Ping docker server before running

src/cmd/rocker-compose/main.go

@@ -555,6 +555,11 @@ func initComposeConfig(ctx *cli.Context, dockerCli *docker.Client) *config.Confi
 		log.Fatal(err)
 	}
 
+	// Check the docker connection before we actually run
+	if err := dockerclient.Ping(dockerCli, 5000); err != nil {
+		log.Fatal(err)
+	}
+
 	return manifest
 }
 

vendor/manifest

@@ -85,13 +85,6 @@
 			"branch": "master",
 			"path": "/src/rocker/test"
 		},
-		{
-			"importpath": "github.com/grammarly/rocker/src/rocker/dockerclient",
-			"repository": "https://github.com/grammarly/rocker",
-			"revision": "79bcadfcce121a8d9fa0f84e231314c6374bf8f3",
-			"branch": "master",
-			"path": "/src/rocker/dockerclient"
-		},
 		{
 			"importpath": "github.com/grammarly/rocker/src/rocker/util",
 			"repository": "https://github.com/grammarly/rocker",
@@ -131,6 +124,13 @@
 			"revision": "4d0275e3fcdd6460c7fe467678b04721bc19c9c7",
 			"branch": "v1",
 			"path": "/src/rocker/textformatter"
+		},
+		{
+			"importpath": "github.com/grammarly/rocker/src/rocker/dockerclient",
+			"repository": "https://github.com/grammarly/rocker",
+			"revision": "80510375c825db6731268f9f4f247a404879c966",
+			"branch": "v1",
+			"path": "/src/rocker/dockerclient"
 		}
 	]
 }

vendor/src/github.com/grammarly/rocker/src/rocker/dockerclient/dockerclient.go

@@ -25,6 +25,7 @@ import (
 	"os"
 	"strconv"
 	"strings"
+	"time"
 
 	"github.com/codegangsta/cli"
 	"github.com/fsouza/go-dockerclient"
@@ -95,6 +96,26 @@ func NewFromCli(c *cli.Context) (*docker.Client, error) {
 	return NewFromConfig(NewConfigFromCli(c))
 }
 
+// Ping pings docker client but with timeout
+// The problem is that for some reason it's impossible to set the
+// default timeout for the go-dockerclient Dialer, need to investigate
+func Ping(client *docker.Client, timeoutMs int) error {
+	var (
+		chErr   = make(chan error)
+		timeout = time.Duration(timeoutMs) * time.Millisecond
+	)
+	go func() {
+		chErr <- client.Ping()
+	}()
+	select {
+	case err := <-chErr:
+		return err
+	case <-time.After(timeout):
+		// TODO: can we kill the ping goroutine?
+		return fmt.Errorf("Failed to reach docker server, timeout %s", timeout)
+	}
+}
+
 // GlobalCliParams returns global params that configures docker client connection
 func GlobalCliParams() []cli.Flag {
 	return []cli.Flag{