resolves issues where failed api calls lead to obscure errors (#7051)

plugins/inputs/ecs/client.go

@@ -1,6 +1,9 @@
 package ecs
 
 import (
+	"fmt"
+	"io"
+	"io/ioutil"
 	"net/http"
 	"net/url"
 	"time"
@@ -50,10 +53,16 @@ func (c *EcsClient) Task() (*Task, error) {
 
 	req, _ := http.NewRequest("GET", c.taskURL, nil)
 	resp, err := c.client.Do(req)
-
 	if err != nil {
 		return nil, err
 	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		// ignore the err here; LimitReader returns io.EOF and we're not interested in read errors.
+		body, _ := ioutil.ReadAll(io.LimitReader(resp.Body, 200))
+		return nil, fmt.Errorf("%s returned HTTP status %s: %q", c.taskURL, resp.Status, body)
+	}
 
 	task, err := unmarshalTask(resp.Body)
 	if err != nil {
@@ -71,11 +80,18 @@ func (c *EcsClient) ContainerStats() (map[string]types.StatsJSON, error) {
 
 	req, _ := http.NewRequest("GET", c.statsURL, nil)
 	resp, err := c.client.Do(req)
-
 	if err != nil {
 		return map[string]types.StatsJSON{}, err
 	}
 
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		// ignore the err here; LimitReader returns io.EOF and we're not interested in read errors.
+		body, _ := ioutil.ReadAll(io.LimitReader(resp.Body, 200))
+		return nil, fmt.Errorf("%s returned HTTP status %s: %q", c.statsURL, resp.Status, body)
+	}
+
 	statsMap, err := unmarshalStats(resp.Body)
 	if err != nil {
 		return map[string]types.StatsJSON{}, err

plugins/inputs/ecs/client_test.go

@@ -107,7 +107,8 @@ func TestEcsClient_Task(t *testing.T) {
 			client: mockDo{
 				do: func(req *http.Request) (*http.Response, error) {
 					return &http.Response{
-						Body: ioutil.NopCloser(rc),
+						StatusCode: http.StatusOK,
+						Body:       ioutil.NopCloser(rc),
 					}, nil
 				},
 			},
@@ -123,11 +124,24 @@ func TestEcsClient_Task(t *testing.T) {
 			wantErr: true,
 		},
 		{
-			name: "malformed resp",
+			name: "malformed 500 resp",
 			client: mockDo{
 				do: func(req *http.Request) (*http.Response, error) {
 					return &http.Response{
-						Body: ioutil.NopCloser(bytes.NewReader([]byte("foo"))),
+						StatusCode: http.StatusInternalServerError,
+						Body:       ioutil.NopCloser(bytes.NewReader([]byte("foo"))),
+					}, nil
+				},
+			},
+			wantErr: true,
+		},
+		{
+			name: "malformed 200 resp",
+			client: mockDo{
+				do: func(req *http.Request) (*http.Response, error) {
+					return &http.Response{
+						StatusCode: http.StatusOK,
+						Body:       ioutil.NopCloser(bytes.NewReader([]byte("foo"))),
 					}, nil
 				},
 			},
@@ -164,7 +178,8 @@ func TestEcsClient_ContainerStats(t *testing.T) {
 			client: mockDo{
 				do: func(req *http.Request) (*http.Response, error) {
 					return &http.Response{
-						Body: ioutil.NopCloser(rc),
+						StatusCode: http.StatusOK,
+						Body:       ioutil.NopCloser(rc),
 					}, nil
 				},
 			},
@@ -181,17 +196,31 @@ func TestEcsClient_ContainerStats(t *testing.T) {
 			wantErr: true,
 		},
 		{
-			name: "malformed resp",
+			name: "malformed 200 resp",
 			client: mockDo{
 				do: func(req *http.Request) (*http.Response, error) {
 					return &http.Response{
-						Body: ioutil.NopCloser(bytes.NewReader([]byte("foo"))),
+						StatusCode: http.StatusOK,
+						Body:       ioutil.NopCloser(bytes.NewReader([]byte("foo"))),
 					}, nil
 				},
 			},
 			want:    map[string]types.StatsJSON{},
 			wantErr: true,
 		},
+		{
+			name: "malformed 500 resp",
+			client: mockDo{
+				do: func(req *http.Request) (*http.Response, error) {
+					return &http.Response{
+						StatusCode: http.StatusInternalServerError,
+						Body:       ioutil.NopCloser(bytes.NewReader([]byte("foo"))),
+					}, nil
+				},
+			},
+			want:    nil,
+			wantErr: true,
+		},
 	}
 
 	for _, tt := range tests {