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CHANGELOG.md

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+# Changelog
+
+## v4.0.0
+
+### Breaking Changes
+
+#### Module
+
+**If you're using k3d as a Go module, please have a look into the code to see all the changes!**
+
+- We're open for chats via Slack or GitHub discussions
+
+- Module is now on `github.com/rancher/k3d/v4` due to lots of breaking changes
+- `pkg/cluster` is now `pkg/client`
+- `ClusterCreate` and `NodeCreate` don't start the entities (containers) anymore
+  - `ClusterRun` and `NodeRun` orchestrate the new Create and Start functionality
+- New config flow: CLIConfig (SimpleConfig) -> ClusterConfig -> Cluster + Opts
+
+#### CLI
+
+- Some flags changed to also use `noun-action` syntax
+  - e.g. `--switch-context --update-default-kubeconfig` -> `--kubeconfig-switch-context --kubeconfig-update-default`
+  - this eases grouping and visibility
+
+### Changes
+
+#### Features
+
+- Registry Support
+  - k3d-managed registry like we had it in k3d v1.x
+  - Option 1: default settings, paired with cluster creation
+    - `k3d cluster create --registry-create` -> New registry for that cluster
+    - `k3d cluster create --registry-use` -> Re-use existing registry
+  - Option 2: customized, managed stand-alone
+    - `k3d registry [create/start/stop/delete]`
+    - Check the documentation, help text and tutorials for more details
+
+- Config File Support
+  - Put all your CLI-Arguments/Flags into a more readable config file and re-use it everywhere (keep it in your repo)
+    - Note: this is not always a 1:1 matching in naming/syntax/semantics
+  - `k3d cluster create --config myconfig.yaml`
+
+    ```yaml
+    apiVersion: k3d.io/v1alpha1
+    kind: Simple
+    name: mycluster
+    servers: 3
+    agents: 2
+    ports:
+      - port: 8080:80
+        nodeFilters:
+          - loadbalancer
+    ```
+
+- [WIP] Support for Lifecycle Hooks
+  - Run any executable at specific stages during the cluster and node lifecycles
+    - e.g. we modify the `registries.yaml` in the `preStart` stage of nodes
+    - Guides will follow
+
+#### Misc
+
+- Now building with Go 1.15
+  - same for the k3d-tools code
+- updated dependencies (including Docker v20.10)