Author: Lisa

Roe v Performance Art

Since the leaked draft overturning Roe v Wade was released, I’ve encountered a number of forums in which women are advocating we all delete any menstruation tracking apps. This seems, to me, like performance art meant as protest. Not an effective solution to the stated problem.

I get the point — people don’t want their data tracked in a place where the state can readily compel production of records. If they have reasonable suspicion that an abortion took place, they can get a warrant for your data. But deleting the app from your phone — that doesn’t actually delete the data on the cloud hosting provider’s side. Deleting the app has the same impact as ceasing to enter new data. Except you’ve inconvenienced yourself by losing access to your old data. Check if an account can be deleted — and learn what the details of ‘delete’ actually mean. In many cases, ‘delete’ means disable and then purge after some delta time elapses. What about backups? For how long would the company be able to produce data if they really needed to?

But before going to extremes to actually delete data, consider if the alternatives are actually any “safer” by your definition. If I were tracking my period on a little paper calendar in my purse or one pinned to the cork board in the rec room? They may get a warrant and seize my paper calendar too. And, really, you could continue to enter “periods” even if they’re not happening. There’s usually a field for ‘notes’ and you could put something in like ‘really painful cramping’ or ‘so many hot flashes’ whenever you actually mean “yeah, this one didn’t happen” — which would make the data the government is able to gather rather meaningless.

Resetting Lost/Forgotten ElasticSearch Admin Passwords

There are a few ways to reset the password on an individual account … but they require you to have a known password. But what about when you don’t have any good passwords? (You might be able to read your kibana.yml and get a known good password, so that would be a good place to check). Provided you have OS access, just create another superuser account using the elasticsearch-users binary:

/usr/share/elasticsearch/bin/elasticsearch-users useradd ljradmin -p S0m3pA5sw0Rd -r superuser

You can then use curl to the ElasticSearch API to reset the elastic account password

curl -s --user ljradmin:S0m3pA5sw0Rd -XPUT "http://127.0.0.1:9200/_xpack/security/user/elastic/_password" -H 'Content-Type: application/json' -d'
{
"password" : "N3wPa5sw0Rd4ElasticU53r"
}
'

 

ElasticSearch ILM – Data Lifecycle

The following defines a simple data lifecycle policy we use for event log data.

Immediately, the data is in the “hot” phase.

After one day, it is moved to the “warm” phase where the number of segments is compressed to 1 (lots-o-segments are good for writing, but since we’re dealing with timescale stats & log data [i.e. something that’s not being written to the next day], there is no need to optimize write performance. The index will be read only, thus can be optimized for read performance). After seven days, the index is frozen (mostly moved out of memory) as in this use case, data generally isn’t used after a week. Thus, there is no need to fill up the server’s memory to speed up access to unused data elements. Since freeze is deprecated in a future version (due to improvements in memory utilization that should obsolete freezing indices), we’ll need to watch our memory usage after upgrading to ES8.

Finally, after fourteen days, the data is deleted.

To use the policy, set it as the template on an index:

Upon creating a new index (ljrlogs-5), the ILM policy has been applied:

Orchard Layout

We should finally be past freezing nights for the season, so it’s time to get the fruit plants out in the orchard. I’ve got a couple of gooseberries and a hardy fig to put somewhere. But, in the next few days, I’ll get the currants, honey berries, seaberries, pawpaw, and cherry trees planted.

Upgrading ElasticSearch – From 7.6 to 7.17

Before upgrading to 8, you must be running at least version 7.17 … so I am first upgrading my ES7 to a new enough version that upgrading to ES8 is possible.

Environment

Not master eligible nodes:
a6b30865c82c.example.com
a6b30865c83c.example.com

Master eligible nodes:
a6b30865c81c.example.com

 

  1. Disable shard allocation

PUT _cluster/settings{  "persistent": {    "cluster.routing.allocation.enable": "primaries"  }}

 

  1. Stop non-essential indexing and flush

POST _flush/synced

  1. Upgrade the non-master eligible nodes first then the master-eligible nodes. One at a time, SSH to the host and upgrade ES
    a. Stop ES

systemctl stop elasticsearch
b. Install the new RPM:
rpm --import https://artifacts.elastic.co/GPG-KEY-elasticsearch
wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-7.17.3-x86_64.rpm
wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-7.17.3-x86_64.rpm.sha512
shasum -a 512 -c elasticsearch-7.17.3-x86_64.rpm.sha512


rpm -U elasticsearch-7.17.3-x86_64.rpm

c. Update configuration for new version
vi /usr/lib/tmpfiles.d/elasticsearch.conf


vi /etc/elasticsearch/elasticsearch.yml # Add the action.auto_create_index as required -- * for all, or you can restrict auto-creation to certain indices

d. Update unit file and start services
systemctl daemon-reload
systemctl enable elasticsearch
systemctl start elasticsearch.service

  1. On the Kibana server, upgrade Kibana to a matching version:systemctl stop kibana
    wget https://artifacts.elastic.co/downloads/kibana/kibana-7.17.3-x86_64.rpm
    rpm -U kibana-7.17.3-x86_64.rpm
    sytemctl daemon-reload
    systemctl enable kibana
    systemctl start kibana
  2. Access the Kibana console and ensure the upgraded node is back online

  1. Re-enable shard allocation

PUT _cluster/settings{"persistent": {"cluster.routing.allocation.enable": null }}

Linux Disk Utilization – Reducing Size of /var/log/sa

We occasionally get alerted that our /var volume is over 80% full … which generally means /var/log has a lot of data, some of which is really useful and some of it not so useful. The application-specific log files already have the shortest retention period that is reasonable (and logs that are rotated out are compressed). Similarly, the system log files rotated through logrotate.conf and logrotate.d/* have been configured with reasonable retention.

Using du -sh /var/log/ showed the /var/log/sa folder took half a gig of space.

This is the daily output from sar (a “daily summary of process accounting” cron’d up with /etc/cron.d/sysstat). This content doesn’t get rotated out with the expected logrotation configuration. It’s got a special configuration at /etc/sysconfig/sysstat — changing the number of days (or, in my case, compressing some of the older files) is a quick way to reduce the amount of space the sar output files consume).