Allow configuration of PVC size from ConfigMap

PVCs are hardcoded to 5Gi and that should be configurable.
For instance Alibaba Container Service does not allow volumes smaller than 20Gi

Add a `config-artifact-pvc` ConfigMap that can be used to store such configuration

Signed-off-by: Carlos Sanchez <carlos@apache.org>

Author: carlossg

config/config-artifact-pvc.yaml

@@ -0,0 +1,23 @@
+# Copyright 2018 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: v1
+kind: ConfigMap
+metadata:
+  name: config-artifact-pvc
+  namespace: tekton-pipelines
+data:
+  # size of the PVC volume
+  # size: 5Gi
+

docs/install.md

@@ -104,8 +104,13 @@ Pipelines need a way to share resources between tasks. The alternatives are a
 [Persistent volume](https://kubernetes.io/docs/concepts/storage/persistent-volumes/)
 or a [GCS storage bucket](https://cloud.google.com/storage/)
 
-The PVC option does not require any configuration, but the GCS storage bucket
-can be configured using a ConfigMap with the name `config-artifact-bucket` with
+The PVC option can be configured using a ConfigMap with the name
+`config-artifact-pvc` and the following attributes:
+
+- size: the size of the volume (5Gi by default)
+ 
+The GCS storage bucket can be configured
+using a ConfigMap with the name `config-artifact-bucket` with
 the following attributes:
 
 - location: the address of the bucket (for example gs://mybucket)

pkg/apis/pipeline/v1alpha1/artifact_pvc.go

@@ -33,7 +33,8 @@ var (
 // ArtifactPVC represents the pvc created by the pipelinerun
 // for artifacts temporary storage
 type ArtifactPVC struct {
-	Name string
+	Name                  string
+	PersistentVolumeClaim *corev1.PersistentVolumeClaim
 }
 
 // GetType returns the type of the artifact storage