Allows selected injected default vars to be merged instead of overwritten

src/ui/ui_render/lib/index.ts

@@ -0,0 +1,20 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+export { mergeVariables } from './merge_variables';

src/ui/ui_render/lib/merge_variables.test.ts

@@ -0,0 +1,206 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { mergeVariables } from './merge_variables';
+
+describe('mergeVariables', () => {
+  it('merges two objects together', () => {
+    const someVariables = {
+      name: 'value',
+      canFoo: true,
+      nested: {
+        anotherVariable: 'ok',
+      },
+    };
+
+    const otherVariables = {
+      otherName: 'value',
+      otherCanFoo: true,
+      otherNested: {
+        otherAnotherVariable: 'ok',
+      },
+    };
+
+    const result = mergeVariables(someVariables, otherVariables);
+
+    expect(result).toEqual({
+      name: 'value',
+      canFoo: true,
+      nested: {
+        anotherVariable: 'ok',
+      },
+      otherName: 'value',
+      otherCanFoo: true,
+      otherNested: {
+        otherAnotherVariable: 'ok',
+      },
+    });
+  });
+
+  it('does not mutate the source objects', () => {
+    const original = {
+      var1: 'original',
+    };
+
+    const set1 = {
+      var1: 'value1',
+      var2: 'value1',
+    };
+
+    const set2 = {
+      var1: 'value2',
+      var2: 'value2',
+      var3: 'value2',
+    };
+
+    const set3 = {
+      var1: 'value3',
+      var2: 'value3',
+      var3: 'value3',
+      var4: 'value3',
+    };
+
+    mergeVariables(original, set1, set2, set3);
+
+    expect(original).toEqual({ var1: 'original' });
+    expect(set1).toEqual({ var1: 'value1', var2: 'value1' });
+    expect(set2).toEqual({ var1: 'value2', var2: 'value2', var3: 'value2' });
+    expect(set3).toEqual({ var1: 'value3', var2: 'value3', var3: 'value3', var4: 'value3' });
+  });
+
+  it('merges multiple objects together, preferring the leftmost values', () => {
+    const original = {
+      var1: 'original',
+    };
+
+    const set1 = {
+      var1: 'value1',
+      var2: 'value1',
+    };
+
+    const set2 = {
+      var1: 'value2',
+      var2: 'value2',
+      var3: 'value2',
+    };
+
+    const set3 = {
+      var1: 'value3',
+      var2: 'value3',
+      var3: 'value3',
+      var4: 'value3',
+    };
+
+    const result = mergeVariables(original, set1, set2, set3);
+
+    expect(result).toEqual({
+      var1: 'original',
+      var2: 'value1',
+      var3: 'value2',
+      var4: 'value3',
+    });
+  });
+
+  it('retains the original variable value if a duplicate entry is found', () => {
+    const someVariables = {
+      name: 'value',
+      canFoo: true,
+      nested: {
+        anotherVariable: 'ok',
+      },
+    };
+
+    const otherVariables = {
+      nested: {
+        otherAnotherVariable: 'ok',
+      },
+    };
+
+    const result = mergeVariables(someVariables, otherVariables);
+    expect(result).toEqual({
+      name: 'value',
+      canFoo: true,
+      nested: {
+        anotherVariable: 'ok',
+      },
+    });
+  });
+
+  it('combines entries within "uiCapabilities"', () => {
+    const someVariables = {
+      name: 'value',
+      canFoo: true,
+      uiCapabilities: {
+        firstCapability: 'ok',
+      },
+    };
+
+    const otherVariables = {
+      uiCapabilities: {
+        secondCapability: 'ok',
+      },
+    };
+
+    const result = mergeVariables(someVariables, otherVariables);
+
+    expect(result).toEqual({
+      name: 'value',
+      canFoo: true,
+      uiCapabilities: {
+        firstCapability: 'ok',
+        secondCapability: 'ok',
+      },
+    });
+  });
+
+  it('does not deeply combine entries within "uiCapabilities"', () => {
+    const someVariables = {
+      name: 'value',
+      canFoo: true,
+      uiCapabilities: {
+        firstCapability: 'ok',
+        nestedCapability: {
+          nestedProp: 'nestedValue',
+        },
+      },
+    };
+
+    const otherVariables = {
+      uiCapabilities: {
+        secondCapability: 'ok',
+        nestedCapability: {
+          otherNestedProp: 'otherNestedValue',
+        },
+      },
+    };
+
+    const result = mergeVariables(someVariables, otherVariables);
+    expect(result).toEqual({
+      name: 'value',
+      canFoo: true,
+      uiCapabilities: {
+        firstCapability: 'ok',
+        secondCapability: 'ok',
+        nestedCapability: {
+          nestedProp: 'nestedValue',
+        },
+      },
+    });
+  });
+});

src/ui/ui_render/lib/merge_variables.ts

@@ -0,0 +1,39 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+const ELIGIBLE_FLAT_MERGE_KEYS = ['uiCapabilities'];
+
+export function mergeVariables(...sources: Array<Record<string, any>>) {
+  const result: Record<string, any> = {};
+
+  for (const source of sources) {
+    Object.entries(source).forEach(([key, value]) => {
+      if (ELIGIBLE_FLAT_MERGE_KEYS.includes(key)) {
+        result[key] = {
+          ...value,
+          ...result[key],
+        };
+      } else if (!result.hasOwnProperty(key)) {
+        result[key] = value;
+      }
+    });
+  }
+
+  return result;
+}

src/ui/ui_render/ui_render_mixin.js

@@ -17,12 +17,12 @@
  * under the License.
  */
 
-import { defaults } from 'lodash';
 import { props, reduce as reduceAsync } from 'bluebird';
 import Boom from 'boom';
 import { resolve } from 'path';
 import { i18n } from '@kbn/i18n';
 import { AppBootstrap } from './bootstrap';
+import { mergeVariables } from './lib';
 
 export function uiRenderMixin(kbnServer, server, config) {
   function replaceInjectedVars(request, injectedVars) {
@@ -40,7 +40,7 @@ export function uiRenderMixin(kbnServer, server, config) {
     const { defaultInjectedVarProviders = [] } = kbnServer.uiExports;
     defaultInjectedVars = defaultInjectedVarProviders
       .reduce((allDefaults, { fn, pluginSpec }) => (
-        defaults(
+        mergeVariables(
           allDefaults,
           fn(kbnServer.server, pluginSpec.readConfigValue(kbnServer.config, []))
         )
@@ -145,7 +145,7 @@ export function uiRenderMixin(kbnServer, server, config) {
         basePath,
         vars: await replaceInjectedVars(
           request,
-          defaults(
+          mergeVariables(
             injectedVarsOverrides,
             await server.getInjectedUiAppVars(app.getId()),
             defaultInjectedVars,