In the world of database management, high availability and data integrity are of most importance. Patroni, a robust open-source solution, offers a way to manage and maintain PostgreSQL high availability clusters seamlessly. However, even with tools like Patroni, you can face challenges.<\/p>\n\n\n\n
I had the mission of setting up a Patroni cluster for a critical application at a customer’s site. The goal was to ensure continuous database availability, automatic failover, and streamlined management. Patroni’s reputation preceded it, promising a smooth and efficient installation process.<\/p>\n\n\n\n
As part of the installation process, I needed to configure PostgreSQL’s `pg_hba.conf` file, which manage client authentication to the databases. To make changes to this file within a Patroni-managed cluster, the command `patronictl edit-config` is typically employed. This command allows for the adjustment of various cluster-related configurations.<\/p>\n\n\n\n
However, I was surprised when I attempted to use `patronictl edit-config` to modify the hba configuration. The tool indicated that changes had been made but it wasn\u2019t editing the content of `pg_hba.conf` file. It was a perplexing and frustrating situation, as I was certain that our configuration adjustments weren’t being recognized.<\/p>\n\n\n\n
After thorough investigation and consultation with Patroni’s documentation and community, we discovered that the actual issue wasn’t with the `patronictl edit-config` command itself, but rather with our initial configuration approach.<\/p>\n\n\n\n
When I had initialized the cluster, I had pre-populated the desired `pg_hba.conf` settings in the `patroni.yml` file under the `postgresql.pg_hba` section. This seemed to be the problem. By including these configurations in advance, I was inadvertently overwriting any subsequent changes made through the Data Center Secret (DCS) mechanism, which `patronictl edit-config` relied on.<\/p>\n\n\n\n
In the world of Patroni, the DCS is a critical component responsible for storing and managing cluster state information. This includes configurations like `pg_hba.conf`. When `patronictl edit-config` is employed, it interacts with the DCS to enact changes. However, in our case, our pre-populated `pg_hba.conf` settings in `patroni.yml` were taking precedence over the DCS changes, effectively rendering any subsequent `patronictl edit-config` attempts ineffective.<\/p>\n\n\n\n
Once the root cause was identified, here are the steps to address the issue:<\/p>\n\n\n\n
1. Review and Adjust `patroni.yml`<\/strong>: I revisited our `patroni.yml` file and removed the pre-existing `pg_hba.conf` configurations<\/p>\n\n\n\n 2. Use `patronictl edit-config`<\/strong>: With the adjustments in place, I employed `patronictl edit-config` to modify the `pg_hba.conf` file as needed. This time, the tool functioned as expected, leveraging the DCS mechanism to enact changes.<\/p>\n\n\n\n 3. Cluster Health Verification<\/strong>: After making the necessary `pg_hba.conf` modifications, I tested the cluster’s health to ensure the changes didn’t negatively impact overall functionality.<\/p>\n\n\n\n There was another possible root cause: the settings hba_file in the patroni.yml file under the section postgresql.hba_file has been configured. My encounter with this configuration conflict provided valuable insights into the various way of working with Patroni clusters. Lessons learned from this experience include:<\/p>\n\n\n\n – Configuration Order Matters<\/strong>: The order in which configurations are applied can significantly impact the behavior of cluster management tools like Patroni.<\/p>\n\n\n\n – DCS and `patronictl edit-config`<\/strong>: Understanding the role of the Data Center Secret (DCS) and its interaction with `patronictl edit-config` is crucial for smooth cluster management.<\/p>\n\n\n\n By sharing my experience, I hope to help others in navigating similar hurdles and optimizing their Patroni-managed clusters.<\/p>\n","protected":false},"excerpt":{"rendered":" In the world of database management, high availability and data integrity are of most importance. Patroni, a robust open-source solution, offers a way to manage and maintain PostgreSQL high availability clusters seamlessly. However, even with tools like Patroni, you can face challenges. The setup: Patroni Cluster Installation I had the mission of setting up a […]<\/p>\n","protected":false},"author":87,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[229,198,83],"tags":[3058,1543,77],"type_dbi":[3059,3060,2749],"class_list":["post-27315","post","type-post","status-publish","format-standard","hentry","category-database-administration-monitoring","category-database-management","category-postgresql","tag-hba","tag-patroni","tag-postgresql","type-hba","type-patroni","type-postgresql"],"acf":[],"yoast_head":"\nAnother possible root cause<\/h2>\n\n\n\n
In case you set this parameter, which should have as a value a path for pg_hba.conf file, the postgres.pg_hba section or the change made with Patroni through DCS will be ignored.
In my case, this parameter was not set.<\/p>\n\n\n\nConclusion<\/h2>\n\n\n\n