Add prefixing to couch to fix the error that was exposed

physical/couchdb/couchdb.go

@@ -22,6 +22,7 @@ import (
 // CouchDBBackend allows the management of couchdb users
 type CouchDBBackend struct {
 	logger     log.Logger
+	prefixed   bool
 	client     *couchDBClient
 	permitPool *physical.PermitPool
 }
@@ -158,6 +159,19 @@ func buildCouchDBBackend(conf map[string]string, logger log.Logger) (*CouchDBBac
 		username = conf["username"]
 	}
 
+	prefixed := true
+	prefixedStr := os.Getenv("COUCHDB_PREFIXED")
+	if prefixedStr == "" {
+		prefixedStr = conf["prefixed"]
+	}
+	if prefixedStr != "" {
+		var err error
+		prefixed, err = strconv.ParseBool(prefixedStr)
+		if err != nil {
+			return nil, err
+		}
+	}
+
 	password := os.Getenv("COUCHDB_PASSWORD")
 	if password == "" {
 		password = conf["password"]
@@ -183,6 +197,7 @@ func buildCouchDBBackend(conf map[string]string, logger log.Logger) (*CouchDBBac
 			password: password,
 			Client:   cleanhttp.DefaultPooledClient(),
 		},
+		prefixed:   prefixed,
 		logger:     logger,
 		permitPool: physical.NewPermitPool(maxParInt),
 	}, nil
@@ -227,6 +242,10 @@ func (m *CouchDBBackend) Delete(key string) error {
 func (m *CouchDBBackend) List(prefix string) ([]string, error) {
 	defer metrics.MeasureSince([]string{"couchdb", "list"}, time.Now())
 
+	if m.prefixed {
+		prefix = "$" + prefix
+	}
+
 	m.permitPool.Acquire()
 	defer m.permitPool.Release()
 
@@ -275,6 +294,10 @@ func NewTransactionalCouchDBBackend(conf map[string]string, logger log.Logger) (
 func (m *CouchDBBackend) GetInternal(key string) (*physical.Entry, error) {
 	defer metrics.MeasureSince([]string{"couchdb", "get"}, time.Now())
 
+	if m.prefixed {
+		key = "$" + key
+	}
+
 	return m.client.get(key)
 }
 
@@ -282,12 +305,17 @@ func (m *CouchDBBackend) GetInternal(key string) (*physical.Entry, error) {
 func (m *CouchDBBackend) PutInternal(entry *physical.Entry) error {
 	defer metrics.MeasureSince([]string{"couchdb", "put"}, time.Now())
 
-	revision, _ := m.client.rev(url.PathEscape(entry.Key))
+	key := entry.Key
+	if m.prefixed {
+		key = "$" + entry.Key
+	}
+
+	revision, _ := m.client.rev(url.PathEscape(key))
 
 	return m.client.put(couchDBEntry{
 		Entry: entry,
 		Rev:   revision,
-		ID:    url.PathEscape(entry.Key),
+		ID:    url.PathEscape(key),
 	})
 }
 
@@ -295,6 +323,10 @@ func (m *CouchDBBackend) PutInternal(entry *physical.Entry) error {
 func (m *CouchDBBackend) DeleteInternal(key string) error {
 	defer metrics.MeasureSince([]string{"couchdb", "delete"}, time.Now())
 
+	if m.prefixed {
+		key = "$" + key
+	}
+
 	revision, _ := m.client.rev(url.PathEscape(key))
 	deleted := true
 	return m.client.put(couchDBEntry{

website/source/docs/configuration/storage/couchdb.html.md

@@ -30,6 +30,12 @@ storage "couchdb" {
 
 ## `couchdb` Parameters
 
+- `prefixed` `(string: "true")` – Specifies whether each value written to
+  CouchDB should be prefixed with `$`. If turned off, Vault may run into error
+  conditions if values are written that begin with an underscore, since it is a
+  reserved prefix in CouchDB. This can also be provided via the environment
+  variable `COUCHDB_PREFIXED`.
+
 - `endpoint` `(string: "")` – Specifies your CouchDB endpoint. This can also be
   provided via the environment variable `COUCHDB_ENDPOINT`.
 

website/source/guides/upgrading/upgrade-to-0.9.0.html.md

@@ -0,0 +1,24 @@
+---
+layout: "guides"
+page_title: "Upgrading to Vault 0.9.0 - Guides"
+sidebar_current: "guides-upgrading-to-0.9.0"
+description: |-
+  This page contains the list of deprecations and important or breaking changes
+  for Vault 0.9.0. Please read it carefully.
+---
+
+# Overview
+
+This page contains the list of deprecations and important or breaking changes
+for Vault 0.9.0 compared to the most recent release. Please read it carefully.
+
+## CouchDB Storage Changes
+
+Vault may write values to storage that start with an underscore (`_`)
+character. This is a reserved character in CouchDB, which can cause breakage.
+As a result, this backend now stores each value prefixed with a `$` character.
+
+If you are upgrading from existing CouchDB usage, you can turn off this
+behavior by setting the `"prefixed"` configuration value to `"false"`.
+Alternately, if you need to handle underscores at the start of keys, you can
+rewrite your existing keys to start with a `$` character.

website/source/layouts/guides.erb

@@ -53,6 +53,9 @@
           <li<%= sidebar_current("guides-upgrading-to-0.8.0") %>>
             <a href="/guides/upgrading/upgrade-to-0.8.0.html">Upgrade to 0.8.0</a>
           </li>
+          <li<%= sidebar_current("guides-upgrading-to-0.9.0") %>>
+            <a href="/guides/upgrading/upgrade-to-0.9.0.html">Upgrade to 0.9.0</a>
+          </li>
         </ul>
       </li>
     </ul>