With --credential-source option implemented, we are still ignoring username field present in this json file, mysql connection assumes it to be from root user.

STR:

1) Prepare credential source file with username present and non root user

2) Try adding mysql service using --credential-srouce parameter

3) mysql connection ignores username provided.

Ticket update:

• service-params-source pmm-admin’s parameter will send all information to pmm-managed which requests pmm-agent to read the file and return credentials
• pmm-agent reads the file and based on content figures out if it is a credentials source or defaults file (in case of MySQL only)
• pmm-admin parameters –username/–password should have the highest priority even if credentials are specified in credentials-source file
• defaults-file is supported only for MySQL instances

The JSON service-params-source format is as follows:

 {  
       "host": string,  
       "port": int, 
       "username": string,
       "password": string,
       "agentpassword": string
  }

The defaults-file (ini) MySQL format is as follows:

[client]
host=127.0.0.1
port=3306
user=root
password=root-password

Tests:

Adding new MySQL:

Check adding MySQL with parameters specified in the service params file (JSON file)
Check adding MySQL with parameters specified without credentials file (JSON file)
Check adding MySQL with credentials file (JSON file) and specified parameters

Check adding MySQL with parameters specified in the service params file (defaults file file)
Check adding MySQL with parameters specified without credentials file (defaults file file)
Check adding MySQL with the service params file (defaults file file) and specified parameters

Adding new ProxySQL/postgreSQL/mongo/haproxy/external:

Check adding instance with parameters specified in the service params file (JSON file)
Check adding instance with parameters specified without credentials file (JSON file)
Check adding instance with credentials file (JSON file) and specified parameters

How to test:

1. Run PMM server.
2. Run MySQL/tested database
3. Run PMM agent and prepare credentials file. e.g.:

[client] 
host=127.0.0.1 
port=12345 
user=root123 
password=root-password123  

or

  { "username": "root123", "password": "root-password123" }

Please remember to pass proper credentials for the database.
4. Use pmm-admin with --service-params-source parameter and path to file 

pmm-admin add mysql --service-params-source=~/.my.cnf 

5. You can replace username/password just to check if have highest priority:

pmm-admin add mysql --service-params-source=~/.my.cnf --username=bad 
pmm-admin add mysql --service-params-source=~/.my.cnf --password=wrong

It should throws credentials error during connection test