License question

[AdolfVonKleist]

Hi I see that xapiand is released under MIT license, but appears to either directly contain or link the xapian core. What is the relationship there, and how do you release xapiand under the MIT license without inheriting the GPL from xapian core? If I use the vanilla xapiand docker container as an appliance to index information in another application, am I obligated to open-source my application too?