Update traffic splitting example to use Release mode (#964)

* Update traffic splitting example to use Release mode

This change updates the traffic splitting example to use release mode
introducing the concepts of the mode in three steps. This change also
simplifies running the commands and removes the need to mutate files on
disk to run through the example.

* Use envsubst instead of perl. Simplify image path

* Use long names for arguments

* Update diff statement

* Add envsubst install instructions

serving/samples/rest-api-go/README.md

@@ -14,8 +14,11 @@ then outputs the stock price.
 1. [Outbound network access](https://github.com/knative/docs/blob/master/serving/outbound-network-access.md)
    enabled for this Service to make external API requests.
 1. The code checked out locally.
+1. `envsubst` installed locally. This is installed by the `gettext` package. If
+   not installed it can be installed by a Linux package manager, or by
+   [Homebrew](https://brew.sh/) on OS X.
 
-```
+```shell
 go get -d github.com/knative/docs/serving/samples/rest-api-go
 ```
 
@@ -35,7 +38,7 @@ To build and push to a container registry using Docker:
 
 1. Move into the sample directory:
 
-```
+```shell
 cd $GOPATH/src/github.com/knative/docs
 ```
 
@@ -43,7 +46,7 @@ cd $GOPATH/src/github.com/knative/docs
    This sample uses
    [Google Container Registry (GCR)](https://cloud.google.com/container-registry/):
 
-```
+```shell
 export REPO="gcr.io/<YOUR_PROJECT_ID>"
 ```
 
@@ -64,31 +67,25 @@ registry specific instructions for both setup and authorizing the image push.
 
 4. Use Docker to build your application container:
 
-```
+```shell
 docker build \
-  --tag "${REPO}/serving/samples/rest-api-go" \
+  --tag "${REPO}/rest-api-go" \
   --file serving/samples/rest-api-go/Dockerfile .
 ```
 
 5. Push your container to a container registry:
 
-```
+```shell
-docker push "${REPO}/serving/samples/rest-api-go"
+docker push "${REPO}/rest-api-go"
 ```
 
-6. Replace the image reference path with our published image path in the
+6. Substitute the image reference path in the template with our published image
-   configuration files (`serving/samples/rest-api-go/sample.yaml`:
+   path. The command below substitutes using the ${REPO} variable into a new
+   file called `serving/samples/rest-api-go/sample.yaml`.
 
-   - Manually replace:
+   ```shell
-     `image: github.com/knative/docs/serving/samples/rest-api-go` with
+   envsubst < serving/samples/rest-api-go/sample-template.yaml > \
-     `image: <YOUR_CONTAINER_REGISTRY>/serving/samples/rest-api-go`
+   serving/samples/rest-api-go/sample.yaml
-
-   Or
-
-   - Use run this command:
-
-   ```
-   perl -pi -e "s@github.com/knative/docs@${REPO}@g" serving/samples/rest-api-go/sample.yaml
    ```
 
 ## Deploy the Service
@@ -96,7 +93,7 @@ docker push "${REPO}/serving/samples/rest-api-go"
 Now that our image is available from the container registry, we can deploy the
 Knative Serving sample:
 
-```
+```shell
 kubectl apply --filename serving/samples/rest-api-go/sample.yaml
 ```
 
@@ -117,42 +114,42 @@ You can inspect the created resources with the following `kubectl` commands:
 
 - View the created Service resource:
 
-```
+```shell
 kubectl get ksvc stock-service-example --output yaml
 ```
 
 - View the created Route resource:
 
-```
+```shell
-kubectl get route -l
+kubectl get route -l \
 "serving.knative.dev/service=stock-service-example" --output yaml
 ```
 
 - View the Kubernetes Service created by the Route
 
-```
+```shell
-kubectl get service -l
+kubectl get service -l \
 "serving.knative.dev/service=stock-service-example" --output yaml
 ```
 
 - View the created Configuration resource:
 
-```
+```shell
-kubectl get configuration -l
+kubectl get configuration -l \
 "serving.knative.dev/service=stock-service-example" --output yaml
 ```
 
 - View the Revision that was created by our Configuration:
 
-```
+```shell
-kubectl get revision -l
+kubectl get revision -l \
 "serving.knative.dev/service=stock-service-example" --output yaml
 ```
 
 - View the Deployment created by our Revision
 
-```
+```shell
-kubectl get deployment -l
+kubectl get deployment -l \
 "serving.knative.dev/service=stock-service-example" --output yaml
 ```
 
@@ -163,9 +160,13 @@ This example assumes you are using the default Ingress Gateway setup for
 Knative. If you customized your gateway, you will want to adjust the enviornment
 variables below.
 
+### Find Ingress Gateway IP
+
+#### Cloud Provider
+
 1. To get the IP address of your Ingress Gateway:
 
-```
+```shell
 INGRESSGATEWAY=istio-ingressgateway
 INGRESSGATEWAY_LABEL=istio
 
@@ -174,25 +175,31 @@ export INGRESS_IP=`kubectl get svc $INGRESSGATEWAY --namespace istio-system \
 echo $INGRESS_IP
 ```
 
-- If your cluster is running outside a cloud provider (for example on Minikube),
+#### Minikube
+
+1. If your cluster is running outside a cloud provider (for example on Minikube),
   your services will never get an external IP address, and your INGRESS_IP will
   be empty. In that case, use the istio `hostIP` and `nodePort` as the ingress
   IP:
 
-```
+```shell
 export INGRESS_IP=$(kubectl get po --selector $INGRESSGATEWAY_LABEL=ingressgateway --namespace istio-system \
   --output 'jsonpath={.items[0].status.hostIP}'):$(kubectl get svc $INGRESSGATEWAY --namespace istio-system \
   --output 'jsonpath={.spec.ports[?(@.port==80)].nodePort}')
 echo $INGRESS_IP
 ```
 
+### Get Service Hostname
+
 2. To get the hostname of the Service:
 
-```
+```shell
 export SERVICE_HOSTNAME=`kubectl get ksvc stock-service-example --output jsonpath="{.status.domain}"`
 echo $SERVICE_HOSTNAME
 ```
 
+### Sending Requests
+
 3. Now use `curl` to make a request to the Service:
 
 - Make a request to the index endpoint:
@@ -202,7 +209,7 @@ Gateway uses the host header to route the request to the Service. This example
 passes the host header to skip DNS configuration. If your cluster has DNS
 configured, you can simply curl the DNS name instead of the ingress gateway IP.
 
-```
+```shell
 curl --header "Host:$SERVICE_HOSTNAME" http://${INGRESS_IP}
 ```
 
@@ -210,7 +217,7 @@ Response body: `Welcome to the stock app!`
 
 - Make a request to the `/stock` endpoint:
 
-```
+```shell
 curl --header "Host:$SERVICE_HOSTNAME" http://${INGRESS_IP}/stock
 ```
 
@@ -218,7 +225,7 @@ Response body: `stock ticker not found!, require /stock/{ticker}`
 
 - Make a request to the `/stock` endpoint with a `ticker` parameter:
 
-```
+```shell
 curl --header "Host:$SERVICE_HOSTNAME" http://${INGRESS_IP}/stock/<ticker>
 ```
 
@@ -235,6 +242,6 @@ between multiple Revisions.
 
 To clean up the sample Service:
 
-```
+```shell
 kubectl delete --filename serving/samples/rest-api-go/sample.yaml
 ```

serving/samples/rest-api-go/sample-template.yaml

@@ -20,14 +20,9 @@ spec:
   runLatest:
     configuration:
       revisionTemplate:
-        metadata:
-          labels:
-            knative.dev/type: container
         spec:
           container:
-            # This is the Go import path for the binary to containerize
+            image: ${REPO}/rest-api-go
-            # and substitute here.
-            image: github.com/knative/docs/serving/samples/rest-api-go
             env:
               - name: RESOURCE
                 value: stock

serving/samples/traffic-splitting/README.md

@@ -1,138 +1,165 @@
 # Simple Traffic Splitting Between Revisions
 
-This samples builds off the [Creating a RESTful Service](../rest-api-go) sample
+This samples builds off of the [Creating a RESTful Service](../rest-api-go) sample
-to illustrate applying a revision, then using that revision for manual traffic
+to illustrate updating a Service to create a new Revision as well as splitting traffic
-splitting.
+between the two created Revisions.
 
 ## Prerequisites
 
-1. [Creating a RESTful Service](../rest-api-go).
+1. Complete the Service creation steps in [Creating a RESTful Service](../rest-api-go).
+1. Move into the docs directory:
+
+```shell
+cd $GOPATH/src/github.com/knative/docs
+```
+
+## Updating to Release Mode
+
+The service was originally created with a mode of `runLatest`. In `runLatest`
+mode, the service serves the latest Revision that is ready to handle incoming
+traffic. To split traffic between multiple Revisions, the Service mode will need
+to be changed to `release` mode. The `release` mode differs from `runLatest` in that
+it requires a `revisions` list. The `revisions` list accepts 1 or 2 Revisions
+that will be served by the base domain of the service. When 2 Revisions are
+present in the list a `rolloutPercent` parameter specifies the percentage of
+traffic to send to each Revision.
+
+This first step will update the Service to release mode with a single Revision.
+
+1. To populate the `revisions` list the name of the created Revision is required.
+The command below captures the names of all created Revisions as an array so it
+can be substituted it into the YAML.
+
+```shell
+REVISIONS=($(kubectl get revision -l "serving.knative.dev/service=stock-service-example" -o \
+jsonpath="{.items[*].metadata.name}"))
+echo ${REVISIONS[*]}
+```
+
+2. The `release_sample.yaml` is setup in this directory to allow enable substituting the
+Revision name into the file with the `envsubst` utility. Executing the
+command below will update the Service to release mode with the queried Revision name.
+
+- Note: The command below expects `$REPO` to still be exported. See
+  [RESTful Service Setup](https://github.com/knative/docs/tree/master/serving/samples/rest-api-go#setup) to set it.
+
+```shell
+CURRENT=${REVISIONS[0]} \
+envsubst < serving/samples/traffic-splitting/release_sample.yaml \
+| kubectl apply --filename -
+```
+
+3. The `spec` of the Service should now show `release` with the Revision name
+retrieved above.
+
+```shell
+kubectl get ksvc stock-service-example --output yaml
+```
 
 ## Updating the Service
 
-This section describes how to create an revision by deploying a new
+This section describes how to create a new Revision by updating your Service.
-configuration.
 
-1. Replace the image reference path with our published image path in the
+A new Revision is created every time a value in the `revisionTemplate` section of
-   configuration files
+the Service `spec` is updated. The `updated_sample.yaml` in this folder changes
-   (`serving/samples/traffic-splitting/updated_configuration.yaml`:
+the environment variable `RESOURCE` from `stock` to `share`. Applying this
+change will result in a new Revision.
 
-   - Manually replace:
+For comparison, you can diff the `release_sample.yaml` with the `updated_sample.yaml`.
-     `image: github.com/knative/docs/serving/samples/rest-api-go` with
-     `image: <YOUR_CONTAINER_REGISTRY>/serving/samples/rest-api-go`
 
-   Or
+```shell
-
+diff serving/samples/traffic-splitting/release_sample.yaml \
-   - Use run this command:
+serving/samples/traffic-splitting/updated_sample.yaml
-
-   ```
-   perl -pi -e "s@github.com/knative/docs@${REPO}@g" serving/samples/rest-api-go/updated_configuration.yaml
-   ```
-
-2. Deploy the new configuration to update the `RESOURCE` environment variable
-   from `stock` to `share`:
-
-```
-kubectl apply --filename serving/samples/traffic-splitting/updated_configuration.yaml
 ```
 
-3. Once deployed, traffic will shift to the new revision automatically. Verify
+1.  Execute the command below to update the environment variable in the Service
-   the deployment by checking the route status:
+    resulting in a new Revision.
 
-```
+```shell
-kubectl get route --output yaml
+CURRENT=${REVISIONS[0]} \
+envsubst < serving/samples/traffic-splitting/updated_sample.yaml \
+| kubectl apply --filename -
 ```
 
-4. When the new route is ready, you can access the new endpoints: The hostname
+2. Since we are using a `release` service, traffic will _not_ shift to the new
-   and IP address can be found in the same manner as the
+   Revision automatically. However, it will be available from the subdomain
-   [Creating a RESTful Service](../rest-api-go) sample:
+   `latest`. This can be verified through the Service status:
 
-```
+```shell
-export SERVICE_HOST=`kubectl get route stock-route-example --output jsonpath="{.status.domain}"`
+kubectl get ksvc stock-service-example --output yaml
-
-# In Knative 0.2.x and prior versions, the `knative-ingressgateway` service was used instead of `istio-ingressgateway`.
-INGRESSGATEWAY=knative-ingressgateway
-
-# The use of `knative-ingressgateway` is deprecated in Knative v0.3.x.
-# Use `istio-ingressgateway` instead, since `knative-ingressgateway`
-# will be removed in Knative v0.4.
-if kubectl get configmap config-istio -n knative-serving &> /dev/null; then
-    INGRESSGATEWAY=istio-ingressgateway
-fi
-
-export SERVICE_IP=`kubectl get svc $INGRESSGATEWAY --namespace istio-system \
-    --output jsonpath="{.status.loadBalancer.ingress[*].ip}"`
 ```
 
-- Make a request to the index endpoint:
+3. The readiness of the Service can be verified through the Service Conditions.
+   When the Service conditions report it is ready again, you can access the new
+   Revision using the same method as found in the [previous sample](../rest-api-go/README.md#access-the-service)
+   by prefixing the Service hostname with `latest.`.
 
-```
+```shell
-curl --header "Host:$SERVICE_HOST" http://${SERVICE_IP}
+curl --header "Host:latest.${SERVICE_HOSTNAME}" http://${INGRESS_IP}
 ```
 
-Response body: `Welcome to the share app!`
+- Hitting the top domain (or `current.`) will hit the Revision at the first
+  index of the `revisions` list:
 
-- Make a request to the `/share` endpoint:
+```shell
-
+curl --header "Host:${SERVICE_HOSTNAME}" http://${INGRESS_IP}
-```
+curl --header "Host:current.${SERVICE_HOSTNAME}" http://${INGRESS_IP}
-curl --header "Host:$SERVICE_HOST" http://${SERVICE_IP}/share
 ```
 
-Response body: `share ticker not found!, require /share/{ticker}`
+## Traffic Splitting
 
-- Make a request to the `/share` endpoint with a `ticker` parameter:
+Updating the service to split traffic between the two revisions is done by
+placing a second revision in of the `revisions` list and specifying a `rolloutPercent`.
+The `rolloutPercent` is the percentage of traffic to send to the second element in
+the list. When the Service is Ready the traffic will be split as desired for the
+base domain, and a subdomain of `candidate` will be available pointing to the
+second Revision.
 
-```
+1. Get the latest list of revisions by executing the command below:
-curl --header "Host:$SERVICE_HOST" http://${SERVICE_IP}/share/<ticker>
+
+```shell
+REVISIONS=($(kubectl get revision -l "serving.knative.dev/service=stock-service-example" --output \
+jsonpath="{.items[*].metadata.name}"))
+echo ${REVISIONS[*]}
 ```
 
-Response body: `share price for ticker <ticker> is <price>`
+2. Update the `revisions` list in
+   `serving/samples/traffic-splitting/split_sample.yaml`. A `rolloutPercent` of
+   50 has already been specified, but can be changed if desired by editing the
+   `split_sample.yaml` file.
 
-## Manual Traffic Splitting
 
-This section describes how to manually split traffic to specific revisions.
+```shell
-
+CURRENT=${REVISIONS[0]} CANDIDATE=${REVISIONS[1]} \
-1. Get your revisions names via:
+envsubst < serving/samples/traffic-splitting/split_sample.yaml \
-
+| kubectl apply --filename -
-```
-kubectl get revisions
 ```
 
-```
+3. Verify the deployment by checking the service status:
-NAME                                AGE
+
-stock-configuration-example-00001   11m
+```shell
-stock-configuration-example-00002   4m
+kubectl get ksvc --output yaml
 ```
 
-2. Update the `traffic` list in `serving/samples/rest-api-go/sample.yaml` as:
+4. Once updated, `curl` requests to the base domain should result in responses split evenly between `Welcome to the share app!` and
+`Welcome to the stock app!`.
 
-```yaml
+```shell
-traffic:
+curl --header "Host:${SERVICE_HOSTNAME}" http://${INGRESS_IP}
-  - revisionName: <YOUR_FIRST_REVISION_NAME>
-    percent: 50
-  - revisionName: <YOUR_SECOND_REVISION_NAME>
-    percent: 50
 ```
 
-3. Deploy your traffic revision:
+5. Much like the `current` and `latest` subdomains there should now be a
+`candidate` subdomain that should return `Welcome to the share app!` as it hits
+the second index of the `revisions` list.
 
+```shell
+curl --header "Host:candidate.${SERVICE_HOSTNAME}" http://${INGRESS_IP}
 ```
-kubectl apply --filename serving/samples/rest-api-go/sample.yaml
-```
-
-4. Verify the deployment by checking the route status:
-
-```
-kubectl get route --output yaml
-```
-
-Once updated, you can make `curl` requests to the API using either `stock` or
-`share` endpoints.
 
 ## Clean Up
 
 To clean up the sample service:
 
-```
+```shell
-kubectl delete --filename serving/samples/traffic-splitting/updated_configuration.yaml
+kubectl delete --filename serving/samples/traffic-splitting/split_sample.yaml
 ```

serving/samples/traffic-splitting/release_sample.yaml

@@ -1,4 +1,4 @@
-# Copyright 2018 The Knative Authors
+# Copyright 2019 The Knative Authors
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -13,25 +13,23 @@
 # limitations under the License.
 
 apiVersion: serving.knative.dev/v1alpha1
-kind: Configuration
+kind: Service
 metadata:
-  name: stock-configuration-example
+  name: stock-service-example
   namespace: default
 spec:
+ release:
+  revisions: ["${CURRENT}"]
+  configuration:
     revisionTemplate:
-    metadata:
-      labels:
-        knative.dev/type: container
       spec:
         container:
-        # This is the Go import path for the binary to containerize
+          image: ${REPO}/rest-api-go
-        # and substitute here.
-        image: github.com/knative/docs/serving/samples/rest-api-go
           env:
             - name: RESOURCE
-            value: share
+              value: stock
           readinessProbe:
             httpGet:
               path: /
-          initialDelaySeconds: 3
+            initialDelaySeconds: 0
             periodSeconds: 3

serving/samples/traffic-splitting/split_sample.yaml

@@ -0,0 +1,36 @@
+# Copyright 2019 The Knative Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+apiVersion: serving.knative.dev/v1alpha1
+kind: Service
+metadata:
+  name: stock-service-example
+  namespace: default
+spec:
+ release:
+  revisions: [ "${CURRENT}", "${CANDIDATE}"]
+  rolloutPercent: 50
+  configuration:
+    revisionTemplate:
+      spec:
+        container:
+          image: ${REPO}/rest-api-go
+          env:
+            - name: RESOURCE
+              value: share
+          readinessProbe:
+            httpGet:
+              path: /
+            initialDelaySeconds: 0
+            periodSeconds: 3

serving/samples/traffic-splitting/updated_sample.yaml

@@ -0,0 +1,35 @@
+# Copyright 2019 The Knative Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+apiVersion: serving.knative.dev/v1alpha1
+kind: Service
+metadata:
+  name: stock-service-example
+  namespace: default
+spec:
+ release:
+  revisions: ["${CURRENT}"]
+  configuration:
+    revisionTemplate:
+      spec:
+        container:
+          image: ${REPO}/rest-api-go
+          env:
+            - name: RESOURCE
+              value: share
+          readinessProbe:
+            httpGet:
+              path: /
+            initialDelaySeconds: 0
+            periodSeconds: 3