Simplify testing with TLS (#4095)

plugins/inputs/mqtt_consumer/README.md

@@ -36,11 +36,11 @@ The plugin expects messages in the
   # username = "telegraf"
   # password = "metricsmetricsmetricsmetrics"
 
-  ## Optional SSL Config
-  # ssl_ca = "/etc/telegraf/ca.pem"
-  # ssl_cert = "/etc/telegraf/cert.pem"
-  # ssl_key = "/etc/telegraf/key.pem"
-  ## Use SSL but skip chain & host verification
+  ## 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
 
   ## Data format to consume.

plugins/inputs/mqtt_consumer/mqtt_consumer.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/influxdata/telegraf"
 	"github.com/influxdata/telegraf/internal"
+	"github.com/influxdata/telegraf/internal/tls"
 	"github.com/influxdata/telegraf/plugins/inputs"
 	"github.com/influxdata/telegraf/plugins/parsers"
 
@@ -33,15 +34,7 @@ type MQTTConsumer struct {
 
 	PersistentSession bool
 	ClientID          string `toml:"client_id"`
-
-	// Path to CA file
-	SSLCA string `toml:"ssl_ca"`
-	// Path to host cert file
-	SSLCert string `toml:"ssl_cert"`
-	// Path to cert key file
-	SSLKey string `toml:"ssl_key"`
-	// Use SSL but skip chain & host verification
-	InsecureSkipVerify bool
+	tls.ClientConfig
 
 	sync.Mutex
 	client mqtt.Client
@@ -83,11 +76,11 @@ var sampleConfig = `
   # username = "telegraf"
   # password = "metricsmetricsmetricsmetrics"
 
-  ## Optional SSL Config
-  # ssl_ca = "/etc/telegraf/ca.pem"
-  # ssl_cert = "/etc/telegraf/cert.pem"
-  # ssl_key = "/etc/telegraf/key.pem"
-  ## Use SSL but skip chain & host verification
+  ## 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
 
   ## Data format to consume.
@@ -236,8 +229,7 @@ func (m *MQTTConsumer) createOpts() (*mqtt.ClientOptions, error) {
 		opts.SetClientID(m.ClientID)
 	}
 
-	tlsCfg, err := internal.GetTLSConfig(
-		m.SSLCert, m.SSLKey, m.SSLCA, m.InsecureSkipVerify)
+	tlsCfg, err := m.ClientConfig.TLSConfig()
 	if err != nil {
 		return nil, err
 	}