CD prow config using tekton

Define an event listener that triggers a tekton task that deploys
prow configurations on a target k8s cluster / namespace from a
give git repo / path.

Closes #1

tekton/config/kubectl-image-nightly-build-cron/cronjob.yaml

@@ -0,0 +1,24 @@
+apiVersion: batch/v1beta1
+kind: CronJob
+metadata:
+  name: image-build-cron-trigger
+spec:
+  schedule: "0 2 * * *"
+  concurrencyPolicy: Forbid
+  jobTemplate:
+    spec:
+      template:
+        spec:
+          containers:
+          - name: trigger
+            env:
+            - name: SINK_URL
+              value: el-image-builder.default.svc.cluster.local:8080
+            - name: GIT_REPOSITORY
+              value: github.com/tekton/plumbing
+            - name: GIT_REVISION
+              value: master
+            - name: TARGET_IMAGE
+              value: gcr.io/tekton-releases/dogfooding/kubectl:latest
+            - name: CONTEXT_PATH
+              value: tekton/images/kubectl

tekton/config/kubectl-image-nightly-build-cron/kustomization.yaml

@@ -0,0 +1,5 @@
+bases:
+- ../nightly-image-build-cron-base
+patchesStrategicMerge:
+- cronjob.yaml
+nameSuffix: "-kubectl"

tekton/images/kubectl/Dockerfile

@@ -0,0 +1,21 @@
+# Copyright 2019 The Tekton 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
+#
+#     http://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.
+FROM alpine:3.10
+LABEL maintainer "Andrea Frittoli <andrea.frittoli@gmail.com>"
+
+RUN apk update && apk add ca-certificates && rm -rf /var/cache/apk/*
+RUN update-ca-certificates
+
+ARG KUBECTL_VERSION=1.16.2
+RUN wget -O/usr/local/bin/kubectl https://storage.googleapis.com/kubernetes-release/release/v$KUBECTL_VERSION/bin/linux/amd64/kubectl

tekton/images/tkn/Dockerfile

@@ -1,4 +1,4 @@
-# Copyright 2018 The Tekton Authors
+# Copyright 2019 The Tekton Authors
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -14,5 +14,8 @@
 FROM alpine:3.10
 LABEL maintainer "Andrea Frittoli <andrea.frittoli@gmail.com>"
 
+RUN apk update && apk add ca-certificates && rm -rf /var/cache/apk/*
+RUN update-ca-certificates
+
 ARG TKN_VERSION=0.4.0
 RUN wget -O- https://github.com/tektoncd/cli/releases/download/v${TKN_VERSION}/tkn_${TKN_VERSION}_Linux_x86_64.tar.gz | tar zxf - -C /usr/local/bin

tekton/resources/prow-config-cd.yaml

@@ -0,0 +1,119 @@
+apiVersion: tekton.dev/v1alpha1
+kind: TriggerBinding
+metadata:
+  name: trigger-to-deploy-prow-config
+spec:
+  params:
+  - name: gitRepository
+    value: $(body.gitRepository)
+  - name: gitRevision
+    value: $(body.gitRevision)
+  - name: configPath
+    value: $(body.configPath)
+  - name: namespace
+    value: $(body.namespace)
+  - name: clusterResource
+    value: $(body.clusterResource)
+---
+apiVersion: tekton.dev/v1alpha1
+kind: EventListener
+metadata:
+  name: prow-config-deployer
+spec:
+  triggers:
+    - name: trigger
+      binding:
+        name: trigger-to-deploy-prow-config
+      template:
+        name: deploy-prow-config
+---
+apiVersion: tekton.dev/v1alpha1
+kind: TriggerTemplate
+metadata:
+  name: deploy-prow-config
+spec:
+  params:
+  - name: gitRepository
+    description: URL of the repository that holds the prow configuration
+  - name: gitRevision
+    description: Git revision
+  - name: namespace
+    description: Namespace to deploy to in the target cluster
+  - name: configPath
+    description: Path in the git repo that holds prow configs
+  - name: clusterResource
+    description: Name of the cluster resource that points to the target cluster
+  resourcetemplates:
+  - apiVersion: tekton.dev/v1alpha1
+    kind: PipelineResource
+    metadata:
+      name: git-source-$(uid)
+    spec:
+      type: git
+      params:
+      - name: revision
+        value: $(params.gitRevision)
+      - name: url
+        value: https://$(params.gitRepository)
+  - apiVersion: tekton.dev/v1alpha1
+    kind: TaskRun
+    metadata:
+      generateName: deploy-prow-config-$(uid)-
+    spec:
+      taskSpec:
+        inputs:
+          params:
+          - name: configPath
+            description: Path in the git repo that holds prow configs
+          - name: namespace
+            description: Namespace to deploy to in the target cluster
+          resources:
+          - name: source
+            type: git
+          - name: prow-cluster
+            type: cluster
+        stepTemplate:
+          env:
+            name: KUBECONFIG
+            value: /workspace/$(inputs.resources.prow-cluster.name)/kubeconfig
+        steps:
+        - name: fetch-current-config
+          image: gcr.io/tekton-releases/dogfooding/kubectl
+          command:
+          - /bin/sh
+          args:
+          - -ce
+          - |
+            kubectl get configmap config -o template --template={{.data}} \
+              > /workspace/config.yaml
+        - name: deploy
+          image: gcr.io/tekton-releases/dogfooding/kubectl
+          command:
+          - /bin/sh
+          args:
+          - -ce
+          - |
+            echo "diff [current-config] [new config]"
+            diff /workspace/config.yaml $(inputs.resources.source.path)/$(inputs.params.configPath)=prow/config.yaml
+            if [ $? -eq 0 ]; then
+              echo "No change in config detected. Nothing to be done."
+              exit 0
+            fi
+            # Apply configuration changes
+            kubectl create configmap config \
+              --from-file=$(inputs.resources.source.path)/$(inputs.params.configPath)=prow/config.yaml \
+              --dry-run -o yaml | \
+              kubectl replace configmap config -n $(inputs.params.namespace) -f -
+      inputs:
+        params:
+        - name: configPath
+          value: $(params.configPath)
+        - name: namespace
+          value: $(params.namespace)
+        resources:
+        - name: source
+          resourceRef:
+            name: git-source-$(uid)
+        - name: prow-cluster
+          resourceRef:
+            name: $(params.clusterResource)