Propose convention for storing operator bundle

This enhancement proposes standards and conventions for storing
operator manifests and metadata as conatiner images.

olm/operator-bundle.md

@@ -0,0 +1,270 @@
+# Operator Bundle
+
+## Release Signoff Checklist
+
+- [ ] Enhancement is `implementable`
+- [ ] Design details are appropriately documented from clear requirements
+- [ ] Test plan is defined
+- [ ] Graduation criteria for dev preview, tech preview, GA
+- [ ] User-facing documentation is created in [openshift/docs]
+
+## Summary
+This enhancement proposes standards and conventions for storing kubernetes manifests and `metadata` associated with an operator as container images in OCI-compliant container registries, and to associate metadata-only images with standard, runnable images.
+
+## Motivation
+There is no standard way to associate and transmit operator manifests and metadata between clusters, or to associate a set of manifests with one or more runnable container images.
+
+Existing non-standard methods include:
+
+* git repositories
+    * see also, kustomize
+* operator-registry directory “bundles”
+* helm charts
+* appregistry
+
+We would like to be able to talk about a set of metadata and manifests, outside the context of a cluster, as representing a particular application or service (in this case, an operator).
+
+By standardizing on a container format for this data, we get many other features for free, such as: identity, distribution, replication, deduplication, signing, and ingress.
+
+### Goals
+* Define a convention for storing operator manifetss and metadata with container image.
+* Build and push metadata using standard container tooling (e.g.docker cli)
+* No union filesystem should be required to consume metadata
+* Have a simple mechanism to apply a bundle to a kubernetes cluster
+
+### Non-Goals
+* Require OCI registries that support any non-standard media types
+* Build on-cluster tooling to interact with bundles
+
+## Proposal
+We delineate the operator metadata from the operator manifests. The operator manifests refers to a set of kubernetes manifest(s) the defines the deployment and RBAC model of the operator. The operator metadata on the other hand are, but not limited to:
+* Information that identifies the operator, it's name, version etc.
+* Additional information that drives the UI: 
+    * Icon
+    * Example CR(s)
+* Channel(s)
+* API(s) provided and required. 
+* Related images.
+
+
+This enhancement proposal focuses on the following:
+* A standard way to store and transmit manifests and metadata associated with an operator.
+* An operator author can specify supporting metadata in a standard and structured manner.
+* A single unique identifier that points to a particular version of an operator bundle (both metadata and manifests).
+
+The following user stories discuss the User Experience.
+
+---
+
+### User Stories
+
+#### Build, Push, Pull Operator Bundle
+As an operator author, I would like to associate operator manifests and metadata with the container image of my operator.
+
+The focus of this user story is to define a standard to store, transmit, inspect and retrieve operator manifests and metadata. The exact format of the metadata is outside of the scope of this story.
+
+*Constraints*:
+* An operator bundle (including both manifests and metadata) should be identifiable using a single versioned identifier. 
+* For an operator The metadata can be downloaded independently of the manifest.
+
+### Implementation Details/Notes/Constraints
+* The initial implementation target will be Docker v2-2 `manifests`, `manifest-lists`, and docker client support, for maximum compatiblity with existing tooling.
+* We want the entire operator bundle to be identifiable and retrievable using the same identifier/URL.
+
+#### Docker
+
+##### Build, Push, Pull Operator Bundle Image
+We use the following labels to annotate the operator bundle image.
+* The label `operators.operatorframework.io.bundle.resources` represents the bundle type:
+    * The value `manifests` implies that this bundle contains operator manifests only.
+    * The value `metadada` implies that this bundle has operator metadata only.
+    * The value `manifests+metadata` implies that this bundle contains both operator metadata and manifets.
+* The label `operators.operatorframework.io.bundle.mediatype` reflects the media type or format of the operator bundle. It could be helm charts, plain kubernetes manifests etc.
+
+The labels will also be put inside a YAML file, as shown below.
+
+*annotations.yaml*
+```yaml
+annotations:
+  operators.operatorframework.io.bundle.resources: "manifests+metadata"
+  operators.operatorframework.io.bundle.mediatype: "registry+v1"
+```
+
+*Notes:*
+* In case of a mismatch, the `annotations.yaml` file is authoritative because on-cluster operator-registry that relies on these annotations has access to the yaml file only.
+* The potential use case for the `LABELS` is - an external off-cluster tool can inspect the image to check the type of a given bundle image without downloading the content.
+
+###### Format
+We can use the following values for `mediatype`: 
+* `registry`: Format used by [Operator Registry](https://github.com/operator-framework/operator-registry#manifest-format) to package an operator.
+* `helm`: Can be used to package a helm chart inside an operator bundle.
+* `plain`: Can be used to package plain k8s manifests inside an operator bundle.
+
+An operator author can also specify the version of the format used inside the bundle. For example,
+```yaml
+operators.operatorframework.io.bundle.mediatype: "registry+v1"
+```
+
+###### Example of an Operator Bundle that uses Operator Registry Format
+This example uses [Operator Registry Manifests](https://github.com/operator-framework/operator-registry#manifest-format) format to build an operator bundle image. The source directory of an operator registry bundle has the following layout.
+```
+$ tree test
+test
+├── 0.1.0
+│   ├── testbackup.crd.yaml
+│   ├── testcluster.crd.yaml
+│   ├── testoperator.v0.1.0.clusterserviceversion.yaml
+│   └── testrestore.crd.yaml
+└── annotations.yaml
+```
+
+`Dockerfile` for operator bundle
+```
+FROM scratch
+
+# We are pushing an operator-registry bundle 
+# that has both metadata and manifests.
+LABEL operators.operatorframework.io.bundle.resources=manifests+metadata
+LABEL operators.operatorframework.io.bundle.mediatype=registry+v1
+
+ADD test/0.1.0 /manifests
+ADD test/annotations.yaml /metadata/annotations.yaml
+```
+
+Below is the directory layout of the operator bundle inside the image.
+```bash
+$ tree
+/
+├── manifests
+│   ├── testbackup.crd.yaml
+│   ├── testcluster.crd.yaml
+│   ├── testoperator.v0.1.0.clusterserviceversion.yaml
+│   └── testrestore.crd.yaml
+└── metadata
+    └── annotations.yaml
+```
+
+*Notes:*
+* The `/manifests` folder is expected to contain resources that can be applied to the cluster using standard tooling like `kubectl`.
+* The `/metadata` folder is expected to contain resources that are not directly appliable. It can be used to store supporting metadata associated with the operator.
+* The image is not runnable, it is built from `scratch`.
+* The first image layer is expected to contain all of `/manifests`
+
+
+###### UX:
+Build, Push and Pull an operator bundle image.
+```
+docker build -f Dockerfile -t quay.io/test/test-operator:v1 .
+docker push quay.io/test/test-operator:v1
+docker pull quay.io/test/test-operator:v1
+```
+
+A tool can inspect an operator bundle image to determine the bundle type and its format.
+```bash
+# inspect the type of the operator bundle.
+docker image inspect quay.io/test/test-operator:v1 | \
+jq '.[0].Config.Labels["operators.operatorframework.io.bundle.resources"]'
+
+"manifests+metadata"
+
+# inspect the format of the operator bundle.
+docker image inspect quay.io/test/test-operator:v1 | \
+jq '.[0].Config.Labels["operators.operatorframework.io.bundle.mediatype"]'
+
+"registry+v1"
+```
+
+### Verify, Run and Test
+
+#### Generate Scaffolding
+As an operator author I want to generate the scaffolding resources that are necessary to create an operator bundle. We provide the operator author with tooling to automatically generate the scaffolding.
+```bash
+$ tree test
+test
+├── 0.1.0
+│   ├── testbackup.crd.yaml
+│   ├── testcluster.crd.yaml
+│   ├── testoperator.v0.1.0.clusterserviceversion.yaml
+│   └── testrestore.crd.yaml
+
+$ cd test
+
+# the following command generates the necessary scaffolding.
+$ operator-framework bundle init --type=registry --bundle-folder=0.1.0
+
+# output:
+#  - test/Dockerfile
+#  - test/annotations.yaml
+```
+
+Once the scaffolding is generated the user can do a `docker build` to create an operator bundle image.
+
+#### Validate an Operator Bundle
+As an operator author I want to validate an operator bundle image so that I can ensure it runs as expected on a cluster.
+```bash
+$ operator-framework bundle validate --image=quay.io/test/test-operator:v1
+```
+
+The validate command will do the following:
+* Make sure the image `label` and `annotations.yaml` are appropriately configured. If there is any mismatch, the tool shoud generate apropriate error message. 
+* Verify that the format of the bundle is valid. If the bundle is of `registry` format, we should verify that the bundle conforms to operator-registry standards.
+
+#### Run the Operator from the Bundle Image
+As an operator author I want to run my operator directly from the bundle image. Once an operator is packaged into a bundle image, we want to give the author ability to run it using `olm` directly from the bundle image.
+```bash
+# The following creates an 'Operator' CR managed by olm.
+cat <<EOF | kubectl apply -f -
+apiVersion: operators.operatorframework.io/v2alpha1
+kind: Operator
+metadata:
+  name: test-operator
+spec:
+  bundle:
+    image: quay.io/test/test-operator:v1
+EOF
+```
+
+Below is an example of how an operator bundle image can be unpacked to apply the manifests on a cluster.
+```bash
+$ docker save quay.io/test/test-operator:v1 -o bundle.tar
+$ tar -xvf bundle.tar
+
+$ tar -tf bundle.tar 
+39d24aee3ad2e8720c12042d5b9ba52ce14a12ed72815a759b41b01b9a8dbc03/
+39d24aee3ad2e8720c12042d5b9ba52ce14a12ed72815a759b41b01b9a8dbc03/VERSION
+39d24aee3ad2e8720c12042d5b9ba52ce14a12ed72815a759b41b01b9a8dbc03/json
+39d24aee3ad2e8720c12042d5b9ba52ce14a12ed72815a759b41b01b9a8dbc03/layer.tar
+58b4c261195b83bc0b12b80b63f8e11fb97b5d369aea80ca7cc558793bb507a0.json
+7b590145954570b3b3b52db41d4fa8950eefed80fd01c937fb3949b863fe0ede/
+7b590145954570b3b3b52db41d4fa8950eefed80fd01c937fb3949b863fe0ede/VERSION
+7b590145954570b3b3b52db41d4fa8950eefed80fd01c937fb3949b863fe0ede/json
+7b590145954570b3b3b52db41d4fa8950eefed80fd01c937fb3949b863fe0ede/layer.tar
+manifest.json
+repositories
+
+# The first image layer contains the manifest resources that
+# can be applied directly to a cluster.
+$ cat manifest.json | jq '.[0].Layers[0]'
+"7b590145954570b3b3b52db41d4fa8950eefed80fd01c937fb3949b863fe0ede/layer.tar"
+
+$ cat manifest.json | jq '.[0].Layers[0]' | xargs tar -xvf
+$ kubectl apply -f ./manifests
+```
+#### Run the Operator from the Bundle Folder
+This applies to an `operator-registry` bundle. As an operator author I want to apply a bundle folder directly on the cluster so that:
+* I can test my changes.
+* I can iterate faster.
+
+```bash
+tree test
+test
+├── 0.1.0
+│   ├── testbackup.crd.yaml
+│   ├── testcluster.crd.yaml
+│   ├── testoperator.v0.1.0.clusterserviceversion.yaml
+│   └── testrestore.crd.yaml
+
+$ kubectl apply -f ./test/0.1.0
+```
+
+This should (re)install the operator in the bundle.