AlertManager does not start in docker properly

General Help/Support
1

Hello everyone,
I am trying to integrate Alertmanager with alertsnitch, which uses the webhook receiver, because this notification mechanism is not natively supported by Alertmanager.

My alertmanager.yml configuration:

global:
 
# We want to send all alerts to alertsnitch and then continue to the
# appropiate handler.
route:
  routes:
  - receiver: alertsnitch
    continue: true

receivers:
- name: alertsnitch
  webhook_configs:
    - url: http://host.docker.internal:9567/webhook

My prometheus.yml configuration:

global:
  scrape_interval:     5s
  scrape_timeout:      3s
  evaluation_interval: 5s
 
# Our alerting rule files
rule_files:
  - alert.rules
 
# Scrape endpoints
scrape_configs:
  - job_name: 'prometheus'
    static_configs:
      - targets: ['host.docker.internal:9090']

  - job_name: 'mysql-exporter'
    static_configs:
      - targets: ['host.docker.internal:9104']
 

alerting:
  alertmanagers:
  - scheme: http
    static_configs:
    - targets: ['host.docker.internal:9093']

My docker-compose configuration (only the part of alertsnitch and alertmanager):

  alertsnitch:

    image: registry.gitlab.com/yakshaving.art/alertsnitch
    container_name: alertsnitch-compose
    ports:
    - '9567:9567'
    environment:
      ALERTSNITCH_DSN: "alertsnitch:alertsnitch@tcp(host.docker.internal:3306)/alertsnitch"
      ALERSTNITCH_BACKEND: "mysql"
    depends_on:
      mysqldb:
        condition: service_healthy

  alertmanager:
     
     restart: always
     image: prom/alertmanager:latest
     container_name: alertmanager
     command:
        - '--config.file=/etc/alertmanager/alertmanager.yml'
        - '--storage.path=/var/lib/alertmanager'
     volumes:
        - ./alertmanager.yml:/etc/alertmanager/alertmanager.yml
        - ./alertmanager_db:/var/lib/alertmanager
     depends_on:
       - prometheus
     ports:
       - '9093:9093'

Log-Errors:

alertmanager      | level=info ts=2021-05-26T08:05:45.390Z caller=main.go:216 msg="Starting Alertmanager" version="(version=0.21.0, branch=HEAD, revision=4c6c03ebfe21009c546e4d1e9b92c371d67c021d)"
alertmanager      | level=info ts=2021-05-26T08:05:45.391Z caller=main.go:217 build_context="(go=go1.14.4, user=root@dee35927357f, date=20200617-08:54:02)"
alertmanager      | level=info ts=2021-05-26T08:05:45.393Z caller=cluster.go:161 component=cluster msg="setting advertise address explicitly" addr=172.22.0.8 port=9094
alertmanager      | level=info ts=2021-05-26T08:05:45.400Z caller=cluster.go:623 component=cluster msg="Waiting for gossip to settle..." interval=2s
alertmanager      | level=info ts=2021-05-26T08:05:45.461Z caller=coordinator.go:119 component=configuration msg="Loading configuration file" file=/etc/alertmanager/alertmanager.yml
alertmanager      | level=error ts=2021-05-26T08:05:45.465Z caller=coordinator.go:124 component=configuration msg="Loading configuration file failed" file=/etc/alertmanager/alertmanager.yml err="root route must specify a default receiver"
alertmanager      | level=info ts=2021-05-26T08:05:45.466Z caller=cluster.go:632 component=cluster msg="gossip not settled but continuing anyway" polls=0 elapsed=65.457ms
alertmanager exited with code 1

Can anyone give me a clue where the error may come from ?

Thankyou!

2

I just found it changing the alertmanager config file to:

global:

receivers:
  - name: default-receiver
  - name: alertsnitch
    webhook_configs:
      - url: http://host.docker.internal:9567/webhook

# We want to send all alerts to alertsnitch and then continue to the
# appropiate handler.
route:
  group_wait: 10s
  group_interval: 5m
  receiver: default-receiver
  repeat_interval: 3h
  
  routes:
    - receiver: alertsnitch
      continue: true