How to fetch .env values to assign alertmanager.yml file (not a valid value)

In my spring boot project, I connect alertmanager with prometheus and grafana but I cannot fetch properties values from `.env` and assign them to `alertmanager.yml` Here is the `alertmanager` part of `docker-compose.yml` ``` alertmanager: image: prom/alertmanager:latest container_name: alertmanager restart: unless-stopped ports: - "9093:9093" volumes: - ./data/alertmanager/config:/etc/alertmanager env_file: - .env command: - '--config.file=/etc/alertmanager/alertmanager.yml' networks: - pdfcompare_network ``` Here is the .env ``` ALERT_RESOLVE_TIMEOUT=5m SMTP_SMARTHOST=smtp.gmail.com:587 SMTP_FROM=gmail_email SMTP_AUTH_USERNAME=gmail_email SMTP_AUTH_PASSWORD=gmail_authentication_password SMTP_REQUIRE_TLS=true ALERT_EMAIL_TO=gmail_email ``` Here is alertmanager.yml ``` global: resolve_timeout: ${ALERT_RESOLVE_TIMEOUT} smtp_smarthost: ${SMTP_SMARTHOST} smtp_from: ${SMTP_FROM} smtp_auth_username: ${SMTP_AUTH_USERNAME} smtp_auth_password: ${SMTP_AUTH_PASSWORD} smtp_require_tls: ${SMTP_REQUIRE_TLS} route: group_by: ['alertname'] group_wait: 30s group_interval: 5m repeat_interval: 5m receiver: 'default' receivers: - name: 'default' webhook_configs: - url: 'http://grafana:3000' email_configs: - to: ${ALERT_EMAIL_TO} send_resolved: true ``` I got this error shown below ``` level=ERROR source=coordinator.go:117 msg="Loading configuration file failed" component=configuration file=/etc/alertmanager/alertmanager.yml err="not a valid duration string: \"${ALERT_RESOLVE_TIMEOUT}\"" ``` How can I fix it?