feat(cdk): add OpenAI API key param

- `SystemParameters` introduces a new parameter
  `openAiApiKeyParameter` that stores the OpenAI API key.
- `ViewerHandler` is granted access to the OpenAI API key parameter.
- `CdkStack` outputs the parameter path of the OpenAI API key as
  `OpenAiApiKeyParameterPath`.

issue codemonger-io#26

cdk/lib/cdk-stack.ts

@@ -130,5 +130,9 @@ export class CdkStack extends Stack {
       description: 'Path to the domain name stored in Parameter Store on AWS Systems Manager',
       value: systemParameters.domainNameParameter.parameterName,
     });
+    new CfnOutput(this, 'OpenAiApiKeyParameterPath', {
+      description: 'Path to the OpenAI API key stored in Parameter Store on AWS Systems Manager',
+      value: systemParameters.openAiApiKeyParameter.parameterName,
+    });
   }
 }

cdk/lib/system-parameters.ts

@@ -9,6 +9,8 @@ export class SystemParameters extends Construct {
   readonly parameterPathPrefix: string;
   /** Parameter for the domain name. */
   readonly domainNameParameter: GhostStringParameter;
+  /** Parameter for the OpenAI API key. */
+  readonly openAiApiKeyParameter: GhostStringParameter;
 
   constructor(scope: Construct, id: string) {
     super(scope, id);
@@ -18,5 +20,8 @@ export class SystemParameters extends Construct {
     this.domainNameParameter = new GhostStringParameter(this, {
       parameterName: `${this.parameterPathPrefix}DOMAIN_NAME`,
     });
+    this.openAiApiKeyParameter = new GhostStringParameter(this, {
+      parameterName: `${this.parameterPathPrefix}OPENAI_API_KEY`,
+    });
   }
 }

cdk/lib/viewer.ts

@@ -54,6 +54,7 @@ export class Viewer extends Construct {
     objectStore.objectsBucket.grantRead(this.handler);
     objectStore.objectTable.grantReadData(this.handler);
     systemParameters.domainNameParameter.grantRead(this.handler);
+    systemParameters.openAiApiKeyParameter.grantRead(this.handler);
     userTable.userTable.grantReadData(this.handler);
 
     this.functionUrl = this.handler.addFunctionUrl({