created docker-prometheus compose file and edited the Prometheus yml file

prom/retrieval/discovery/marathon/client.go

@@ -0,0 +1,47 @@
+// Copyright 2015 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package marathon
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"net/http"
+)
+
+// AppListClient defines a function that can be used to get an application list from marathon.
+type AppListClient func(url string) (*AppList, error)
+
+// FetchMarathonApps requests a list of applications from a marathon server.
+func FetchMarathonApps(url string) (*AppList, error) {
+	resp, err := http.Get(url)
+	if err != nil {
+		return nil, err
+	}
+
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	return parseAppJSON(body)
+}
+
+func parseAppJSON(body []byte) (*AppList, error) {
+	apps := &AppList{}
+	err := json.Unmarshal(body, apps)
+	if err != nil {
+		return nil, err
+	}
+	return apps, nil
+}

prom/retrieval/discovery/marathon/constants.go

@@ -0,0 +1,32 @@
+// Copyright 2015 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package marathon
+
+import (
+	clientmodel "github.com/prometheus/client_golang/model"
+)
+
+const (
+	// metaLabelPrefix is the meta prefix used for all meta labels in this discovery.
+	metaLabelPrefix = clientmodel.MetaLabelPrefix + "marathon_"
+	// appLabelPrefix is the prefix for the application labels.
+	appLabelPrefix = metaLabelPrefix + "app_label_"
+
+	// appLabel is used for the name of the app in Marathon.
+	appLabel clientmodel.LabelName = metaLabelPrefix + "app"
+	// imageLabel is the label that is used for the docker image running the service.
+	imageLabel clientmodel.LabelName = metaLabelPrefix + "image"
+	// taskLabel contains the mesos task name of the app instance.
+	taskLabel clientmodel.LabelName = metaLabelPrefix + "task"
+)

prom/retrieval/discovery/marathon/conversion.go

@@ -0,0 +1,71 @@
+// Copyright 2015 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package marathon
+
+import (
+	"fmt"
+
+	clientmodel "github.com/prometheus/client_golang/model"
+
+	"github.com/prometheus/prometheus/config"
+)
+
+// AppsToTargetGroups takes an array of Marathon apps and converts them into target groups.
+func AppsToTargetGroups(apps *AppList) map[string]*config.TargetGroup {
+	tgroups := map[string]*config.TargetGroup{}
+	for _, a := range apps.Apps {
+		group := createTargetGroup(&a)
+		tgroups[group.Source] = group
+	}
+	return tgroups
+}
+
+func createTargetGroup(app *App) *config.TargetGroup {
+	var (
+		targets = targetsForApp(app)
+		appName = clientmodel.LabelValue(app.ID)
+		image   = clientmodel.LabelValue(app.Container.Docker.Image)
+	)
+	tg := &config.TargetGroup{
+		Targets: targets,
+		Labels: clientmodel.LabelSet{
+			appLabel:   appName,
+			imageLabel: image,
+		},
+		Source: app.ID,
+	}
+
+	for ln, lv := range app.Labels {
+		ln = appLabelPrefix + ln
+		tg.Labels[clientmodel.LabelName(ln)] = clientmodel.LabelValue(lv)
+	}
+
+	return tg
+}
+
+func targetsForApp(app *App) []clientmodel.LabelSet {
+	targets := make([]clientmodel.LabelSet, 0, len(app.Tasks))
+	for _, t := range app.Tasks {
+		target := targetForTask(&t)
+		targets = append(targets, clientmodel.LabelSet{
+			clientmodel.AddressLabel: clientmodel.LabelValue(target),
+			taskLabel:                clientmodel.LabelValue(t.ID),
+		})
+	}
+	return targets
+}
+
+func targetForTask(task *Task) string {
+	return fmt.Sprintf("%s:%d", task.Host, task.Ports[0])
+}

prom/retrieval/discovery/marathon/objects.go

@@ -0,0 +1,45 @@
+// Copyright 2015 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package marathon
+
+// Task describes one instance of a service running on Marathon.
+type Task struct {
+	ID    string   `json:"id"`
+	Host  string   `json:"host"`
+	Ports []uint32 `json:"ports"`
+}
+
+// DockerContainer describes a container which uses the docker runtime.
+type DockerContainer struct {
+	Image string `json:"image"`
+}
+
+// Container describes the runtime an app in running in.
+type Container struct {
+	Docker DockerContainer `json:"docker"`
+}
+
+// App describes a service running on Marathon.
+type App struct {
+	ID           string            `json:"id"`
+	Tasks        []Task            `json:"tasks"`
+	RunningTasks int               `json:"tasksRunning"`
+	Labels       map[string]string `json:"labels"`
+	Container    Container         `json:"container"`
+}
+
+// AppList is a list of Marathon apps.
+type AppList struct {
+	Apps []App `json:"apps"`
+}

prom/retrieval/discovery/marathon/url.go

@@ -0,0 +1,29 @@
+// Copyright 2015 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package marathon
+
+import (
+	"fmt"
+	"math/rand"
+)
+
+const appListPath string = "/v2/apps/?embed=apps.tasks"
+
+// RandomAppsURL randomly selects a server from an array and creates
+// an URL pointing to the app list.
+func RandomAppsURL(servers []string) string {
+	// TODO: If possible update server list from Marathon at some point.
+	server := servers[rand.Intn(len(servers))]
+	return fmt.Sprintf("%s%s", server, appListPath)
+}