Use feature flag for when to use server cache

2 files changed, 17 insertions, 2 deletions

diff --git a/configserver/pom.xml b/configserver/pom.xml
index a9cade47446..f932a963d14 100644
--- a/configserver/pom.xml
+++ b/configserver/pom.xml
@@ -168,6 +168,12 @@
     </dependency>
     <dependency>
       <groupId>com.yahoo.vespa</groupId>
+      <artifactId>flags</artifactId>
+      <version>${project.version}</version>
+      <scope>provided</scope>
+    </dependency>
+    <dependency>
+      <groupId>com.yahoo.vespa</groupId>
       <artifactId>serviceview</artifactId>
       <version>${project.version}</version>
       <scope>compile</scope>
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/application/Application.java b/configserver/src/main/java/com/yahoo/vespa/config/server/application/Application.java
index 06a4c12fb32..f72ab1b07ac 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/application/Application.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/application/Application.java
@@ -23,6 +23,8 @@ import com.yahoo.vespa.config.server.UnknownConfigDefinitionException;
 import com.yahoo.vespa.config.server.modelfactory.ModelResult;
 import com.yahoo.vespa.config.server.monitoring.MetricUpdater;
 import com.yahoo.vespa.config.util.ConfigUtils;
+import com.yahoo.vespa.flags.FeatureFlag;
+import com.yahoo.vespa.flags.FileFlagSource;
 
 import java.util.Objects;
 import java.util.Set;
@@ -109,7 +111,7 @@ public class Application implements ModelResult {
             debug("Resolving config " + cacheKey);
         }
 
-        if ( ! req.noCache()) {
+        if (useCache(req)) {
             ConfigResponse config = cache.get(cacheKey);
             if (config != null) {
                 if (logDebug()) {
@@ -136,7 +138,7 @@ public class Application implements ModelResult {
 
         ConfigResponse configResponse = responseFactory.createResponse(payload, def.getCNode(), appGeneration, internalRedeploy);
         metricUpdater.incrementProcTime(System.currentTimeMillis() - start);
-        if ( ! req.noCache()) {
+        if (useCache(req)) {
             cache.put(cacheKey, configResponse, configResponse.getConfigMd5());
             metricUpdater.setCacheConfigElems(cache.configElems());
             metricUpdater.setCacheChecksumElems(cache.checkSumElems());
@@ -144,6 +146,13 @@ public class Application implements ModelResult {
         return configResponse;
     }
 
+    private boolean useCache(GetConfigRequest request) {
+        if (request.noCache())
+            return false;
+        else
+            return new FeatureFlag("use-config-server-cache", true, new FileFlagSource()).value();
+    }
+
     private boolean logDebug() {
         return log.isLoggable(LogLevel.DEBUG);
     }