WIP: feat(cloudwatch): enable expressions and multiple metrics

packages/@aws-cdk/aws-cloudwatch/lib/alarm.ts

@@ -2,7 +2,7 @@ import { Construct, IResource, Lazy, Resource, Stack } from '@aws-cdk/core';
 import { IAlarmAction } from './alarm-action';
 import { CfnAlarm } from './cloudwatch.generated';
 import { HorizontalAnnotation } from './graph';
-import { CreateAlarmOptions } from './metric';
+import { BaseAlarmProps, CreateAlarmOptions } from './metric';
 import { IMetric } from './metric-types';
 import { parseStatistic } from './util.statistic';
 
@@ -18,10 +18,20 @@ export interface IAlarm extends IResource {
   readonly alarmName: string;
 }
 
+/**
+ * TODO
+ */
+export interface ComplexAlarmProps extends BaseAlarmProps {
+  /**
+   * TODO
+   */
+  readonly alarmTimeSeries: CfnAlarm.MetricDataQueryProperty[]
+}
+
 /**
  * Properties for Alarms
  */
-export interface AlarmProps extends CreateAlarmOptions {
+export interface SimpleAlarmProps extends CreateAlarmOptions {
   /**
    * The metric to add the alarm on
    *
@@ -31,6 +41,8 @@ export interface AlarmProps extends CreateAlarmOptions {
   readonly metric: IMetric;
 }
 
+export type AlarmProps = SimpleAlarmProps | ComplexAlarmProps;
+
 /**
  * Comparison operator for evaluating alarms
  */
@@ -73,6 +85,10 @@ export enum TreatMissingData {
   MISSING = 'missing'
 }
 
+function isComplexAlarm(props: ComplexAlarmProps | SimpleAlarmProps): props is ComplexAlarmProps {
+  return (props as ComplexAlarmProps).alarmTimeSeries !== undefined;
+}
+
 /**
  * An alarm on a CloudWatch metric
  */
@@ -103,7 +119,13 @@ export class Alarm extends Resource implements IAlarm {
   /**
    * The metric object this alarm was based on
    */
-  public readonly metric: IMetric;
+  public readonly metric?: IMetric;
+
+  /**
+   * The list of metrics. Used if the alarms requires more than one metric.
+   * @attribute todo
+   */
+  public readonly alarmTimeSeries?: CfnAlarm.MetricDataQueryProperty[];
 
   private alarmActionArns?: string[];
   private insufficientDataActionArns?: string[];
@@ -121,7 +143,27 @@ export class Alarm extends Resource implements IAlarm {
 
     const comparisonOperator = props.comparisonOperator || ComparisonOperator.GREATER_THAN_OR_EQUAL_TO_THRESHOLD;
 
-    const config = props.metric.toAlarmConfig();
+    let config;
+    let label;
+    // TODO: refactor
+    if (isComplexAlarm(props)) {
+      this.alarmTimeSeries = props.alarmTimeSeries;
+      config = dropUndef({...props, metrics: props.alarmTimeSeries, alarmTimeSeries: undefined});
+    } else {
+      this.metric = props.metric;
+      const alarmConfig = props.metric.toAlarmConfig();
+      config = {
+        ...dropUndef(alarmConfig),
+        // Alarm overrides
+        ...dropUndef({
+          period: props.period && props.period.toSeconds(),
+          statistic: renderIfSimpleStatistic(props.statistic),
+          extendedStatistic: renderIfExtendedStatistic(props.statistic)
+        })
+      };
+
+      label = `${this.metric} ${OPERATOR_SYMBOLS[comparisonOperator]} ${props.threshold} for ${props.evaluationPeriods} datapoints within ${describePeriod(props.evaluationPeriods * alarmConfig.period)}`;
+    }
 
     const alarm = new CfnAlarm(this, 'Resource', {
       // Meta
@@ -142,14 +184,7 @@ export class Alarm extends Resource implements IAlarm {
       insufficientDataActions: Lazy.listValue({ produce: (() => this.insufficientDataActionArns) }),
       okActions: Lazy.listValue({ produce: () => this.okActionArns }),
 
-      // Metric
-      ...dropUndef(config),
-      ...dropUndef({
-        // Alarm overrides
-        period: props.period && props.period.toSeconds(),
-        statistic: renderIfSimpleStatistic(props.statistic),
-        extendedStatistic: renderIfExtendedStatistic(props.statistic),
-      })
+      ...config
     });
 
     this.alarmArn = this.getResourceArnAttribute(alarm.attrArn, {
@@ -160,10 +195,8 @@ export class Alarm extends Resource implements IAlarm {
     });
     this.alarmName = this.getResourceNameAttribute(alarm.ref);
 
-    this.metric = props.metric;
     this.annotation = {
-      // tslint:disable-next-line:max-line-length
-      label: `${this.metric} ${OPERATOR_SYMBOLS[comparisonOperator]} ${props.threshold} for ${props.evaluationPeriods} datapoints within ${describePeriod(props.evaluationPeriods * config.period)}`,
+      label,
       value: props.threshold,
     };
   }

packages/@aws-cdk/aws-cloudwatch/lib/expression.ts

@@ -0,0 +1,76 @@
+import { CfnAlarm } from "./cloudwatch.generated";
+import { AlarmTimeSeriesProps, ITimeSeries, TimeSeriesJson, ToJsonProps } from "./timeseries";
+import MetricDataQueryProperty = CfnAlarm.MetricDataQueryProperty;
+
+/**
+ * TODO
+ */
+export interface IExpression extends ITimeSeries {
+    /**
+     * Math or search expression
+     */
+    expression: string
+    /**
+     * Unique ID
+     */
+    id: string
+    /**
+     * Label for this expression when added to a Graph in a Dashboard
+     */
+    label?: string
+}
+
+/**
+ * TODO
+ */
+export interface ExpressionProps {
+    /**
+     * TODO
+     */
+    readonly expression: string
+    /**
+     * TODO
+     */
+    readonly id: string
+    /**
+     * TODO
+     * @default TODO
+     */
+    readonly label?: string
+}
+
+/**
+ * TODOs
+ */
+export class Expression implements IExpression {
+    /**
+     * TODO
+     */
+    public expression: string;
+    /**
+     * TODO
+     */
+    public id: string;
+    /**
+     * TODO
+     * @default TODO
+     */
+    public label?: string;
+
+    constructor(props: ExpressionProps) {
+        this.expression = props.expression;
+        this.id = props.id;
+        this.label = props.label;
+    }
+
+    public toJson(_props: ToJsonProps = {}): TimeSeriesJson {
+        return [this];
+    }
+
+    public toAlarmTimeSeries(props: AlarmTimeSeriesProps = {}): MetricDataQueryProperty {
+        return {
+            ...this,
+            returnData: props.returnData
+        };
+    }
+}

packages/@aws-cdk/aws-cloudwatch/lib/graph.ts

@@ -1,7 +1,7 @@
 import cdk = require('@aws-cdk/core');
-import { IAlarm } from "./alarm";
-import { IMetric } from "./metric-types";
-import { ConcreteWidget } from "./widget";
+import { IAlarm } from './alarm';
+import { TimeSeriesJson } from './timeseries';
+import { ConcreteWidget } from './widget';
 
 /**
  * Basic properties for widgets that display metrics
@@ -120,14 +120,10 @@ export class AlarmWidget extends ConcreteWidget {
  */
 export interface GraphWidgetProps extends MetricWidgetProps {
   /**
-   * Metrics to display on left Y axis
+   * Time series to display
+   * @default no time series will be displayed
    */
-  readonly left?: IMetric[];
-
-  /**
-   * Metrics to display on right Y axis
-   */
-  readonly right?: IMetric[];
+  readonly timeSeries?: TimeSeriesJson[];
 
   /**
    * Annotations for the left Y axis
@@ -169,8 +165,7 @@ export class GraphWidget extends ConcreteWidget {
   public toJson(): any[] {
     const horizontalAnnoations =  (this.props.leftAnnotations || []).map(mapAnnotation('left')).concat(
       (this.props.rightAnnotations || []).map(mapAnnotation('right')));
-    const metrics = (this.props.left || []).map(m => metricJson(m, 'left')).concat(
-      (this.props.right || []).map(m => metricJson(m, 'right')));
+
     return [{
       type: 'metric',
       width: this.width,
@@ -182,7 +177,7 @@ export class GraphWidget extends ConcreteWidget {
         title: this.props.title,
         region: this.props.region || cdk.Aws.REGION,
         stacked: this.props.stacked,
-        metrics: metrics.length > 0 ? metrics : undefined,
+        metrics: this.props.timeSeries,
         annotations: horizontalAnnoations.length > 0 ? { horizontal: horizontalAnnoations } : undefined,
         yAxis: {
           left: this.props.leftYAxis !== undefined ? this.props.leftYAxis : undefined,
@@ -198,9 +193,9 @@ export class GraphWidget extends ConcreteWidget {
  */
 export interface SingleValueWidgetProps extends MetricWidgetProps {
   /**
-   * Metrics to display
+   * Time series to display
    */
-  readonly metrics: IMetric[];
+  readonly timeSeries: TimeSeriesJson[];
 
   /**
    * Whether to show the value from the entire time range.
@@ -232,7 +227,7 @@ export class SingleValueWidget extends ConcreteWidget {
         view: 'singleValue',
         title: this.props.title,
         region: this.props.region || cdk.Aws.REGION,
-        metrics: this.props.metrics.map(m => metricJson(m, 'left')),
+        metrics: this.props.timeSeries,
         setPeriodToTimeRange: this.props.setPeriodToTimeRange
       }
     }];
@@ -299,28 +294,3 @@ function mapAnnotation(yAxis: string): ((x: HorizontalAnnotation) => any) {
     return { ...a, yAxis };
   };
 }
-
-/**
- * Return the JSON structure which represents this metric in a graph
- *
- * This will be called by GraphWidget, no need for clients to call this.
- */
-function metricJson(metric: IMetric, yAxis: string): any[] {
-  const config = metric.toGraphConfig();
-
-  // Namespace and metric Name
-  const ret: any[] = [
-    config.namespace,
-    config.metricName,
-  ];
-
-  // Dimensions
-  for (const dim of (config.dimensions || [])) {
-    ret.push(dim.name, dim.value);
-  }
-
-  // Options
-  ret.push({ yAxis, ...config.renderingProperties });
-
-  return ret;
-}

packages/@aws-cdk/aws-cloudwatch/lib/index.ts

@@ -7,6 +7,8 @@ export * from './metric';
 export * from './metric-types';
 export * from './text';
 export * from './widget';
+export * from './timeseries';
+export * from './expression';
 
 // AWS::CloudWatch CloudFormation Resources:
 export * from './cloudwatch.generated';