Don't request missing parameter store parameters

howdju-service-common/lib/initializers/parameterStore.test.ts

@@ -1,7 +1,15 @@
+import {
+  Command,
+  DescribeParametersCommand,
+  GetParametersCommand,
+} from "@aws-sdk/client-ssm";
 import { toJson } from "howdju-common";
 
 describe("parameterStore", () => {
   describe("getParameterStoreConfig", () => {
+    afterEach(() => {
+      jest.clearAllMocks();
+    });
     it("should return deserialized parameters", async () => {
       // Arrange
       jest.mock("@aws-sdk/client-ssm", () => {
@@ -11,15 +19,18 @@ describe("parameterStore", () => {
         return {
           GetParametersCommand: jest.requireActual("@aws-sdk/client-ssm")
             .GetParametersCommand,
+          DescribeParametersCommand: jest.requireActual("@aws-sdk/client-ssm")
+            .DescribeParametersCommand,
           SSMClient: jest.fn().mockImplementation(() => {
             return ssmClient;
           }),
         };
       });
 
       const environment = "test";
+      const databaseConnectionInfoName = `/${environment}/database-connection-info`;
       const expected = {
-        DATABASE_CONNECTION_INFO: {
+        "database-connection-info": {
           host: "the-host",
           database: "the-db-name",
           username: "the-username",
@@ -30,13 +41,28 @@ describe("parameterStore", () => {
       const ssmClient = new SSMClient();
       // We mocked the constructor always to return the same instance, so mocking this one will
       // mock the one in parameterStore.ts too.
-      ssmClient.send.mockResolvedValue({
-        Parameters: [
-          {
-            Name: "/test/DATABASE_CONNECTION_INFO",
-            Value: toJson(expected.DATABASE_CONNECTION_INFO),
-          },
-        ],
+      ssmClient.send.mockImplementation((command: Command) => {
+        if (command instanceof GetParametersCommand) {
+          return {
+            Parameters: [
+              {
+                Name: databaseConnectionInfoName,
+                Value: toJson(expected["database-connection-info"]),
+              },
+            ],
+          };
+        }
+        if (command instanceof DescribeParametersCommand) {
+          return {
+            Parameters: [
+              {
+                Name: databaseConnectionInfoName,
+                Type: "String",
+              },
+            ],
+          };
+        }
+        throw new Error("Unexpected command type");
       });
 
       const { getParameterStoreConfig } =
@@ -48,5 +74,77 @@ describe("parameterStore", () => {
       // Assert
       expect(result).toEqual(expected);
     });
+
+    it("only requests extant parameters", async () => {
+      // Arrange
+      jest.mock("@aws-sdk/client-ssm", () => {
+        const ssmClient = {
+          send: jest.fn(),
+        };
+        return {
+          GetParametersCommand: jest.requireActual("@aws-sdk/client-ssm")
+            .GetParametersCommand,
+          DescribeParametersCommand: jest.requireActual("@aws-sdk/client-ssm")
+            .DescribeParametersCommand,
+          SSMClient: jest.fn().mockImplementation(() => {
+            return ssmClient;
+          }),
+        };
+      });
+
+      const environment = "test";
+      const databaseConnectionInfoName = `/${environment}/database-connection-info`;
+      const expected = {
+        "database-connection-info": {
+          host: "the-host",
+          database: "the-db-name",
+          username: "the-username",
+          password: "the-password",
+        },
+      };
+      const { SSMClient } = jest.requireMock("@aws-sdk/client-ssm");
+      const ssmClient = new SSMClient();
+      // We mocked the constructor always to return the same instance, so mocking this one will
+      // mock the one in parameterStore.ts too.
+      ssmClient.send.mockImplementation((command: Command) => {
+        if (command instanceof GetParametersCommand) {
+          return {
+            Parameters: [
+              {
+                Name: databaseConnectionInfoName,
+                Value: toJson(expected["database-connection-info"]),
+              },
+            ],
+          };
+        }
+        if (command instanceof DescribeParametersCommand) {
+          return {
+            Parameters: [
+              {
+                Name: databaseConnectionInfoName,
+                Type: "String",
+              },
+            ],
+          };
+        }
+        throw new Error("Unexpected command type");
+      });
+
+      const { getParameterStoreConfig } =
+        jest.requireActual("./parameterStore");
+
+      // Act
+      await getParameterStoreConfig(environment);
+
+      // Assert
+      expect(ssmClient.send).toHaveBeenCalledTimes(2);
+      const getParametersCall = ssmClient.send.mock.calls.find(
+        ([command]: [Command]) => command instanceof GetParametersCommand
+      );
+      const getParametersCommand = getParametersCall[0];
+      expect(getParametersCommand.input).toMatchObject({
+        Names: [databaseConnectionInfoName],
+      });
+    });
   });
 });

howdju-service-common/lib/initializers/parameterStore.ts

@@ -1,11 +1,13 @@
 import {
   SSMClient,
   GetParametersCommand,
+  DescribeParametersCommand,
   Parameter,
 } from "@aws-sdk/client-ssm";
 import { PoolConfig } from "pg";
 
 import { logger } from "howdju-common";
+import { groupBy } from "lodash";
 
 const client = new SSMClient();
 
@@ -30,13 +32,18 @@ export async function getParameterStoreConfig(
     return {} as AsyncConfig;
   }
 
+  const parameterNames = [
+    `/${environment}/${DATABASE_CONNECTION_INFO}`,
+    `/${environment}/${SCRAPING_ANT_API_KEY}`,
+    `/${environment}/${ZEN_ROWS_API_KEY}`,
+  ];
+
+  // GetParametersCommand throws for missing parameters, so filter out the missing ones.
+  const extantParameterNames = await getExtantParameterNames(parameterNames);
+
   const response = await client.send(
     new GetParametersCommand({
-      Names: [
-        `/${environment}/${DATABASE_CONNECTION_INFO}`,
-        `/${environment}/${SCRAPING_ANT_API_KEY}`,
-        `/${environment}/${ZEN_ROWS_API_KEY}`,
-      ],
+      Names: extantParameterNames,
       WithDecryption: true,
     })
   );
@@ -82,6 +89,28 @@ export async function getParameterStoreConfig(
   return pairs.reduce((acc, cur) => ({ ...acc, ...cur }), {}) as AsyncConfig;
 }
 
+async function getExtantParameterNames(
+  parameterNames: string[]
+): Promise<string[]> {
+  const response = await client.send(
+    new DescribeParametersCommand({
+      ParameterFilters: [{ Key: "Name", Values: parameterNames }],
+    })
+  );
+  const foundParameterNames = new Set(
+    response.Parameters?.map((parameter) => parameter.Name) || []
+  );
+  const results = groupBy(parameterNames, (name) =>
+    foundParameterNames.has(name)
+  );
+  if (results.false?.length) {
+    logger.warn(
+      `Missing Parameter Store parameters: ${results.false.join(", ")}`
+    );
+  }
+  return results.true || [];
+}
+
 function extractName(fullName: string) {
   const index = fullName.lastIndexOf("/");
   if (index < 0) {