Recovering Kibana After Upgrade


Elastic is doing rapid development with Elasticsearch. As of this writing, they’re now on version 6.5.3 – when 6.5.2 was released less than 2 weeks ago!  Luckily, with a package install from repo (such as RPM on CentOS/RHEL), the upgrade process to minor versions is less painful.  However, it’s not without its pitfall. For example, an  upgrade from version 6.4.x to the latest 6.5.x could lead to Kibana not able to start due to incompatible indices.

In order to alleviate this, shutdown the Kibana service, and instruct Elasticsearch to perform a recovery on the .kibana index:

curl --user elasticuser:userpassword -s

If it’s connected to a big cluster with a lot of shards, speed up the recovery process without using replicas:

curl --user elasticuser:userpassword -H 'Content-Type: application/json' -XPUT '' -d '{ "index" : { "number_of_replicas" : 0 } }'

Give it a few minutes (depending how much data is there) and then start up Kibana service.  If, for some reason, it still takes a long time, there may be a problem with the migration process.  The kibana.log may indicate something like this:

{“type”:”log”,”@timestamp”:”2018-12-12T17:17:40Z”,”tags”:[“warning”,”stats-collection”],”pid”:15141,”message”:”Unable to fetch data from kibana_settings collector”}
{“type”:”log”,”@timestamp”:”2018-12-12T17:17:42Z”,”tags”:[“reporting”,”warning”],”pid”:15141,”message”:”Enabling the Chromium sandbox provides an additional layer of protection.”}
{“type”:”log”,”@timestamp”:”2018-12-12T17:17:42Z”,”tags”:[“info”,”migrations”],”pid”:15141,”message”:”Creating index .kibana_2.”}
{“type”:”log”,”@timestamp”:”2018-12-12T17:17:44Z”,”tags”:[“warning”,”migrations”],”pid”:15141,”message”:”Another Kibana instance appears to be migrating the index. Waiting for that migration to complete. If no other Kibana instance is attempting migrations, you can get past this message by deleting index .kibana_2 and restarting Kibana.”}

Shutdown Kibana again, and delete the .kibana_2 index:

curl --user elasticuser:userpassword -XDELETE

Start the Kibana service again and give it a few more minutes to perform house-keeping.  Kibana should be up and running now.

Deleting Entries in Elasticsearch Based On Timestamp

It’s inevitable after ingesting lots of server logs into Elasticsearch, there’s a requirement to delete partial logs, either they were incorrect data or loaded more than once.  When there are millions of data, it’s just inefficient to drop all of the index and start over from the beginning.  Luckily, there’s a solution by using Elasticsearch range by query API:

POST apachelogs-2018.11.02/_delete_by_query?wait_for_completion=false
   "query": {
      "range": {
          "@timestamp": { 
               "gte" : "02/11/2018",
               "lte" : "02/11/2018",
               "time_zone": "-07:00",
               "format": "dd/MM/yyyy||yyyy"

The directive ?wait_for_completion=false is for use in Kibana dev tools since the GUI will give a gateway timeout if the task takes more than 30 seconds.  Instead, the option will send the task into the background and not wait for it to complete in Kibana UI.

Another important note, the logs are stored in UTC time zone, by default.  Elastic Support and Training staff have confirmed this. Deleting without specifying a timezone will look like partial deletion.  This same problem happens when dropping just one particular day (ie. apachelogs-2018.11.12) index since the entries will overlap with the next day’s index.  Thus, in this case, since it’s a requirement to delete the entire Nov 2 timestamped data, a specific time zone (Pacific Daylight Time) “-07:00” is necessary.

The data will then look like this in Kibana’s Discovery tool:

Deleting An Entire Day Out Of Elasticsearch

Converting UTF-16 to ASCII Format Text Files

For those dealing with Windows applications, sometimes the app writes logs with UTF-16 character encoding.  This is the case with Titan-FTP (commercial) software that writes the logs in that format.  Using cygwin or Linux grep command to search through the file will not return any result!  When using vi to examine the file, the escape characters doesn’t show up. The dos2unix command will not strip them, neither.

Fortunately, there is an easy way out. The utility iconv will help convert the file to make it searchable (read: Useful) again.

iconv -c -f utf-16 -t ascii file.log > newfile.log