I am not proud of it.

Why did I choose to do this.
I could get some more sleep but I choose to write this.
I just want some snapshot before I start breaking stuff.

docker/docker.go

@@ -0,0 +1,128 @@
+package docker
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"os"
+	"os/signal"
+	"strings"
+	"sync"
+	"syscall"
+	"time"
+
+	"net/http"
+
+	"github.com/moby/moby/client"
+)
+
+// Add mutex.
+var ApiClient *client.Client;
+var scale sync.Map;
+var token string = "12345";
+
+type aService struct{
+	ServiceId string `json:"serviceId"`;
+	VolumeNames []string `json:"volumeNames"`;
+	Node string `json:"node"`;
+}
+
+func Run(){
+	ctx, _ := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM);
+
+	var err error;
+	ApiClient, err = client.New(client.FromEnv);
+	if(err != nil){
+		panic("Docker client was not able to init from env!" + err.Error());
+	}
+
+	info, err := ApiClient.Info(context.Background(), client.InfoOptions{});
+	if(err != nil){
+		panic("Error getting info!" + err.Error());
+	}
+
+	if(!info.Info.Swarm.ControlAvailable){
+		panic("Node is not a swarm manager.");
+	}
+
+	server := &http.Server{
+		Addr: ":1234",
+	}
+
+	http.HandleFunc("/services", listServices);
+	http.HandleFunc("/scale/down", scaleDown);
+	http.HandleFunc("/scale/up", scaleUp);
+	http.HandleFunc("/prepare", prepare);
+	go func(){
+		err = server.ListenAndServe(); 
+		if err == http.ErrServerClosed {
+			return;
+
+		}
+		if(err != nil){
+			panic("Unable to start http server!" + err.Error());
+		}
+
+	}();
+
+	time.Sleep(10*time.Millisecond);
+	<-ctx.Done();
+	fmt.Println("Stopping http server.");
+	server.Close();
+	fmt.Println("Exiting!");
+}
+
+func bearerAuth(w http.ResponseWriter, r *http.Request)bool {
+	authHeader := r.Header.Get("Authorization")
+	expected := "Bearer " + token
+
+	if authHeader != expected {
+		w.WriteHeader(http.StatusUnauthorized)
+		fmt.Fprintln(w, "Unauthorized")
+		return false;
+	}
+	return true;
+}
+
+func listServices(w http.ResponseWriter, r *http.Request){
+	if(r.Method != http.MethodGet){
+		w.WriteHeader(http.StatusMethodNotAllowed);
+		return;
+	}
+
+	if !bearerAuth(w,r) {return};
+
+	list, err := ApiClient.ServiceList(context.Background(), client.ServiceListOptions{});
+	if(err != nil){
+		panic("Unable to list services!" + err.Error());
+	}
+
+	var services []aService;
+
+	for _, service:= range list.Items{
+		var settings map[string]string = service.Spec.Labels; 
+		
+
+		if(settings["blazena.enable"] != "true"){
+			continue;
+
+		}
+
+		targetVolumes := strings.Split(settings["blazena.volumes"], ",");
+
+		services = append(services, aService{
+			ServiceId: service.ID,
+			VolumeNames: targetVolumes,
+			Node: settings["blazena.node"],
+		});
+
+	}
+
+	bytes, err := json.Marshal(services);
+
+	if err != nil{
+		panic("Error during response encoding!" + err.Error());
+	}
+
+	fmt.Fprint(w, string(bytes));
+}

docker/prepare.go

@@ -0,0 +1,69 @@
+package docker
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/moby/moby/api/types/swarm"
+	"github.com/moby/moby/api/types/mount"
+	"github.com/moby/moby/client"
+)
+
+func prepare(w http.ResponseWriter, r *http.Request){
+	if r.Method != http.MethodPost{
+		w.WriteHeader(http.StatusMethodNotAllowed);
+		fmt.Fprint(w, "Method Not Allowed");
+		return;
+	}
+
+	//TODO: add token auth
+
+	rawBody, err := io.ReadAll(r.Body);
+	if err != nil {
+		panic("Failed to read body!");
+	}
+
+	var bodyDecoded struct{
+		volume string
+		node string
+	};
+
+	err = json.Unmarshal(rawBody, &bodyDecoded);
+	if err != nil {
+		panic("Failed to unmarshal json."+ err.Error());
+	}
+
+	maxConcurrent := uint64(1);
+	totalCompletions := uint64(1);
+	targetVolume := bodyDecoded.volume;
+	targetNode := bodyDecoded.node;
+	
+	ApiClient.ServiceCreate(context.Background(), client.ServiceCreateOptions{
+		Spec: swarm.ServiceSpec{
+			Mode: swarm.ServiceMode{
+				ReplicatedJob: &swarm.ReplicatedJob{
+					MaxConcurrent: &maxConcurrent,
+					TotalCompletions: &totalCompletions,
+				},
+			},
+			TaskTemplate: swarm.TaskSpec{
+				ContainerSpec: &swarm.ContainerSpec{
+					Image: "docker.io/library/alpine:latest",
+					Mounts: []mount.Mount{
+						mount.Mount{
+							Source: targetVolume,
+							Target: "/volume",
+							Type: "bind",
+						},
+					},
+				},
+				Placement: &swarm.Placement{
+					Constraints: []string{"node.hostname=="+targetNode},
+				},
+			},
+		},
+	});
+}

docker/scale.go

@@ -0,0 +1,105 @@
+package docker;
+import(
+	"net/http"
+	"io"
+	"encoding/json"
+	"context"
+	"github.com/moby/moby/client"
+);
+
+func scaleDown(w http.ResponseWriter, r *http.Request){
+	if r.Method != http.MethodPost {
+		w.WriteHeader(http.StatusMethodNotAllowed);
+		return;
+	}
+
+	if !bearerAuth(w, r) {return}
+
+	rawBody, err := io.ReadAll(r.Body);
+	if err != nil {
+		panic("Failed to read body!" + err.Error());
+	}
+
+	var parsedBody struct{
+		ServiceId string `json:"serviceId"`;
+	};
+
+	err = json.Unmarshal(rawBody, &parsedBody);
+	if err != nil{
+		panic("Failed to unmarshal request body!"+ err.Error());
+	}
+
+	inspectresoult, err := ApiClient.ServiceInspect(context.Background(), parsedBody.ServiceId, client.ServiceInspectOptions{});
+
+	if err != nil{
+		panic("Error inspecting service!"+ err.Error());
+	}
+
+	originalScale := inspectresoult.Service.Spec.Mode.Replicated.Replicas;
+	updatedSpec := inspectresoult.Service.Spec;
+
+	newScale := uint64(0);
+	updatedSpec.Mode.Replicated.Replicas = &newScale;
+
+	scale.Store(parsedBody.ServiceId, *originalScale);
+
+	_, err = ApiClient.ServiceUpdate(context.Background(), parsedBody.ServiceId, client.ServiceUpdateOptions{
+		Spec: updatedSpec,
+		Version: inspectresoult.Service.Version,
+	});
+
+	if(err != nil){
+		panic("Failed to update service."+ err.Error());
+	}
+}
+
+func scaleUp(w http.ResponseWriter, r *http.Request){
+	if r.Method != http.MethodPost {
+		w.WriteHeader(http.StatusMethodNotAllowed);
+		return;
+	}
+
+	if !bearerAuth(w, r) {return}
+
+
+	rawBody, err := io.ReadAll(r.Body);
+	if err != nil {
+		panic("Failed to read body!");
+	}
+
+	var parsedBody struct{
+		ServiceId string `json:"serviceId"`;
+	};
+
+	err = json.Unmarshal(rawBody, &parsedBody);
+	if err != nil{
+		panic("Failed to unmarshal request body!"+ err.Error());
+	}
+
+	inspectresoult, err := ApiClient.ServiceInspect(context.Background(), parsedBody.ServiceId, client.ServiceInspectOptions{});
+
+	if err != nil{
+		panic("Error inspecting service!"+ err.Error());
+	}
+
+	originalScale, ok := scale.Load(parsedBody.ServiceId);  
+	if(!ok){
+		panic("Its not okay!");
+	}
+
+	originalScaleChecked, ok := originalScale.(uint64);
+	if(!ok){
+		panic("Its very not okay!")
+	}
+	updatedSpec := inspectresoult.Service.Spec;
+
+	updatedSpec.Mode.Replicated.Replicas = &originalScaleChecked;
+
+
+	ApiClient.ServiceUpdate(context.Background(), parsedBody.ServiceId, client.ServiceUpdateOptions{
+		Spec: updatedSpec,
+		Version: inspectresoult.Service.Version,
+		
+	});
+
+}