docker: move docker-update-hosts restart into the script

Author: saltydk

roles/docker/files/docker-update-hosts

@@ -4,20 +4,53 @@ set -e -u -o pipefail
 hosts_file=/etc/hosts
 begin_block="# BEGIN DOCKER CONTAINERS"
 end_block="# END DOCKER CONTAINERS"
+monitor_interval=${1:-3600}  # Use the first argument as the interval, with a default of 3600 seconds
+
+# Cleanup function to execute upon receiving a signal
+cleanup() {
+    echo "Caught signal, exiting..."
+    exit 0  # Exit cleanly
+}
+
+# Trap SIGTERM and SIGINT to call the cleanup function
+trap cleanup SIGTERM SIGINT
 
 if ! grep -Fxq "$begin_block" "$hosts_file"; then
     echo -e "\n${begin_block}\n${end_block}\n" >> "$hosts_file"
 fi
 
-(echo "| container start |" && docker events) | \
-while read event; do
-    if [[ "$event" == *" container start "* ]] || [[ "$event" == *" network disconnect "* ]]; then
-        hosts_file_tmp="$(mktemp)"
-        docker container ls -q | xargs -r docker container inspect | \
-        jq -r '.[] | if (.NetworkSettings.Networks[].IPAddress | length > 0) then "\(.NetworkSettings.Networks[].IPAddress) \(.NetworkSettings.Networks[].Aliases | select(length > 0) | join(" ")) \(.Name | sub("^/"; "") | sub("_1$"; "") | sub("-1$"; "")).saltbox" else "# no ip address: \(.Name | sub("^/"; ""))" end' | \
-        sed -ne "/^${begin_block}$/ {p; r /dev/stdin" -e ":a; n; /^${end_block}$/ {p; b}; ba}; p" "$hosts_file" \
-        > "$hosts_file_tmp"
-        chmod 644 "$hosts_file_tmp"
-        mv "$hosts_file_tmp" "$hosts_file"
-    fi
-done
+# Function to update the hosts file with current Docker containers' info
+update_hosts_file() {
+    local hosts_file_tmp="$(mktemp)"
+    docker container ls -q | xargs -r docker container inspect | \
+    jq -r '.[] | if (.NetworkSettings.Networks[].IPAddress | length > 0) then "\(.NetworkSettings.Networks[].IPAddress) \(.NetworkSettings.Networks[].Aliases | select(length > 0) | join(" ")) \(.Name | sub("^/"; "") | sub("_1$"; "") | sub("-1$"; "")).saltbox" else "# no ip address: \(.Name | sub("^/"; ""))" end' | \
+    sed -ne "/^${begin_block}$/ {p; r /dev/stdin" -e ":a; n; /^${end_block}$/ {p; b}; ba}; p" "$hosts_file" \
+    > "$hosts_file_tmp"
+    chmod 644 "$hosts_file_tmp"
+    mv "$hosts_file_tmp" "$hosts_file"
+}
+
+# Main monitoring function
+monitor_docker_events() {
+    # Immediately update the hosts file at the start
+    update_hosts_file
+
+    # Listen for Docker events and update hosts file accordingly
+    docker events --format '{{json .}}' | while read event; do
+        update_hosts_file
+    done
+}
+
+# Main loop
+while true; do
+    # Run the monitoring in the background
+    monitor_docker_events &
+    monitor_pid=$!
+
+    # Wait for the specified interval or until the monitoring process exits
+    sleep "$monitor_interval" & wait $!
+
+    # After the interval, or if sleep is interrupted, proceed to stop the monitoring process
+    kill "$monitor_pid" 2>/dev/null
+    wait "$monitor_pid" 2>/dev/null || true  # Suppress errors if the process has already exited
+done

roles/docker/templates/docker-update-hosts.service.j2

@@ -14,8 +14,7 @@ After=docker.service
 PartOf=docker.service
 
 [Service]
-ExecStart=/usr/local/bin/docker-update-hosts
-RuntimeMaxSec={{ docker_update_hosts_service_runtime_max }}
+ExecStart=/usr/local/bin/docker-update-hosts {{ docker_update_hosts_service_runtime_max }}
 Restart=always
 RestartSec=20s
 StartLimitInterval=0