Add ILM policy setting to data_stream manifest file (#90)

Add ILM policy setting to data_stream manifest file

code/go/internal/validator/test/packages/good/data_stream/ilm_policy/elasticsearch/ilm/diagnostics.json

@@ -0,0 +1,15 @@
+{
+    "policy": {
+        "phases": {
+            "hot": {
+                "min_age": "0ms",
+                "actions": {
+                    "rollover": {
+                        "max_size": "10gb",
+                        "max_age": "1d"
+                    }
+                }
+            }
+        }
+    }
+}

code/go/internal/validator/test/packages/good/data_stream/ilm_policy/fields/some_fields.yml

@@ -0,0 +1,14 @@
+- name: source
+  title: Source
+  group: 2
+  type: group
+  fields:
+    - name: geo.city_name
+      level: core
+      type: keyword
+      description: City name.
+      ignore_above: 1024
+- name: foobar
+  type: text
+  description: A field with a pattern defined
+  pattern: '^[a-zA-Z]$'

code/go/internal/validator/test/packages/good/data_stream/ilm_policy/manifest.yml

@@ -0,0 +1,6 @@
+title: Hidden data stream and ilm policy overrride
+type: metrics
+ilm_policy: diagnostics
+elasticsearch:
+  index_template.mappings:
+    dynamic: false

versions/1/changelog.yml

@@ -21,6 +21,9 @@
   - description: Allow `condition` under inputs.
     type: enhancement
     link: https://github.com/elastic/package-spec/pull/87
+  - description: Add `ilm_policy` to data stream manifest.yml
+    type: enhancement
+    link: https://github.com/elastic/package-spec/pull/90
   - description: Add `hidden` fields to data stream manifest file.
     type: enhancement
     link: https://github.com/elastic/package-spec/pull/91

versions/1/data_stream/manifest.spec.yml

@@ -87,6 +87,11 @@ spec:
       - beta
       examples:
       - beta
+    ilm_policy:
+      description: The name of an existing ILM (Index Lifecycle Management) policy
+      type: string
+      examples:
+      - diagnostics
     type:
       description: Type of data stream
       type: string

versions/1/data_stream/spec.yml

@@ -34,6 +34,22 @@ spec:
       name: elasticsearch
       additionalContents: false
       contents:
+      - description: Folder containing Elasticsearch ILM Policy Definition
+        type: folder
+        name: ilm
+        additionalContents: false
+        contents:
+        - description: Supporting ILM policy definitions in YAML
+          type: file
+          pattern: '^.+\.yml$'
+          # TODO Determine if special handling of `---` is required (issue: https://github.com/elastic/package-spec/pull/54)
+          contentMediaType: "application/x-yaml; require-document-dashes=true"
+          required: false
+        - description: Supporting ILM policy definitions in JSON
+          type: file
+          pattern: '^.+\.json$'
+          contentMediaType: "application/json"
+          required: false
       - description: Folder containing Elasticsearch Ingest Node pipeline definitions
         type: folder
         name: ingest_pipeline