I import a flow-File using following curl command
curl http://localhost:54321/3/NodePersistentStorage.bin/notebook/my-model \
-H "Content-Type: multipart/form-data" \
-H "Cookie: _gcl_au=123456" \
-F "file=@path/to/my-model.flow"
The flow file get's imported.
Question: Do you know if there is a REST/HTTP-call to run all commands which are contained in the flow file?
People don't really automate Flows since there are scripting APIs for R and python. But, there are some ancient tricks you can try to revive if you really want to. You won't find any support for them, though.
Take a look at this ancient commit from 2015 which has the run-flow.coffee and run-flow.js scripts:
https://github.com/h2oai/h2o-3/tree/cd026d6dd71085c6f1fa91d5a27216b9ab86b39a/scripts
Note it requires a client-side phantomjs to work, which might defeat the point for you.
Sometime in the past these files were actually deleted from the top-of-tree repo, but you can still fish them out from history and try to revive the concept if you think it's useful for you.