Added comment

2 files changed, 9 insertions, 1 deletions

diff --git a/docker-api/src/main/java/com/yahoo/vespa/hosted/dockerapi/DockerException.java b/docker-api/src/main/java/com/yahoo/vespa/hosted/dockerapi/DockerException.java
index 67a8f42020b..b5b622977fb 100644
--- a/docker-api/src/main/java/com/yahoo/vespa/hosted/dockerapi/DockerException.java
+++ b/docker-api/src/main/java/com/yahoo/vespa/hosted/dockerapi/DockerException.java
@@ -1,6 +1,9 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.vespa.hosted.dockerapi;
 
+/**
+ * This exception wraps any exception thrown by docker-java
+ */
 @SuppressWarnings("serial")
 public class DockerException extends RuntimeException {
     public DockerException(String message) {
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/nodeagent/NodeAgentImpl.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/nodeagent/NodeAgentImpl.java
index 5b81fa5ba7d..8169b9daee8 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/nodeagent/NodeAgentImpl.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/nodeagent/NodeAgentImpl.java
@@ -403,9 +403,14 @@ public class NodeAgentImpl implements NodeAgent {
                 logger.info(e.getMessage());
                 addDebugMessage(e.getMessage());
             } catch (DockerException e) {
+                // When a new version of node-admin app is released, there is a brief period of time when both
+                // new and old version run together. If one of them stats/stops/deletes the container it manages,
+                // the other's assumption of containerState may become incorrect. It'll then start making invalid
+                // requests, for example to start a container that is already running, the containerState should
+                // therefore be reset if we get an exception from docker.
                 numberOfUnhandledException++;
                 containerState = UNKNOWN;
-                addDebugMessage("Caught a DockerExecption, resetting containerState to " + containerState);
+                logger.error("Caught a DockerExecption, resetting containerState to " + containerState, e);
             } catch (Exception e) {
                 numberOfUnhandledException++;
                 logger.error("Unhandled exception, ignoring.", e);