diff --git a/README.md b/README.md
index b4d5eabf1..04be56b93 100644
--- a/README.md
+++ b/README.md
@@ -694,7 +694,11 @@ There are available some environment variables that could be used to change some
     - `ELASTIC_PACKAGE_SERVERLESS_PIPELINE_TEST_DISABLE_COMPARE_RESULTS`: If set to `true`, the results from pipeline tests are not compared to avoid errors from GeoIP.
     - `ELASTIC_PACKAGE_DISABLE_ELASTIC_AGENT_WOLFI`: If set to `true`, the Elastic Agent image used for running agents will be using the Ubuntu docker images
       (e.g. `docker.elastic.co/elastic-agent/elastic-agent-complete`). If set to `false`, the Elastic Agent image used for the running agents will be based on the wolfi
+<<<<<<< HEAD
+      images (e.g. `docker.elastic.co/elastic-agent/elastic-agent-wolfi`). Default: `true`.
+=======
       images (e.g. `docker.elastic.co/elastic-agent/elastic-agent-wolfi`). Default: `false`.
+>>>>>>> upstream/main
 
 - To configure the Elastic stack to be used by `elastic-package`:
     - `ELASTIC_PACKAGE_ELASTICSEARCH_HOST`: Host of the elasticsearch (e.g. https://127.0.0.1:9200)
diff --git a/internal/agentdeployer/agent.go b/internal/agentdeployer/agent.go
index fdb6aeb05..a523ec152 100644
--- a/internal/agentdeployer/agent.go
+++ b/internal/agentdeployer/agent.go
@@ -101,7 +101,7 @@ func (d *DockerComposeAgentDeployer) SetUp(ctx context.Context, agentInfo AgentI
 	logger.Debug("setting up agent using Docker Compose agent deployer")
 	d.agentRunID = agentInfo.Test.RunID
 
-	appConfig, err := install.Configuration()
+	appConfig, err := install.Configuration(install.OptionWithStackVersion(d.stackVersion))
 	if err != nil {
 		return nil, fmt.Errorf("can't read application configuration: %w", err)
 	}
@@ -112,7 +112,7 @@ func (d *DockerComposeAgentDeployer) SetUp(ctx context.Context, agentInfo AgentI
 	}
 
 	env := append(
-		appConfig.StackImageRefs(d.stackVersion).AsEnv(),
+		appConfig.StackImageRefs().AsEnv(),
 		fmt.Sprintf("%s=%s", serviceLogsDirEnv, agentInfo.Logs.Folder.Local),
 		fmt.Sprintf("%s=%s", localCACertEnv, caCertPath),
 		fmt.Sprintf("%s=%s", fleetPolicyEnv, d.policyName),
@@ -264,14 +264,14 @@ func (d *DockerComposeAgentDeployer) installDockerCompose(agentInfo AgentInfo) (
 		stackVersion = config.Parameters[stack.ParamServerlessLocalStackVersion]
 	}
 
-	appConfig, err := install.Configuration()
+	agentImage, err := selectElasticAgentImage(stackVersion, agentInfo.Agent.BaseImage)
 	if err != nil {
-		return "", fmt.Errorf("can't read application configuration: %w", err)
+		return "", nil
 	}
 
 	resourceManager := resource.NewManager()
 	resourceManager.AddFacter(resource.StaticFacter{
-		"agent_image":            appConfig.StackImageRefs(stackVersion).ElasticAgent,
+		"agent_image":            agentImage,
 		"user":                   agentInfo.Agent.User,
 		"capabilities":           strings.Join(agentInfo.Agent.LinuxCapabilities, ","),
 		"runtime":                agentInfo.Agent.Runtime,
@@ -303,6 +303,16 @@ func (d *DockerComposeAgentDeployer) installDockerCompose(agentInfo AgentInfo) (
 	return customAgentDir, nil
 }
 
+func selectElasticAgentImage(stackVersion, agentBaseImage string) (string, error) {
+	appConfig, err := install.Configuration(install.OptionWithAgentBaseImage(agentBaseImage), install.OptionWithStackVersion(stackVersion))
+	if err != nil {
+		return "", fmt.Errorf("can't read application configuration: %w", err)
+	}
+
+	agentImage := appConfig.StackImageRefs().ElasticAgent
+	return agentImage, nil
+}
+
 func (d *DockerComposeAgentDeployer) installDockerfileResources(agentSettings AgentSettings, folder string) error {
 	agentResources := []resource.Resource{
 		&resource.File{
diff --git a/internal/agentdeployer/info.go b/internal/agentdeployer/info.go
index 15152c34f..919c2ef98 100644
--- a/internal/agentdeployer/info.go
+++ b/internal/agentdeployer/info.go
@@ -26,6 +26,8 @@ type AgentScript struct {
 type AgentSettings struct {
 	// User user to run Elastic Agent process
 	User string `config:"user"`
+	// BaseImage elastic-agent base image to be used for testing
+	BaseImage string `config:"base_image"`
 	// PidMode selects the host PID mode
 	// (From docker-compose docs) Turns on sharing between container and the host
 	// operating system the PID address space
diff --git a/internal/agentdeployer/kubernetes.go b/internal/agentdeployer/kubernetes.go
index c6aeb07c8..f29f816f2 100644
--- a/internal/agentdeployer/kubernetes.go
+++ b/internal/agentdeployer/kubernetes.go
@@ -179,7 +179,7 @@ var elasticAgentManagedYamlTmpl string
 func getElasticAgentYAML(profile *profile.Profile, stackVersion, policyName, agentName string) ([]byte, error) {
 	logger.Debugf("Prepare YAML definition for Elastic Agent running in stack v%s", stackVersion)
 
-	appConfig, err := install.Configuration()
+	appConfig, err := install.Configuration(install.OptionWithStackVersion(stackVersion))
 	if err != nil {
 		return nil, fmt.Errorf("can't read application configuration: %w", err)
 	}
@@ -196,7 +196,7 @@ func getElasticAgentYAML(profile *profile.Profile, stackVersion, policyName, age
 		"fleetURL":                    "https://fleet-server:8220",
 		"kibanaURL":                   "https://kibana:5601",
 		"caCertPem":                   caCert,
-		"elasticAgentImage":           appConfig.StackImageRefs(stackVersion).ElasticAgent,
+		"elasticAgentImage":           appConfig.StackImageRefs().ElasticAgent,
 		"elasticAgentTokenPolicyName": getTokenPolicyName(stackVersion, policyName),
 		"agentName":                   agentName,
 	})
diff --git a/internal/install/application_configuration.go b/internal/install/application_configuration.go
index ce2f90ffa..8e393cd27 100644
--- a/internal/install/application_configuration.go
+++ b/internal/install/application_configuration.go
@@ -71,7 +71,9 @@ func DefaultConfiguration() *ApplicationConfiguration {
 
 // ApplicationConfiguration represents the configuration of the elastic-package.
 type ApplicationConfiguration struct {
-	c configFile
+	c              configFile
+	agentBaseImage string
+	stackVersion   string
 }
 
 type configFile struct {
@@ -119,12 +121,12 @@ func (ir ImageRefs) AsEnv() []string {
 }
 
 // StackImageRefs function selects the appropriate set of Docker image references for the given stack version.
-func (ac *ApplicationConfiguration) StackImageRefs(version string) ImageRefs {
-	refs := ac.c.Stack.ImageRefOverridesForVersion(version)
-	refs.ElasticAgent = stringOrDefault(refs.ElasticAgent, fmt.Sprintf("%s:%s", selectElasticAgentImageName(version), version))
-	refs.Elasticsearch = stringOrDefault(refs.Elasticsearch, fmt.Sprintf("%s:%s", elasticsearchImageName, version))
-	refs.Kibana = stringOrDefault(refs.Kibana, fmt.Sprintf("%s:%s", kibanaImageName, version))
-	refs.Logstash = stringOrDefault(refs.Logstash, fmt.Sprintf("%s:%s", logstashImageName, version))
+func (ac *ApplicationConfiguration) StackImageRefs() ImageRefs {
+	refs := ac.c.Stack.ImageRefOverridesForVersion(ac.stackVersion)
+	refs.ElasticAgent = stringOrDefault(refs.ElasticAgent, fmt.Sprintf("%s:%s", selectElasticAgentImageName(ac.stackVersion, ac.agentBaseImage), ac.stackVersion))
+	refs.Elasticsearch = stringOrDefault(refs.Elasticsearch, fmt.Sprintf("%s:%s", elasticsearchImageName, ac.stackVersion))
+	refs.Kibana = stringOrDefault(refs.Kibana, fmt.Sprintf("%s:%s", kibanaImageName, ac.stackVersion))
+	refs.Logstash = stringOrDefault(refs.Logstash, fmt.Sprintf("%s:%s", logstashImageName, ac.stackVersion))
 	return refs
 }
 
@@ -148,7 +150,7 @@ func (ac *ApplicationConfiguration) SetCurrentProfile(name string) {
 
 // selectElasticAgentImageName function returns the appropriate image name for Elastic-Agent depending on the stack version.
 // This is mandatory as "elastic-agent-complete" is available since 7.15.0-SNAPSHOT.
-func selectElasticAgentImageName(version string) string {
+func selectElasticAgentImageName(version, agentBaseImage string) string {
 	if version == "" { // as version is optional and can be empty
 		return elasticAgentImageName
 	}
@@ -164,20 +166,41 @@ func selectElasticAgentImageName(version string) string {
 	if ok && strings.ToLower(valueEnv) != "false" {
 		disableWolfiImages = true
 	}
-	if !disableWolfiImages && !v.LessThan(elasticAgentWolfiVersion) {
+	switch {
+	case !disableWolfiImages && !v.LessThan(elasticAgentWolfiVersion) && agentBaseImage != "complete":
 		return elasticAgentWolfiImageName
-	}
-	if !v.LessThan(elasticAgentCompleteOwnNamespaceVersion) {
+	case !v.LessThan(elasticAgentCompleteOwnNamespaceVersion):
 		return elasticAgentCompleteImageName
-	}
-	if !v.LessThan(elasticAgentCompleteFirstSupportedVersion) {
+	case !v.LessThan(elasticAgentCompleteFirstSupportedVersion):
 		return elasticAgentCompleteLegacyImageName
+	default:
+		return elasticAgentImageName
+	}
+}
+
+type configurationOptions struct {
+	agentBaseImage string
+	stackVersion   string
+}
+
+type ConfigurationOption func(*configurationOptions)
+
+// OptionWithAgentBaseImage sets the agent image type to be used.
+func OptionWithAgentBaseImage(agentBaseImage string) ConfigurationOption {
+	return func(opts *configurationOptions) {
+		opts.agentBaseImage = agentBaseImage
+	}
+}
+
+// OptionWithStackVersion sets the Elastic Stack version to be used.
+func OptionWithStackVersion(stackVersion string) ConfigurationOption {
+	return func(opts *configurationOptions) {
+		opts.stackVersion = stackVersion
 	}
-	return elasticAgentImageName
 }
 
 // Configuration function returns the elastic-package configuration.
-func Configuration() (*ApplicationConfiguration, error) {
+func Configuration(options ...ConfigurationOption) (*ApplicationConfiguration, error) {
 	configPath, err := locations.NewLocationManager()
 	if err != nil {
 		return nil, fmt.Errorf("can't read configuration directory: %w", err)
@@ -197,9 +220,18 @@ func Configuration() (*ApplicationConfiguration, error) {
 		return nil, fmt.Errorf("can't unmarshal configuration file: %w", err)
 	}
 
-	return &ApplicationConfiguration{
-		c: c,
-	}, nil
+	configOptions := configurationOptions{}
+	for _, option := range options {
+		option(&configOptions)
+	}
+
+	configuration := ApplicationConfiguration{
+		c:              c,
+		agentBaseImage: configOptions.agentBaseImage,
+		stackVersion:   configOptions.stackVersion,
+	}
+
+	return &configuration, nil
 }
 
 func stringOrDefault(value string, defaultValue string) string {
diff --git a/internal/install/application_configuration_test.go b/internal/install/application_configuration_test.go
index 5f20f3419..f41302ae2 100644
--- a/internal/install/application_configuration_test.go
+++ b/internal/install/application_configuration_test.go
@@ -12,61 +12,72 @@ import (
 
 func TestSelectElasticAgentImageName_NoVersion(t *testing.T) {
 	var version string
-	selected := selectElasticAgentImageName(version)
+	selected := selectElasticAgentImageName(version, "")
 	assert.Equal(t, selected, elasticAgentImageName)
 }
 
 func TestSelectElasticAgentImageName_OlderStack(t *testing.T) {
 	version := "7.14.99-SNAPSHOT"
-	selected := selectElasticAgentImageName(version)
+	selected := selectElasticAgentImageName(version, "")
 	assert.Equal(t, selected, elasticAgentImageName)
 }
 
 func TestSelectElasticAgentImageName_FirstStackWithCompleteAgent(t *testing.T) {
 	version := stackVersion715
-	selected := selectElasticAgentImageName(version)
+	selected := selectElasticAgentImageName(version, "")
 	assert.Equal(t, selected, elasticAgentCompleteLegacyImageName)
 }
 
 func TestSelectElasticAgentImageName_NextStackWithAgentComplete(t *testing.T) {
 	version := "7.16.0-SNAPSHOT"
-	selected := selectElasticAgentImageName(version)
+	selected := selectElasticAgentImageName(version, "")
 	assert.Equal(t, selected, elasticAgentCompleteLegacyImageName)
 }
 
 func TestSelectElasticAgentImageName_OwnNamespace(t *testing.T) {
 	version := "8.2.0-SNAPSHOT"
-	selected := selectElasticAgentImageName(version)
+	selected := selectElasticAgentImageName(version, "")
 	assert.Equal(t, selected, elasticAgentCompleteImageName)
 }
 
 func TestSelectElasticAgentImageName_OwnNamespace_Release(t *testing.T) {
 	version := "8.2.0"
-	selected := selectElasticAgentImageName(version)
+	selected := selectElasticAgentImageName(version, "")
 	assert.Equal(t, selected, elasticAgentCompleteImageName)
 }
 
 func TestSelectElasticAgentImageName_NextStackInOwnNamespace(t *testing.T) {
 	version := "8.4.0-SNAPSHOT"
-	selected := selectElasticAgentImageName(version)
+	selected := selectElasticAgentImageName(version, "")
 	assert.Equal(t, selected, elasticAgentCompleteImageName)
 }
 
 func TestSelectElasticAgentImageName_WolfiImage(t *testing.T) {
 	version := "8.16.0-SNAPSHOT"
-	selected := selectElasticAgentImageName(version)
+	selected := selectElasticAgentImageName(version, "")
 	assert.Equal(t, selected, elasticAgentWolfiImageName)
 }
 
 func TestSelectElasticAgentImageName_DisableWolfiImageEnvVar(t *testing.T) {
 	version := "8.16.0-SNAPSHOT"
 	t.Setenv(disableElasticAgentWolfiEnvVar, "true")
-	selected := selectElasticAgentImageName(version)
+	selected := selectElasticAgentImageName(version, "")
 	assert.Equal(t, selected, elasticAgentCompleteImageName)
 }
 func TestSelectElasticAgentImageName_EnableWolfiImageEnvVar(t *testing.T) {
 	version := "8.16.0-SNAPSHOT"
 	t.Setenv(disableElasticAgentWolfiEnvVar, "false")
-	selected := selectElasticAgentImageName(version)
+	selected := selectElasticAgentImageName(version, "")
+	assert.Equal(t, selected, elasticAgentWolfiImageName)
+}
+
+func TestSelectCompleteElasticAgentImageName_ForceCompleteImage(t *testing.T) {
+	version := "8.16.0-SNAPSHOT"
+	selected := selectElasticAgentImageName(version, "complete")
+	assert.Equal(t, selected, elasticAgentCompleteImageName)
+}
+func TestSelectCompleteElasticAgentImageName_ForceDefaultImage(t *testing.T) {
+	version := "8.16.0-SNAPSHOT"
+	selected := selectElasticAgentImageName(version, "default")
 	assert.Equal(t, selected, elasticAgentWolfiImageName)
 }
diff --git a/internal/servicedeployer/custom_agent.go b/internal/servicedeployer/custom_agent.go
index 1931b1bd6..6f9ee5253 100644
--- a/internal/servicedeployer/custom_agent.go
+++ b/internal/servicedeployer/custom_agent.go
@@ -72,7 +72,7 @@ func NewCustomAgentDeployer(options CustomAgentDeployerOptions) (*CustomAgentDep
 func (d *CustomAgentDeployer) SetUp(ctx context.Context, svcInfo ServiceInfo) (DeployedService, error) {
 	logger.Warn("DEPRECATED - setting up service using Docker Compose service deployer")
 
-	appConfig, err := install.Configuration()
+	appConfig, err := install.Configuration(install.OptionWithStackVersion(d.stackVersion))
 	if err != nil {
 		return nil, fmt.Errorf("can't read application configuration: %w", err)
 	}
@@ -90,7 +90,7 @@ func (d *CustomAgentDeployer) SetUp(ctx context.Context, svcInfo ServiceInfo) (D
 	svcInfo.Hostname = dockerCustomAgentName
 
 	env := append(
-		appConfig.StackImageRefs(d.stackVersion).AsEnv(),
+		appConfig.StackImageRefs().AsEnv(),
 		fmt.Sprintf("%s=%s", serviceLogsDirEnv, svcInfo.Logs.Folder.Local),
 		fmt.Sprintf("%s=%s", localCACertEnv, caCertPath),
 		fmt.Sprintf("%s=%s", fleetPolicyEnv, d.policyName),
diff --git a/internal/servicedeployer/kubernetes.go b/internal/servicedeployer/kubernetes.go
index 3b967285b..2d982d416 100644
--- a/internal/servicedeployer/kubernetes.go
+++ b/internal/servicedeployer/kubernetes.go
@@ -229,7 +229,7 @@ var elasticAgentManagedYamlTmpl string
 func getElasticAgentYAML(profile *profile.Profile, stackVersion, policyName string) ([]byte, error) {
 	logger.Debugf("Prepare YAML definition for Elastic Agent running in stack v%s", stackVersion)
 
-	appConfig, err := install.Configuration()
+	appConfig, err := install.Configuration(install.OptionWithStackVersion(stackVersion))
 	if err != nil {
 		return nil, fmt.Errorf("can't read application configuration: %w", err)
 	}
@@ -246,7 +246,7 @@ func getElasticAgentYAML(profile *profile.Profile, stackVersion, policyName stri
 		"fleetURL":                    "https://fleet-server:8220",
 		"kibanaURL":                   "https://kibana:5601",
 		"caCertPem":                   caCert,
-		"elasticAgentImage":           appConfig.StackImageRefs(stackVersion).ElasticAgent,
+		"elasticAgentImage":           appConfig.StackImageRefs().ElasticAgent,
 		"elasticAgentTokenPolicyName": getTokenPolicyName(stackVersion, policyName),
 	})
 	if err != nil {
diff --git a/internal/stack/compose.go b/internal/stack/compose.go
index a0afa8b85..483e638e8 100644
--- a/internal/stack/compose.go
+++ b/internal/stack/compose.go
@@ -56,14 +56,14 @@ func dockerComposeBuild(ctx context.Context, options Options) error {
 		return fmt.Errorf("could not create docker compose project: %w", err)
 	}
 
-	appConfig, err := install.Configuration()
+	appConfig, err := install.Configuration(install.OptionWithStackVersion(options.StackVersion))
 	if err != nil {
 		return fmt.Errorf("can't read application configuration: %w", err)
 	}
 
 	opts := compose.CommandOptions{
 		Env: newEnvBuilder().
-			withEnvs(appConfig.StackImageRefs(options.StackVersion).AsEnv()).
+			withEnvs(appConfig.StackImageRefs().AsEnv()).
 			withEnv(stackVariantAsEnv(options.StackVersion)).
 			withEnvs(options.Profile.ComposeEnvVars()).
 			build(),
@@ -82,14 +82,14 @@ func dockerComposePull(ctx context.Context, options Options) error {
 		return fmt.Errorf("could not create docker compose project: %w", err)
 	}
 
-	appConfig, err := install.Configuration()
+	appConfig, err := install.Configuration(install.OptionWithStackVersion(options.StackVersion))
 	if err != nil {
 		return fmt.Errorf("can't read application configuration: %w", err)
 	}
 
 	opts := compose.CommandOptions{
 		Env: newEnvBuilder().
-			withEnvs(appConfig.StackImageRefs(options.StackVersion).AsEnv()).
+			withEnvs(appConfig.StackImageRefs().AsEnv()).
 			withEnv(stackVariantAsEnv(options.StackVersion)).
 			withEnvs(options.Profile.ComposeEnvVars()).
 			build(),
@@ -113,14 +113,14 @@ func dockerComposeUp(ctx context.Context, options Options) error {
 		args = append(args, "-d")
 	}
 
-	appConfig, err := install.Configuration()
+	appConfig, err := install.Configuration(install.OptionWithStackVersion(options.StackVersion))
 	if err != nil {
 		return fmt.Errorf("can't read application configuration: %w", err)
 	}
 
 	opts := compose.CommandOptions{
 		Env: newEnvBuilder().
-			withEnvs(appConfig.StackImageRefs(options.StackVersion).AsEnv()).
+			withEnvs(appConfig.StackImageRefs().AsEnv()).
 			withEnv(stackVariantAsEnv(options.StackVersion)).
 			withEnvs(options.Profile.ComposeEnvVars()).
 			build(),
@@ -140,14 +140,14 @@ func dockerComposeDown(ctx context.Context, options Options) error {
 		return fmt.Errorf("could not create docker compose project: %w", err)
 	}
 
-	appConfig, err := install.Configuration()
+	appConfig, err := install.Configuration(install.OptionWithStackVersion(options.StackVersion))
 	if err != nil {
 		return fmt.Errorf("can't read application configuration: %w", err)
 	}
 
 	downOptions := compose.CommandOptions{
 		Env: newEnvBuilder().
-			withEnvs(appConfig.StackImageRefs(options.StackVersion).AsEnv()).
+			withEnvs(appConfig.StackImageRefs().AsEnv()).
 			withEnv(stackVariantAsEnv(options.StackVersion)).
 			withEnvs(options.Profile.ComposeEnvVars()).
 			build(),
diff --git a/internal/stack/logs.go b/internal/stack/logs.go
index 0e821e0e7..7e6356de3 100644
--- a/internal/stack/logs.go
+++ b/internal/stack/logs.go
@@ -17,7 +17,7 @@ import (
 )
 
 func dockerComposeLogsSince(ctx context.Context, serviceName string, profile *profile.Profile, since time.Time) ([]byte, error) {
-	appConfig, err := install.Configuration()
+	appConfig, err := install.Configuration(install.OptionWithStackVersion(install.DefaultStackVersion))
 	if err != nil {
 		return nil, fmt.Errorf("can't read application configuration: %w", err)
 	}
@@ -31,7 +31,7 @@ func dockerComposeLogsSince(ctx context.Context, serviceName string, profile *pr
 
 	opts := compose.CommandOptions{
 		Env: newEnvBuilder().
-			withEnvs(appConfig.StackImageRefs(install.DefaultStackVersion).AsEnv()).
+			withEnvs(appConfig.StackImageRefs().AsEnv()).
 			withEnv(stackVariantAsEnv(install.DefaultStackVersion)).
 			withEnvs(profile.ComposeEnvVars()).
 			build(),
diff --git a/internal/stack/serverlessresources.go b/internal/stack/serverlessresources.go
index 3c94d227d..058290665 100644
--- a/internal/stack/serverlessresources.go
+++ b/internal/stack/serverlessresources.go
@@ -32,18 +32,19 @@ var (
 )
 
 func applyServerlessResources(profile *profile.Profile, stackVersion string, config Config) error {
-	appConfig, err := install.Configuration()
+	appConfig, err := install.Configuration(install.OptionWithStackVersion(stackVersion))
 	if err != nil {
 		return fmt.Errorf("can't read application configuration: %w", err)
 	}
+	imageRefs := appConfig.StackImageRefs()
 
 	stackDir := filepath.Join(profile.ProfilePath, ProfileStackPath)
 
 	resourceManager := resource.NewManager()
 	resourceManager.AddFacter(resource.StaticFacter{
 		"agent_version":      stackVersion,
-		"agent_image":        appConfig.StackImageRefs(stackVersion).ElasticAgent,
-		"logstash_image":     appConfig.StackImageRefs(stackVersion).Logstash,
+		"agent_image":        imageRefs.ElasticAgent,
+		"logstash_image":     imageRefs.Logstash,
 		"elasticsearch_host": esHostWithPort(config.ElasticsearchHost),
 		"username":           config.ElasticsearchUsername,
 		"password":           config.ElasticsearchPassword,
diff --git a/internal/testrunner/runners/system/tester.go b/internal/testrunner/runners/system/tester.go
index 61f2a00ef..db640f693 100644
--- a/internal/testrunner/runners/system/tester.go
+++ b/internal/testrunner/runners/system/tester.go
@@ -422,6 +422,11 @@ func (r *tester) createAgentInfo(policy *kibana.Policy, config *testConfig, runI
 		info.Agent.User = "root"
 	}
 
+	// This could be removed once package-spec adds this new field
+	if !slices.Contains([]string{"", "default", "complete"}, info.Agent.BaseImage) {
+		return agentdeployer.AgentInfo{}, fmt.Errorf("invalid value for agent.base_image: %q", info.Agent.BaseImage)
+	}
+
 	return info, nil
 }
 
@@ -648,7 +653,7 @@ func isSyntheticSourceModeEnabled(ctx context.Context, api *elasticsearch.API, d
 
 	// It seems that some index modes enable synthetic source mode even when it is not explicitly mentioned
 	// in the mappings. So assume that when these index modes are used, the synthetic mode is also used.
-	var syntheticsIndexModes = []string{
+	syntheticsIndexModes := []string{
 		"logs", // Replaced in 8.15.0 with "logsdb", see https://github.com/elastic/elasticsearch/pull/111054
 		"logsdb",
 		"time_series",
diff --git a/tools/readme/readme.md.tmpl b/tools/readme/readme.md.tmpl
index d916b2ef1..0191f2f65 100644
--- a/tools/readme/readme.md.tmpl
+++ b/tools/readme/readme.md.tmpl
@@ -236,7 +236,11 @@ There are available some environment variables that could be used to change some
     - `ELASTIC_PACKAGE_SERVERLESS_PIPELINE_TEST_DISABLE_COMPARE_RESULTS`: If set to `true`, the results from pipeline tests are not compared to avoid errors from GeoIP.
     - `ELASTIC_PACKAGE_DISABLE_ELASTIC_AGENT_WOLFI`: If set to `true`, the Elastic Agent image used for running agents will be using the Ubuntu docker images
       (e.g. `docker.elastic.co/elastic-agent/elastic-agent-complete`). If set to `false`, the Elastic Agent image used for the running agents will be based on the wolfi
+<<<<<<< HEAD
+      images (e.g. `docker.elastic.co/elastic-agent/elastic-agent-wolfi`). Default: `true`.
+=======
       images (e.g. `docker.elastic.co/elastic-agent/elastic-agent-wolfi`). Default: `false`.
+>>>>>>> upstream/main
 
 - To configure the Elastic stack to be used by `elastic-package`:
     - `ELASTIC_PACKAGE_ELASTICSEARCH_HOST`: Host of the elasticsearch (e.g. https://127.0.0.1:9200)