Define build time dependencies

test/packages/good/deps.yml

@@ -0,0 +1,4 @@
+build:
+  - name: ecs
+    version: "1.9"
+    reference: git@7a11f3e1f7d8f05e8f06623fd98254b8cb34c441

versions/1/changelog.yml

@@ -129,4 +129,7 @@
     link: https://github.com/elastic/package-spec/pull/176
   - description: Validate if field groups don't have units and metric types defined
     type: enhancement
-    link: https://github.com/elastic/package-spec/pull/183
+    link: https://github.com/elastic/package-spec/pull/183
+  - description: Define build-time dependencies
+    type: enhancement
+    link: https://github.com/elastic/package-spec/pull/181

versions/1/deps.spec.yml

@@ -0,0 +1,32 @@
+##
+## Describes the specification for the package's main manifest.yml file
+##
+spec:
+  # Everything under here follows JSON schema (https://json-schema.org/), written as YAML for readability
+  type: object
+  additionalProperties: false
+  properties:
+    build:
+      type: array
+      description: Build-time dependencies
+      items:
+        type: object
+        additionalProperties: false
+        properties:
+          name:
+            type: string
+            description: Name of the dependency
+            enum:
+              - ecs
+          version:
+            type: string
+            description: Version of the dependency
+          reference:
+            type: string
+            description: Source reference
+            pattern: 'git@[a-z0-9]{40}'
+        required:
+          - name
+          - reference
+  required:
+  - build

versions/1/manifest.spec.yml

@@ -273,6 +273,34 @@ spec:
           pattern: '^(([a-zA-Z0-9-]+)|([a-zA-Z0-9-]+\/[a-zA-Z0-9-]+))$'
       required:
       - github
+    build:
+      type: object
+      additionalProperties: false
+      properties:
+        dependencies:
+          type: array
+          description: Build-time dependencies
+          items:
+            type: object
+            additionalProperties: false
+            properties:
+              name:
+                type: string
+                description: Name of the dependency
+                enum:
+                  - ecs
+              version:
+                type: string
+                description: Version of the dependency
+              reference:
+                type: string
+                description: Source reference
+                pattern: 'git@[a-z0-9]{40}'
+            required:
+              - name
+              - reference
+      required:
+        - dependencies
   required:
   - format_version
   - name

versions/1/spec.yml

@@ -13,6 +13,11 @@ spec:
     name: "manifest.yml"
     required: true
     $ref: "./manifest.spec.yml"
+  - description: Package dependencies manifest
+    type: file
+    contentMediaType: "application/x-yaml"
+    name: "deps.yml"
+    $ref: "./deps.spec.yml"
   - description: The package's CHANGELOG file
     type: file
     contentMediaType: "application/x-yaml"