Allow using a local Docker image, e.g., for tests

.github/workflows/ci.yml

@@ -120,6 +120,7 @@ jobs:
       POSEIDON_AWS_ENABLED: true
       POSEIDON_AWS_ENDPOINT: ${{ secrets.POSEIDON_AWS_ENDPOINT }}
       POSEIDON_AWS_FUNCTIONS: ${{ secrets.POSEIDON_AWS_FUNCTIONS }}
+      POSEIDON_NOMAD_DISABLEFORCEPULL: true
     steps:
       - name: Checkout repository
         uses: actions/checkout@v2

configuration.example.yaml

@@ -42,6 +42,8 @@ nomad:
     keyfile: ./poseidon.key
   # Nomad namespace to use. If unset, 'default' is used
   namespace: poseidon
+  # Prefer local Docker images over pulling them from a registry. Images with the `latest` tag will always be force pulled by Nomad regardless of this configuration.
+  disableforcepull: true
 
 aws:
   # Specifies whether AWS should be used as executor.

internal/config/config.go

@@ -42,7 +42,8 @@ var (
 				CertFile: "",
 				KeyFile:  "",
 			},
-			Namespace: "default",
+			Namespace:        "default",
+			DisableForcePull: false,
 		},
 		AWS: AWS{
 			Enabled:   false,
@@ -88,12 +89,13 @@ func (s *server) URL() *url.URL {
 
 // Nomad configures the used Nomad cluster.
 type Nomad struct {
-	Enabled   bool
+	Enabled          bool
-	Address   string
+	Address          string
-	Port      int
+	Port             int
-	Token     string
+	Token            string
-	TLS       TLS
+	TLS              TLS
-	Namespace string
+	Namespace        string
+	DisableForcePull bool
 }
 
 // URL returns the URL for the configured Nomad cluster.

internal/nomad/job.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	nomadApi "github.com/hashicorp/nomad/api"
+	"github.com/openHPI/poseidon/internal/config"
 	"github.com/openHPI/poseidon/pkg/dto"
 	"strconv"
 	"strings"
@@ -146,7 +147,11 @@ func FindAndValidateDefaultTask(taskGroup *nomadApi.TaskGroup) *nomadApi.Task {
 func SetForcePullFlag(job *nomadApi.Job, value bool) {
 	taskGroup := FindAndValidateDefaultTaskGroup(job)
 	task := FindAndValidateDefaultTask(taskGroup)
-	task.Config["force_pull"] = value
+	if config.Config.Nomad.DisableForcePull {
+		task.Config["force_pull"] = false
+	} else {
+		task.Config["force_pull"] = value
+	}
 }
 
 // IsEnvironmentTemplateID checks if the passed job id belongs to a template job.

internal/nomad/job_test.go

@@ -2,6 +2,7 @@ package nomad
 
 import (
 	nomadApi "github.com/hashicorp/nomad/api"
+	"github.com/openHPI/poseidon/internal/config"
 	"github.com/openHPI/poseidon/pkg/dto"
 	"github.com/openHPI/poseidon/tests/helpers"
 	"github.com/stretchr/testify/assert"
@@ -96,6 +97,27 @@ func TestFindOrCreateTask(t *testing.T) {
 	})
 }
 
+func TestSetForcePullFlag(t *testing.T) {
+	_, job := helpers.CreateTemplateJob()
+	taskGroup := FindAndValidateDefaultTaskGroup(job)
+	task := FindAndValidateDefaultTask(taskGroup)
+
+	t.Run("Ignoring passed value if DisableForcePull", func(t *testing.T) {
+		config.Config.Nomad.DisableForcePull = true
+		SetForcePullFlag(job, true)
+		assert.Equal(t, false, task.Config["force_pull"])
+	})
+
+	t.Run("Using passed value if not DisableForcePull", func(t *testing.T) {
+		config.Config.Nomad.DisableForcePull = false
+		SetForcePullFlag(job, true)
+		assert.Equal(t, true, task.Config["force_pull"])
+
+		SetForcePullFlag(job, false)
+		assert.Equal(t, false, task.Config["force_pull"])
+	})
+}
+
 func TestIsEnvironmentTemplateID(t *testing.T) {
 	assert.True(t, IsEnvironmentTemplateID("template-42"))
 	assert.False(t, IsEnvironmentTemplateID("template-42-100"))