Simplify testing with TLS (#4095)

plugins/inputs/httpjson/README.md

@@ -34,11 +34,11 @@ Deprecated (1.6): use the [http](../http) input.
   #   "my_tag_2"
   # ]
 
-  ## 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
 
   ## HTTP Request Parameters (all values must be strings).  For "GET" requests, data

plugins/inputs/httpjson/httpjson.go

@@ -12,6 +12,7 @@ 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"
 )
@@ -29,15 +30,7 @@ type HttpJson struct {
 	ResponseTimeout internal.Duration
 	Parameters      map[string]string
 	Headers         map[string]string
-
-	// 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
 
 	client HTTPClient
 }
@@ -100,11 +93,11 @@ var sampleConfig = `
   #   "my_tag_2"
   # ]
 
-  ## 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
 
   ## HTTP parameters (all values must be strings).  For "GET" requests, data
@@ -133,8 +126,7 @@ func (h *HttpJson) Gather(acc telegraf.Accumulator) error {
 	var wg sync.WaitGroup
 
 	if h.client.HTTPClient() == nil {
-		tlsCfg, err := internal.GetTLSConfig(
-			h.SSLCert, h.SSLKey, h.SSLCA, h.InsecureSkipVerify)
+		tlsCfg, err := h.ClientConfig.TLSConfig()
 		if err != nil {
 			return err
 		}