Changes `disable_remote_exec` default to true so remote exec is opt-in.

command/agent/config.go

@@ -640,7 +640,7 @@ type Config struct {
 
 	// DisableRemoteExec is used to turn off the remote execution
 	// feature. This is for security to prevent unknown scripts from running.
-	DisableRemoteExec bool `mapstructure:"disable_remote_exec"`
+	DisableRemoteExec *bool `mapstructure:"disable_remote_exec"`
 
 	// DisableUpdateCheck is used to turn off the automatic update and
 	// security bulletin checking.
@@ -828,6 +828,7 @@ func DefaultConfig() *Config {
 		ACLDefaultPolicy:   "allow",
 		ACLDisabledTTL:     120 * time.Second,
 		ACLEnforceVersion8: Bool(true),
+		DisableRemoteExec:  Bool(true),
 		RetryInterval:      30 * time.Second,
 		RetryIntervalWan:   30 * time.Second,
 
@@ -1696,8 +1697,8 @@ func MergeConfig(a, b *Config) *Config {
 	if len(b.WatchPlans) != 0 {
 		result.WatchPlans = append(result.WatchPlans, b.WatchPlans...)
 	}
-	if b.DisableRemoteExec {
-		result.DisableRemoteExec = true
+	if b.DisableRemoteExec != nil {
+		result.DisableRemoteExec = b.DisableRemoteExec
 	}
 	if b.DisableUpdateCheck {
 		result.DisableUpdateCheck = true

command/agent/config_test.go

@@ -783,14 +783,19 @@ func TestDecodeConfig(t *testing.T) {
 		t.Fatalf("bad: %#v", config)
 	}
 
-	// remote exec
-	input = `{"disable_remote_exec": true}`
+	// Remote exec is disabled by default.
+	config = DefaultConfig()
+	if *config.DisableRemoteExec != true {
+		t.Fatalf("bad: %#v", config)
+	}
+
+	// Test re-enabling remote exec.
+	input = `{"disable_remote_exec": false}`
 	config, err = DecodeConfig(bytes.NewReader([]byte(input)))
 	if err != nil {
 		t.Fatalf("err: %s", err)
 	}
-
-	if !config.DisableRemoteExec {
+	if *config.DisableRemoteExec != false {
 		t.Fatalf("bad: %#v", config)
 	}
 
@@ -1723,7 +1728,7 @@ func TestMergeConfig(t *testing.T) {
 				"handler": "foobar",
 			},
 		},
-		DisableRemoteExec: true,
+		DisableRemoteExec: Bool(true),
 		Telemetry: Telemetry{
 			StatsiteAddr:    "127.0.0.1:7250",
 			StatsitePrefix:  "stats_prefix",

command/agent/user_event.go

@@ -209,7 +209,7 @@ func (a *Agent) ingestUserEvent(msg *UserEvent) {
 	// Special handling for internal events
 	switch msg.Name {
 	case remoteExecName:
-		if a.config.DisableRemoteExec {
+		if *a.config.DisableRemoteExec {
 			a.logger.Printf("[INFO] agent: ignoring remote exec event (%s), disabled.", msg.ID)
 		} else {
 			go a.handleRemoteExec(msg)

command/exec_test.go

@@ -28,7 +28,9 @@ func TestExecCommand_implements(t *testing.T) {
 }
 
 func TestExecCommandRun(t *testing.T) {
-	a1 := testAgent(t)
+	a1 := testAgentWithConfig(t, func(c *agent.Config) {
+		c.DisableRemoteExec = agent.Bool(false)
+	})
 	defer a1.Shutdown()
 	waitForLeader(t, a1.httpAddr)
 
@@ -46,11 +48,14 @@ func TestExecCommandRun(t *testing.T) {
 }
 
 func TestExecCommandRun_CrossDC(t *testing.T) {
-	a1 := testAgent(t)
+	a1 := testAgentWithConfig(t, func(c *agent.Config) {
+		c.DisableRemoteExec = agent.Bool(false)
+	})
 	defer a1.Shutdown()
 
 	a2 := testAgentWithConfig(t, func(c *agent.Config) {
 		c.Datacenter = "dc2"
+		c.DisableRemoteExec = agent.Bool(false)
 	})
 	defer a2.Shutdown()
 
@@ -136,7 +141,9 @@ func TestExecCommand_Validate(t *testing.T) {
 }
 
 func TestExecCommand_Sessions(t *testing.T) {
-	a1 := testAgent(t)
+	a1 := testAgentWithConfig(t, func(c *agent.Config) {
+		c.DisableRemoteExec = agent.Bool(false)
+	})
 	defer a1.Shutdown()
 	waitForLeader(t, a1.httpAddr)
 
@@ -177,7 +184,9 @@ func TestExecCommand_Sessions(t *testing.T) {
 }
 
 func TestExecCommand_Sessions_Foreign(t *testing.T) {
-	a1 := testAgent(t)
+	a1 := testAgentWithConfig(t, func(c *agent.Config) {
+		c.DisableRemoteExec = agent.Bool(false)
+	})
 	defer a1.Shutdown()
 	waitForLeader(t, a1.httpAddr)
 
@@ -228,7 +237,9 @@ func TestExecCommand_Sessions_Foreign(t *testing.T) {
 }
 
 func TestExecCommand_UploadDestroy(t *testing.T) {
-	a1 := testAgent(t)
+	a1 := testAgentWithConfig(t, func(c *agent.Config) {
+		c.DisableRemoteExec = agent.Bool(false)
+	})
 	defer a1.Shutdown()
 	waitForLeader(t, a1.httpAddr)
 
@@ -285,7 +296,9 @@ func TestExecCommand_UploadDestroy(t *testing.T) {
 }
 
 func TestExecCommand_StreamResults(t *testing.T) {
-	a1 := testAgent(t)
+	a1 := testAgentWithConfig(t, func(c *agent.Config) {
+		c.DisableRemoteExec = agent.Bool(false)
+	})
 	defer a1.Shutdown()
 	waitForLeader(t, a1.httpAddr)
 

website/source/docs/agent/options.html.markdown

@@ -632,7 +632,8 @@ Consul will not enable TLS for the HTTP API unless the `https` port has been ass
 
 * <a name="disable_remote_exec"></a><a href="#disable_remote_exec">`disable_remote_exec`</a>
   Disables support for remote execution. When set to true, the agent will ignore any incoming
-  remote exec requests.
+  remote exec requests. In versions of Consul prior to 0.8, this defaulted to false. In Consul
+  0.8 the default was changed to true, to make remote exec opt-in instead of opt-out.
 
 * <a name="disable_update_check"></a><a href="#disable_update_check">`disable_update_check`</a>
   Disables automatic checking for security bulletins and new version releases.

website/source/docs/upgrade-specific.html.markdown

@@ -37,7 +37,13 @@ and update any scripts that passed a custom `-rpc-addr` to the following command
 
 The [`acl_enforce_version_8`](/docs/agent/options.html#acl_enforce_version_8) configuration now defaults to `true` to enable [full version 8 ACL support](/docs/internals/acl.html#version_8_acls) by default. If you are upgrading an existing cluster with ACLs enabled, you will need to set this to `false` during the upgrade on **both Consul agents and Consul servers**. Version 8 ACLs were also changed so that [`acl_datacenter`](/docs/agent/options.html#acl_datacenter) must be set on agents in order to enable the agent-side enforcement of ACLs. This makes for a smoother experience in clusters where ACLs aren't enabled at all, but where the agents would have to wait to contact a Consul server before learning that.
 
-#### <a name="raft_protocol"></a><a href="#raft_protocol">Raft Protocol Version Compatibility</a>
+#### Remote Exec Is Now Opt-In
+
+The default for [`disable_remote_exec`](/docs/agent/options.html#disable_remote_exec) was
+changed to "true", so now operators need to opt-in to having agents support running
+commands remotely via [`consul exec`](/docs/commands/exec.html).
+
+#### Raft Protocol Version Compatibility
 
 When upgrading to Consul 0.8.0 from a version lower than 0.7.0, users will need to
 set the [`-raft-protocol`](/docs/agent/options.html#_raft_protocol) option to 1 in