Add a telemetry_config.go to refactor client.go

agent/hcp/client/telemetry_config.go

@@ -0,0 +1,168 @@
+package client
+
+import (
+	"fmt"
+	"net/url"
+	"regexp"
+	"strings"
+	"time"
+
+	"github.com/hashicorp/go-hclog"
+	"github.com/hashicorp/go-multierror"
+	hcptelemetry "github.com/hashicorp/hcp-sdk-go/clients/cloud-consul-telemetry-gateway/preview/2023-04-14/client/consul_telemetry_service"
+
+	"github.com/hashicorp/consul/agent/hcp/config"
+)
+
+// MetricsConfig holds metrics specific configuration for the TelemetryConfig.
+// The endpoint field overrides the TelemetryConfig endpoint.
+type MetricsConfig struct {
+	Labels   map[string]string
+	Filters  *regexp.Regexp
+	Endpoint *url.URL
+}
+
+// RefreshConfig contains configuration for the periodic fetch of configuration from HCP by
+// the TelemetryConfigProvider, which enables dynamic configuration changes as the server is running.
+type RefreshConfig struct {
+	RefreshInterval time.Duration
+}
+
+// TelemetryConfig contains configuration for telemetry data forwarded by Consul servers
+// to the HCP Telemetry gateway.
+type TelemetryConfig struct {
+	MetricsConfig *MetricsConfig
+	RefreshConfig *RefreshConfig
+}
+
+// MetricsEnabled returns true if a metrics endpoint exists.
+func (t *TelemetryConfig) MetricsEnabled() bool {
+	return t.MetricsConfig.Endpoint != nil
+}
+
+func validateAgentTelemetryConfigPayload(resp *hcptelemetry.AgentTelemetryConfigOK) error {
+	if resp.Payload == nil {
+		return fmt.Errorf("missing payload")
+	}
+
+	if resp.Payload.TelemetryConfig == nil {
+		return fmt.Errorf("missing telemetry config")
+	}
+
+	if resp.Payload.RefreshConfig == nil {
+		return fmt.Errorf("missing refresh config")
+	}
+
+	if resp.Payload.TelemetryConfig.Metrics == nil {
+		return fmt.Errorf("missing metrics config")
+	}
+
+	return nil
+}
+
+// convertAgentTelemetryResponse validates the AgentTelemetryConfig payload and converts it into a TelemetryConfig object.
+func convertAgentTelemetryResponse(resp *hcptelemetry.AgentTelemetryConfigOK, logger hclog.Logger, cfg config.CloudConfig) (*TelemetryConfig, error) {
+	refreshInterval, err := time.ParseDuration(resp.Payload.RefreshConfig.RefreshInterval)
+	if err != nil {
+		return nil, fmt.Errorf("invalid refresh interval: %w", err)
+	}
+
+	telemetryConfig := resp.Payload.TelemetryConfig
+
+	metricsEndpoint, err := convertMetricEndpoint(telemetryConfig.Endpoint, telemetryConfig.Metrics.Endpoint)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse metrics endpoint: %w", err)
+	}
+
+	metricsFilters, err := convertMetricFilters(telemetryConfig.Metrics.IncludeList)
+	if err != nil {
+		// Do not fail on bad regex, as we can update these later on dynamically.
+		logger.Error("failed to parse regex filters", "error", err)
+	}
+
+	metricLabels := convertMetricLabels(telemetryConfig.Labels, cfg)
+
+	return &TelemetryConfig{
+		MetricsConfig: &MetricsConfig{
+			Endpoint: metricsEndpoint,
+			Labels:   metricLabels,
+			Filters:  metricsFilters,
+		},
+		RefreshConfig: &RefreshConfig{
+			RefreshInterval: refreshInterval,
+		},
+	}, nil
+}
+
+// MetricsEndpoint returns a url for the export of metrics, if a valid endpoint was obtained.
+// It returns no error, and no url, if an empty endpoint is retrieved (server not registered with CCM).
+// It returns an error, and no url, if a bad endpoint is retrieved.
+func convertMetricEndpoint(telemetryEndpoint string, metricsEndpoint string) (*url.URL, error) {
+	// Telemetry endpoint overriden by metrics specific endpoint, if given.
+	endpoint := telemetryEndpoint
+	if metricsEndpoint != "" {
+		endpoint = metricsEndpoint
+	}
+
+	// If endpoint is empty, server not registered with CCM, no error returned.
+	if endpoint == "" {
+		return nil, nil
+	}
+
+	// Endpoint from CTW has no metrics path, so it must be added.
+	rawUrl := endpoint + metricsGatewayPath
+	u, err := url.ParseRequestURI(rawUrl)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse url: %w", err)
+	}
+
+	return u, nil
+}
+
+// filterRegex returns a valid regex used to filter metrics.
+// It returns error if there are 0 valid regex filters given.
+func convertMetricFilters(payloadFilters []string) (*regexp.Regexp, error) {
+	var mErr error
+	filters := payloadFilters
+	validFilters := make([]string, 0, len(filters))
+	for _, filter := range filters {
+		_, err := regexp.Compile(filter)
+		if err != nil {
+			mErr = multierror.Append(mErr, fmt.Errorf("compilation of filter %q failed: %w", filter, err))
+			continue
+		}
+		validFilters = append(validFilters, filter)
+	}
+
+	if len(validFilters) == 0 {
+		return nil, multierror.Append(mErr, fmt.Errorf("no valid filters"))
+	}
+
+	// Combine the valid regex strings with OR.
+	finalRegex := strings.Join(validFilters, "|")
+	composedRegex, err := regexp.Compile(finalRegex)
+	if err != nil {
+		return nil, fmt.Errorf("failed to compile regex: %w", err)
+	}
+
+	return composedRegex, nil
+}
+
+// convertMetricLabels returns a set of <key, value> string pairs that must be added as attributes to all exported telemetry data.
+func convertMetricLabels(payloadLabels map[string]string, cfg config.CloudConfig) map[string]string {
+	labels := make(map[string]string)
+	nodeID := string(cfg.NodeID)
+	if nodeID != "" {
+		labels["node_id"] = nodeID
+	}
+
+	if cfg.NodeName != "" {
+		labels["node_name"] = cfg.NodeName
+	}
+
+	for k, v := range payloadLabels {
+		labels[k] = v
+	}
+
+	return labels
+}