Yes but only once when the app starts up.

On Friday, September 8, 2023 at 10:04:45 AM UTC-6 Mike Bayer wrote:

> assuming proper indentation it looks fine.  are your print statements 
> being seen ?
>
> On Fri, Sep 8, 2023, at 11:54 AM, Steven Schierholz wrote:
>
> Ok that makes sense and clarifies some stuff for me. I have tried your 
> implementation but it doesn't seem like its getting new connections. We are 
> using sessionmaker(). So basically this is what we are doing. Can you help 
> me understand if we are doing this right and if any changes need to happen 
> to make this work? Sorry the tabbing is not right after paste. Thanks for 
> your help!
>
>
>
> *# Create the engine to connect to the database*engine = create_engine(
>   f"postgresql+psycopg2://test:password@{pg_host}:5432/{pg_database}",
>
> *  # connect_args=ssl_args,*  connect_args={"options": "-c timezone=utc"},
>   pool_pre_ping=*True*,
>   encoding="utf8",
> )
>
> @event.listens_for(engine, "do_connect")
> *def *receive_do_connect(dialect, conn_rec, cargs, cparams):
>
>
> *# Getting the postgres details* *try*:
>
> *# Get the configs* configs = Properties()
>
>
> *# Open the file to get the values needed* *with **open*(
> "/var/secrets/pgsql/vault-credentials.properties", "rb") *as *config_file:
> configs.load(config_file)
>
>
> *# Get each of the properties, hopefully* pg_user = configs.get("username"
> ).data
> pg_password = configs.get("password").data
>
> *except **FileNotFoundError*:
>
>
> *# Use whats in the environment* pg_user = os.getenv("pg_user")
> pg_password = os.getenv("pg_password")
>
> *print*("Connecting to db with username: ", pg_user)
> *print*("Connecting to db with password: ", pg_password)
>
> cparams["user"] = pg_user
> cparams["password"] = pg_password
>
> session_factory = sessionmaker(bind=engine)
> sqla_session = session_factory()
>
> # Then using the sqla_session to execute queries and make modifications to 
> the database
> On Thursday, September 7, 2023 at 4:26:05 PM UTC-6 Mike Bayer wrote:
>
>
> no, create_engine() does not connect at all.     connections occur when 
> you first call `engine.connect()`.   From that point, the behavior of 
> subsequent `engine.connect()` calls depends on connection pool 
> configuration.   all connection pools have points at which they continue to 
> establish new connections as the application proceeds, it's just a question 
> of how often and under what circumstances.    The default QueuePool will 
> make new connections when it goes into "overflow", as well as when existing 
> connections are invalidated due to connectivity problems or if the 
> pool_recycle timeout is reached.
>
>
>
> On Thu, Sep 7, 2023, at 2:34 PM, Steven Schierholz wrote:
>
> That makes sense but doesn't connect only happen once when create_engine() 
> is called?
>
> On Thursday, September 7, 2023 at 12:00:35 PM UTC-6 Mike Bayer wrote:
>
>
> the documentation for this pattern is at 
> https://docs.sqlalchemy.org/en/20/core/engines.html#generating-dynamic-authentication-tokens
>  
> , and a completely specific example is at 
> https://docs.sqlalchemy.org/en/20/dialects/mssql.html#mssql-pyodbc-access-tokens
>  
> .   Basically your application needs to have some way to retrieve the 
> correct credentials as it runs, and you hook that into the event to 
> populate the connect arguments with the correct credentials.
>
> On Thu, Sep 7, 2023, at 1:54 PM, Steven Schierholz wrote:
>
> So I have seen some chats here about cred refresh from vault and some 
> suggestions have been to use @event.listens_for(engine, "do_connect") to 
> update creds when the connection is established. My understanding of this 
> is that connecting to the database should only happen once when my flask 
> application starts up, but I need to update the creds without restarting my 
> application so I'm not sure that the event listener will work in my case.
>
> Am I understanding that correctly? If so, is there a way to get the right 
> creds to pass to the engine for sqlalchemy every 24 hours when the creds 
> from vault get updated without restarting my application?
>
>
> --
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>  
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>  
> http://www.sqlalchemy.org/
>  
> To post example code, please provide an MCVE: Minimal, Complete, and 
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>
> -- 
> SQLAlchemy - 
> The Python SQL Toolkit and Object Relational Mapper
>  
> http://www.sqlalchemy.org/
>  
> To post example code, please provide an MCVE: Minimal, Complete, and 
> Verifiable Example. See http://stackoverflow.com/help/mcve for a full 
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>

-- 
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http://www.sqlalchemy.org/

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