Flink with SBT : Expose metrics to Prometheus

Question

I have a Flink application written in Scala that I build with SBT. My goal is to expose Flink metrics to Prometheus. Prometheus runs in a Docker instance and my Flink application is lauched with SBT on my computer.

Prometheus is working fine, I can see many metrics (for example my Docker metrics) but I can't see any Flink metric.

I've configured the file prometheus.yml with the following settings :

scrape_configs:
  - job_name: 'flink'
    static_configs:
      - targets: ['host.docker.internal:9250', 'host.docker.internal:9251']

and in my flink application, I've add the following config :

val conf = new Configuration()
conf.setLong("rest.port", 8082)
conf.setString("metrics.reporters", "prom")
conf.setString("metrics.reporter.prom.class", "org.apache.flink.metrics.prometheus.PrometheusReporter")
conf.setString("metrics.reporter.prom.port", "9250-9260")

When I run Prometheus and my flink application, and I go to the metrics page, all flink targets are down (picture here).

Any suggestions about what I'm doing wrong ?

Thanks a lot.