Add params section to Pipelinerun doc

Adds params section to Pipelinerun doc to explain
how to specify params in a Pipelinerun Spec

Add examples in `examples/v1alpha1/pipelineruns` and `examples/v1beta1/pipelineruns`

Fixes #2153

Signed-off-by: Nikhil Thomas <nikthoma@redhat.com>

docs/pipelineruns.md

@@ -13,12 +13,13 @@ Creation of a `PipelineRun` will trigger the creation of
 
 - [Syntax](#syntax)
  - [Resources](#resources)
+ - [Params](#params)
  - [Service account](#service-account)
  - [Service accounts](#service-accounts)
  - [Pod Template](#pod-template)
  - [Workspaces](#workspaces)
 - [Cancelling a PipelineRun](#cancelling-a-pipelinerun)
-- [Examples](https://github.com/tektoncd/pipeline/tree/master/examples/pipelineruns)
+- [Examples](https://github.com/tektoncd/pipeline/tree/master/examples/v1beta1/pipelineruns)
 - [Logs](logs.md)
 - [LimitRanges](#limitranges)
 
@@ -39,6 +40,7 @@ following fields:
 - Optional:
  - [`resources`](#resources) - Specifies which
  [`PipelineResources`](resources.md) to use for this `PipelineRun`.
+ - [`params`](#params) - Specifies which params to be passed to the pipeline specified/referenced by this pipeline run.
  - [`serviceAccountName`](#service-account) - Specifies a `ServiceAccount` resource
  object that enables your build to run with the defined authentication
  information. When a `ServiceAccount` isn't specified, the `default-service-account`
@@ -171,6 +173,23 @@ spec:
  value: gcr.io/christiewilson-catfactory/leeroy-app
 ```
 
+### Params
+
+While writing a Pipelinerun, we can specify params that need to be bound to
+the input params of the pipeline specified/referenced by the Pipelinerun.
+
+This means that a Pipeline can be run with different input params, by writing Pipelineruns
+which bound different input values to the Pipeline params.
+
+```yaml
+spec:
+ params:
+ - name: pl-param-x
+ value: "100"
+ - name: pl-param-y
+ value: "500"
+```
+
 ### Service Account
 
 Specifies the `name` of a `ServiceAccount` resource object. Use the

examples/v1alpha1/pipelineruns/pipelinerun-with-params.yaml

@@ -0,0 +1,92 @@
+apiVersion: tekton.dev/v1alpha1
+kind: Pipeline
+metadata:
+ name: pipeline-with-params
+spec:
+ params:
+ - name: pl-param-x
+ type: string
+ default: "1"
+ - name: pl-param-y
+ type: string
+ default: "1"
+ tasks:
+ - name: sum-params
+ taskRef:
+ name: sum-params
+ params:
+ - name: a
+ value: "$(params.pl-param-x)"
+ - name: b
+ value: "$(params.pl-param-y)"
+ - name: multiply-params
+ taskRef:
+ name: multiply-params
+ params:
+ - name: a
+ value: "$(params.pl-param-x)"
+ - name: b
+ value: "$(params.pl-param-y)"
+---
+apiVersion: tekton.dev/v1alpha1
+kind: Task
+metadata:
+ name: sum-params
+ annotations:
+ description: |
+ A simple task that sums the two provided integers
+spec:
+ inputs:
+ params:
+ - name: a
+ type: string
+ default: "1"
+ description: The first integer
+ - name: b
+ type: string
+ default: "1"
+ description: The second integer
+ steps:
+ - name: sum
+ image: bash:latest
+ script: |
+ #!/usr/bin/env bash
+ echo -n $(( "$(inputs.params.a)" + "$(inputs.params.b)" ))
+---
+apiVersion: tekton.dev/v1alpha1
+kind: Task
+metadata:
+ name: multiply-params
+ annotations:
+ description: |
+ A simple task that multiplies the two provided integers
+spec:
+ inputs:
+ params:
+ - name: a
+ type: string
+ default: "1"
+ description: The first integer
+ - name: b
+ type: string
+ default: "1"
+ description: The second integer
+ steps:
+ - name: product
+ image: bash:latest
+ script: |
+ #!/usr/bin/env bash
+ echo -n $(( "$(inputs.params.a)" * "$(inputs.params.b)" ))
+---
+apiVersion: tekton.dev/v1alpha1
+kind: PipelineRun
+metadata:
+ name: pipelinerun-with-params
+spec:
+ params:
+ - name: pl-param-x
+ value: "100"
+ - name: pl-param-y
+ value: "500"
+ pipelineRef:
+ name: pipeline-with-params

examples/v1beta1/pipelineruns/pipelinerun-with-params.yaml

@@ -0,0 +1,90 @@
+apiVersion: tekton.dev/v1beta1
+kind: Pipeline
+metadata:
+ name: pipeline-with-params
+spec:
+ params:
+ - name: pl-param-x
+ type: string
+ default: "1"
+ - name: pl-param-y
+ type: string
+ default: "1"
+ tasks:
+ - name: sum-params
+ taskRef:
+ name: sum-params
+ params:
+ - name: a
+ value: "$(params.pl-param-x)"
+ - name: b
+ value: "$(params.pl-param-y)"
+ - name: multiply-params
+ taskRef:
+ name: multiply-params
+ params:
+ - name: a
+ value: "$(params.pl-param-x)"
+ - name: b
+ value: "$(params.pl-param-y)"
+---
+apiVersion: tekton.dev/v1beta1
+kind: Task
+metadata:
+ name: sum-params
+ annotations:
+ description: |
+ A simple task that sums the two provided integers
+spec:
+ params:
+ - name: a
+ type: string
+ default: "1"
+ description: The first integer
+ - name: b
+ type: string
+ default: "1"
+ description: The second integer
+ steps:
+ - name: sum
+ image: bash:latest
+ script: |
+ #!/usr/bin/env bash
+ echo -n $(( "$(inputs.params.a)" + "$(inputs.params.b)" ))
+---
+apiVersion: tekton.dev/v1beta1
+kind: Task
+metadata:
+ name: multiply-params
+ annotations:
+ description: |
+ A simple task that multiplies the two provided integers
+spec:
+ params:
+ - name: a
+ type: string
+ default: "1"
+ description: The first integer
+ - name: b
+ type: string
+ default: "1"
+ description: The second integer
+ steps:
+ - name: product
+ image: bash:latest
+ script: |
+ #!/usr/bin/env bash
+ echo -n $(( "$(inputs.params.a)" * "$(inputs.params.b)" ))
+---
+apiVersion: tekton.dev/v1beta1
+kind: PipelineRun
+metadata:
+ name: pipelinerun-with-params
+spec:
+ params:
+ - name: pl-param-x
+ value: "100"
+ - name: pl-param-y
+ value: "500"
+ pipelineRef:
+ name: pipeline-with-params