feat(internal): add Thoth client and simple ASN checker

Signed-off-by: Xe Iaso <me@xeiaso.net>

internal/thoth/thoth.go

@@ -0,0 +1,69 @@
+package thoth
+
+import (
+	"context"
+	"crypto/tls"
+	"fmt"
+
+	iptoasnv1 "github.com/TecharoHQ/thoth-proto/gen/techaro/thoth/iptoasn/v1"
+	grpcprom "github.com/grpc-ecosystem/go-grpc-middleware/providers/prometheus"
+	"github.com/prometheus/client_golang/prometheus"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials"
+	healthv1 "google.golang.org/grpc/health/grpc_health_v1"
+)
+
+type Client struct {
+	thothURL string
+
+	conn    *grpc.ClientConn
+	health  healthv1.HealthClient
+	iptoasn iptoasnv1.IpToASNServiceClient
+}
+
+func New(ctx context.Context, thothURL, apiToken string) (*Client, error) {
+	clMetrics := grpcprom.NewClientMetrics(
+		grpcprom.WithClientHandlingTimeHistogram(
+			grpcprom.WithHistogramBuckets([]float64{0.001, 0.01, 0.1, 0.3, 0.6, 1, 3, 6, 9, 20, 30, 60, 90, 120}),
+		),
+	)
+	prometheus.DefaultRegisterer.Register(clMetrics)
+
+	conn, err := grpc.DialContext(
+		ctx,
+		thothURL,
+		grpc.WithTransportCredentials(credentials.NewTLS(&tls.Config{})),
+		grpc.WithChainUnaryInterceptor(
+			clMetrics.UnaryClientInterceptor(),
+			authUnaryClientInterceptor(apiToken),
+		),
+		grpc.WithChainStreamInterceptor(
+			clMetrics.StreamClientInterceptor(),
+			authStreamClientInterceptor(apiToken),
+		),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("can't dial thoth at %s: %w", thothURL, err)
+	}
+
+	hc := healthv1.NewHealthClient(conn)
+
+	resp, err := hc.Check(ctx, &healthv1.HealthCheckRequest{})
+	if err != nil {
+		return nil, fmt.Errorf("can't verify thoth health at %s: %w", thothURL, err)
+	}
+
+	if resp.Status != healthv1.HealthCheckResponse_SERVING {
+		return nil, fmt.Errorf("thoth is not healthy, wanted %s but got %s", healthv1.HealthCheckResponse_SERVING, resp.Status)
+	}
+
+	return &Client{
+		conn:    conn,
+		health:  hc,
+		iptoasn: iptoasnv1.NewIpToASNServiceClient(conn),
+	}, nil
+}
+
+func (c *Client) Close() error {
+	return c.conn.Close()
+}