From de6e845abdd1f1853d80ee46c85df768bcade274 Mon Sep 17 00:00:00 2001
From: Andy Zhou <andy@andyz.dev>
Date: Wed, 29 May 2019 08:12:32 -0700
Subject: [PATCH] Support docker machine for kubeconfig.yaml

The kubeconfig.yaml generated by K3S uses local host as the host name by
default. It won't work when running with docker machine.

This patch detects if the docker environment is set up with docker
machine. If it is, then replace the host name to the IP address of
the docker machine.
---
 cli/cluster.go        | 20 ++++++++++++++++++--
 cli/docker-machine.go | 26 ++++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 2 deletions(-)
 create mode 100644 cli/docker-machine.go

diff --git a/cli/cluster.go b/cli/cluster.go
index 68151fc2..96e544d0 100644
--- a/cli/cluster.go
+++ b/cli/cluster.go
@@ -9,6 +9,7 @@ import (
 	"os"
 	"path"
 	"strconv"
+	"strings"
 
 	"github.com/docker/docker/api/types"
 	"github.com/docker/docker/api/types/filters"
@@ -139,8 +140,23 @@ func createKubeConfigFile(cluster string) error {
 	}
 	defer kubeconfigfile.Close()
 
-	// write to file, skipping the first 512 bytes which contain file metadata and trimming any NULL characters
-	_, err = kubeconfigfile.Write(bytes.Trim(readBytes[512:], "\x00"))
+	// write to file, skipping the first 512 bytes which contain file metadata
+	// and trimming any NULL characters
+	trimBytes := bytes.Trim(readBytes[512:], "\x00")
+
+	// If running on a docker machine, replace localhost with
+	// docker machine's IP
+	dockerMachineIp, err := getDockerMachineIp()
+	if err != nil {
+		return err
+	}
+
+	if dockerMachineIp != "" {
+		s := string(trimBytes)
+		s = strings.Replace(s, "localhost", dockerMachineIp, 1)
+		trimBytes = []byte(s)
+	}
+	_, err = kubeconfigfile.Write(trimBytes)
 	if err != nil {
 		return fmt.Errorf("ERROR: couldn't write to kubeconfig.yaml\n%+v", err)
 	}
diff --git a/cli/docker-machine.go b/cli/docker-machine.go
new file mode 100644
index 00000000..f0d243cf
--- /dev/null
+++ b/cli/docker-machine.go
@@ -0,0 +1,26 @@
+package run
+
+import (
+	"os"
+	"os/exec"
+	"strings"
+)
+
+func getDockerMachineIp() (string, error) {
+	machine := os.ExpandEnv("$DOCKER_MACHINE_NAME")
+
+	if machine == "" {
+		return "", nil
+	}
+
+	dockerMachinePath, err := exec.LookPath("docker-machine")
+	if err != nil {
+		return "", err
+	}
+
+	out, err := exec.Command(dockerMachinePath, "ip").Output()
+
+	ipStr := strings.TrimSuffix(string(out), "\n")
+	ipStr = strings.TrimSuffix(ipStr, "\r")
+	return ipStr, err
+}