How to configure prometheus with alertmanager? - docker-compose

Question

docker-compose.yml:
This is the docker-compose to run the prometheus, node-exporter and alert-manager service. All the services are running great. Even the health status in target menu of prometheus shows ok.
version: '2'
services:
prometheus:
image: prom/prometheus
privileged: true
volumes:
- ./prometheus.yml:/etc/prometheus/prometheus.yml
- ./alertmanger/alert.rules:/alert.rules
command:
- '--config.file=/etc/prometheus/prometheus.yml'
ports:
- '9090:9090'
node-exporter:
image: prom/node-exporter
ports:
- '9100:9100'
alertmanager:
image: prom/alertmanager
privileged: true
volumes:
- ./alertmanager/alertmanager.yml:/alertmanager.yml
command:
- '--config.file=/alertmanager.yml'
ports:
- '9093:9093'
prometheus.yml
This is the prometheus config file with targets and alerts target sets. The alertmanager target url is working fine.
global:
scrape_interval: 5s
external_labels:
monitor: 'my-monitor'
# this is where I have simple alert rules
rule_files:
- ./alertmanager/alert.rules
scrape_configs:
- job_name: 'prometheus'
static_configs:
- targets: ['localhost:9090']
- job_name: 'node-exporter'
static_configs:
- targets: ['node-exporter:9100']
alerting:
alertmanagers:
- static_configs:
- targets: ['some-ip:9093']
alert.rules:
Just a simple alert rules to show alert when service is down
ALERT service_down
IF up == 0
alertmanager.yml
This is to send the message on slack when alerting occurs.
global:
slack_api_url: 'https://api.slack.com/apps/A90S3Q753'
route:
receiver: 'slack'
receivers:
- name: 'slack'
slack_configs:
- send_resolved: true
username: 'tara gurung'
channel: '#general'
api_url: 'https://hooks.slack.com/services/T52GRFN3F/B90NMV1U2/QKj1pZu3ZVY0QONyI5sfsdf'
Problems:
All the containers are working fine I am not able to figure out the exact problem.What am I really missing. Checking the alerts in prometheus shows.
Alerts
No alerting rules defined

Answer 1

Your ./alertmanager/alert.rules file is not included in your docker config, so it is not available in the container. You need to add it to the prometheus service:
prometheus:
image: prom/prometheus
privileged: true
volumes:
- ./prometheus.yml:/etc/prometheus/prometheus.yml
- ./alertmanager/alert.rules:/alertmanager/alert.rules
command:
- '--config.file=/etc/prometheus/prometheus.yml'
ports:
- '9090:9090'
And probably give an absolute path inside prometheus.yml:
rule_files:
- "/alertmanager/alert.rules"
You also need to make sure you alerting rules are valid. Please see the prometheus docs for details and examples. You alert.rules file should look something like this:
groups:
- name: example
rules:
# Alert for any instance that is unreachable for >5 minutes.
- alert: InstanceDown
expr: up == 0
for: 5m
Once you have multiple files, it may be better to add the entire directory as a volume rather than individual files.

Answer 2

If you need answers to this question see the explanation on this link
How to make alert rules visible on Prometheus User Interface?
Your alert rules inside the prometheus.yml should look like this
rule_files:
- "/etc/prometheus/alert.rules.yml"
You need to stop the alertmanager and prometheus containers and run this
docker run -d --name prometheus_ops -p 9191:9090 -v $(pwd)/prometheus.yml:/etc/prometheus/prometheus.yml -v $(pwd)/alert.rules.yml:/etc/prometheus/alert.rules.yml prom/prometheus
Verify if you can see the alert.rule config path : Prometheus container ID and go to cd /etc/prometheus
docker exec -it fa99f733f69b sh