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|
package client
import (
"bytes"
"context"
"fmt"
"io"
"net/http"
)
const templateMetrics string = `Active connections: %d
server accepts handled requests
%d %d %d
Reading: %d Writing: %d Waiting: %d
`
// NginxClient allows you to fetch NGINX metrics from the stub_status page.
type NginxClient struct {
httpClient *http.Client
apiEndpoint string
}
// StubStats represents NGINX stub_status metrics.
type StubStats struct {
Connections StubConnections
Requests int64
}
// StubConnections represents connections related metrics.
type StubConnections struct {
Active int64
Accepted int64
Handled int64
Reading int64
Writing int64
Waiting int64
}
// NewNginxClient creates an NginxClient.
func NewNginxClient(httpClient *http.Client, apiEndpoint string) *NginxClient {
client := &NginxClient{
apiEndpoint: apiEndpoint,
httpClient: httpClient,
}
return client
}
// GetStubStats fetches the stub_status metrics.
func (client *NginxClient) GetStubStats() (*StubStats, error) {
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
req, err := http.NewRequestWithContext(ctx, http.MethodGet, client.apiEndpoint, nil)
if err != nil {
return nil, fmt.Errorf("failed to create a get request: %w", err)
}
resp, err := client.httpClient.Do(req)
if err != nil {
return nil, fmt.Errorf("failed to get %v: %w", client.apiEndpoint, err)
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
return nil, fmt.Errorf("expected %v response, got %v", http.StatusOK, resp.StatusCode)
}
body, err := io.ReadAll(resp.Body)
if err != nil {
return nil, fmt.Errorf("failed to read the response body: %w", err)
}
r := bytes.NewReader(body)
stats, err := parseStubStats(r)
if err != nil {
return nil, fmt.Errorf("failed to parse response body %q: %w", string(body), err)
}
return stats, nil
}
func parseStubStats(r io.Reader) (*StubStats, error) {
var s StubStats
if _, err := fmt.Fscanf(r, templateMetrics,
&s.Connections.Active,
&s.Connections.Accepted,
&s.Connections.Handled,
&s.Requests,
&s.Connections.Reading,
&s.Connections.Writing,
&s.Connections.Waiting); err != nil {
return nil, fmt.Errorf("failed to scan template metrics: %w", err)
}
return &s, nil
}
|
