Postgresql

Overview

Load the configuration from Postgresql database. This retriever is useful when you are using Postgresql and want to use a database to store your configuration files.

Postgresql Table Format

If you use Postgresql to store your flags, you need a specific format to store your flags.

The table should have the following columns:

• flag_name: the name of your feature flag.
• flagset: the name of your flagset, if you don't use a flagset, you can leave this column empty.
• config: the configuration of your feature flag in JSON format.

note

You can customize the column names by configuring the retriever options. The example above uses the default column names that works out of the box.

You can also add more columns to the table for your own needs, but only those 3 fields are mandatory to work with the GO Feature Flagretriever.

init_table.sql

-- ----------------------------------------------------------------------------
-- GO FEATURE FLAG POSTGRESQL RETRIEVER INITIALIZATION SCRIPT
-- This script is used to initialize the PostgreSQL database for the Go Feature Flag retriever.
-- This is a very minimal setup for the retriever, you can add more columns or constraints to the table if you need to.
-- ----------------------------------------------------------------------------

-- Enable UUID extension if not already enabled
CREATE EXTENSION IF NOT EXISTS "uuid-ossp";

-- Create the go_feature_flag table
CREATE TABLE IF NOT EXISTS go_feature_flag (
    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
    flag_name VARCHAR(255) NOT NULL,
    flagset VARCHAR(255) NOT NULL,
    config JSONB NOT NULL
);

-- Create indexes for better query performance
CREATE INDEX IF NOT EXISTS idx_go_feature_flag_flagset ON go_feature_flag(flagset);
CREATE INDEX IF NOT EXISTS idx_go_feature_flag_flag_name ON go_feature_flag(flag_name);
CREATE INDEX IF NOT EXISTS idx_go_feature_flag_flagset_flag_name ON go_feature_flag(flagset, flag_name);

-- Add a unique constraint to prevent duplicate flags in the same flagset
ALTER TABLE go_feature_flag ADD CONSTRAINT unique_flag_per_flagset UNIQUE (flag_name, flagset);

You can use the init_table.sql file as a reference to create your table.

Filter on flagset

The Postgresql retriever, is flagset aware. This means that when you are using flagsets, the retriever will only retrieve the flags for the specific flagset.
To do this, the retriever will use the flagset name in your flagset configuration to add a WHERE clause to the query and filter on the flagset column.

warning

When you are using flagsets, be sure to use the same name in your flagset configuration as the one used in the flagset column in your postgres table.

Configure the relay proxy

To configure your relay proxy to use the Postgresql retriever, you need to add the following configuration to your relay proxy configuration file:

goff-proxy.yaml

# ...
retrievers:
  - kind: postgresql
    uri: "postgres://user:password@localhost:5432/dbname"
    table: "go_feature_flag"
# ...

Field name	Mandatory	Type	Default	Description
kind		string	none	Value should be postgresql. This field is mandatory and describes which retriever you are using.
uri		string	none	Connection URI of your postgres instance.
table		string	none	Name of the table where your flags are stored.
columns		object	none	Custom column name mapping. See How to use custom column names for more details.

How to use custom column names

You can use custom column names by configuring the columns field.

goff-proxy.yaml

# ...
retrievers:
  - kind: postgresql
    uri: "postgres://user:password@localhost:5432/dbname"
    table: "go_feature_flag"
    columns:
      flag_name: "name"
      flagset: "namespace"
      config: "settings"

The columns field, is a map of the default column names to the custom column names in your postgres table.

Configure the GO Module

To configure your GO module to use the Postgresql retriever, you need to add the following configuration to your ffclient.Config{} object:

example.go

err := ffclient.Init(ffclient.Config{
    PollingInterval: 3 * time.Second,
	  Retriever: &postgresql.Retriever{
      URI: "postgres://user:password@localhost:5432/dbname",
      Table: "go_feature_flag",
      Columns: map[string]string{
        "flag_name": "name",
        "flagset": "namespace",
        "config": "settings",
      },
    },
})
defer ffclient.Close()

Field	Mandatory	Description
uri		Connection URI of your postgres instance.
table		Name of the table where your flags are stored.
columns		Custom column name mapping. See How to use custom column names for more details.