Support mounting volumes and init hooks via config

[anisaoshafi]

Closes DEVX-925.

Adds a per-container volumes list to config.toml for arbitrary bind mounts. The main use case being Snowflake init hooks (scripts mounted into /etc/localstack/init/ready.d/ that run on startup).

[[containers]]
type = "snowflake"
port = "4566"
volumes = ["./init.sf.sql:/etc/localstack/init/ready.d/init.sf.sql"]

• Docker-style "host:container[:ro]" specs.
• Relative sources resolve against the config file's directory; ~/ is expanded (the Docker SDK treats a non-absolute source as a named volume, so this is required). Windows drive-letter sources (C:\...) are handled.
• Extra mounts must already exist (init-hook entries are files); only the persistence dir is auto-created.

volume vs volumes

The singular volume and the plural volumes are not general synonyms; they overlap only for the persistence directory:

• volume only sets the persistent-state dir, always mounted to /var/lib/localstack (the dir managed by lstk volume path / lstk volume clear).
• volumes is a superset: it can mount arbitrary paths and set the persistence dir, via the entry whose container target is /var/lib/localstack.

So these are equivalent for persistence:

volume  = "/data"
# same persistence mount as
volumes = ["/data:/var/lib/localstack"]

Differences to keep in mind:

• volume cannot express init hooks or any non-persistence mount — use volumes.
• A volumes source is path-resolved (relative → config dir, ~/ expanded); the legacy volume value is used verbatim, so prefer an absolute path there.
• Declaring the persistence dir in both volume and a volumes entry with different sources is a configuration error; the same source in both is allowed.

volume stays supported for backward compatibility so existing config.toml don't break.

[anisaoshafi]

@mmaureenliu would you like to give it a try and see how this works for snowflake? In my test it works, but wanted to double check I'm doing the right thing. Any feedback is welcome!

[mmaureenliu]

@mmaureenliu would you like to give it a try and see how this works for snowflake? In my test it works, but wanted to double check I'm doing the right thing. Any feedback is welcome!

Do I just build from this branch and run it with snowflake?

[anisaoshafi]

@mmaureenliu would you like to give it a try and see how this works for snowflake? In my test it works, but wanted to double check I'm doing the right thing. Any feedback is welcome!

Do I just build from this branch and run it with snowflake?

Yes, please.
Use make build; add the snowflake init hook in the volumes variable in config.toml; then start lstk via ./bin/lstk