add multi-branch workflow example

Signed-off-by: Aidan Oldershaw <aoldershaw@pivotal.io>

pipelines/multi-branch/template.yml

@@ -0,0 +1,81 @@
+resource_types:
+- name: terraform
+  type: registry-image
+  source:
+    repository: ljfranklin/terraform-resource
+
+- name: gcs
+  type: registry-image
+  source:
+    repository: frodenas/gcs-resource
+
+resources:
+- name: branch
+  type: git
+  source:
+    uri: https://github.com/concourse/examples
+    branch: ((branch))
+
+- name: examples
+  type: git
+  source:
+    uri: https://github.com/concourse/examples
+
+- name: build-artifact
+  type: gcs
+  source:
+    bucket: concourse-examples
+    json_key: ((concourse_artifacts_json_key))
+    regexp: multi-branch/features/((feature))/my-app-(.+)\.tgz
+
+- name: staging-env
+  type: terraform
+  source:
+    env_name: ((feature))
+    backend_type: gcs
+    backend_config:
+      bucket: concourse-examples
+      prefix: multi-branch/terraform
+      credentials: ((concourse_artifacts_json_key))
+
+jobs:
+- name: test
+  plan:
+  - in_parallel:
+    - get: branch
+      trigger: true
+    - get: examples
+  - task: unit
+    file: examples/tasks/go-test.yml
+    input_mapping: {repo: branch}
+    params: {MODULE: apps/golang}
+
+- name: build
+  plan:
+  - in_parallel:
+    - get: branch
+      passed: [test]
+      trigger: true
+    - get: examples
+  - task: build
+    file: examples/tasks/go-build.yml
+    params:
+      MODULE: apps/golang
+      BINARY_NAME: my-app
+    input_mapping: {repo: branch}
+  - put: build-artifact
+    params: {file: "binary/my-app-*.tgz"}
+
+- name: deploy
+  plan:
+  - in_parallel:
+    - get: build-artifact
+      passed: [build]
+      trigger: true
+    - get: examples
+  - load_var: bundle_url
+    file: build-artifact/url
+  - put: staging-env
+    params:
+      terraform_source: examples/terraform/staging
+      vars: {bundle_url: ((.:bundle_url))}

pipelines/multi-branch/tracker.yml

@@ -0,0 +1,83 @@
+resource_types:
+- name: git-branches
+  type: registry-image
+  source:
+    repository: aoldershaw/git-branches-resource
+
+resources:
+- name: feature-branches
+  type: git-branches
+  source:
+    uri: https://github.com/concourse/examples
+    branch_regex: 'feature/(?P<feature>.*)'
+
+- name: examples
+  type: git
+  source:
+    uri: https://github.com/concourse/examples
+
+jobs:
+- name: set-feature-pipelines
+  plan:
+  - in_parallel:
+    - get: feature-branches
+      trigger: true
+    - get: examples
+  - load_var: branches
+    file: feature-branches/branches.json
+  - across:
+    - var: branch
+      values: ((.:branches))
+    set_pipeline: dev
+    file: examples/pipelines/multi-branch/template.yml
+    instance_vars: {feature: ((.:branch.groups.feature))}
+    vars: {branch: ((.:branch.name))}
+
+- name: cleanup-inactive-workspaces
+  plan:
+  - get: feature-branches
+    passed: [set-feature-pipelines]
+    trigger: true
+  - load_var: active_branches
+    file: feature-branches/branches.json
+  - task: cleanup
+    config:
+      platform: linux
+      image_resource:
+        type: registry-image
+        source: {repository: hashicorp/terraform}
+      params:
+        ACTIVE_BRANCHES: ((.:active_branches))
+        TERRAFORM_BACKEND_CONFIG:
+          terraform:
+            backend:
+              gcs:
+                bucket: concourse-examples
+                prefix: multi-branch/terraform
+                credentials: ((concourse_artifacts_json_key))
+      run:
+        path: sh
+        args:
+        - -c
+        - |
+          set -euo pipefail
+
+          apk add jq
+
+          active_features="$(echo "$ACTIVE_BRANCHES" | jq '[.[].groups.feature]')"
+
+          echo "$TERRAFORM_BACKEND_CONFIG" > backend.tf.json
+          terraform init
+          active_workspaces="$(terraform workspace list | grep -v '^[*]' | tr -d ' ' | jq --raw-input --slurp 'split("\n") | map(select(. != ""))')"
+
+          jq -nr "$active_workspaces - $active_features | .[]" | while read extra_workspace
+          do
+            echo "deleting workspace $extra_workspace"
+            terraform workspace select "$extra_workspace"
+            terraform init
+
+            terraform destroy -auto-approve
+
+            terraform workspace select default
+            terraform workspace delete "$extra_workspace"
+          done

tasks/go-build.yml

@@ -0,0 +1,28 @@
+platform: linux
+
+image_resource:
+  type: registry-image
+  source: { repository: golang }
+
+inputs:
+- name: repo
+  path: .
+
+outputs:
+- name: binary
+
+params:
+  MODULE:
+  BINARY_NAME:
+
+run:
+  path: sh
+  args:
+  - -ce
+  - |
+    root=$(pwd)
+    cd "$MODULE"
+    go build -o "/tmp/$BINARY_NAME"
+
+    timestamp=$(date '+%Y%m%d%H%M%S')
+    tar czf "$root/binary/$BINARY_NAME-$timestamp.tgz" -C /tmp "$BINARY_NAME"

tasks/go-test.yml

@@ -0,0 +1,20 @@
+platform: linux
+
+image_resource:
+  type: registry-image
+  source: { repository: golang }
+
+inputs:
+- name: repo
+  path: .
+
+params:
+  MODULE:
+
+run:
+  path: sh
+  args:
+  - -ce
+  - |
+    cd "$MODULE"
+    go test -v ./...

terraform/staging/main.tf

@@ -0,0 +1,13 @@
+variable "bundle_url" {
+  type = string
+}
+
+resource "null_resource" "fake_deployment" {
+  triggers = {
+    bundle_url = var.bundle_url
+  }
+
+  provisioner "local-exec" {
+    command = "echo \"pretending to deploy from ${var.bundle_url}\"..."
+  }
+}