feat: Add docs for PostgreSQL db usage in EdgeX (#1376)

* feat: Add docs for PostgreSQL db usage in EdgeX

Resolves #1375. Add docs for PostgreSQL db usage in EdgeX.

Signed-off-by: Lindsey Cheng <beckysocute@gmail.com>

* fix: Replace app-http-export with my-service in known secrets section

Replace app-http-export with my-service in the configuring known secrets section.

Signed-off-by: Lindsey Cheng <beckysocute@gmail.com>

* fix: Replace my-service with myservice

Replace my-service with myservice.

Signed-off-by: Lindsey Cheng <beckysocute@gmail.com>

---------

Signed-off-by: Lindsey Cheng <beckysocute@gmail.com>

docs_src/microservices/general/database/Ch-Postgres.md

@@ -0,0 +1,76 @@
+# PostgreSQL
+
+EdgeX Foundry also supports PostgreSQL as the persistence database.
+
+PostgreSQL is an open-source object-relational database system (licensed under the PostgreSQL License) that offers exceptional scalability and performance, with support for both relational and document (JSON) data models.
+
+## Pre-Defined Users with Privileges
+
+Each EdgeX service that connects to PostgreSQL uses different users depending on whether it's operating in secure or non-secure mode.
+
+In non-secure mode, all services use the default `postgres` user to access the PostgreSQL database.
+
+In secure mode, each EdgeX service is assigned a unique username and password, with limited privileges. These users are restricted to accessing only the table schemas owned by their respective services. 
+For instance, the Core Data service owns the `core_data` schema and is permitted to use the `core_data` user to access the database. This `core_data` user is granted privileges specific to the tables within the `core_data` schema.
+
+## Using PostgreSQL Database
+
+PostgreSQL database can be started and used as the persistence store in the Docker-based EdgeX deployment.
+
+Please refer to [Use PostgreSQL as the persistence layer in EdgeX](https://github.com/edgexfoundry/edgex-compose?tab=readme-ov-file#use-postgresql-as-the-persistence-layer-in-edgex) for the instructions to run the EdgeX services along with PostgreSQL database.
+
+## (Optional) Configure add-on services to access PostgreSQL
+
+This section introduces how to configure add-on services to access PostgreSQL database in secure mode.
+
+For more information about add-on services, see [Configuring Add-on Service](../../../security/Ch-Configuring-Add-On-Services/).
+
+### Configure known secrets for add-on services
+
+The `EDGEX_ADD_KNOWN_SECRETS` environment variable on `secretstore-setup` allows for known secrets
+to be added to an add-on service's `Secret Store`.
+
+The `known` secret for PostgreSQL is the `PostgreSQL credentials` identified by
+the name `postgres`. Any add-on service needing access to the `PostgreSQL` such as
+App Service HTTP Export with Store and Forward enabled will need the `PostgreSQL credentials`
+put in its `Secret Store`.
+
+Note that the steps needed for connecting add-on services to the `Secure MessageBus` are:
+
+1. Utilizing the `security-bootstrapper` to ensure proper startup sequence
+2. Creating the `Secret Store` for the add-on service
+3. Adding the `postgres` known secret to the add-on service's `Secret Store`
+
+and if the add-on service is not connecting to the PostgreSQL database, then this step can be skipped.
+
+So given an example for service `myservice` to use the PostgreSQL database in secure mode,
+we need to tell `secretstore-setup` to add the `postgres` known secret to `Secret Store` for `myservice`.
+This can be done through the configuration of adding `postgres[myservice]` into the environment variable
+`EDGEX_ADD_KNOWN_SECRETS` in `secretstore-setup` service's environment section, in which `postgres` is the name of
+the `known secret` and `myservice` is the service key of the add-on service.
+
+```yaml
+...
+  secretstore-setup:
+    container_name: edgex-secretstore-setup
+    depends_on:
+    - security-bootstrapper
+    - vault
+    environment:
+      EDGEX_ADD_SECRETSTORE_TOKENS: myservice
+      EDGEX_ADD_KNOWN_SECRETS: postgres[myservice],message-bus[myservice],message-bus[device-virtual]
+...
+
+```
+
+In the above `docker-compose` section of `secretstore-setup`, we specify the known secret of
+`postgres` to add/copy the PostgreSQL database credentials to the `Secret Store` for the `myservice` service.
+
+We can also use the alternative or simpler form of `EDGEX_ADD_KNOWN_SECRETS` environment variable's value like
+
+```yaml
+    EDGEX_ADD_KNOWN_SECRETS: postgres[myservice],message-bus[myservice],message-bus[device-virtual]
+```
+
+in which all add-on services are put together in a comma separated list associated with the
+known secret `postgres`.

docs_src/microservices/core/database/Ch-Redis.md → docs_src/microservices/general/database/Ch-Redis.md

@@ -1,4 +1,4 @@
-# Redis Database
+# Redis
 
 EdgeX Foundry's reference implementation database (for sensor data, metadata and all things that need to be persisted in a database) is Redis.
 

docs_src/microservices/support/cronScheduler/GettingStarted.md

@@ -97,31 +97,8 @@ A schedule action record records the information of a [ScheduleAction](#schedule
 
 ## Running Services with Support Cron Scheduler
 
-The simplest way to run all the required services with support cron scheduler is to use the [Predefined Compose File](https://github.com/edgexfoundry/edgex-compose/) from a terminal window.
-
-1. Clone [https://github.com/edgexfoundry/edgex-compose/](https://github.com/edgexfoundry/edgex-compose/)
-
-2. Run the services
-    ```
-    docker compose -f docker-compose-postgres-no-secty.yml up -d
-    ```
-    Or run the services on ARM64 system
-    ```
-    docker compose -f docker-compose-postgres-no-secty-arm64.yml up -d
-    ```
-This runs, in non-secure mode, all the standard EdgeX services, including Support Cron Scheduler, along with the Device Virtual.
-
-To stop the services
-
-```
-docker compose -f docker-compose-postgres-no-secty.yml down
-```
-
-Or stop the services on ARM64 system
-
-```
-docker compose -f docker-compose-postgres-no-secty-arm64.yml down
-```
+Please refer to [Using PostgreSQL Database](../../general/database/Ch-Postgres/#using-postgresql-database) for instructions on how to get EdgeX services up and running with PostgreSQL database.
+Following the steps in this guide, the Support Cron Scheduler service will be included among the services that are started.
 
 <!-- TODO -->
 <!-- ## Running Services without Support Cron Scheduler -->

mkdocs.yml

@@ -105,7 +105,6 @@ nav:
             - Source Code: microservices/core/command/SourceCode.md
             - Additional Details:
               - Regex Get Command: microservices/core/command/details/RegexGetCommand.md
-        - microservices/core/database/Ch-Redis.md
       - Supporting: 
         - microservices/support/Ch-SupportingServices.md
         - Notifications:
@@ -328,6 +327,9 @@ nav:
         - V3 Migration: microservices/configuration/V3MigrationCommonConfig.md
       - microservices/general/index.md
       - microservices/general/messagebus.md
+      - Database:
+        - microservices/general/database/Ch-Redis.md
+        - microservices/general/database/Ch-Postgres.md
     - Security:
       - Security Services: security/Ch-Security.md
       - security/Ch-SecretStore.md