monitor.sh.j2

#!/usr/bin/env bash
# vim: set ft=sh:

CONSUL_SERVICE_FILE='/etc/consul/service_{{ nim_waku_consul_config_name }}.json'

function date_iso8691(){
    date -u +"%Y-%m-%dT%H:%M:%SZ"
}

function event_loop () {
    while read EVENT; do
        echo "${EVENT}" | jq -c \
            '{ time, commit: .Actor.Attributes.commit, Action }'
        update_consul && { update_service_timestamp; reload_consul; }
    done
}

function get_meta_attr() {
    echo "${EVENT}" | jq -r ".Actor.Attributes.${1} // \"unknown\""
}

function update_service_json() {
    # Uglier but MUCH less effort than using the API.
    sed "${CONSUL_SERVICE_FILE}" \
{% for field in nim_waku_monitor_meta_fields %}
        -e 's#"{{ field }}": ".*"#"{{ field }}": "'$(get_meta_attr {{ field }})'"#' \
{% endfor %}
        | sponge "${CONSUL_SERVICE_FILE}" 
}

function update_service_timestamp() {
    sed "${CONSUL_SERVICE_FILE}" \
        -e 's#"timestamp": ".*"#"timestamp": "'$(date_iso8691)'"#' \
        | sponge "${CONSUL_SERVICE_FILE}" 
  }

function update_consul () {
    BEFORE=$(md5sum "${CONSUL_SERVICE_FILE}")
    update_service_json
    AFTER=$(md5sum "${CONSUL_SERVICE_FILE}")
    # Avoid unnecessary reloads.
    [[ "${BEFORE}" == "${AFTER}" ]] && return 1 || return 0
}

function reload_consul() {
    echo "Changes detected, reloading Consul."
    systemctl reload consul
}

docker system events \
    --format='{% raw %}{{ json . }}{% endraw %}' \
    --filter='container={{ nim_waku_cont_name }}' \
{% for event in nim_waku_monitor_docker_events %}
    --filter='event={{ event }}' \
{% endfor %}
    | event_loop