Add KV#update for patch support

lib/vault/api/kv.rb

@@ -122,6 +122,32 @@ def write_metadata(path, metadata = {})
       true
     end
 
+    # Update the secret at the given path with the given data. Note that the
+    # data must be a {Hash}! Data will be merged with existing values.
+    #
+    # Note: This will raise an error if used on KV Secrets Engine Version 1.
+    #
+    # @example
+    #   Vault.kv.write("secret/multiple", password: "secret") #=> #<Vault::Secret lease_id="">
+    #
+    # @param [String] path
+    #   the path to update
+    # @param [Hash] data
+    #   the data to merge
+    #
+    # @return [Secret]
+    def update(path, data = {}, options = {})
+      headers = extract_headers!(options)
+      headers["Content-Type"] = "application/merge-patch+json"
+      json = client.patch("/v1/#{mount}/data/#{encode_path(path)}", JSON.fast_generate(:data => data), headers)
+      if json.nil?
+        return true
+      else
+        return Secret.decode(json)
+      end
+    end
+
+
     # Delete the secret at the given path. If the secret does not exist, vault
     # will still return true.
     #

spec/integration/api/kv_spec.rb

@@ -118,6 +118,38 @@ module Vault
       end
     end
 
+    describe "#update" do
+      it "merges data and returns the secret" do
+        subject.write("test-update", zip: "zap")
+        subject.update("test-update", zig: "zag")
+        result = subject.read("test-update")
+        expect(result).to be
+        expect(result.data).to eq(zip: "zap", zig: "zag")
+      end
+
+      it "raises an error if the path does not exist" do
+        expect {
+          subject.update("test-update-non-existent", zig: "zag")
+        }.to raise_error(Vault::HTTPClientError, /404/)
+      end
+
+      it "raises an error if the path has been deleted" do
+        expect {
+          subject.write("test-update-deleted", zip: "zap")
+          subject.delete("test-update-deleted")
+          subject.update("test-update-deleted", zig: "zag")
+        }.to raise_error(Vault::HTTPClientError, /404/)
+      end
+
+      it "raises an error if the path has been destroyed" do
+        expect {
+          subject.write("test-update-destroyed", zip: "zap")
+          subject.delete("test-update-destroyed")
+          subject.update("test-update-destroyed", zig: "zag")
+        }.to raise_error(Vault::HTTPClientError, /404/)
+      end
+    end
+
     describe "#delete" do
       it "deletes the secret" do
         subject.write("delete", foo: "bar")