Add TLS & credentials configuration for nats_consumer input plugin (influxdata#6195)

Author: mmelnyk

plugins/inputs/nats_consumer/README.md

@@ -12,13 +12,22 @@ instances of telegraf can read from a NATS cluster in parallel.
 [[inputs.nats_consumer]]
   ## urls of NATS servers
   servers = ["nats://localhost:4222"]
-  ## Use Transport Layer Security
-  secure = false
   ## subject(s) to consume
   subjects = ["telegraf"]
   ## name a queue group
   queue_group = "telegraf_consumers"
 
+  ## Optional credentials
+  # username = ""
+  # password = ""
+
+  ## Optional TLS Config
+  # tls_ca = "/etc/telegraf/ca.pem"
+  # tls_cert = "/etc/telegraf/cert.pem"
+  # tls_key = "/etc/telegraf/key.pem"
+  ## Use TLS but skip chain & host verification
+  # insecure_skip_verify = false
+
   ## Sets the limits for pending msgs and bytes for each subscription
   ## These shouldn't need to be adjusted except in very high throughput scenarios
   # pending_message_limit = 65536

plugins/inputs/nats_consumer/nats_consumer.go

@@ -7,6 +7,7 @@ import (
 	"sync"
 
 	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/internal/tls"
 	"github.com/influxdata/telegraf/plugins/inputs"
 	"github.com/influxdata/telegraf/plugins/parsers"
 	nats "github.com/nats-io/go-nats"
@@ -34,7 +35,11 @@ type natsConsumer struct {
 	QueueGroup string   `toml:"queue_group"`
 	Subjects   []string `toml:"subjects"`
 	Servers    []string `toml:"servers"`
-	Secure     bool     `toml:"secure"`
+	Username   string   `toml:"username"`
+	Password   string   `toml:"password"`
+	tls.ClientConfig
+	// Legacy; Should be deprecated
+	Secure bool `toml:"secure"`
 
 	// Client pending limits:
 	PendingMessageLimit int `toml:"pending_message_limit"`
@@ -61,13 +66,24 @@ type natsConsumer struct {
 var sampleConfig = `
   ## urls of NATS servers
   servers = ["nats://localhost:4222"]
-  ## Use Transport Layer Security
+  ## Deprecated: Use Transport Layer Security
   secure = false
   ## subject(s) to consume
   subjects = ["telegraf"]
   ## name a queue group
   queue_group = "telegraf_consumers"
 
+  ## Optional credentials
+  # username = ""
+  # password = ""
+
+  ## Optional TLS Config
+  # tls_ca = "/etc/telegraf/ca.pem"
+  # tls_cert = "/etc/telegraf/cert.pem"
+  # tls_key = "/etc/telegraf/key.pem"
+  ## Use TLS but skip chain & host verification
+  # insecure_skip_verify = false
+
   ## Sets the limits for pending msgs and bytes for each subscription
   ## These shouldn't need to be adjusted except in very high throughput scenarios
   # pending_message_limit = 65536
@@ -125,7 +141,25 @@ func (n *natsConsumer) Start(acc telegraf.Accumulator) error {
 	// override servers if any were specified
 	opts.Servers = n.Servers
 
-	opts.Secure = n.Secure
+	// override authentication, if any was specified
+	if n.Username != "" {
+		opts.User = n.Username
+		opts.Password = n.Password
+	}
+
+	// override TLS, if it was specified
+	tlsConfig, err := n.ClientConfig.TLSConfig()
+	if err != nil {
+		return err
+	}
+	if tlsConfig != nil {
+		// set NATS connection TLS options
+		opts.Secure = true
+		opts.TLSConfig = tlsConfig
+	} else {
+		// should be deprecated; use TLS
+		opts.Secure = n.Secure
+	}
 
 	if n.conn == nil || n.conn.IsClosed() {
 		n.conn, connectErr = opts.Connect()