Fix a bug where ES sends a string and migrations expect a boolean

src/server/saved_objects/migrations/core/determine_migration_action.test.ts

@@ -63,7 +63,30 @@ describe('determineMigrationAction', () => {
       doc: {
         dynamic: 'strict',
         properties: {
-          hello: { dynamic: true, goober: 'pea' },
+          hello: { dynamic: 'true', goober: 'pea' },
+          world: { baz: 'bing' },
+        },
+      },
+    };
+
+    expect(determineMigrationAction(actual, expected)).toEqual(MigrationAction.None);
+  });
+
+  test('requires no action if mappings differ only by equivalent coerced properties', () => {
+    const actual = {
+      doc: {
+        dynamic: 'strict',
+        properties: {
+          hello: { dynamic: 'false', baz: '2', foo: 'bar' },
+          world: { baz: 'bing' },
+        },
+      },
+    };
+    const expected = {
+      doc: {
+        dynamic: 'strict',
+        properties: {
+          hello: { dynamic: false, baz: 2, foo: 'bar' },
           world: { baz: 'bing' },
         },
       },

src/server/saved_objects/migrations/core/determine_migration_action.ts

@@ -74,7 +74,11 @@ function diffSubProperty(actual: any, expected: any): MigrationAction {
   // We have a leaf property, so we do a comparison. A change (e.g. 'text' -> 'keyword')
   // should result in a migration.
   if (typeof actual !== 'object') {
-    return _.isEqual(actual, expected) ? MigrationAction.None : MigrationAction.Migrate;
+    // We perform a string comparison here, because Elasticsearch coerces some primitives
+    // to string (such as dynamic: true and dynamic: 'true'), so we report a mapping
+    // equivalency if the string comparison checks out. This does mean that {} === '[object Object]'
+    // by this logic, but that is an edge case which should not occur in mapping definitions.
+    return `${actual}` === `${expected}` ? MigrationAction.None : MigrationAction.Migrate;
   }
 
   // Recursively compare the sub properties
@@ -87,5 +91,5 @@ function diffSubProperty(actual: any, expected: any): MigrationAction {
 }
 
 function isDynamic(prop: any) {
-  return prop.dynamic === true || prop.dynamic === 'true';
+  return prop && `${prop.dynamic}` === 'true';
 }