Fix linting issue

Fix linting issue

Fix problems in README

Add use unregistered reads

plugins/inputs/opcua/README.md

@@ -96,6 +96,7 @@ Plugin minimum tested version: 1.16
     ## Set additional valid status codes, StatusOK (0x0) is always considered valid
     # additional_valid_status_codes = ["0xC0"]
 
+  # [inputs.opcua.request_workarounds]
     ## Use unregistered reads instead of registered reads
     # use_unregistered_reads = false
 ```
@@ -109,7 +110,7 @@ An OPC UA node ID may resemble: "ns=3;s=Temperature". In this example:
 - This example temperature node has a value of 79.0
 To gather data from this node enter the following line into the 'nodes' property above:
 
-```shell
+```text
 {field_name="temp", namespace="3", identifier_type="s", identifier="Temperature"},
 ```
 
@@ -156,16 +157,13 @@ This example group configuration has two groups with two nodes each:
 
 ## Connection Service
 
-This plugin actively reads to retrieve data from the OPC server. 
-This is done every `interval`. 
+This plugin actively reads to retrieve data from the OPC server.
+This is done every `interval`.
 
 ## Metrics
 
 The metrics collected by this input plugin will depend on the
 configured `nodes` and `group`.
-## Metrics
-
-Metrics are produced according to the defined node ID and group configuration.
 
 ## Example Output
 

plugins/inputs/opcua/opcua_reader.go

@@ -14,8 +14,9 @@ import (
 
 type OpcUaReader struct {
 	ReadClientConfig
+	Log telegraf.Logger `toml:"-"`
+
 	client *ReadClient
-	Log    telegraf.Logger `toml:"-"`
 }
 
 //go:embed sample.conf
@@ -26,9 +27,10 @@ func (*OpcUaReader) SampleConfig() string {
 }
 
 // Init Initialise all required objects
-func (o *OpcUaReader) Init() (err error) {
+func (o *OpcUaReader) Init() error {
+	var err error
 	o.client, err = o.ReadClientConfig.CreateReadClient(o.Log)
-	return
+	return err
 }
 
 // Gather defines what data the plugin will gather.

plugins/inputs/opcua/opcua_reader_test.go

@@ -44,6 +44,9 @@ nodes = [{name="name4", identifier="4000", tags=[["tag1", "override"]]}]
 
 [inputs.opcua.workarounds]
 additional_valid_status_codes = ["0xC0"]
+
+[inputs.opcua.request_workarounds]
+use_unregistered_reads = true
 `
 
 	c := config.NewConfig()
@@ -105,4 +108,5 @@ additional_valid_status_codes = ["0xC0"]
 		},
 	}, o.ReadClientConfig.Groups)
 	require.Equal(t, opcua.OpcUAWorkarounds{AdditionalValidStatusCodes: []string{"0xC0"}}, o.ReadClientConfig.Workarounds)
+	require.Equal(t, ReadClientWorkarounds{UseUnregisteredReads: true}, o.ReadClientConfig.ReadClientWorkarounds)
 }

plugins/inputs/opcua/read_client.go

@@ -5,12 +5,17 @@ import (
 	"fmt"
 	"github.com/gopcua/opcua/ua"
 	"github.com/influxdata/telegraf"
-	opcuaclient "github.com/influxdata/telegraf/plugins/common/opcua"
+	"github.com/influxdata/telegraf/plugins/common/opcua"
 	"github.com/influxdata/telegraf/plugins/common/opcua/input"
 	"github.com/influxdata/telegraf/selfstat"
 )
 
+type ReadClientWorkarounds struct {
+	UseUnregisteredReads bool `toml:"use_unregistered_reads"`
+}
+
 type ReadClientConfig struct {
+	ReadClientWorkarounds ReadClientWorkarounds `toml:"request_workarounds"`
 	input.InputClientConfig
 }
 
@@ -20,6 +25,7 @@ type ReadClient struct {
 
 	ReadSuccess selfstat.Stat
 	ReadError   selfstat.Stat
+	Workarounds ReadClientWorkarounds
 
 	// internal values
 	req *ua.ReadRequest
@@ -39,6 +45,7 @@ func (rc *ReadClientConfig) CreateReadClient(log telegraf.Logger) (*ReadClient,
 		OpcUAInputClient: inputClient,
 		ReadSuccess:      selfstat.Register("opcua", "read_success", tags),
 		ReadError:        selfstat.Register("opcua", "read_error", tags),
+		Workarounds:      rc.ReadClientWorkarounds,
 	}, nil
 }
 
@@ -48,21 +55,28 @@ func (o *ReadClient) Connect() error {
 		return err
 	}
 
-	regResp, err := o.Client.RegisterNodes(&ua.RegisterNodesRequest{
-		NodesToRegister: o.NodeIDs,
-	})
-	if err != nil {
-		return fmt.Errorf("registerNodes failed: %v", err)
-	}
-
 	readValueIds := make([]*ua.ReadValueID, len(o.NodeIDs))
-	for i, v := range regResp.RegisteredNodeIDs {
-		readValueIds[i] = &ua.ReadValueID{NodeID: v}
+	if o.Workarounds.UseUnregisteredReads {
+		for i, nid := range o.NodeIDs {
+			readValueIds[i] = &ua.ReadValueID{NodeID: nid}
+		}
+	} else {
+		regResp, err := o.Client.RegisterNodes(&ua.RegisterNodesRequest{
+			NodesToRegister: o.NodeIDs,
+		})
+		if err != nil {
+			return fmt.Errorf("registerNodes failed: %v", err)
+		}
+
+		for i, v := range regResp.RegisteredNodeIDs {
+			readValueIds[i] = &ua.ReadValueID{NodeID: v}
+		}
 	}
+
 	o.req = &ua.ReadRequest{
 		MaxAge:             2000,
-		NodesToRead:        readValueIds,
 		TimestampsToReturn: ua.TimestampsToReturnBoth,
+		NodesToRead:        readValueIds,
 	}
 
 	err = o.read()
@@ -74,7 +88,7 @@ func (o *ReadClient) Connect() error {
 }
 
 func (o *ReadClient) ensureConnected() error {
-	if o.State == opcuaclient.Disconnected {
+	if o.State == opcua.Disconnected {
 		err := o.Connect()
 		if err != nil {
 			return err
@@ -91,7 +105,7 @@ func (o *ReadClient) CurrentValues() ([]telegraf.Metric, error) {
 	}
 
 	err = o.read()
-	if err != nil && o.State == opcuaclient.Connected {
+	if err != nil && o.State == opcua.Connected {
 		// We do not return the disconnect error, as this would mask the
 		// original problem, but we do log it
 		disconnectErr := o.Disconnect(context.Background())

plugins/inputs/opcua/sample.conf

@@ -86,5 +86,6 @@
     ## Set additional valid status codes, StatusOK (0x0) is always considered valid
     # additional_valid_status_codes = ["0xC0"]
 
+  # [inputs.opcua.request_workarounds]
     ## Use unregistered reads instead of registered reads
     # use_unregistered_reads = false

plugins/inputs/opcua_listener/README.md

@@ -110,7 +110,7 @@ An OPC UA node ID may resemble: "ns=3;s=Temperature". In this example:
 - This example temperature node has a value of 79.0
 To gather data from this node enter the following line into the 'nodes' property above:
 
-```shell
+```text
 {field_name="temp", namespace="3", identifier_type="s", identifier="Temperature"},
 ```
 
@@ -157,9 +157,9 @@ This example group configuration has two groups with two nodes each:
 
 ## Connection Service
 
-This plugin subscribes to the specified nodes to receive data from 
-the OPC server. The updates are received at most as fast as the 
-`subscription_interval`. 
+This plugin subscribes to the specified nodes to receive data from
+the OPC server. The updates are received at most as fast as the
+`subscription_interval`.
 
 ## Metrics
 

plugins/inputs/opcua_listener/opcua_listener.go

@@ -24,9 +24,10 @@ func (*OpcUaListener) SampleConfig() string {
 	return sampleConfig
 }
 
-func (o *OpcUaListener) Init() (err error) {
+func (o *OpcUaListener) Init() error {
+	var err error
 	o.client, err = o.SubscribeClientConfig.CreateSubscribeClient(o.Log)
-	return
+	return err
 }
 
 func (o *OpcUaListener) Gather(_ telegraf.Accumulator) error {