Respect KUBECACHEDIR environment variable (#975)

This adds a check for the existence of a (non-empty) `KUBECACHEDIR`
environment variable that will be used to construct the cache directory
path if present.

pkg/cmd/cmd.go

@@ -4,6 +4,7 @@ import (
  "context"
  "path/filepath"
  "runtime"
+ "os"
 
  "github.com/google/wire"
  "github.com/int128/kubelogin/pkg/infrastructure/logger"
@@ -23,8 +24,17 @@ type Interface interface {
  Run(ctx context.Context, args []string, version string) int
 }
 
+func getDefaultTokenCacheDir(key, fallback string) string {
+ if value, ok := os.LookupEnv(key); ok {
+ return value
+ }
+ return fallback
+}
+
 var defaultListenAddress = []string{"127.0.0.1:8000", "127.0.0.1:18000"}
-var defaultTokenCacheDir = filepath.Join("~", ".kube", "cache", "oidc-login")
+var defaultTokenCacheDir = filepath.Join(
+ getDefaultTokenCacheDir("KUBECACHEDIR", filepath.Join("~", ".kube", "cache")),
+ "oidc-login")
 
 const defaultAuthenticationTimeoutSec = 180