default `Dockerfile` generated by [Install the Polyn CLI](https://github.com/SpiffInc/polyn-cli) can help you create an image with the latest changes and nessary environment to run polyn commands. The `bin/apply_changes.sh` script can be used to execute the polyn commands you need to update your production NATS server. You'll need to pass in `env` variables for `NATS_SERVERS` and `NATS_CREDENTIALS`. Also any `env` variables needed to connect to your remote state storage.