rudimentary Prometheus container retrieval

swarm.go

@@ -15,7 +15,7 @@ import (
  "github.com/spf13/cobra"
 )
 
-var prometheusContainerID = "b171793f9e26"
+var prometheusService string
 
 // allocateIP returns the 3rd last IP in the network range.
 func allocateIP(netCIDR *net.IPNet) string {
@@ -29,13 +29,13 @@ func allocateIP(netCIDR *net.IPNet) string {
  return allocIP.String()
 }
 
-func connectNetworks(networks map[string]swarm.Network) {
+func connectNetworks(networks map[string]swarm.Network, containerID string) {
  cli, err := client.NewEnvClient()
  if err != nil {
  panic(err)
  }
 
- prometheusContainer, err := cli.ContainerInspect(context.Background(), prometheusContainerID)
+ prometheusContainer, err := cli.ContainerInspect(context.Background(), containerID)
  if err != nil {
  panic(err)
  }
@@ -56,14 +56,14 @@ func connectNetworks(networks map[string]swarm.Network) {
  panic(err)
  }
  prometheusIP := allocateIP(netCIDR)
- fmt.Println("Connecting network ", netwrk.Spec.Name, "(", netCIDR.IP, ") to ", prometheusContainerID, "(", prometheusIP, ")")
+ fmt.Println("Connecting network ", netwrk.Spec.Name, "(", netCIDR.IP, ") to ", containerID, "(", prometheusIP, ")")
  netconfig := &network.EndpointSettings{
  IPAMConfig: &network.EndpointIPAMConfig{
  IPv4Address: prometheusIP,
  },
  }
 
- err = cli.NetworkConnect(context.Background(), netwrk.ID, prometheusContainerID, netconfig)
+ err = cli.NetworkConnect(context.Background(), netwrk.ID, containerID, netconfig)
  if err != nil {
  panic(err)
  }
@@ -86,12 +86,31 @@ func writeSDConfig(scrapeTargets []scrapeTarget) {
  }
 }
 
+func findPrometheusContainer(serviceName string) string {
+ cli, err := client.NewEnvClient()
+ if err != nil {
+ panic(err)
+ }
+
+ taskFilters := filters.NewArgs()
+ taskFilters.Add("desired-state", string(swarm.TaskStateRunning))
+ taskFilters.Add("service", serviceName)
+
+ promTasks, err := cli.TaskList(context.Background(), types.TaskListOptions{Filters: taskFilters})
+ if err != nil {
+ panic(err)
+ }
+
+ return promTasks[0].Status.ContainerStatus.ContainerID
+}
+
 type scrapeTarget struct {
  Targets []string
  Labels map[string]string
 }
 
 func discoverSwarm(cmd *cobra.Command, args []string) {
+ findPrometheusContainer(prometheusService)
  cli, err := client.NewEnvClient()
  if err != nil {
  panic(err)
@@ -135,7 +154,8 @@ func discoverSwarm(cmd *cobra.Command, args []string) {
  }
  }
 
- connectNetworks(taskNetworks)
+ prometheusContainerID := findPrometheusContainer(prometheusService)
+ connectNetworks(taskNetworks, prometheusContainerID)
  writeSDConfig(scrapeTargets)
 }
 
@@ -147,6 +167,8 @@ func main() {
  Run: discoverSwarm,
  }
 
+ cmdDiscover.Flags().StringVarP(&prometheusService, "prometheus", "p", "prometheus", "Name of the Prometheus service")
+
  var rootCmd = &cobra.Command{Use: "promswarm"}
  rootCmd.AddCommand(cmdDiscover)
  rootCmd.Execute()