Warn if /var disk space is full and add a solution message

pkg/minikube/machine/fix.go

@@ -59,6 +59,7 @@ func fixHost(api libmachine.API, cc *config.ClusterConfig, n *config.Node) (*hos
 	if err != nil {
 		return h, errors.Wrap(err, "Error loading existing host. Please try running [minikube delete], then run [minikube start] again.")
 	}
+	defer postStartValidations(h, cc.Driver)
 
 	driverName := h.Driver.DriverName()
 

pkg/minikube/machine/start.go

@@ -23,6 +23,8 @@ import (
 	"os/exec"
 	"path"
 	"path/filepath"
+	"strconv"
+	"strings"
 	"time"
 
 	"github.com/docker/machine/libmachine"
@@ -149,6 +151,7 @@ func createHost(api libmachine.API, cfg *config.ClusterConfig, n *config.Node) (
 	if err != nil {
 		return nil, errors.Wrap(err, "new host")
 	}
+	defer postStartValidations(h, cfg.Driver)
 
 	h.HostOptions.AuthOptions.CertDir = localpath.MiniPath()
 	h.HostOptions.AuthOptions.StorePath = localpath.MiniPath()
@@ -202,6 +205,26 @@ func timedCreateHost(h *host.Host, api libmachine.API, t time.Duration) error {
 	}
 }
 
+// postStartValidations are validations against the host after it is created
+func postStartValidations(h *host.Host, drvName string) {
+	if !driver.IsKIC(drvName) {
+		return
+	}
+	// make sure /var isn't full, otherwise warn
+	output, err := h.RunSSHCommand("df -h /var | awk 'NR==2{print $5}'")
+	if err != nil {
+		glog.Warning("error running df -h /var: %v", err)
+	}
+	output = strings.Trim(output, "\n")
+	percentageFull, err := strconv.Atoi(output[:len(output)-1])
+	if err != nil {
+		glog.Warning("error getting % of /var that is free: %v", err)
+	}
+	if percentageFull >= 99 {
+		out.WarningT("The docker daemon is almost out of memory, run 'docker system prune' to free up space.")
+	}
+}
+
 // postStart are functions shared between startHost and fixHost
 func postStartSetup(h *host.Host, mc config.ClusterConfig) error {
 	glog.Infof("post-start starting for %q (driver=%q)", h.Name, h.DriverName)

pkg/minikube/problem/err_map.go

@@ -578,3 +578,12 @@ var stateProblems = map[string]match{
 		Issues: []int{7256},
 	},
 }
+
+// dockerProblems are issues relating to issues with the docker driver
+var dockerProblems = map[string]match{
+	"NO_SPACE_ON_DEVICE": {
+		Regexp: re(`No space left on device`),
+		Advice: "Run 'docker system prune' to delete unused data and free up space on the device",
+		Issues: []int{9024},
+	},
+}

pkg/minikube/problem/problem.go

@@ -104,6 +104,7 @@ func FromError(err error, goos string) *Problem {
 		netProblems,
 		deployProblems,
 		stateProblems,
+		dockerProblems,
 	}
 
 	var osMatch *Problem