Deprecated implicit parameters

Tekton Pipelines resources are verbose mostly because of explicitly propagating Parameters. Implicit Parameters feature was added to reduce the verbosity. However, there are challenges caused by mutating specifications to support Implicit Parameters. This PR deprecates existing implementation of implicit parameters. A followup PR will address improvements to this and allow propagating paramaters that the task requires.

Author: chitrangpatel

docs/pipelineruns.md

@@ -15,7 +15,6 @@ weight: 500
       - [Remote Pipelines](#remote-pipelines)
     - [Specifying <code>Resources</code>](#specifying-resources)
     - [Specifying <code>Parameters</code>](#specifying-parameters)
-      - [Implicit Parameters](#implicit-parameters)
     - [Specifying custom <code>ServiceAccount</code> credentials](#specifying-custom-serviceaccount-credentials)
     - [Mapping <code>ServiceAccount</code> credentials to <code>Tasks</code>](#mapping-serviceaccount-credentials-to-tasks)
     - [Specifying a <code>Pod</code> template](#specifying-a-pod-template)
@@ -284,75 +283,6 @@ case is when your CI system autogenerates `PipelineRuns` and it has `Parameters`
 provide to all `PipelineRuns`. Because you can pass in extra `Parameters`, you don't have to
 go through the complexity of checking each `Pipeline` and providing only the required params.
 
-#### Implicit Parameters
-
-**([alpha only](https://github.com/tektoncd/pipeline/blob/main/docs/install.md#alpha-features))**
-
-When using an inlined spec, parameters from the parent `PipelineRun` will be
-available to any inlined specs without needing to be explicitly defined. This
-allows authors to simplify specs by automatically propagating top-level
-parameters down to other inlined resources.
-
-```yaml
-apiVersion: tekton.dev/v1beta1
-kind: PipelineRun
-metadata:
-  generateName: echo-
-spec:
-  params:
-    - name: MESSAGE
-      value: "Good Morning!"
-  pipelineSpec:
-    tasks:
-      - name: echo-message
-        taskSpec:
-          steps:
-            - name: echo
-              image: ubuntu
-              script: |
-                #!/usr/bin/env bash
-                echo "$(params.MESSAGE)"
-```
-
-On creation, this will resolve to a fully-formed spec and will be returned back
-to clients to avoid ambiguity:
-
-```yaml
-apiVersion: tekton.dev/v1beta1
-kind: PipelineRun
-metadata:
-  generateName: echo-
-spec:
-  params:
-  - name: MESSAGE
-    value: Good Morning!
-  pipelineSpec:
-    params:
-    - name: MESSAGE
-      type: string
-    tasks:
-    - name: echo-message
-      params:
-      - name: MESSAGE
-        value: $(params.MESSAGE)
-      taskSpec:
-        params:
-        - name: MESSAGE
-          type: string
-        spec: null
-        steps:
-        - name: echo
-          image: ubuntu
-          script: |
-            #!/usr/bin/env bash
-            echo "$(params.MESSAGE)"
-```
-
-Note that all implicit Parameters will be passed through to inlined resources
-(i.e. PipelineRun -> Pipeline -> Tasks) even if they are not used.
-Extra parameters passed this way should generally be safe (since they aren't
-actually used), but may result in more verbose specs being returned by the API.
-
 ### Specifying custom `ServiceAccount` credentials
 
 You can execute the `Pipeline` in your `PipelineRun` with a specific set of credentials by

docs/taskruns.md

@@ -14,7 +14,6 @@ weight: 300
   - [Tekton Bundles](#tekton-bundles)
   - [Remote Tasks](#remote-tasks)
   - [Specifying `Parameters`](#specifying-parameters)
-    - [Implicit Parameters](#implicit-parameters)
     - [Extra Parameters](#extra-parameters)
   - [Specifying `Resources`](#specifying-resources)
   - [Specifying `Resource` limits](#specifying-resource-limits)
@@ -198,60 +197,6 @@ spec:
 
 **Note:** If a parameter does not have an implicit default value, you must explicitly set its value.
 
-#### Implicit Parameters
-
-**([alpha only](https://github.com/tektoncd/pipeline/blob/main/docs/install.md#alpha-features))**
-
-When using an inlined `taskSpec`, parameters from the parent `TaskRun` will be
-available to the `Task` without needing to be explicitly defined.
-
-```yaml
-apiVersion: tekton.dev/v1beta1
-kind: TaskRun
-metadata:
-  generateName: hello-
-spec:
-  params:
-    - name: message
-      value: "hello world!"
-  taskSpec:
-    # There are no explicit params defined here.
-    # They are derived from the TaskRun params above.
-    steps:
-    - name: default
-      image: ubuntu
-      script: |
-        echo $(params.message)
-```
-
-On creation, this will resolve to a fully-formed spec and will be returned back
-to clients to avoid ambiguity:
-
-```yaml
-apiVersion: tekton.dev/v1beta1
-kind: TaskRun
-metadata:
-  generateName: hello-
-spec:
-  params:
-    - name: message
-      value: "hello world!"
-  taskSpec:
-    params:
-    - name: message
-      type: string
-    steps:
-    - name: default
-      image: ubuntu
-      script: |
-        echo $(params.message)
-```
-
-Note that all implicit Parameters will be passed through to inlined resource,
-even if they are not used. Extra parameters passed this way should generally
-be safe (since they aren't actually used), but may result in more verbose specs
-being returned by the API.
-
 #### Extra Parameters
 
 **([alpha only](https://github.com/tektoncd/pipeline/blob/main/docs/install.md#alpha-features))**