Add the ability to specify an http(s) URL for config (#34)

* Add the ability to specify an http(s) URL for config

* Update cmd/root.go

cmd/root.go

@@ -17,13 +17,19 @@ package cmd
 import (
 	"flag"
 	"fmt"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"net/url"
 	"os"
+	"strings"
 
 	nova_helm "github.com/fairwindsops/nova/pkg/helm"
 	"github.com/fairwindsops/nova/pkg/output"
 	"github.com/spf13/cobra"
 	"github.com/spf13/pflag"
 	"github.com/spf13/viper"
+	"k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/klog"
 )
 
@@ -84,6 +90,16 @@ func initConfig() {
 		return
 	}
 
+	if strings.HasPrefix(cfgFile, "https://") || strings.HasPrefix(cfgFile, "http://") {
+		klog.V(2).Infof("detected URL for config location")
+		var err error
+		cfgFile, err = downloadConfig(cfgFile)
+		if err != nil {
+			klog.Fatalf("failed to download config: %s", err.Error())
+		}
+		defer os.Remove(cfgFile)
+	}
+
 	// Read config
 	viper.SetConfigFile(cfgFile)
 	klog.V(2).Infof("using config file: %s", cfgFile)
@@ -92,6 +108,43 @@ func initConfig() {
 	}
 }
 
+func downloadConfig(cfgURL string) (string, error) {
+	fileURL, err := url.Parse(cfgURL)
+	if err != nil {
+		return "", err
+	}
+	path := fileURL.Path
+	segments := strings.Split(path, "/")
+	fileName := segments[len(segments)-1]
+
+	file, err := ioutil.TempFile("", fmt.Sprintf("*-%s", fileName))
+	if err != nil {
+		return "", err
+	}
+
+	client := http.Client{
+		CheckRedirect: func(r *http.Request, via []*http.Request) error {
+			r.URL.Opaque = r.URL.Path
+			return nil
+		},
+	}
+	// Put content on file
+	resp, err := client.Get(cfgURL)
+	if err != nil {
+		return "", &errors.StatusError{}
+	}
+	defer resp.Body.Close()
+
+	size, err := io.Copy(file, resp.Body)
+
+	defer file.Close()
+
+	tmpConfig := file.Name()
+	klog.V(2).Infof("downloaded config file %s with size %d", tmpConfig, size)
+
+	return tmpConfig, nil
+}
+
 var rootCmd = &cobra.Command{
 	Use:   "nova",
 	Short: "nova",

go.mod

@@ -6,6 +6,7 @@ require (
 	// required for dependency issue: https://github.com/kubernetes/client-go/issues/628
 	github.com/Azure/go-autorest v12.2.0+incompatible
 	github.com/DATA-DOG/go-sqlmock v1.4.1 // indirect
+	github.com/cavaliercoder/grab v2.0.0+incompatible
 	github.com/fsnotify/fsnotify v1.4.9 // indirect
 	github.com/jmoiron/sqlx v1.2.0 // indirect
 	github.com/lib/pq v1.5.2 // indirect
@@ -28,6 +29,7 @@ require (
 	helm.sh/helm v2.16.6+incompatible
 	helm.sh/helm/v3 v3.1.2
 	k8s.io/apiextensions-apiserver v0.18.1 // indirect
+	k8s.io/apimachinery v0.18.1
 	k8s.io/client-go v1.5.1
 	k8s.io/helm v2.16.5+incompatible
 	k8s.io/klog v1.0.0

go.sum

@@ -90,6 +90,9 @@ github.com/bugsnag/bugsnag-go v0.0.0-20141110184014-b1d153021fcd/go.mod h1:2oa8n
 github.com/bugsnag/osext v0.0.0-20130617224835-0dd3f918b21b/go.mod h1:obH5gd0BsqsP2LwDJ9aOkm/6J86V6lyAXCoQWGw3K50=
 github.com/bugsnag/panicwrap v0.0.0-20151223152923-e2c28503fcd0/go.mod h1:D/8v3kj0zr8ZAKg1AQ6crr+5VwKN5eIywRkfhyM/+dE=
 github.com/casbin/casbin/v2 v2.1.2/go.mod h1:YcPU1XXisHhLzuxH9coDNf2FbKpjGlbCg3n9yuLkIJQ=
+github.com/cavaliercoder/grab v1.0.0 h1:H6VQ1NiLO7AvXM6ZyaInnoZrRLeo2FoUTQEcXln4bvQ=
+github.com/cavaliercoder/grab v2.0.0+incompatible h1:wZHbBQx56+Yxjx2TCGDcenhh3cJn7cCLMfkEPmySTSE=
+github.com/cavaliercoder/grab v2.0.0+incompatible/go.mod h1:tTBkfNqSBfuMmMBFaO2phgyhdYhiZQ/+iXCZDzcDsMI=
 github.com/cenkalti/backoff v2.2.1+incompatible/go.mod h1:90ReRw6GdpyfrHakVjL/QHaoyV4aDUVVkXQJJJ3NXXM=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
 github.com/cespare/xxhash v1.1.0/go.mod h1:XrSqR1VqqWfGrhpAt58auRo0WTKS1nRRg3ghfAqPWnc=