This patch splits git-clone task from the git directory

Changes include:
  - moves git-clone task to the task directory
  - copies and modifies readme file for git-clone from git directory
  - copies examples and tests directory from git directory

Issue: #386

Signed-off-by: Puneet Punamiya <ppunamiy@redhat.com>

task/git-clone/0.1/README.md

@@ -0,0 +1,56 @@
+# Git Task
+
+This `Task` is Git task to work with repositories used by other tasks
+in your Pipeline.
+## `git-clone`
+
+**Please Note: this Task is only compatible with Tekton Pipelines versions 0.11-rc1 and greater!**
+
+This `Task` has two required inputs:
+
+1. The URL of a git repo to clone provided with the `url` param.
+2. A Workspace called `output`.
+
+The `git-clone` `Task` will clone a repo from the provided `url` into the
+`output` Workspace. By default the repo will be cloned into the root of
+your Workspace. You can clone into a subdirectory by setting this `Task`'s
+`subdirectory` param.
+
+This `Task` does the job of the legacy `GitResource` `PipelineResource` and
+is intended as its replacement. This is part of our plan to [offer replacement
+`Tasks` for Pipeline Resources](https://github.com/tektoncd/catalog/issues/95)
+as well as
+[document those replacements](https://github.com/tektoncd/pipeline/issues/1369).
+
+### Workspaces
+
+* **output**: A workspace for this Task to fetch the git repository in to.
+
+### Parameters
+
+* **url**: git url to clone (_required_)
+* **revision**: git revision to checkout (branch, tag, sha, ref…) (_default:_ master)
+* **refspec**: git refspec to fetch before checking out revision (_default_:refs/heads/master:refs/heads/master)
+* **submodules**: defines if the resource should initialize and fetch the submodules (_default_: true)
+* **depth**: performs a shallow clone where only the most recent commit(s) will be fetched (_default_: 1)
+* **sslVerify**: defines if http.sslVerify should be set to true or false in the global git config (_default_: true)
+* **subdirectory**: subdirectory inside the "output" workspace to clone the git repo into (_default:_ "")
+* **deleteExisting**: clean out the contents of the repo's destination directory if it already exists before cloning the repo there (_default_: false)
+* **httpProxy**: git HTTP proxy server for non-SSL requests
+* **httpsProxy**: git HTTPS proxy server for SSL requests
+* **noProxy**: git no proxy - opt out of proxying HTTP/HTTPS requests
+
+### Results
+
+* **commit**: The precise commit SHA that was fetched by this Task
+
+## Usage
+
+### `git-clone`
+
+The following pipelines demonstrate usage of the git-clone Task:
+
+- [Cloning a branch](./examples/git-clone-checking-out-a-branch.yaml)
+- [Checking out a specific git commit](./examples/git-clone-checking-out-a-commit.yaml)
+- [Checking out a git tag and using the "commit" Task Result](./examples/using-git-clone-task-result.yaml)
+

task/git-clone/0.1/examples/git-cli/pipeline.yaml

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+---
+apiVersion: tekton.dev/v1beta1
+kind: Pipeline
+metadata:
+  name: git-pipeline
+spec:
+  workspaces:
+    - name: shared-workspace
+    - name: input
+  tasks:
+    - name: fetch-repository
+      taskRef:
+        name: git-clone
+      workspaces:
+        - name: output
+          workspace: shared-workspace
+      params:
+        - name: url
+          value: https://github.com/kelseyhightower/nocode
+        - name: subdirectory
+          value: ""
+        - name: deleteExisting
+          value: "true"
+    - name: git-cli
+      taskRef:
+        name: git-cli
+      runAfter:
+        - fetch-repository
+      workspaces:
+        - name: source
+          workspace: shared-workspace
+        - name: input
+          workspace: input
+      params:
+        - name: GIT_USER_NAME
+          value: git_username
+        - name: GIT_USER_EMAIL
+          value: git_email
+        - name: GIT_SCRIPT
+          value: |
+
+            cp $(workspaces.input.path)/* $(workspaces.source.path)
+            git add .
+            git commit -m 'Add sample file'
+            git push origin master
+  results:
+    - name: commit
+---
+apiVersion: tekton.dev/v1beta1
+kind: PipelineRun
+metadata:
+  name: git-pipeline-run
+spec:
+  serviceAccountName: git-service-account
+  pipelineRef:
+    name: git-pipeline
+  workspaces:
+    - name: shared-workspace
+      persistentvolumeclaim:
+        claimName: source-pvc
+    - name: input
+      configmap:
+        name: files

task/git-clone/0.1/examples/git-cli/pvc.yaml

@@ -0,0 +1,11 @@
+---
+apiVersion: v1
+kind: PersistentVolumeClaim
+metadata:
+  name: source-pvc
+spec:
+  resources:
+    requests:
+      storage: 500Mi
+  accessModes:
+    - ReadWriteOnce

task/git-clone/0.1/examples/git-cli/secret.yaml

@@ -0,0 +1,13 @@
+---
+apiVersion: v1
+kind: Secret
+metadata:
+  name: github-auth
+  annotations:
+    # Replace with the desired domain name.
+    tekton.dev/git-0: https://github.com
+type: kubernetes.io/basic-auth
+stringData:
+  username: git_username
+  # Access token should be provided here, if 2 factor authentication is enabled.
+  password: git_password

task/git-clone/0.1/examples/git-cli/service-account.yaml

@@ -0,0 +1,7 @@
+---
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: git-service-account
+secrets:
+  - name: github-auth

task/git-clone/0.1/examples/git-clone-checking-out-a-branch.yaml

@@ -0,0 +1,86 @@
+apiVersion: tekton.dev/v1beta1
+kind: Pipeline
+metadata:
+  name: cat-branch-readme
+spec:
+  description: |
+    cat-branch-readme takes a git repository and a branch name and
+    prints the README.md file from that branch. This is an example
+    Pipeline demonstrating the following:
+      - Using the git-clone catalog Task to clone a branch
+      - Passing a cloned repo to subsequent Tasks using a Workspace.
+      - Ordering Tasks in a Pipeline using "runAfter" so that
+        git-clone completes before we try to read from the Workspace.
+      - Using a volumeClaimTemplate Volume as a Workspace.
+      - Avoiding hard-coded paths by using a Workspace's path
+        variable instead.
+  params:
+  - name: repo-url
+    type: string
+    description: The git repository URL to clone from.
+  - name: branch-name
+    type: string
+    description: The git branch to clone.
+  workspaces:
+  - name: shared-data
+    description: |
+      This workspace will receive the cloned git repo and be passed
+      to the next Task for the repo's README.md file to be read.
+  tasks:
+  - name: fetch-repo
+    taskRef:
+      name: git-clone
+    workspaces:
+    - name: output
+      workspace: shared-data
+    params:
+    - name: url
+      value: $(params.repo-url)
+    - name: revision
+      value: $(params.branch-name)
+  - name: cat-readme
+    runAfter: ["fetch-repo"]  # Wait until the clone is done before reading the readme.
+    workspaces:
+    - name: source
+      workspace: shared-data
+    taskSpec:
+      workspaces:
+      - name: source
+      steps:
+      - image: zshusers/zsh:4.3.15
+        script: |
+          #!/usr/bin/env zsh
+          cat $(workspaces.source.path)/README.md
+---
+apiVersion: tekton.dev/v1beta1
+kind: PipelineRun
+metadata:
+  name: git-clone-checking-out-a-branch
+spec:
+  podTemplate:
+    affinity:
+      podAntiAffinity:
+        requiredDuringSchedulingIgnoredDuringExecution:
+        - labelSelector:
+            matchExpressions:
+            - key: "tekton.dev/pipelineRun"
+              operator: In
+              values:
+              - git-clone-checking-out-a-branch
+          topologyKey: kubernetes.io/hostname
+  pipelineRef:
+    name: cat-branch-readme
+  workspaces:
+  - name: shared-data
+    volumeClaimTemplate:
+      spec:
+        accessModes:
+        - ReadWriteOnce
+        resources:
+          requests:
+            storage: 1Gi
+  params:
+  - name: repo-url
+    value: https://github.com/tektoncd/pipeline.git
+  - name: branch-name
+    value: release-v0.12.x

task/git-clone/0.1/examples/git-clone-checking-out-a-commit.yaml

@@ -0,0 +1,87 @@
+apiVersion: tekton.dev/v1beta1
+kind: Pipeline
+metadata:
+  name: checking-out-a-revision
+spec:
+  description: |
+    checking-out-a-revision takes a git repository and a commit SHA
+    and validates that cloning the revision succeeds. This is an example
+    Pipeline demonstrating the following:
+      - Using the git-clone catalog Task to clone a specific commit
+      - Passing a cloned repo to subsequent Tasks using a Workspace.
+      - Ordering Tasks in a Pipeline using "runAfter" so that
+        git-clone completes before we try to read from the Workspace.
+      - Using a volumeClaimTemplate Volume as a Workspace.
+      - Avoiding hard-coded paths by using a Workspace's path
+        variable instead.
+  params:
+  - name: repo-url
+    type: string
+    description: The git repository URL to clone from.
+  - name: commit
+    type: string
+    description: The git commit to fetch.
+  workspaces:
+  - name: shared-data
+    description: |
+      This workspace will receive the cloned git repo and be passed
+      to the next Task for the commit to be checked.
+  tasks:
+  - name: fetch-repo
+    taskRef:
+      name: git-clone
+    workspaces:
+    - name: output
+      workspace: shared-data
+    params:
+    - name: url
+      value: $(params.repo-url)
+    - name: revision
+      value: $(params.commit)
+  - name: compare-received-commit-to-expected
+    runAfter: ["fetch-repo"]  # Wait until the clone is done before reading the readme.
+    params:
+    - name: expected-commit
+      value: $(params.commit)
+    workspaces:
+    - name: source
+      workspace: shared-data
+    taskSpec:
+      params:
+      - name: expected-commit
+      workspaces:
+      - name: source
+      steps:
+      - image: alpine/git:v2.24.3
+        script: |
+          #!/usr/bin/env sh
+          cd $(workspaces.source.path)
+          receivedCommit=$(git rev-parse HEAD)
+          if [ $receivedCommit != $(params.expected-commit) ]; then
+            echo "Expected commit $(params.expected-commit) but received $receivedCommit."
+            exit 1
+          else
+            echo "Received commit $receivedCommit as expected."
+          fi
+---
+apiVersion: tekton.dev/v1beta1
+kind: PipelineRun
+metadata:
+  generateName: git-clone-checking-out-a-commit-
+spec:
+  pipelineRef:
+    name: checking-out-a-revision
+  workspaces:
+  - name: shared-data
+    volumeClaimTemplate:
+      spec:
+        accessModes:
+        - ReadWriteOnce
+        resources:
+          requests:
+            storage: 500Mi
+  params:
+  - name: repo-url
+    value: https://github.com/tektoncd/pipeline.git
+  - name: commit
+    value: 301b41380e95382a18b391c2165fa3a6a3de93b0  # Tekton Pipeline's first ever commit!

task/git-clone/0.1/examples/git-rebase/run.yaml

@@ -0,0 +1,74 @@
+apiVersion: tekton.dev/v1beta1
+kind: Pipeline
+metadata:
+  name: git-rebase-pipeline
+spec:
+  workspaces:
+    - name: shared-workspace
+  tasks:
+    - name: fetch-repository
+      taskRef:
+        name: git-clone
+      workspaces:
+        - name: output
+          workspace: shared-workspace
+      params:
+        - name: url
+          value: https://github.com/divyansh42/squash-test.git
+        - name: subdirectory
+          value: ""
+        - name: deleteExisting
+          value: "true"
+        - name: depth
+          value: "10"
+        - name: refspec
+          value: "refs/heads/master:refs/heads/master"
+    - name: git-rebase
+      taskRef:
+        name: git-rebase
+      runAfter:
+        - fetch-repository
+      workspaces:
+        - name: source
+          workspace: shared-workspace
+      params:
+        - name: SQUASH_COUNT
+          value: "2"
+        - name: COMMIT_MSG
+          value: "squashed commit"
+        - name: GIT_USER_NAME
+          value: "divyansh42"
+        - name: GIT_USER_EMAIL
+          value: diagrwa@redhat.com
+        - name: PULL_REMOTE_NAME
+          value: origin
+        - name: PULL_REMOTE_URL
+          value: https://github.com/divyansh42/squash-test.git
+        - name: PULL_BRANCH_NAME
+          value: feature
+        - name: PUSH_REMOTE_NAME
+          value: origin
+        - name: PUSH_REMOTE_URL
+          value: https://github.com/divyansh42/squash-test.git
+        - name: PUSH_BRANCH_NAME
+          value: master
+  results:
+    - name: commit
+---
+apiVersion: tekton.dev/v1beta1
+kind: PipelineRun
+metadata:
+  name: git-rebase-pipeline-run
+spec:
+  serviceAccountName: git-rebase-service-account
+  pipelineRef:
+    name: git-rebase-pipeline
+  workspaces:
+    - name: shared-workspace
+      volumeClaimTemplate:
+        spec:
+          accessModes:
+          - ReadWriteOnce
+          resources:
+            requests:
+              storage: 500Mi

task/git-clone/0.1/examples/git-rebase/secret.yaml

@@ -0,0 +1,10 @@
+apiVersion: v1
+kind: Secret
+metadata:
+  name: github-auth
+  annotations:
+    tekton.dev/git-0: https://github.com  # Replace with the desired domain name.
+type: kubernetes.io/basic-auth
+stringData:
+  username: $(username)
+  password: $(password)  # Access token should be provided here, if 2 factor authentication is enabled.

task/git-clone/0.1/examples/git-rebase/service-account.yaml

@@ -0,0 +1,6 @@
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: git-rebase-service-account
+secrets:
+  - name: github-auth

task/git-clone/0.1/examples/using-git-clone-result.yaml

@@ -0,0 +1,78 @@
+apiVersion: tekton.dev/v1beta1
+kind: Pipeline
+metadata:
+  name: validate-tag-sha
+spec:
+  description: |
+    validate-tag-sha takes a git repository, tag name, and a commit SHA and
+    checks whether the given tag resolves to that commit. This example
+    Pipeline demonstrates the following:
+      - How to use the git-clone catalog Task
+      - How to use the git-clone Task's "commit" Task Result from another Task.
+      - How to discard the contents of the git repo when it isn't needed by
+        passing an `emptyDir` Volume as its "output" workspace.
+  params:
+  - name: repo-url
+    type: string
+    description: The git repository URL to clone from.
+  - name: tag-name
+    type: string
+    description: The git tag to clone.
+  - name: expected-sha
+    type: string
+    description: The expected SHA to be received for the supplied revision.
+  workspaces:
+  - name: output
+  tasks:
+  - name: fetch-repository
+    taskRef:
+      name: git-clone
+    workspaces:
+    - name: output
+      workspace: output
+    params:
+    - name: url
+      value: $(params.repo-url)
+    - name: revision
+      value: $(params.tag-name)
+  - name: validate-revision-sha
+    params:
+    - name: revision-name
+      value: $(params.tag-name)
+    - name: expected-sha
+      value: $(params.expected-sha)
+    - name: received-sha
+      value: $(tasks.fetch-repository.results.commit)
+    taskSpec:
+      params:
+      - name: revision-name
+      - name: expected-sha
+      - name: received-sha
+      steps:
+      - image: zshusers/zsh:4.3.15
+        script: |
+          #!/usr/bin/env zsh
+          if [ "$(params.expected-sha)" != "$(params.received-sha)" ]; then
+            echo "Expected revision $(params.revision-name) to have SHA $(params.expected-sha)."
+            exit 1
+          else
+            echo "Revision $(params.revision-name) has expected SHA $(params.expected-sha)."
+          fi
+---
+apiVersion: tekton.dev/v1beta1
+kind: PipelineRun
+metadata:
+  generateName: using-git-clone-result-
+spec:
+  pipelineRef:
+    name: validate-tag-sha
+  workspaces:
+  - name: output
+    emptyDir: {}  # We don't care about the repo contents in this example, just the "commit" result
+  params:
+  - name: repo-url
+    value: https://github.com/tektoncd/pipeline.git
+  - name: tag-name
+    value: v0.12.1
+  - name: expected-sha
+    value: a54dd3984affab47f3018852e61a1a6f9946ecfa

task/git-clone/0.1/tests/run.yaml

@@ -0,0 +1,175 @@
+---
+apiVersion: tekton.dev/v1beta1
+kind: TaskRun
+metadata:
+  name: git-cli-run
+spec:
+  taskRef:
+    name: git-cli
+  workspaces:
+    - name: source
+      emptyDir: {}
+    - name: input
+      emptyDir: {}
+  params:
+    - name: GIT_SCRIPT
+      value: |
+        git init
+        git remote add origin https://github.com/kelseyhightower/nocode
+        git pull origin master
+---
+apiVersion: tekton.dev/v1alpha1
+kind: TaskRun
+metadata:
+  name: git-clone-run-noargs
+spec:
+  workspaces:
+    - name: output
+      emptyDir: {}
+  taskRef:
+    name: git-clone
+  inputs:
+    params:
+      - name: url
+        value: https://github.com/kelseyhightower/nocode
+---
+apiVersion: tekton.dev/v1alpha1
+kind: TaskRun
+metadata:
+  name: git-clone-run-tag
+spec:
+  workspaces:
+    - name: output
+      emptyDir: {}
+  taskRef:
+    name: git-clone
+  inputs:
+    params:
+      - name: url
+        value: https://github.com/kelseyhightower/nocode
+      - name: revision
+        value: 1.0.0
+
+---
+apiVersion: tekton.dev/v1alpha1
+kind: TaskRun
+metadata:
+  name: git-clone-run-no-submodules
+spec:
+  workspaces:
+    - name: output
+      emptyDir: {}
+  taskRef:
+    name: git-clone
+  inputs:
+    params:
+      - name: url
+        value: https://github.com/githubtraining/example-dependency
+      - name: submodules
+        value: "false"
+---
+apiVersion: tekton.dev/v1alpha1
+kind: TaskRun
+metadata:
+  name: git-clone-run-no-depth-2
+spec:
+  workspaces:
+    - name: output
+      emptyDir: {}
+  taskRef:
+    name: git-clone
+  inputs:
+    params:
+      - name: url
+        value: https://github.com/kelseyhightower/nocode
+      - name: depth
+        value: "2"
+---
+apiVersion: tekton.dev/v1alpha1
+kind: TaskRun
+metadata:
+  name: git-clone-run-sslverify-none
+spec:
+  workspaces:
+    - name: output
+      emptyDir: {}
+  taskRef:
+    name: git-clone
+  inputs:
+    params:
+      - name: url
+        value: https://github.com/kelseyhightower/nocode
+      - name: sslVerify
+        value: "false"
+---
+apiVersion: tekton.dev/v1alpha1
+kind: TaskRun
+metadata:
+  name: git-clone-run-subdirectory
+spec:
+  workspaces:
+    - name: output
+      emptyDir: {}
+  taskRef:
+    name: git-clone
+  inputs:
+    params:
+      - name: url
+        value: https://github.com/kelseyhightower/nocode
+      - name: subdirectory
+        value: "hellomoto"
+---
+apiVersion: tekton.dev/v1alpha1
+kind: TaskRun
+metadata:
+  name: git-clone-run-delete-existing
+spec:
+  workspaces:
+    - name: output
+      emptyDir: {}
+  taskRef:
+    name: git-clone
+  inputs:
+    params:
+      - name: url
+        value: https://github.com/kelseyhightower/nocode
+      - name: deleteExisting
+        value: "true"
+---
+apiVersion: tekton.dev/v1alpha1
+kind: TaskRun
+metadata:
+  name: git-batch-merge-test-mode-merge
+spec:
+  workspaces:
+    - name: output
+      emptyDir: {}
+  taskRef:
+    name: git-batch-merge
+  inputs:
+    params:
+      - name: url
+        value: https://github.com/kelseyhightower/nocode
+      - name: mode
+        value: "merge"
+      - name: batchedRefs
+        value: "refs/pull/4014/head refs/pull/3894/head"
+---
+apiVersion: tekton.dev/v1alpha1
+kind: TaskRun
+metadata:
+  name: git-batch-merge-test-mode-merge-cherry-pick
+spec:
+  workspaces:
+    - name: output
+      emptyDir: {}
+  taskRef:
+    name: git-batch-merge
+  inputs:
+    params:
+      - name: url
+        value: https://github.com/kelseyhightower/nocode
+      - name: mode
+        value: "cherry-pick"
+      - name: batchedRefs
+        value: "refs/pull/4014/head refs/pull/3894/head"