6. Ensure backwards compatibility between the latest provider and production consumer

It's all very well knowing that your consumer/provider are compatible with the head versions of each other, but if you want to be able to deploy your consumer and provider independently, you also need to be sure that the latest version of the provider is compatible with the production version of the consumer. The ability to do this is a major selling point of Pact.

Tags allow you ensure backwards compatibility between production and head versions of your applications by allowing the provider to verify the pact associated with the latest production version as well as the latest master version. This enables the safe deployment workflow described in step 7.

1. Add a step to your deployment process so that when the consumer is deployed to an environment, the relevant pacticipant version in the broker is tagged with the name of the environment (eg. test, production). This functionality is provided by the pact broker CLI which is available as a standalone executable, and a Docker image.
2. Add the new tag names to the list of pacts the provider will verify (eg. { consumerVersionSelectors: { tag: "main", latest: true }, { tag: "test", latest: true }, { tag: "production", latest: true } }).

Make sure that you use the same agreed upon names for each environment for all subsequent applications. (eg. is it prod or is it production?) Having a mix of environment names will not allow you to successfully use the can-i-deploy tool to ensure safe deployments.