Add annotate config demo function (#161)

* Add annotate config demo function

* Use getAll instead of get(isKubernetesObject)

Author: prachirp

ts/demo-functions/build/annotate_config.Dockerfile

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+FROM node:lts-alpine as builder
+
+RUN mkdir -p /home/node/app && \
+    chown -R node:node /home/node/app
+
+USER node
+
+WORKDIR /home/node/app
+
+# Install dependencies and cache them.
+COPY --chown=node:node package*.json ./
+RUN npm ci --ignore-scripts
+
+# Build the source.
+COPY --chown=node:node tsconfig.json .
+COPY --chown=node:node src src
+RUN npm run build && \
+    npm prune --production && \
+    rm -r src tsconfig.json
+
+#############################################
+
+FROM node:lts-alpine
+
+# Run as non-root user as a best-practices:
+# https://github.com/nodejs/docker-node/blob/master/docs/BestPractices.md
+USER node
+
+WORKDIR /home/node/app
+
+COPY --from=builder /home/node/app /home/node/app
+
+ENTRYPOINT ["node", "/home/node/app/dist/annotate_config_run.js"]

ts/demo-functions/src/annotate_config.ts

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+import { Configs, addAnnotation } from 'kpt-functions';
+
+const ANNOTATION_NAME = 'annotation_name';
+const ANNOTATION_VALUE = 'annotation_value';
+
+export async function annotateConfig(configs: Configs) {
+  const annotationName = configs.getFunctionConfigValueOrThrow(ANNOTATION_NAME);
+  const annotationValue = configs.getFunctionConfigValueOrThrow(
+    ANNOTATION_VALUE
+  );
+  configs
+    .getAll()
+    .forEach((n) => addAnnotation(n, annotationName, annotationValue));
+}
+
+annotateConfig.usage = `
+Adds an annotation to all configuration files.
+
+Configured using a ConfigMap with the following keys:
+
+${ANNOTATION_NAME}: Annotation name to add to configs.
+${ANNOTATION_VALUE}: Annotation value to add to configs.
+
+Example:
+
+To add an annotation 'org: sre-supported' to Namespaces:
+
+apiVersion: v1
+kind: ConfigMap
+data:
+  ${ANNOTATION_NAME}: org
+  ${ANNOTATION_VALUE}: sre-supported
+metadata:
+  name: my-config
+`;

ts/demo-functions/src/annotate_config_run.ts

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+import { annotateConfig } from './annotate_config';
+import { run } from 'kpt-functions';
+
+run(annotateConfig);

ts/demo-functions/src/annotate_config_test.ts

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+import { Configs, TestRunner } from 'kpt-functions';
+import { annotateConfig } from './annotate_config';
+import { ConfigMap, Namespace } from './gen/io.k8s.api.core.v1';
+import { FunctionConfigError } from 'kpt-functions';
+
+const RUNNER = new TestRunner(annotateConfig);
+const TEST_NAMESPACE = 'testNamespace';
+const TEST_ANNOTATION_NAME = 'configsupport';
+const TEST_ANNOTATION_VALUE = 'ops-supported';
+const FUNC_CONFIG: ConfigMap = new ConfigMap({
+  metadata: { name: 'config' },
+  data: {
+    annotation_name: TEST_ANNOTATION_NAME,
+    annotation_value: TEST_ANNOTATION_VALUE,
+  },
+});
+
+describe('annotateConfig', () => {
+  it(
+    'empty input ok',
+    RUNNER.assertCallback(new Configs(undefined, FUNC_CONFIG), 'unchanged')
+  );
+
+  it(
+    'requires functionConfig',
+    RUNNER.assertCallback(undefined, undefined, FunctionConfigError)
+  );
+
+  it('adds annotation namespace when metadata.annotations is undefined', async () => {
+    const input = new Configs(undefined, FUNC_CONFIG);
+    input.insert(Namespace.named(TEST_NAMESPACE));
+
+    const output = new Configs();
+    output.insert(
+      new Namespace({
+        metadata: {
+          name: TEST_NAMESPACE,
+          annotations: { [TEST_ANNOTATION_NAME]: TEST_ANNOTATION_VALUE },
+        },
+      })
+    );
+
+    await RUNNER.assert(input, output);
+  });
+
+  it('adds annotation to namespace when metadata.annotations is defined', async () => {
+    const input = new Configs(undefined, FUNC_CONFIG);
+    input.insert(
+      new Namespace({
+        metadata: {
+          name: TEST_NAMESPACE,
+          annotations: { a: 'b' },
+        },
+      })
+    );
+
+    const output = new Configs();
+    output.insert(
+      new Namespace({
+        metadata: {
+          name: TEST_NAMESPACE,
+          annotations: {
+            a: 'b',
+            [TEST_ANNOTATION_NAME]: TEST_ANNOTATION_VALUE,
+          },
+        },
+      })
+    );
+
+    await RUNNER.assert(input, output);
+  });
+});