agent: add disable_idle_connections configurable (#15986)

* agent: add disable_keep_alives configurable

* Add empty test

* Add website doc

* Change to disable_idle_connections

* Update tests and doc

* Add note about env

* Changelog

* Change to slice

* Remove unused disable keep alive methods

* Add invalid value test

api/client.go

@@ -720,6 +720,24 @@ func (c *Client) SetMaxRetries(retries int) {
 	c.config.MaxRetries = retries
 }
 
+func (c *Client) SetMaxIdleConnections(idle int) {
+	c.modifyLock.RLock()
+	defer c.modifyLock.RUnlock()
+	c.config.modifyLock.Lock()
+	defer c.config.modifyLock.Unlock()
+
+	c.config.HttpClient.Transport.(*http.Transport).MaxIdleConns = idle
+}
+
+func (c *Client) MaxIdleConnections() int {
+	c.modifyLock.RLock()
+	defer c.modifyLock.RUnlock()
+	c.config.modifyLock.Lock()
+	defer c.config.modifyLock.Unlock()
+
+	return c.config.HttpClient.Transport.(*http.Transport).MaxIdleConns
+}
+
 func (c *Client) MaxRetries() int {
 	c.modifyLock.RLock()
 	defer c.modifyLock.RUnlock()

changelog/15986.txt

@@ -0,0 +1,2 @@
+```release-note:improvement
+agent: Added `disable_idle_connections` configuration to disable leaving idle connections open in auto-auth, caching and templating.

command/agent.go

@@ -368,13 +368,24 @@ func (c *AgentCommand) Run(args []string) int {
 			client.SetNamespace(config.AutoAuth.Method.Namespace)
 		}
 		templateNamespace = client.Headers().Get(consts.NamespaceHeaderName)
+
+		sinkClient, err := client.CloneWithHeaders()
+		if err != nil {
+			c.UI.Error(fmt.Sprintf("Error cloning client for file sink: %v", err))
+			return 1
+		}
+
+		if config.DisableIdleConnsAutoAuth {
+			sinkClient.SetMaxIdleConnections(-1)
+		}
+
 		for _, sc := range config.AutoAuth.Sinks {
 			switch sc.Type {
 			case "file":
 				config := &sink.SinkConfig{
 					Logger:    c.logger.Named("sink.file"),
 					Config:    sc.Config,
-					Client:    client,
+					Client:    sinkClient,
 					WrapTTL:   sc.WrapTTL,
 					DHType:    sc.DHType,
 					DeriveKey: sc.DeriveKey,
@@ -490,9 +501,19 @@ func (c *AgentCommand) Run(args []string) int {
 	if config.Cache != nil {
 		cacheLogger := c.logger.Named("cache")
 
+		proxyClient, err := client.CloneWithHeaders()
+		if err != nil {
+			c.UI.Error(fmt.Sprintf("Error cloning client for caching: %v", err))
+			return 1
+		}
+
+		if config.DisableIdleConnsAutoAuth {
+			proxyClient.SetMaxIdleConnections(-1)
+		}
+
 		// Create the API proxier
 		apiProxy, err := cache.NewAPIProxy(&cache.APIProxyConfig{
-			Client:                 client,
+			Client:                 proxyClient,
 			Logger:                 cacheLogger.Named("apiproxy"),
 			EnforceConsistency:     enforceConsistency,
 			WhenInconsistentAction: whenInconsistent,
@@ -505,7 +526,7 @@ func (c *AgentCommand) Run(args []string) int {
 		// Create the lease cache proxier and set its underlying proxier to
 		// the API proxier.
 		leaseCache, err = cache.NewLeaseCache(&cache.LeaseCacheConfig{
-			Client:      client,
+			Client:      proxyClient,
 			BaseContext: ctx,
 			Proxier:     apiProxy,
 			Logger:      cacheLogger.Named("leasecache"),
@@ -793,14 +814,19 @@ func (c *AgentCommand) Run(args []string) int {
 
 		// Auth Handler is going to set its own retry values, so we want to
 		// work on a copy of the client to not affect other subsystems.
-		clonedClient, err := c.client.CloneWithHeaders()
+		ahClient, err := c.client.CloneWithHeaders()
 		if err != nil {
 			c.UI.Error(fmt.Sprintf("Error cloning client for auth handler: %v", err))
 			return 1
 		}
+
+		if config.DisableIdleConnsAutoAuth {
+			ahClient.SetMaxIdleConnections(-1)
+		}
+
 		ah := auth.NewAuthHandler(&auth.AuthHandlerConfig{
 			Logger:                       c.logger.Named("auth.handler"),
-			Client:                       clonedClient,
+			Client:                       ahClient,
 			WrapTTL:                      config.AutoAuth.Method.WrapTTL,
 			MinBackoff:                   config.AutoAuth.Method.MinBackoff,
 			MaxBackoff:                   config.AutoAuth.Method.MaxBackoff,
@@ -811,7 +837,7 @@ func (c *AgentCommand) Run(args []string) int {
 
 		ss := sink.NewSinkServer(&sink.SinkServerConfig{
 			Logger:        c.logger.Named("sink.server"),
-			Client:        client,
+			Client:        ahClient,
 			ExitAfterAuth: exitAfterAuth,
 		})
 

command/agent/config/config.go

@@ -30,8 +30,14 @@ type Config struct {
 	Vault                      *Vault                     `hcl:"vault"`
 	TemplateConfig             *TemplateConfig            `hcl:"template_config"`
 	Templates                  []*ctconfig.TemplateConfig `hcl:"templates"`
+	DisableIdleConns           []string                   `hcl:"disable_idle_connections"`
+	DisableIdleConnsCaching    bool                       `hcl:"-"`
+	DisableIdleConnsTemplating bool                       `hcl:"-"`
+	DisableIdleConnsAutoAuth   bool                       `hcl:"-"`
 }
 
+const DisableIdleConnsEnv = "VAULT_AGENT_DISABLE_IDLE_CONNECTIONS"
+
 func (c *Config) Prune() {
 	for _, l := range c.Listeners {
 		l.RawConfig = nil
@@ -260,6 +266,28 @@ func LoadConfig(path string) (*Config, error) {
 		result.Vault.Retry.NumRetries = 0
 	}
 
+	if disableIdleConnsEnv := os.Getenv(DisableIdleConnsEnv); disableIdleConnsEnv != "" {
+		result.DisableIdleConns, err = parseutil.ParseCommaStringSlice(strings.ToLower(disableIdleConnsEnv))
+		if err != nil {
+			return nil, fmt.Errorf("error parsing environment variable %s: %v", DisableIdleConnsEnv, err)
+		}
+	}
+
+	for _, subsystem := range result.DisableIdleConns {
+		switch subsystem {
+		case "auto-auth":
+			result.DisableIdleConnsAutoAuth = true
+		case "caching":
+			result.DisableIdleConnsCaching = true
+		case "templating":
+			result.DisableIdleConnsTemplating = true
+		case "":
+			continue
+		default:
+			return nil, fmt.Errorf("unknown disable_idle_connections value: %s", subsystem)
+		}
+	}
+
 	return result, nil
 }
 

command/agent/config/config_test.go

@@ -1033,3 +1033,310 @@ func TestLoadConfigFile_EnforceConsistency(t *testing.T) {
 		t.Fatal(diff)
 	}
 }
+
+func TestLoadConfigFile_Disable_Idle_Conns_All(t *testing.T) {
+	config, err := LoadConfig("./test-fixtures/config-disable-idle-connections-all.hcl")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expected := &Config{
+		SharedConfig: &configutil.SharedConfig{
+			PidFile: "./pidfile",
+		},
+		DisableIdleConns:           []string{"auto-auth", "caching", "templating"},
+		DisableIdleConnsCaching:    true,
+		DisableIdleConnsAutoAuth:   true,
+		DisableIdleConnsTemplating: true,
+		AutoAuth: &AutoAuth{
+			Method: &Method{
+				Type:      "aws",
+				MountPath: "auth/aws",
+				Namespace: "my-namespace/",
+				Config: map[string]interface{}{
+					"role": "foobar",
+				},
+			},
+			Sinks: []*Sink{
+				{
+					Type:   "file",
+					DHType: "curve25519",
+					DHPath: "/tmp/file-foo-dhpath",
+					AAD:    "foobar",
+					Config: map[string]interface{}{
+						"path": "/tmp/file-foo",
+					},
+				},
+			},
+		},
+		Vault: &Vault{
+			Address: "http://127.0.0.1:1111",
+			Retry: &Retry{
+				ctconfig.DefaultRetryAttempts,
+			},
+		},
+	}
+
+	config.Prune()
+	if diff := deep.Equal(config, expected); diff != nil {
+		t.Fatal(diff)
+	}
+}
+
+func TestLoadConfigFile_Disable_Idle_Conns_Auto_Auth(t *testing.T) {
+	config, err := LoadConfig("./test-fixtures/config-disable-idle-connections-auto-auth.hcl")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expected := &Config{
+		SharedConfig: &configutil.SharedConfig{
+			PidFile: "./pidfile",
+		},
+		DisableIdleConns:           []string{"auto-auth"},
+		DisableIdleConnsCaching:    false,
+		DisableIdleConnsAutoAuth:   true,
+		DisableIdleConnsTemplating: false,
+		AutoAuth: &AutoAuth{
+			Method: &Method{
+				Type:      "aws",
+				MountPath: "auth/aws",
+				Namespace: "my-namespace/",
+				Config: map[string]interface{}{
+					"role": "foobar",
+				},
+			},
+			Sinks: []*Sink{
+				{
+					Type:   "file",
+					DHType: "curve25519",
+					DHPath: "/tmp/file-foo-dhpath",
+					AAD:    "foobar",
+					Config: map[string]interface{}{
+						"path": "/tmp/file-foo",
+					},
+				},
+			},
+		},
+		Vault: &Vault{
+			Address: "http://127.0.0.1:1111",
+			Retry: &Retry{
+				ctconfig.DefaultRetryAttempts,
+			},
+		},
+	}
+
+	config.Prune()
+	if diff := deep.Equal(config, expected); diff != nil {
+		t.Fatal(diff)
+	}
+}
+
+func TestLoadConfigFile_Disable_Idle_Conns_Templating(t *testing.T) {
+	config, err := LoadConfig("./test-fixtures/config-disable-idle-connections-templating.hcl")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expected := &Config{
+		SharedConfig: &configutil.SharedConfig{
+			PidFile: "./pidfile",
+		},
+		DisableIdleConns:           []string{"templating"},
+		DisableIdleConnsCaching:    false,
+		DisableIdleConnsAutoAuth:   false,
+		DisableIdleConnsTemplating: true,
+		AutoAuth: &AutoAuth{
+			Method: &Method{
+				Type:      "aws",
+				MountPath: "auth/aws",
+				Namespace: "my-namespace/",
+				Config: map[string]interface{}{
+					"role": "foobar",
+				},
+			},
+			Sinks: []*Sink{
+				{
+					Type:   "file",
+					DHType: "curve25519",
+					DHPath: "/tmp/file-foo-dhpath",
+					AAD:    "foobar",
+					Config: map[string]interface{}{
+						"path": "/tmp/file-foo",
+					},
+				},
+			},
+		},
+		Vault: &Vault{
+			Address: "http://127.0.0.1:1111",
+			Retry: &Retry{
+				ctconfig.DefaultRetryAttempts,
+			},
+		},
+	}
+
+	config.Prune()
+	if diff := deep.Equal(config, expected); diff != nil {
+		t.Fatal(diff)
+	}
+}
+
+func TestLoadConfigFile_Disable_Idle_Conns_Caching(t *testing.T) {
+	config, err := LoadConfig("./test-fixtures/config-disable-idle-connections-caching.hcl")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expected := &Config{
+		SharedConfig: &configutil.SharedConfig{
+			PidFile: "./pidfile",
+		},
+		DisableIdleConns:           []string{"caching"},
+		DisableIdleConnsCaching:    true,
+		DisableIdleConnsAutoAuth:   false,
+		DisableIdleConnsTemplating: false,
+		AutoAuth: &AutoAuth{
+			Method: &Method{
+				Type:      "aws",
+				MountPath: "auth/aws",
+				Namespace: "my-namespace/",
+				Config: map[string]interface{}{
+					"role": "foobar",
+				},
+			},
+			Sinks: []*Sink{
+				{
+					Type:   "file",
+					DHType: "curve25519",
+					DHPath: "/tmp/file-foo-dhpath",
+					AAD:    "foobar",
+					Config: map[string]interface{}{
+						"path": "/tmp/file-foo",
+					},
+				},
+			},
+		},
+		Vault: &Vault{
+			Address: "http://127.0.0.1:1111",
+			Retry: &Retry{
+				ctconfig.DefaultRetryAttempts,
+			},
+		},
+	}
+
+	config.Prune()
+	if diff := deep.Equal(config, expected); diff != nil {
+		t.Fatal(diff)
+	}
+}
+
+func TestLoadConfigFile_Disable_Idle_Conns_Empty(t *testing.T) {
+	config, err := LoadConfig("./test-fixtures/config-disable-idle-connections-empty.hcl")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expected := &Config{
+		SharedConfig: &configutil.SharedConfig{
+			PidFile: "./pidfile",
+		},
+		DisableIdleConns:           []string{},
+		DisableIdleConnsCaching:    false,
+		DisableIdleConnsAutoAuth:   false,
+		DisableIdleConnsTemplating: false,
+		AutoAuth: &AutoAuth{
+			Method: &Method{
+				Type:      "aws",
+				MountPath: "auth/aws",
+				Namespace: "my-namespace/",
+				Config: map[string]interface{}{
+					"role": "foobar",
+				},
+			},
+			Sinks: []*Sink{
+				{
+					Type:   "file",
+					DHType: "curve25519",
+					DHPath: "/tmp/file-foo-dhpath",
+					AAD:    "foobar",
+					Config: map[string]interface{}{
+						"path": "/tmp/file-foo",
+					},
+				},
+			},
+		},
+		Vault: &Vault{
+			Address: "http://127.0.0.1:1111",
+			Retry: &Retry{
+				ctconfig.DefaultRetryAttempts,
+			},
+		},
+	}
+
+	config.Prune()
+	if diff := deep.Equal(config, expected); diff != nil {
+		t.Fatal(diff)
+	}
+}
+
+func TestLoadConfigFile_Disable_Idle_Conns_Env(t *testing.T) {
+	err := os.Setenv(DisableIdleConnsEnv, "auto-auth,caching,templating")
+	defer os.Unsetenv(DisableIdleConnsEnv)
+
+	if err != nil {
+		t.Fatal(err)
+	}
+	config, err := LoadConfig("./test-fixtures/config-disable-idle-connections-empty.hcl")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expected := &Config{
+		SharedConfig: &configutil.SharedConfig{
+			PidFile: "./pidfile",
+		},
+		DisableIdleConns:           []string{"auto-auth", "caching", "templating"},
+		DisableIdleConnsCaching:    true,
+		DisableIdleConnsAutoAuth:   true,
+		DisableIdleConnsTemplating: true,
+		AutoAuth: &AutoAuth{
+			Method: &Method{
+				Type:      "aws",
+				MountPath: "auth/aws",
+				Namespace: "my-namespace/",
+				Config: map[string]interface{}{
+					"role": "foobar",
+				},
+			},
+			Sinks: []*Sink{
+				{
+					Type:   "file",
+					DHType: "curve25519",
+					DHPath: "/tmp/file-foo-dhpath",
+					AAD:    "foobar",
+					Config: map[string]interface{}{
+						"path": "/tmp/file-foo",
+					},
+				},
+			},
+		},
+		Vault: &Vault{
+			Address: "http://127.0.0.1:1111",
+			Retry: &Retry{
+				ctconfig.DefaultRetryAttempts,
+			},
+		},
+	}
+
+	config.Prune()
+	if diff := deep.Equal(config, expected); diff != nil {
+		t.Fatal(diff)
+	}
+}
+
+func TestLoadConfigFile_Bad_Value_Disable_Idle_Conns(t *testing.T) {
+	_, err := LoadConfig("./test-fixtures/bad-config-disable-idle-connections.hcl")
+	if err == nil {
+		t.Fatal("should have error, it didn't")
+	}
+}

command/agent/config/test-fixtures/bad-config-disable-idle-connections.hcl

@@ -0,0 +1,27 @@
+pid_file = "./pidfile"
+disable_idle_connections = ["foo","caching","templating"]
+
+auto_auth {
+  method {
+    type      = "aws"
+    namespace = "my-namespace/"
+
+    config = {
+      role = "foobar"
+    }
+  }
+
+  sink {
+    type = "file"
+    config = {
+      path = "/tmp/file-foo"
+    }
+    aad = "foobar"
+    dh_type = "curve25519"
+    dh_path = "/tmp/file-foo-dhpath"
+  }
+}
+
+vault {
+  address = "http://127.0.0.1:1111"
+}

command/agent/config/test-fixtures/config-disable-idle-connections-all.hcl

@@ -0,0 +1,27 @@
+pid_file = "./pidfile"
+disable_idle_connections = ["auto-auth","caching","templating"]
+
+auto_auth {
+  method {
+    type      = "aws"
+    namespace = "my-namespace/"
+
+    config = {
+      role = "foobar"
+    }
+  }
+
+  sink {
+    type = "file"
+    config = {
+      path = "/tmp/file-foo"
+    }
+    aad = "foobar"
+    dh_type = "curve25519"
+    dh_path = "/tmp/file-foo-dhpath"
+  }
+}
+
+vault {
+  address = "http://127.0.0.1:1111"
+}

command/agent/config/test-fixtures/config-disable-idle-connections-auto-auth.hcl

@@ -0,0 +1,27 @@
+pid_file = "./pidfile"
+disable_idle_connections = ["auto-auth"]
+
+auto_auth {
+  method {
+    type      = "aws"
+    namespace = "my-namespace/"
+
+    config = {
+      role = "foobar"
+    }
+  }
+
+  sink {
+    type = "file"
+    config = {
+      path = "/tmp/file-foo"
+    }
+    aad = "foobar"
+    dh_type = "curve25519"
+    dh_path = "/tmp/file-foo-dhpath"
+  }
+}
+
+vault {
+  address = "http://127.0.0.1:1111"
+}

command/agent/config/test-fixtures/config-disable-idle-connections-caching.hcl

@@ -0,0 +1,27 @@
+pid_file = "./pidfile"
+disable_idle_connections = ["caching"]
+
+auto_auth {
+  method {
+    type      = "aws"
+    namespace = "my-namespace/"
+
+    config = {
+      role = "foobar"
+    }
+  }
+
+  sink {
+    type = "file"
+    config = {
+      path = "/tmp/file-foo"
+    }
+    aad = "foobar"
+    dh_type = "curve25519"
+    dh_path = "/tmp/file-foo-dhpath"
+  }
+}
+
+vault {
+  address = "http://127.0.0.1:1111"
+}

command/agent/config/test-fixtures/config-disable-idle-connections-empty.hcl

@@ -0,0 +1,27 @@
+pid_file = "./pidfile"
+disable_idle_connections = []
+
+auto_auth {
+  method {
+    type      = "aws"
+    namespace = "my-namespace/"
+
+    config = {
+      role = "foobar"
+    }
+  }
+
+  sink {
+    type = "file"
+    config = {
+      path = "/tmp/file-foo"
+    }
+    aad = "foobar"
+    dh_type = "curve25519"
+    dh_path = "/tmp/file-foo-dhpath"
+  }
+}
+
+vault {
+  address = "http://127.0.0.1:1111"
+}

command/agent/config/test-fixtures/config-disable-idle-connections-templating.hcl

@@ -0,0 +1,27 @@
+pid_file = "./pidfile"
+disable_idle_connections = ["templating"]
+
+auto_auth {
+  method {
+    type      = "aws"
+    namespace = "my-namespace/"
+
+    config = {
+      role = "foobar"
+    }
+  }
+
+  sink {
+    type = "file"
+    config = {
+      path = "/tmp/file-foo"
+    }
+    aad = "foobar"
+    dh_type = "curve25519"
+    dh_path = "/tmp/file-foo-dhpath"
+  }
+}
+
+vault {
+  address = "http://127.0.0.1:1111"
+}

command/agent/template/template.go

@@ -107,6 +107,7 @@ func (ts *Server) Run(ctx context.Context, incoming chan string, templates []*ct
 	// configuration
 	var runnerConfig *ctconfig.Config
 	var runnerConfigErr error
+
 	if runnerConfig, runnerConfigErr = newRunnerConfig(ts.config, templates); runnerConfigErr != nil {
 		return fmt.Errorf("template server failed to runner generate config: %w", runnerConfigErr)
 	}
@@ -244,6 +245,11 @@ func newRunnerConfig(sc *ServerConfig, templates ctconfig.TemplateConfigs) (*ctc
 		conf.Vault.DefaultLeaseDuration = &sc.AgentConfig.TemplateConfig.StaticSecretRenderInt
 	}
 
+	if sc.AgentConfig.DisableIdleConnsTemplating {
+		idleConns := -1
+		conf.Vault.Transport.MaxIdleConns = &idleConns
+	}
+
 	conf.Vault.SSL = &ctconfig.SSLConfig{
 		Enabled:    pointerutil.BoolPtr(false),
 		Verify:     pointerutil.BoolPtr(false),

website/content/docs/agent/index.mdx

@@ -144,6 +144,10 @@ These are the currently-available general configuration option:
   with code `0` after a single successful auth, where success means that a
   token was retrieved and all sinks successfully wrote it
 
+- `disable_idle_connections` `(string array: [])` - A list of strings that disables idle connections for various features in Vault Agent.
+  Valid values include: `auto-auth`, `caching` and `templating`. Can also be configured by setting the `VAULT_AGENT_DISABLE_IDLE_CONNECTIONS` 
+  environment variable as a comma separated string. This environment variable will override any values found in a configuration file.
+
 - `template` <code>([template][template]: <optional\>)</code> - Specifies options used for templating Vault secrets to files.
 
 - `template_config` <code>([template_config][template-config]: <optional\>)</code> - Specifies templating engine behavior.