fix: use default socket path for TCP connections (#669)

Signed-off-by: Matej Vasek <mvasek@redhat.com>

docker/docker_client.go

@@ -41,6 +41,14 @@ func NewClient(defaultHost string) (dockerClient client.CommonAPIClient, dockerH
 
 	_url, err = url.Parse(dockerHost)
 	isSSH := err == nil && _url.Scheme == "ssh"
+	isTCP := err == nil && _url.Scheme == "tcp"
+
+	if isTCP {
+		// With TCP, it's difficult to determine how to expose the daemon socket to lifecycle containers,
+		// so we are defaulting to standard docker location by returning empty string.
+		// This should work well most of the time.
+		dockerHost = ""
+	}
 
 	if !isSSH {
 		dockerClient, err = client.NewClientWithOpts(client.FromEnv, client.WithAPIVersionNegotiation())

docker/docker_client_test.go

@@ -18,7 +18,7 @@ import (
 
 // Test that we are creating client in accordance
 // with the DOCKER_HOST environment variable
-func TestNewDockerClient(t *testing.T) {
+func TestNewClient(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), time.Minute*1)
 	defer cancel()
 
@@ -41,6 +41,38 @@ func TestNewDockerClient(t *testing.T) {
 	}
 }
 
+func TestNewClient_DockerHost(t *testing.T) {
+	tests := []struct {
+		name                     string
+		dockerHostEnvVar         string
+		expectedRemoteDockerHost string
+	}{
+		{
+			name:                     "tcp",
+			dockerHostEnvVar:         "tcp://10.0.0.1:1234",
+			expectedRemoteDockerHost: "",
+		},
+		{
+			name:                     "unix",
+			dockerHostEnvVar:         "unix:///some/path/docker.sock",
+			expectedRemoteDockerHost: "unix:///some/path/docker.sock",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			defer WithEnvVar(t, "DOCKER_HOST", tt.dockerHostEnvVar)()
+			_, host, err := docker.NewClient(client.DefaultDockerHost)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if host != tt.expectedRemoteDockerHost {
+				t.Errorf("expected docker host %q, but got %q", tt.expectedRemoteDockerHost, host)
+			}
+		})
+	}
+
+}
+
 func startMockDaemon(t *testing.T, sock string) func() {
 
 	server := http.Server{}