Add basic nomad integration and runner provider

nomad/nomad.go

@@ -0,0 +1,71 @@
+package nomad
+
+import (
+	nomadApi "github.com/hashicorp/nomad/api"
+	"net/url"
+)
+
+// ExecutorApi provides access to an container orchestration solution
+type ExecutorApi interface {
+	LoadJobList() (list []*nomadApi.JobListStub, err error)
+	GetJobScale(jobId string) (jobScale int, err error)
+	SetJobScaling(jobId string, count int, reason string) (err error)
+	LoadRunners(jobId string) (runnerIds []string, err error)
+}
+
+// ApiClient provides access to the Nomad functionality
+type ApiClient struct {
+	client *nomadApi.Client
+}
+
+// New creates a new api client.
+// One client is usually sufficient for the complete runtime of the API.
+func New(nomadURL *url.URL) (ExecutorApi, error) {
+	client := &ApiClient{}
+	err := client.init(nomadURL)
+	return client, err
+}
+
+// init prepares an apiClient to be able to communicate to a provided Nomad API.
+func (apiClient *ApiClient) init(nomadURL *url.URL) (err error) {
+	apiClient.client, err = nomadApi.NewClient(&nomadApi.Config{
+		Address:   nomadURL.String(),
+		TLSConfig: &nomadApi.TLSConfig{},
+	})
+	return err
+}
+
+// LoadJobList loads the list of jobs from the Nomad api.
+func (apiClient *ApiClient) LoadJobList() (list []*nomadApi.JobListStub, err error) {
+	list, _, err = apiClient.client.Jobs().List(nil)
+	return
+}
+
+// GetJobScale returns the scale of the passed job.
+func (apiClient *ApiClient) GetJobScale(jobId string) (jobScale int, err error) {
+	status, _, err := apiClient.client.Jobs().ScaleStatus(jobId, nil)
+	if err != nil {
+		return
+	}
+	// ToDo: Consider counting also the placed and desired allocations
+	jobScale = status.TaskGroups[jobId].Running
+	return
+}
+
+// SetJobScaling sets the scaling count of the passed job to Nomad.
+func (apiClient *ApiClient) SetJobScaling(jobId string, count int, reason string) (err error) {
+	_, _, err = apiClient.client.Jobs().Scale(jobId, jobId, &count, reason, false, nil, nil)
+	return
+}
+
+// LoadRunners loads the allocations of the specified job.
+func (apiClient *ApiClient) LoadRunners(jobId string) (runnerIds []string, err error) {
+	list, _, err := apiClient.client.Jobs().Allocations(jobId, true, nil)
+	if err != nil {
+		return nil, err
+	}
+	for _, stub := range list {
+		runnerIds = append(runnerIds, stub.ID)
+	}
+	return
+}