Merge pull request #2168 from owncloud/extensions-template-adr

[docs-only] draft an adr for extension templates

docs/ocis/adr/0008-extension-template.md

@@ -0,0 +1,66 @@
+---
+title: "8. Extension Template"
+---
+
+* Status: proposed
+* Deciders: @c0rby <!-- optional -->
+* Date: 2021-06-10
+
+Technical Story: [description | ticket/issue URL] <!-- optional -->
+
+## Context and Problem Statement
+
+We want to accelerate and simplify extension development by removing the necessity to type or copy the boilerplate code. Can we provide a template or a similar mechanism to aid when developing new extensions?
+
+
+## Decision Drivers <!-- optional -->
+
+* The solution should be easily maintainable.
+  * It should always be up-to-date.
+* The solution should be easy to use.
+
+## Considered Options
+
+* Use [boilr](https://github.com/tmrts/boilr)
+* Create a template git repository.
+* Use [ocis-hello](https://github.com/owncloud/ocis-hello/) as a "template"
+
+## Decision Outcome
+
+Chosen option: "[option 1]", because [justification. e.g., only option, which meets k.o. criterion decision driver | which resolves force force | … | comes out best (see below)].
+
+### Positive Consequences: <!-- optional -->
+
+* [e.g., improvement of quality attribute satisfaction, follow-up decisions required, …]
+* …
+
+### Negative consequences: <!-- optional -->
+
+* [e.g., compromising quality attribute, follow-up decisions required, …]
+* …
+
+## Pros and Cons of the Options <!-- optional -->
+
+### [boilr](https://github.com/tmrts/boilr)
+
+We have a boilr template already. [boilr-ocis-extension](https://github.com/owncloud/boilr-ocis-extension/)
+This approach is nice because it provides placeholders which can be filled during the generation of a new extension from the template. It also provides prompts for the placeholder values during generation.
+
+* Good, because with the placeholders it is hard to miss values which should be changed
+* Bad, because maintaining is more complex
+
+### Template git repository
+
+Create a git repository with an extension containing the boilerplate code.
+
+* Good, because we can use the usual tools for QA and dependency scanning/updating.
+* Good, because it doesn't require any additional tool.
+
+### [ocis-hello](https://github.com/owncloud/ocis-hello/) as a "template"
+
+We have the ocis-hello repository which acts as an example extension containing a grpc and http service and a web UI. It also demonstrates the usage of the settings service.
+
+* Good, because it contains a bit more code than just the plain boilerplate
+* Good, because the integration into oCIS is already tested for the Hello extension (eg. with Proxy and Settings). This will ensure, that the example extension is up to date.
+* Bad, because if you don't require all features you have to delete stuff
+