Use duration type for options for Docker auto-scaling delays (#524)

.gitignore

@@ -7,3 +7,5 @@
 /dist/
 /*.private.env.json
 /kustomization.yml
+
+/*.pem

.run/run (in docker).run.xml

@@ -0,0 +1,22 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="run (in docker)" type="GoApplicationRunConfiguration" factoryName="Go Application">
+    <module name="mc-router" />
+    <working_directory value="$PROJECT_DIR$" />
+    <parameters value="--debug --in-docker" />
+    <EXTENSION ID="net.ashald.envfile">
+      <option name="IS_ENABLED" value="false" />
+      <option name="IS_SUBST" value="false" />
+      <option name="IS_PATH_MACRO_SUPPORTED" value="false" />
+      <option name="IS_IGNORE_MISSING_FILES" value="false" />
+      <option name="IS_ENABLE_EXPERIMENTAL_INTEGRATIONS" value="false" />
+      <ENTRIES>
+        <ENTRY IS_ENABLED="true" PARSER="runconfig" IS_EXECUTABLE="false" />
+      </ENTRIES>
+    </EXTENSION>
+    <kind value="DIRECTORY" />
+    <package value="github.com/itzg/mc-router" />
+    <directory value="$PROJECT_DIR$/cmd/mc-router" />
+    <filePath value="$PROJECT_DIR$/cmd/mc-router/main.go" />
+    <method v="2" />
+  </configuration>
+</component>

.run/run (in docker, auto scale).run.xml

@@ -0,0 +1,22 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="run (in docker, auto scale)" type="GoApplicationRunConfiguration" factoryName="Go Application">
+    <module name="mc-router" />
+    <working_directory value="$PROJECT_DIR$" />
+    <parameters value="--mapping localhost=localhost:25566 --in-docker --docker-socket=&quot;&quot; --auto-scale-up --auto-scale-down --auto-scale-down-after=30s" />
+    <EXTENSION ID="net.ashald.envfile">
+      <option name="IS_ENABLED" value="false" />
+      <option name="IS_SUBST" value="false" />
+      <option name="IS_PATH_MACRO_SUPPORTED" value="false" />
+      <option name="IS_IGNORE_MISSING_FILES" value="false" />
+      <option name="IS_ENABLE_EXPERIMENTAL_INTEGRATIONS" value="false" />
+      <ENTRIES>
+        <ENTRY IS_ENABLED="true" PARSER="runconfig" IS_EXECUTABLE="false" />
+      </ENTRIES>
+    </EXTENSION>
+    <kind value="DIRECTORY" />
+    <package value="github.com/itzg/mc-router" />
+    <directory value="$PROJECT_DIR$/cmd/mc-router" />
+    <filePath value="$PROJECT_DIR$/cmd/mc-router/main.go" />
+    <method v="2" />
+  </configuration>
+</component>

README.md

@@ -744,6 +744,31 @@ then add the _Artifact Registry Reader_ Role to the _Compute Engine default serv
 then use e.g. `gcloud auth configure-docker europe-docker.pkg.dev` or equivalent one time (to create a `~/.docker/config.json`),
 and then use e.g. `--default-repo=europe-docker.pkg.dev/YOUR-PROJECT/YOUR-ARTIFACT-REGISTRY` option for `skaffold dev`.
 
+### Running in devcontainer
+
+This approach is useful for testing changes for [Docker auto scaling](#docker-auto-scale-updown).
+
+With IntelliJ Ultimate, [use these instructions](https://www.jetbrains.com/help/idea/start-dev-container-inside-ide.html). It is recommended to use the option to mount sources.
+
+![Start devcontainer in IntelliJ](docs/intellij-devcontainer.png)
+
+Use the example compose file [in examples/docker-discovery](examples/docker-discovery/compose.yml) or similar with `network_mode` set to "bridge" to ensure that the mc-router instance running within the devcontainer can reach the backend servers.
+
+When applying the `mc-router.host` label to containers to be auto-discovered, it's easiest to use an external host of "localhost":
+
+```yaml
+  vanilla:
+    image: itzg/minecraft-server
+    environment:
+      EULA: "TRUE"
+    labels:
+      mc-router.host: "localhost"
+```
+
+Run one of the labeled services by clicking the run icon in the gutter.
+
+
+
 ### Performing snapshot release with Docker
 
 ```bash

examples/docker-discovery/compose.yml

@@ -14,7 +14,7 @@ services:
     environment:
       EULA: "TRUE"
     labels:
-      mc-router.host: "localhost.itzg.me"
+      mc-router.host: "localhost"
     # To allow for routing from devcontainer
     network_mode: bridge
   paper:

server/configs.go

@@ -10,7 +10,7 @@ type WebhookConfig struct {
 type AutoScale struct {
 	Up         bool          `usage:"Scale from zero on access. For Kubernetes, increases StatefulSet replicas from 0 to 1. For Docker, starts or unpauses the container when accessed"`
 	Down       bool          `default:"false" usage:"Scale to zero after idle. For Kubernetes, decreases StatefulSet replicas from 1 to 0. For Docker, gracefully stops the container when there are no connections"`
-	DownAfter  string `default:"10m" usage:"Server scale down delay after there are no connections"`
+	DownAfter  time.Duration `default:"10m" usage:"Server scale down delay after there are no connections"`
 	AllowDeny  string        `usage:"Path to config for server allowlists and denylists. If a global/server entry is specified, only players allowed to connect to the server will be able to trigger a scale up when -auto-scale-up is enabled or cancel active down scalers when -auto-scale-down is enabled"`
 	AsleepMOTD string        `usage:"MOTD to display when auto-scaled down servers are accessed; if empty, no status will be served"`
 }
@@ -37,9 +37,9 @@ type Config struct {
 	KubeNamespace          string            `usage:"The namespace to watch or blank for all, which is the default"`
 	InDocker               bool              `usage:"Use Docker service discovery"`
 	InDockerSwarm          bool              `usage:"Use Docker Swarm service discovery"`
-	DockerSocket           string            `default:"unix:///var/run/docker.sock" usage:"Path to Docker socket to use"`
+	DockerSocket           string            `usage:"Path to Docker socket to use"`
-	DockerTimeout          int               `default:"0" usage:"Timeout configuration in seconds for the Docker integrations"`
+	DockerTimeout          time.Duration     `usage:"Timeout (as duration) for the Docker integrations"`
-	DockerRefreshInterval  int               `default:"15" usage:"Refresh interval in seconds for the Docker integrations"`
+	DockerRefreshInterval  time.Duration     `default:"15s" usage:"Refresh interval (as duration) for the Docker integrations"`
 	DockerApiVersion       string            `usage:"Instead of auto-negotiating, use specific Docker API version"`
 	MetricsBackend         string            `default:"discard" usage:"Backend to use for metrics exposure/publishing: discard,expvar,influxdb,prometheus"`
 	MetricsBackendConfig   MetricsBackendConfig

server/docker.go

@@ -32,8 +32,8 @@ type dockerWatcherConfig struct {
 	autoScaleUp     bool
 	autoScaleDown   bool
 	socket          string
-	timeoutSeconds         int
+	timeout         time.Duration
-	refreshIntervalSeconds int
+	refreshInterval time.Duration
 	apiVersion      string
 }
 
@@ -47,12 +47,12 @@ func (c *dockerWatcherConfig) apiVersionOpt() client.Opt {
 	}
 }
 
-func NewDockerWatcher(socket string, timeoutSeconds int, refreshIntervalSeconds int, autoScaleUp bool, autoScaleDown bool, dockerApiVersion string) IDockerWatcher {
+func NewDockerWatcher(socket string, timeout time.Duration, refreshInterval time.Duration, autoScaleUp bool, autoScaleDown bool, dockerApiVersion string) IDockerWatcher {
 	return &dockerWatcherImpl{
 		config: dockerWatcherConfig{
 			socket:          socket,
-			timeoutSeconds:         timeoutSeconds,
+			timeout:         timeout,
-			refreshIntervalSeconds: refreshIntervalSeconds,
+			refreshInterval: refreshInterval,
 			autoScaleUp:     autoScaleUp,
 			autoScaleDown:   autoScaleDown,
 			apiVersion:      dockerApiVersion,
@@ -225,24 +225,25 @@ func (w *dockerWatcherImpl) monitorContainers(ctx context.Context) error {
 func (w *dockerWatcherImpl) Start(ctx context.Context) error {
 	var err error
 
-	timeout := time.Duration(w.config.timeoutSeconds) * time.Second
-	refreshInterval := time.Duration(w.config.refreshIntervalSeconds) * time.Second
-
 	opts := []client.Opt{
-		client.WithHost(w.config.socket),
+		client.FromEnv,
-		client.WithTimeout(timeout),
+		client.WithTimeout(w.config.timeout),
 		client.WithHTTPHeaders(map[string]string{
 			"User-Agent": "mc-router ",
 		}),
 		w.config.apiVersionOpt(),
 	}
+	if w.config.socket != "" {
+		opts = append(opts, client.WithHost(w.config.socket))
+	}
 
 	w.client, err = client.NewClientWithOpts(opts...)
 	if err != nil {
 		return err
 	}
 
-	ticker := time.NewTicker(refreshInterval)
+	// TODO: replace all this with events listening
+	ticker := time.NewTicker(w.config.refreshInterval)
 
 	logrus.Trace("Performing initial listing of Docker containers")
 	initialContainers, err := w.listContainers(ctx)

server/docker_swarm.go

@@ -19,12 +19,12 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
-func NewDockerSwarmWatcher(socket string, timeoutSeconds int, refreshIntervalSeconds int, autoScaleUp bool, autoScaleDown bool, dockerApiVersion string) IDockerWatcher {
+func NewDockerSwarmWatcher(socket string, timeout time.Duration, refreshInterval time.Duration, autoScaleUp bool, autoScaleDown bool, dockerApiVersion string) IDockerWatcher {
 	return &dockerSwarmWatcherImpl{
 		config: dockerWatcherConfig{
 			socket:          socket,
-			timeoutSeconds:         timeoutSeconds,
+			timeout:         timeout,
-			refreshIntervalSeconds: refreshIntervalSeconds,
+			refreshInterval: refreshInterval,
 			autoScaleUp:     autoScaleUp,
 			autoScaleDown:   autoScaleDown,
 			apiVersion:      dockerApiVersion,
@@ -61,12 +61,9 @@ func (w *dockerSwarmWatcherImpl) makeSleeperFunc(_ *routableService) SleeperFunc
 func (w *dockerSwarmWatcherImpl) Start(ctx context.Context) error {
 	var err error
 
-	timeout := time.Duration(w.config.timeoutSeconds) * time.Second
-	refreshInterval := time.Duration(w.config.refreshIntervalSeconds) * time.Second
-
 	opts := []client.Opt{
 		client.WithHost(w.config.socket),
-		client.WithTimeout(timeout),
+		client.WithTimeout(w.config.timeout),
 		client.WithHTTPHeaders(map[string]string{
 			"User-Agent": "mc-router ",
 		}),
@@ -78,7 +75,7 @@ func (w *dockerSwarmWatcherImpl) Start(ctx context.Context) error {
 		return err
 	}
 
-	ticker := time.NewTicker(refreshInterval)
+	ticker := time.NewTicker(w.config.refreshInterval)
 	serviceMap := map[string]*routableService{}
 
 	logrus.Trace("Performing initial listing of Docker containers")

server/down_scaler.go

@@ -56,7 +56,6 @@ func (ds *downScalerImpl) Begin(backendEndpoint string) {
 		scaleDownCancel()
 	}
 
-	logrus.WithField("backendEndpoint", backendEndpoint).Debug("Beginning scale down")
 	scaleDownContext, scaleDownContextCancellation := context.WithCancel(ds.parentContext)
 	ds.contextCancellations[backendEndpoint] = scaleDownContextCancellation
 	go ds.scaleDown(scaleDownContext, backendEndpoint)
@@ -78,12 +77,18 @@ func (ds *downScalerImpl) Cancel(backendEndpoint string) {
 }
 
 func (ds *downScalerImpl) scaleDown(ctx context.Context, backendEndpoint string) {
+	logrus.WithField("backendEndpoint", backendEndpoint).
+		WithField("delay", ds.delay).
+		Debug("Starting scale-down timer")
 	for {
 		select {
 		case <-ctx.Done():
 			return
 		case <-time.After(ds.delay):
 			sleepers := Routes.GetSleepers(backendEndpoint)
+			logrus.WithField("backendEndpoint", backendEndpoint).
+				WithField("sleepers", len(sleepers)).
+				Debug("Found sleepers to use")
 			if len(sleepers) == 0 {
 				return
 			}

server/server.go

@@ -7,7 +7,6 @@ import (
 	"os"
 	"runtime/pprof"
 	"strconv"
-	"time"
 
 	"github.com/sirupsen/logrus"
 )
@@ -50,10 +49,7 @@ func NewServer(ctx context.Context, config *Config) (*Server, error) {
 	metricsBuilder := NewMetricsBuilder(config.MetricsBackend, &config.MetricsBackendConfig)
 
 	downScalerEnabled := config.AutoScale.Down && (config.InKubeCluster || config.KubeConfig != "" || config.InDocker)
-	downScalerDelay, err := time.ParseDuration(config.AutoScale.DownAfter)
+	downScalerDelay := config.AutoScale.DownAfter
-	if err != nil {
-		return nil, fmt.Errorf("could not parse auto-scale-down-after duration: %w", err)
-	}
 	// Only one instance should be created
 	DownScaler = NewDownScaler(ctx, downScalerEnabled, downScalerDelay)