Default Job Cache
As the name suggests, this cache is salt’s default for storing job data. It uses Salt master’s local storage to store and cache data which we can find inside the job cache directory. This system is the simplest caching system as it does not require further management or configuration. This feature makes the default caching system very suitable for deployments.
By default, the jobs stored in this cache will get erased after 24 hours. However, it allows us to change this buffer time to a different period. We can do so by setting the keep_jobs parameter to a different value. We can find this option inside the master’s configuration file. This parameter accepts the value in hours.
For example, if we want the jobs cached for two days, then we can write the following code:
keep_jobs: 48.
Reducing the Size of the Default Job Cache
We know that every cache consumes memory. The Default Job Cache may create overhead and system lag if it caches a large number of minions (greater than 5000). A simple solution to this problem is to disable the job cache. Disabling the cache will lead to the unavailability of job data.
However, this approach is not recommended. If we remove the cache, the master will take a lot of time to access the desired results. It is always better to have a fast input-output system.
Nevertheless, you can avoid caching of data by setting the job_cache parameter to False. Now, the master will not create a cache but a JID directory. This directory will store a jid file for each job. So if you want to reduce the burden on the Salt master, you can set the job_cache to False and change the keep_jobs option to a lower value, such as 1.
Note that while lowering the value of the keep_jobs options, you should always keep it above zero. A zero value of this option means the cache will never get empty.
As we discussed above, storing a large amount of data on local storage is inefficient. So many deployments use external storage to cache data. This method allows them to keep the results of executed jobs for extended periods. Salt provides mainly two types of external storage, the master job cache and the external job cache.
The external job cache returns the data directly from the minions. At the same time, the master job cache returns data from the master.
Frequently Asked Questions
What are the advantages of using the master job cache?
Master job cache is a type of external cache system of salt. The main benefit of using this system is that only a single connection is required. We prefer it for databases and similar systems.
What is the main advantage of using the external job cache?
The main advantage of using the external salt cache is that data is stored directly from the minions. This method decreases the load on the Salt master.
Where can I find the default job cache directory in Salt?
You can find the default job cache directory in the jobs folder inside the master directory, var->cache->salt->master->jobs.
Conclusion
In this article, we discussed the Cache management system in Salt. We discussed job caching, the default job cache, and how to manipulate it. We also learned about reducing the size of the job cache.
We sincerely hope the above discussion helped you understand Cache management in Salt. You can refer to our blogs on job management and access control if you wish to learn more about Salt.
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