Exposing container service to host

[vapid pendant]

Hi all!

I am trying to expose a redis container service to the host system. But I do lack some basic fundamentals I guess.

Imagine following dagger approach:

async def main():
    async with dagger.Connection(dagger.Config(log_output=sys.stderr)) as client:
        redis_srv =  (
            client.container()
            .from_("redis")
            .with_exposed_port(6379)
            .with_mounted_cache("/redis_data", client.cache_volume("my-redis"))
            .with_workdir("/redis_data")
            .as_service()
        )

        redis_cli = (
            client.container()
            .from_("redis")
            .with_service_binding("redis-srv", redis_srv)
            .with_entrypoint(["redis-cli", "-h", "redis-srv"])
        )
        await redis_cli.with_exec(["set", "foo", "abc"]).with_exec(["save"]).stdout()

        tunnel = await client.host().tunnel(redis_srv).start()
        endpoint = await tunnel.endpoint()

        return endpoint

Within the main I am able to query the service etc. as expected. However, outside I am not. I guess I do miss something obvious.
I thought, that I might be able to call the service like so:

endpoint = await main()
host, port = endpoint.split(":")
r = redis.Redis(host=host, port=6379, decode_responses=True)
print(r.get("foo"))

But in this case, I get a connection error.

Thanks for the help 🙂

[near rapids]

If you leave the with dagger.Connection context, the connection to the engine will be closed. Everything you need to do in dagger needs to be inside that context.

See the cookbook on Organize pipeline code into modules & classes.

[woeful moat]

👋 that's because the tunnel method uses a random port as frontend automatically to avoid port collisions so you need to use the endpoint variable to get the right host:port values. You can still make it use any port you want by using the ports argument in the tunnel method

[vapid pendant]

This makes a lot of sense and is so obvious ... 🙂 thanks

[vapid pendant]

Well, that is basically what I do right? I expose the port etc. and (as @near rapids mentioned) as long as I am within the with statement, I can connect to the service.

[woeful moat]

r = redis.Redis(host=host, port=6379, decode_responses=True)

here I see you're hardcoding 6379. This won't be the port when exposing via tunnel

if you print endpoint, you'll see it uses a different port

[vapid pendant]

You are right, tunnel provides another port. I will use that one for the connection.

[vapid pendant]

Thanks both of you, works now like I expect 🙂