[INJICERT-499] Added postgres plugin config docs

postgres-dataprovider-plugin/README.md

@@ -0,0 +1,85 @@
+## Configuration docs for Postgres Plugin
+
+- Pre-requisites
+  Authorisation Provider should expose the unique identifier in the `sub` field of the JWT token.
+  Eg. If one is using eSignet with mock-identity-system:0.10.0 and above it can be achieved by setting:
+  ```mosip.mock.ida.kyc.psut.field=individualId```
+  where individualId will be the identifier to locate the identity in the expected identity registry.
+
+1. Create the tables with all the fields that should be returned by the Postgres Data Provider Plugin within the certify postgres database.
+    - Refer the following query for insertion in DB:
+      ```
+        CREATE TABLE certify.<table_name> (
+                 attribute_1 <type> NOT NULL,
+                 attribute_2 <type> NOT NULL,
+                 ...
+                 CONSTRAINT pk_id_code PRIMARY KEY (<identifier>)
+             );
+      ```
+
+2. The schema context containing all the required fields should be hosted in a public url.
+    - Refer this link for an existing context: [Registration Receipt Schema](https://piyush7034.github.io/my-files/registration_receipt.json)
+      Eg: https://<username>.github.io/<project_name>/<file_name>.json
+    - Also change the respective credential name:
+      ```
+         {
+             "@context": {
+                 "@version": 1.1,
+                 "@protected": true,
+                 "type": "@type",
+                 "schema": "https://schema.org/",
+                 "<credential_name>": {
+                     "@id": "https://<username>.github.io/<project_name>/<file_name>.json#<credential_name>"
+                 },
+                 <field1>: "schema:<type>"
+                 <field2>: "schema:<type>"
+                 ...
+             }
+         }
+      ```
+    - The primary_key should be a identifier that is existing in the current mock_identity_system records.
+      Eg: If "1234" is present in mock_identity table, then same identifier should be used for inserting records in the certify data tables
+    - When the authentication is done using this particular identifier then the record from certify tables can be fetched by the postgres plugin and returned as a JSON Object.
+
+3. Insert the templates in the DB with credential subject containing all the fields which must be the part of issued credential.
+    - Eg: Find the below template for reference:
+         ```
+             {
+               "@context": [
+                 "https://www.w3.org/2018/credentials/v1",
+                 "https://piyush7034.github.io/my-files/registration-receipt.json",
+                 "https://w3id.org/security/suites/ed25519-2020/v1"
+               ],
+               "issuer": "${issuer}",
+               "type": [
+                 "VerifiableCredential",
+                 "RegistrationReceiptCredential"
+               ],
+               "issuanceDate": "${validFrom}",
+               "expirationDate": "${validUntil}",
+               "credentialSubject": {
+                   "attributeName1": "${<attribute1>}",
+                   "attributeName2": "${<attribute2>}"
+                   ...
+               }
+             }
+         ```
+    - For referring the table creation and template insertion, see the sql scripts under certify_init.sql file: [certify-init](https://github.com/mosip/inji-certify/blob/develop/docker-compose/docker-compose-injistack/certify_init.sql)
+
+4. inji-config changes:
+    - Refer to the properties file in [inji-config](https://github.com/mosip/inji-config) that corresponds to the postgres plugin implementation.
+      [Certify Postgres Land Registry](https://github.com/mosip/inji-config/blob/develop/certify-postgres-landregistry.properties)
+    - The value for the property `mosip.certify.integration.data-provider-plugin` must be set to `PostgresDataProviderPlugin`
+    - Refer to the below property for setting the query value against the scope for the credential that is to be issued:
+       ```
+      mosip.certify.data-provider-plugin.postgres.scope-query-mapping={
+         `credential_scope`: `select * from certify.<table_name> where <table_id>=:id`
+       }
+      ```
+    - Add the scope defined above and the type of credential in the well-known config of the properties file. Refer to the property `mosip.certify.key-values` for the same.
+    - Add the fields from the respective table in the well-known config.
+
+5. mosip-config changes:
+    - Refer to the [authentication-config](https://github.com/mosip/mosip-config/pull/7653) properties file in mosip-config repo(esignet-mock in this case).
+    - Add the required scopes under `mosip.esignet.supported.credential.scopes` config.
+    - Also add the scopes under `mosip.esignet.credential.scope-resource-mapping` config.