> ## Documentation Index > Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt > Use this file to discover all available pages before exploring further. # Demo Prometheus Alert Manager Installation > This guide covers installing Alertmanager on a Linux VM and configuring it to send alerts to Slack. In this guide, you’ll install Alertmanager on a Linux VM and configure it to send alerts directly to Slack. We’ll cover downloading the binary, inspecting defaults, setting up Slack webhooks, and reloading Alertmanager without downtime. ## Prerequisites * A Linux VM with internet access * `wget`, `tar`, and `curl` installed * A Slack workspace with permissions to create Incoming Webhooks ## 1. Download and Extract Alertmanager Download the latest Alertmanager release (v0.22.2) and unpack it: ```bash theme={null} wget https://github.com/prometheus/alertmanager/releases/download/v0.22.2/alertmanager-0.22.2.linux-amd64.tar.gz tar xzvf alertmanager-0.22.2.linux-amd64.tar.gz ``` Change into the directory and verify the contents: ```bash theme={null} cd alertmanager-0.22.2.linux-amd64/ ll ``` Expected output: ```text theme={null} total 47796 -rwxr-xr-x 1 root root 27407406 Jun 27 07:51 alertmanager* -rw-r--r-- 1 root root 1813684 Jun 27 07:52 alertmanager.yml -rwxr-xr-x 1 root root 9340 Jun 27 15:56 amtool* -rw-r--r-- 1 root root 4158 Jun 27 15:56 NOTICE -rw-r--r-- 1 root root 1470 Jun 27 15:56 LICENSE ``` ## 2. Inspect the Default Configuration Open `alertmanager.yml` to review the default routing and inhibition settings: ```yaml theme={null} route: group_by: ['alertname'] group_wait: 30s group_interval: 5m repeat_interval: 1h receiver: 'web.hook' receivers: - name: 'web.hook' webhook_configs: - url: 'http://127.0.0.1:5001' inhibit_rules: - source_match: severity: 'critical' target_match: severity: 'warning' equal: ['alertname', 'dev', 'instance'] ``` ## 3. Start Alertmanager Launch Alertmanager and confirm it listens on port `9093`: ```bash theme={null} ./alertmanager ``` You should see logs like: ```text theme={null} level=info ts=2021-06-27T15:39:57.100Z caller=main.go:221 msg="Starting Alertmanager" version="(version=0.22.2, branch=HEAD, revision=...)" level=info ts=2021-06-27T15:39:57.514 msg="Listening address=:9093" level=info ts=2021-06-27T15:39:57.514 msg="TLS is disabled." http2=false ``` Open your browser at `http://:9093` to verify the UI. ## 4. Configure Slack Notifications To route alerts to Slack, update `alertmanager.yml` with your workspace’s Incoming Webhook URL. Refer to the [official Prometheus Alertmanager documentation](https://prometheus.io/docs/alerting/latest/alertmanager/) for complete configuration options and notification templates. ![The image shows a webpage from the Prometheus documentation, specifically focusing on the configuration of Alertmanager. It includes a navigation menu on the left and detailed configuration instructions on the right.](https://kodekloud.com/kk-media/image/upload/v1752873550/notes-assets/images/DevSecOps-Kubernetes-DevOps-Security-Demo-Prometheus-Alert-Manager-Installation/prometheus-alertmanager-configuration-webpage.jpg) ![The image shows a webpage from the Prometheus documentation, specifically the "Notification Template Reference" section. It includes information about data structures and notification templates used in Alertmanager.](https://kodekloud.com/kk-media/image/upload/v1752873551/notes-assets/images/DevSecOps-Kubernetes-DevOps-Security-Demo-Prometheus-Alert-Manager-Installation/prometheus-notification-template-reference.jpg) Below is a sample Slack configuration—replace `` with your actual webhook URL and adjust the `channel` as needed: ```yaml theme={null} global: resolve_timeout: 1m slack_api_url: '' route: receiver: 'slack-notifications' group_by: ['alertname', 'datacenter', 'app'] group_wait: 30s group_interval: 5m repeat_interval: 1h receivers: - name: 'slack-notifications' slack_configs: - send_resolved: true api_url: '' channel: '#alerts' username: '{{ template "slack.default.username" . }}' color: '{{ if eq .Status "firing" }}danger{{ else }}good{{ end }}' title: > {{ $status := .Status | toUpper }}{{ if eq $status "FIRING" }}:{{ .Alerts.Firing | len }}{{ end }} {{ .CommonLabels.alertname }} for {{ .CommonLabels.job }} text: | {{ range .Alerts -}} *Alert:* {{ .Annotations.summary }} *Description:* {{ .Annotations.description }} {{ end }} short_fields: false footer: '{{ template "slack.default.footer" . }}' icon_emoji: '{{ template "slack.default.iconemoji" . }}' ``` ### Create a Slack Incoming Webhook 1. In Slack, **Create an App** (e.g., “Prometheus Alerting”). 2. Enable **Incoming Webhooks** and add a webhook to your target channel. 3. Copy the generated URL and insert it in both `slack_api_url` and `api_url` above. 4. Save `alertmanager.yml`. ## 5. Reload Alertmanager Configuration Reload without downtime by sending an HTTP POST: ```bash theme={null} curl -X POST http://localhost:9093/-/reload ``` Refresh the UI (`http://:9093`) to confirm your Slack receiver is active. ## Next Steps * Configure Prometheus to forward alerts to Alertmanager * Define custom alerting rules in Prometheus * Explore advanced routing and inhibition in Alertmanager ## Links and References * [Prometheus Alertmanager Docs](https://prometheus.io/docs/alerting/latest/alertmanager/) * [Slack Incoming Webhooks](https://api.slack.com/messaging/webhooks)