Nagios Core in a Rocky Linux Container

Build the Image

Build and push the image to Docker Hub:

docker build --no-cache -t dhml/nagios:$(git rev-parse --short=12 HEAD) .
docker tag dhml/nagios:$(git rev-parse --short=12 HEAD) dhml/nagios:latest
docker push dhml/nagios:$(git rev-parse --short=12 HEAD)
docker push dhml/nagios:latest

Configure Nagios

Modify the contents of the conf/ directory accordingly. The contents here are pared down version of those present by default after installing the nagios package in the Rocky Linux 8.4 container.

Validate Nagios Configuration

docker run -it --rm \
-v $(pwd)/conf:/etc/nagios \
dhml/nagios:latest \
/usr/sbin/nagios -v /etc/nagios/nagios.cfg

Sending Nagios Alerts via E-mail

This is handled by msmtp in the container. Environment variables MSMTP_HOST (the host to relay mail to) and MSMTP_FROM (the envelope from address) may be optionally set when running the container. If both of these are set, the system-wide configuration file /etc/msmtprc will be written allowing alert e-mail to be relayed. See the msmtp documentation for details. Note that SMTP authentication is not yet supported.

Sending Nagios Alerts to Microsoft Teams via Webhooks

https://github.com/isaac-galvan/nagios-teams-notify

Configure a command such as the following:

define command {
    command_name    notify_teams
    command_line    /usr/bin/printf "$LONGSERVICEOUTPUT$" | /usr/local/bin/notify-teams.py "$NOTIFICATIONTYPE$: $HOSTALIAS$/$SERVICEDESC$ is $SERVICESTATE$" "$SERVICEOUTPUT$" <teams-channel-webhook-url>
}

Then configure this command in host, service or contact definitions.

Run Container in Docker

export MSMTP_HOST=relay.example.com
export MSMTP_FROM=noreply@nagios.example.com
docker run \
-d \
--env MSMTP_HOST \
--env MSMTP_FROM \
--name nagios \
-p 8080:80 \
--rm \
-v $(pwd)/conf:/etc/nagios \
-v $(pwd)/logs/httpd:/var/log/httpd \
-v $(pwd)/logs/php-fpm:/var/log/php-fpm \
-v $(pwd)/logs/nagios:/var/log/nagios \
dhml/nagios:latest

Proceed to: http://localhost:8080/nagios/ . The default username and password are both nagiosadmin.

Run Rootless Container in Podman

export MSMTP_HOST=relay.example.com
export MSMTP_FROM=noreply@nagios.example.com
podman run \
--cap-add=CAP_NET_RAW \
-d \
--env MSMTP_HOST \
--env MSMTP_FROM \
--name nagios \
-p 8080:80 \
--rm \
-v $(pwd)/conf:/etc/nagios \
-v $(pwd)/logs/httpd:/var/log/httpd \
-v $(pwd)/logs/php-fpm:/var/log/php-fpm \
-v $(pwd)/logs/nagios:/var/log/nagios \
docker://dhml/nagios

Proceed to: http://localhost:8080/nagios/ . The default username and password are both nagiosadmin.

Manage Nagios Services

docker exec -it nagios /usr/bin/supervisorctl status
docker exec -it nagios /usr/bin/supervisorctl restart httpd
docker exec -it nagios /usr/bin/supervisorctl restart php-fpm
docker exec -it nagios /usr/bin/supervisorctl restart nagios