Prometheus with Dockerfile - docker

Question

I have the following Dockerfile:
FROM prom/prometheus
ADD prometheus.yml /etc/prometheus/
with prometheus.yml:
global:
scrape_interval: 15s
external_labels:
monitor: 'codelab-monitor'
scrape_configs:
- job_name: 'prometheus'
metrics_path: /metrics
scrape_interval: 15s
static_configs:
- targets: ['localhost:9090']
- job_name: 'auth-service'
scrape_interval: 15s
metrics_path: /actuator/prometheus
static_configs:
- targets: ['localhost:8080']
And run it with the following command:
docker build -t prometheus .
docker run -d -p 9090:9090 --rm prometheus
prometheus has status up
auth-service has status down (Get "http://localhost:8080/actuator/prometheus": dial tcp 127.0.0.1:8080: connect: connection refused)
How can I solve problem with auth-service, because from local machine I can get metrics from this address http://localhost:8080/actuator/prometheus:
v.balun#macbook-vbalun Trainter-Prometheus % curl -X GET
http://localhost:8080/actuator/prometheus
# HELP jvm_memory_committed_bytes The amount of memory in bytes that is committed for the
Java virtual machine to use
# TYPE jvm_memory_committed_bytes gauge
jvm_memory_committed_bytes{area="heap",id="G1 Survivor Space",} 4194304.0
jvm_memory_committed_bytes{area="heap",id="G1 Old Gen",} 3.145728E7
jvm_memory_committed_bytes{area="nonheap",id="Metaspace",} 3.0982144E7
jvm_memory_committed_bytes{area="nonheap",id="CodeHeap 'non-nmethods'",} 2555904.0
jvm_memory_committed_bytes{area="heap",id="G1 Eden Space",} 2.7262976E7
jvm_memory_committed_bytes{area="nonheap",id="Compressed Class Space",} 4325376.0
jvm_memory_committed_bytes{area="nonheap",id="CodeHeap 'non-profiled nmethods'",} 6291456.0

Answer 1

The issue you are having seems not related to prometheus, it seems it is at the docker network level.
Inside your prometheus container you are saying this:
static_configs:
- targets: ['localhost:8080']
But remember that localhost is NOT now your physical host (As when you ran it locally outside Docker), it's now inside the container, and inside the same container most likely you don't have your service running...
With the information provided I suggest you the following:
Try first instead localhost use your real IP, depending on the network configuration you are using for your container, it will be enough...
You can use instead localhost the ip address of your auth-service, this is the one given by docker, you can run a docker inspect... to get it.
If #1 and #2 didn't work and if auth-service is running in another container inside the same physical host, then you could use a bridge network to make the communication between the containers possible, more details here: https://docs.docker.com/network/bridge/
👆 Once both containers are running in the same network you can use the container name to reference it instead localhost, something like:
static_configs:
- targets: ['auth-service:8080']