Query node group min and max size from AWS ASG API (#576)

(cherry picked from commit c7f430f)

Author: deliahu

pkg/lib/aws/autoscaling.go

@@ -0,0 +1,61 @@
+/*
+Copyright 2019 Cortex Labs, Inc.
+
+Licensed 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.
+*/
+
+package aws
+
+import (
+	"github.com/aws/aws-sdk-go/service/autoscaling"
+	"github.com/cortexlabs/cortex/pkg/lib/errors"
+)
+
+// if specified, all tags must be present
+func (c *Client) AutoscalingGroups(tags map[string]string) ([]*autoscaling.Group, error) {
+	var asgs []*autoscaling.Group
+
+	err := c.autoscaling.DescribeAutoScalingGroupsPages(nil,
+		func(page *autoscaling.DescribeAutoScalingGroupsOutput, lastPage bool) bool {
+			for _, asg := range page.AutoScalingGroups {
+				asgTags := make(map[string]string, len(asg.Tags))
+				for _, asgTag := range asg.Tags {
+					if asgTag.Key != nil && asgTag.Value != nil {
+						asgTags[*asgTag.Key] = *asgTag.Value
+					}
+				}
+
+				missingTag := false
+				for key, value := range tags {
+					if asgTags[key] != value {
+						missingTag = true
+						break
+					}
+				}
+
+				if missingTag {
+					continue
+				}
+
+				asgs = append(asgs, asg)
+			}
+
+			return true
+		})
+
+	if err != nil {
+		return nil, errors.WithStack(err)
+	}
+
+	return asgs, nil
+}

pkg/lib/aws/aws.go

@@ -19,6 +19,7 @@ package aws
 import (
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/aws/session"
+	"github.com/aws/aws-sdk-go/service/autoscaling"
 	"github.com/aws/aws-sdk-go/service/cloudwatch"
 	"github.com/aws/aws-sdk-go/service/cloudwatchlogs"
 	"github.com/aws/aws-sdk-go/service/s3"
@@ -33,6 +34,7 @@ type Client struct {
 	Bucket               string
 	S3                   *s3.S3
 	stsClient            *sts.STS
+	autoscaling          *autoscaling.AutoScaling
 	CloudWatchLogsClient *cloudwatchlogs.CloudWatchLogs
 	CloudWatchMetrics    *cloudwatch.CloudWatch
 	AccountID            string
@@ -50,6 +52,7 @@ func New(region string, bucket string, withAccountID bool) (*Client, error) {
 		Region:               region,
 		S3:                   s3.New(sess),
 		stsClient:            sts.New(sess),
+		autoscaling:          autoscaling.New(sess),
 		CloudWatchMetrics:    cloudwatch.New(sess),
 		CloudWatchLogsClient: cloudwatchlogs.New(sess),
 	}

pkg/operator/endpoints/info.go

@@ -17,13 +17,30 @@ limitations under the License.
 package endpoints
 
 import (
+	"fmt"
 	"net/http"
 
+	"github.com/cortexlabs/cortex/pkg/lib/errors"
 	"github.com/cortexlabs/cortex/pkg/operator/api/schema"
 	"github.com/cortexlabs/cortex/pkg/operator/config"
 )
 
 func Info(w http.ResponseWriter, r *http.Request) {
+	asgs, err := config.AWS.AutoscalingGroups(map[string]string{"alpha.eksctl.io/nodegroup-name": "ng-1"})
+	if err != nil {
+		RespondError(w, errors.WithStack(err))
+		return
+	}
+
+	if len(asgs) != 1 {
+		message := fmt.Sprintf("found %d matching autoscaling groups, expected only one", len(asgs))
+		RespondError(w, errors.New(message)) // unexpected
+		return
+	}
+
+	config.Cluster.MinInstances = asgs[0].MinSize
+	config.Cluster.MaxInstances = asgs[0].MaxSize
+
 	response := schema.InfoResponse{ClusterConfig: config.Cluster}
 	Respond(w, response)
 }