refactor(internal): export internal packages (#887)

* refactor: export internal packages

* refactor(server): define Server

* refactor: fix lint issues

* test(integration): fix imports

pkg/commands/config/cache.go

@@ -0,0 +1,31 @@
+package config
+
+import (
+	"strings"
+
+	"github.com/urfave/cli/v2"
+	"golang.org/x/xerrors"
+)
+
+// CacheConfig holds the config for cache
+type CacheConfig struct {
+	CacheBackend string
+}
+
+// NewCacheConfig returns an instance of CacheConfig
+func NewCacheConfig(c *cli.Context) CacheConfig {
+	return CacheConfig{
+		CacheBackend: c.String("cache-backend"),
+	}
+}
+
+// Init initialize the CacheConfig
+func (c *CacheConfig) Init() error {
+	// "redis://" or "fs" are allowed for now
+	// An empty value is also allowed for testability
+	if !strings.HasPrefix(c.CacheBackend, "redis://") &&
+		c.CacheBackend != "fs" && c.CacheBackend != "" {
+		return xerrors.Errorf("unsupported cache backend: %s", c.CacheBackend)
+	}
+	return nil
+}