{"level":"error","time":"...","message":"Gateway exited with an error: could not open simple config file \"\": open : The system cannot find the file specified."}

syntax = "proto3";

option go_package = "example.com/looper/protobuf";

package looper;

// The greeting service definition.
service Looper {
  rpc GetValue(ValueRequest) returns (ValueReply) {}
}

message ValueRequest {}

message ValueReply {
  int32 value = 1;
}

package main

import (
	"context"
	"log"
	"net"
	"google.golang.org/grpc"
	pb "example.com/looper/protobuf"
)

const (
	port = ":50051"
)

type server struct {
	pb.UnimplementedLooperServer
}

func (s *server) GetValue(ctx context.Context, in *pb.ValueRequest) (*pb.ValueReply, error) {
	return &pb.ValueReply{Value: 23}, nil
}

func main() {
	lis, err := net.Listen("tcp", port)
	if err != nil {
		log.Fatalf("failed to listen: %v", err)
	}
	s := grpc.NewServer()
	pb.RegisterLooperServer(s, &server{})
	if err := s.Serve(lis); err != nil {
		log.Fatalf("failed to serve: %v", err)
	}
}

/path/to/repo/gnmi-gateway/gnmi-gateway
$ ls -l
CONTRIBUTING.md
LICENSE
Makefile
README.md
docs/
examples/
gateway/
gateway-config-example.json
gnmi-gateway*
go.mod
go.sum
main.go
server.crt
server.key
targets-example.json
targets-example.yaml
targets.yaml

---
connection:
  localhost:
    addresses:
      - localhost:50051
    #credentials:
      #username: myusername
      #password: mypassword
    request: demo-request
    meta: {}
request:
  demo-request:
    target: "*"
    paths:
      - "/"
    #  - /components
    #  - /interfaces/interface[name=*]/state/counters
    #  - /interfaces/interface[name=*]/ethernet/state/counters
    #  - /interfaces/interface[name=*]/subinterfaces/subinterface[index=*]/state/counters
    #  - /qos/interfaces/interface[interface-id=*]/output/queues/queue[name=*]/state

make build && ./gnmi-gateway -EnableGNMIServer     -ServerTLSCert=server.crt     -ServerTLSKey=server.key     -TargetLoaders=simple     -TargetJSONFile=targets.yaml -Exporters=debug

{
  "request": {
    "default": {
      "subscribe": {
        "prefix": {
        },
        "subscription": [
          {
            "path": {
              "elem": [
                {
                  "name": "interfaces"
                }
              ]
            }
          }
        ]
      }
    }
  },
  "target": {
    "athena-gnmi-server": {
      "addresses": [
        "localhost:8080"
      ],
      "credentials": {
        "username": "admin",
        "password": "admin"
      },
      "request": "default",
      "meta": {
        "NoTLSVerify": "yes"
      }
    }
  }
}

$ docker run     -it --rm     -p 59100:59100     -v $(pwd)/examples/gnmi-prometheus/targets.json:/opt/gnmi-gateway/targets.json

WARNING: Published ports are discarded when using host network mode
{"level":"info","time":"2021-01-22T02:26:40Z","message":"Starting GNMI Gateway."}
{"level":"info","time":"2021-01-22T02:26:40Z","message":"Clustering is NOT enabled. No locking or cluster coordination will happen."}
{"level":"info","time":"2021-01-22T02:26:40Z","message":"Starting connection manager."}
{"level":"info","time":"2021-01-22T02:26:40Z","message":"Starting gNMI server on 0.0.0.0:9339."}
{"level":"info","time":"2021-01-22T02:26:40Z","message":"Starting Prometheus exporter."}
{"level":"info","time":"2021-01-22T02:26:40Z","message":"Connection manager received a target control message: 1 inserts 0 removes"}
{"level":"info","time":"2021-01-22T02:26:40Z","message":"Initializing target athena-gnmi-server ([localhost:8080]) map[NoTLSVerify:yes]."}
{"level":"info","time":"2021-01-22T02:26:40Z","message":"Target athena-gnmi-server: Connecting"}
{"level":"info","time":"2021-01-22T02:26:40Z","message":"Target athena-gnmi-server: Subscribing"}
{"level":"info","time":"2021-01-22T02:26:40Z","message":"Target athena-gnmi-server: Connected"}
{"level":"info","time":"2021-01-22T02:26:40Z","message":"Starting Prometheus HTTP server."}
{"level":"info","time":"2021-01-22T02:26:40Z","message":"Target athena-gnmi-server: Disconnected"}
E0122 02:26:40.826565       1 reconnect.go:114] client.Subscribe (target "athena-gnmi-server") failed: target 'athena-gnmi-server' cache update error: update is stale, update is stale, update is stale, update is stale, update is stale, update is stale, update is stale, update is stale, update is stale, update is stale, update is stale, update is stale, update is stale: { timestamp:1611282400 prefix:/athena-gnmi-server update:[ { path:/interfaces/interface[name=tx]/state/counters/in-octets val:&{2048000000} } { path:/interfaces/interface[name=tx]/state/counters/out-octets val:&{1518000000} } { path:/interfaces/interface[name=tx]/state/counters/out-pkts val:&{4000000} } { path:/interfaces/interface[name=tx]/config/description val:&{localhost:5555;1} } { path:/interfaces/interface[name=tx]/ethernet/state/counters/in-crc-errors val:&{0} } { path:/interfaces/interface[name=tx]/config/type val:&{ethernetCsmacd} } { path:/interfaces/interface[name=tx]/state/out-rate val:&{[0 0 0 0]} } { path:/interfaces/interface[name=tx]/state/counters/in-pkts val:&{4000000} } { path:/interfaces/interface[name=tx]/ethernet/config/port-speed val:&{SPEED_1GB} } { path:/interfaces/interface[name=tx]/state/in-rate val:&{[0 0 0 0]} } { path:/interfaces/interface[name=tx]/config/name val:&{tx} } { path:/interfaces/interface[name=tx]/name val:&{tx} } { path:/interfaces/interface[name=tx]/state/oper-status val:&{UP} } ] }; reconnecting in 552.330144ms
{"level":"info","time":"2021-01-22T02:26:41Z","message":"Target athena-gnmi-server: Connected"}
{"level":"info","time":"2021-01-22T02:26:41Z","message":"Target athena-gnmi-server: Disconnected"}

I0121 18:38:42.289725    8200 data_client.go:306] Notifications: [timestamp:1611283122 update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"state"} elem:{name:"out-rate"}} val:{bytes_val:"\x00\x00\x00\x00"}} update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"state"} elem:{name:"counters"} elem:{name:"in-pkts"}} val:{uint_val:4000002}} update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"state"} elem:{name:"counters"} elem:{name:"out-octets"}} val:{uint_val:1518000000}} update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"state"} elem:{name:"counters"} elem:{name:"out-pkts"}} val:{uint_val:4000002}} update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"config"} elem:{name:"description"}} val:{string_val:"localhost:5555;1"}} update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"ethernet"} elem:{name:"state"} elem:{name:"counters"} elem:{name:"in-crc-errors"}} val:{uint_val:0}} update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"ethernet"} elem:{name:"config"} elem:{name:"port-speed"}} val:{string_val:"SPEED_1GB"}} update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"name"}} val:{string_val:"tx"}} update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"config"} elem:{name:"type"}} val:{string_val:"ethernetCsmacd"}} update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"state"} elem:{name:"counters"} elem:{name:"in-octets"}} val:{uint_val:2048000414}} update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"state"} elem:{name:"in-rate"}} val:{bytes_val:"\x00\x00\x00\x00"}} update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"config"} elem:{name:"name"}} val:{string_val:"tx"}} update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"state"} elem:{name:"oper-status"}} val:{string_val:"UP"}}]. Err <nil>

  wget https://raw.githubusercontent.com/Azure/sonic-telemetry/master/patches/gnmi_cli.all.patch; patch -p4 < gnmi_cli.all.patch

$ gnmi_cli -a localhost:8080 -logtostderr -insecure -t ATHENA  -query "/device/interfaces"  -qt s -streaming_type SAMPLE  -streaming_sample_interval 2 -v 5 -display_type s
I0121 18:43:35.681664    8544 register.go:113] Attempting client types: [gnmi]
I0121 18:43:35.741912    8544 register.go:126] client "gnmi" create with type *client.Client
I0121 18:43:35.752914    8544 client.go:186] update:{timestamp:1611283415 update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"state"} elem:{name:"counters"} elem:{name:"in-octets"}} val:{uint_val:2048000414}} update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"ethernet"} elem:{name:"state"} elem:{name:"counters"} elem:{name:"in-crc-errors"}} val:{uint_val:0}} update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"ethernet"} elem:{name:"config"} elem:{name:"port-speed"}} val:{string_val:"SPEED_1GB"}} update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"config"} elem:{name:"name"}} val:{string_val:"tx"}} update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"state"} elem:{name:"out-rate"}} val:{bytes_val:"\x00\x00\x00\x00"}} update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"state"} elem:{name:"counters"} elem:{name:"in-pkts"}} val:{uint_val:4000002}} update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"state"} elem:{name:"counters"} elem:{name:"out-octets"}} val:{uint_val:1518000000}} update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"state"} elem:{name:"counters"} elem:{name:"out-pkts"}} val:{uint_val:4000002}} update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"config"} elem:{name:"description"}} val:{string_val:"localhost:5555;1"}} update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"state"} elem:{name:"in-rate"}} val:{bytes_val:"\x00\x00\x00\x00"}} update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"name"}} val:{string_val:"tx"}} update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"state"} elem:{name:"oper-status"}} val:{string_val:"UP"}} update:{path:{elem:{name:"interfaces"} elem:{name:"interface" key:{key:"name" value:"tx"}} elem:{name:"config"} elem:{name:"type"}} val:{string_val:"ethernetCsmacd"}}}
interfaces/interface/tx/state/counters/in-octets, 2048000414
interfaces/interface/tx/ethernet/state/counters/in-crc-errors, 0
interfaces/interface/tx/ethernet/config/port-speed, SPEED_1GB
interfaces/interface/tx/config/name, tx
interfaces/interface/tx/state/out-rate, [0 0 0 0]
interfaces/interface/tx/state/counters/in-pkts, 4000002
interfaces/interface/tx/state/counters/out-octets, 1518000000
interfaces/interface/tx/state/counters/out-pkts, 4000002
interfaces/interface/tx/config/description, localhost:5555;1
interfaces/interface/tx/state/in-rate, [0 0 0 0]
interfaces/interface/tx/name, tx
interfaces/interface/tx/state/oper-status, UP
interfaces/interface/tx/config/type, ethernetCsmacd

"level":"info","time":"2021-01-17T23:09:08Z","message":"Target lab1-fab1-pod1-leaf1.hyposcaler.net: Connected"}
panic: counter cannot decrease in value

goroutine 49 [running]:
github.com/prometheus/client_golang/prometheus.(*counter).Add(0xc0010d3560, 0xc115413c00000000)
        /go/pkg/mod/github.com/prometheus/[email protected]/prometheus/counter.go:109 +0x116
github.com/openconfig/gnmi-gateway/gateway/exporters/prometheus.(*PrometheusExporter).Export(0xc0005b2270, 0xc004a4e5d0)
        /opt/gnmi-gateway/gateway/exporters/prometheus/prometheus.go:103 +0x22f
github.com/openconfig/gnmi-gateway/gateway.(*CacheClient).run(0xc00478bb00)
        /opt/gnmi-gateway/gateway/gateway.go:150 +0x55
created by github.com/openconfig/gnmi-gateway/gateway.NewCacheClient
        /opt/gnmi-gateway/gateway/gateway.go:136 +0x1bf
 

./gnmi-gateway --version
gnmi-gateway version v0.11.1-002a9b0 (Built 2021-08-23T22:15:23Z)

root@XXXX-XXXX-logs:~# gnmic -a <hostname>:6030 -u <user> -p <password> --insecure subscribe --path "/interfaces/interface/state/counters" --stream-mode on_change > output.txt
^Croot@XXXX-XXXX-logs:~# tail output.txt 
    {
      "Path": "interfaces/interface[name=Management1]/state/counters/out-unicast-pkts",
      "values": {
        "interfaces/interface/state/counters/out-unicast-pkts": 237966235
      }
    }
  ]
}

You can see I get output

{
  "request": {
    "default": {
      "subscribe": {
        "prefix": {
        },
        "subscription": [
          {
            "path": {
              "elem": [
                {
                  "name": "/interfaces/interface/state/counters"
                }
              ]
            }
          }
        ]
      }
    }
  },
  "target": {
    "<host>": {
      "addresses": [
        "<host>:6030"
      ],
      "credentials": {
        "username": "xxxxxx",
        "password": "xxxxxx"
      },
      "request": "default",
      "meta": {
        "NoTLSVerify": "yes"
      }
    }

  }
}

{"level":"info","time":"2021-08-23T18:22:58-07:00","message":"Target <host>.gh.st: Disconnected"}
E0823 18:22:58.050605   71921 reconnect.go:114] client.Subscribe (target "<host>.st") failed: rpc error: code = InvalidArgument desc = failed to subscribe to /\/interfaces\/interface\/state\/counters: path invalid: failed to access node "/interfaces/interface/state/counters" in node ""; reconnecting in 1.040217184s
INFO: 2021/08/23 18:22:58 [transport] transport: loopyWriter.run returning. connection error: desc = "transport is closing"

go:1.14.6|py:3.7.3|tomas@vm2:~/gnmi/gnmi-gateway release$ GRPC_GO_LOG_VERBOSITY_LEVEL=99 GRPC_GO_LOG_SEVERITY_LEVEL=info ./gnmi-gateway -TargetLoaders=json -TargetJSONFile=./examples/gnmi-prometheus/targets.json -EnableGNMIServer -Exporters=prometheus -OpenConfigDirectory=./oc-models/ -ServerTLSCert=server.crt -ServerTLSKey=server.key
{"level":"info","time":"2020-11-07T19:37:59Z","message":"Starting GNMI Gateway."}
{"level":"info","time":"2020-11-07T19:37:59Z","message":"Clustering is NOT enabled. No locking or cluster coordination will happen."}
{"level":"info","time":"2020-11-07T19:37:59Z","message":"Starting connection manager."}
{"level":"info","time":"2020-11-07T19:37:59Z","message":"Starting gNMI server on 0.0.0.0:9339."}
{"level":"info","time":"2020-11-07T19:37:59Z","message":"Starting Prometheus exporter."}
{"level":"info","time":"2020-11-07T19:37:59Z","message":"Connection manager received a target control message: 1 inserts 0 removes"}
{"level":"info","time":"2020-11-07T19:37:59Z","message":"Initializing target gcp-r1 ([192.168.249.4:3333]) map[NoTLS:yes]."}
{"level":"info","time":"2020-11-07T19:37:59Z","message":"Target gcp-r1: Connecting"}
{"level":"info","time":"2020-11-07T19:37:59Z","message":"Target gcp-r1: Subscribing"}
INFO: 2020/11/07 19:37:59 parsed scheme: ""
INFO: 2020/11/07 19:37:59 scheme "" not registered, fallback to default scheme
INFO: 2020/11/07 19:37:59 ccResolverWrapper: sending update to cc: {[{192.168.249.4:3333  <nil> 0 <nil>}] <nil> <nil>}
INFO: 2020/11/07 19:37:59 ClientConn switching balancer to "pick_first"
INFO: 2020/11/07 19:37:59 Channel switches to new LB policy "pick_first"
INFO: 2020/11/07 19:37:59 Subchannel Connectivity change to CONNECTING
INFO: 2020/11/07 19:37:59 Subchannel picks a new address "192.168.249.4:3333" to connect
INFO: 2020/11/07 19:37:59 pickfirstBalancer: UpdateSubConnState: 0xc0005aa270, {CONNECTING <nil>}
INFO: 2020/11/07 19:37:59 Channel Connectivity change to CONNECTING
WARNING: 2020/11/07 19:37:59 grpc: addrConn.createTransport failed to connect to {192.168.249.4:3333 192.168.249.4:3333 <nil> 0 <nil>}. Err: connection error: desc = "transport: authentication handshake failed: tls: first record does not look like a TLS handshake". Reconnecting...
INFO: 2020/11/07 19:37:59 Subchannel Connectivity change to TRANSIENT_FAILURE
INFO: 2020/11/07 19:37:59 pickfirstBalancer: UpdateSubConnState: 0xc0005aa270, {TRANSIENT_FAILURE connection error: desc = "transport: authentication handshake failed: tls: first record does not look like a TLS handshake"}
INFO: 2020/11/07 19:37:59 Channel Connectivity change to TRANSIENT_FAILURE
{"level":"info","time":"2020-11-07T19:38:00Z","message":"Starting Prometheus HTTP server."}
INFO: 2020/11/07 19:38:00 Subchannel Connectivity change to CONNECTING
INFO: 2020/11/07 19:38:00 Subchannel picks a new address "192.168.249.4:3333" to connect
INFO: 2020/11/07 19:38:00 pickfirstBalancer: UpdateSubConnState: 0xc0005aa270, {CONNECTING <nil>}
INFO: 2020/11/07 19:38:00 Channel Connectivity change to CONNECTING
WARNING: 2020/11/07 19:38:00 grpc: addrConn.createTransport failed to connect to {192.168.249.4:3333 192.168.249.4:3333 <nil> 0 <nil>}. Err: connection error: desc = "transport: authentication handshake failed: tls: first record does not look like a TLS handshake". Reconnecting...

go:1.14.6|py:3.7.3|tomas@vm2:~/gnmi/gnmi-gateway release$ cat examples/gnmi-prometheus/targets.json 
{
  "request": {
    "default": {
      "subscribe": {
        "prefix": {
        },
        "subscription": [
          {
            "path": {
              "elem": [
                {
                  "name": "interfaces"
                }
              ]
            }
          }
        ]
      }
    }
  },
  "target": {
    "gcp-r1": {
      "addresses": [
        "192.168.249.4:3333"
      ],
      "credentials": {
        "username": "xxx",
        "password": "xxx"
      },
      "request": "default",
      "meta": {
        "NoTLS": "yes"
      }
    }
  }
}

bash-4.2# tcpdump -i any "tcp port 3333 and (tcp[((tcp[12] & 0xf0) >> 2)] = 0x16)"

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on any, link-type LINUX_SLL (Linux cooked v1), capture size 262144 bytes
19:47:01.367197  In 1e:3d:5b:13:d8:fe (oui Unknown) ethertype IPv4 (0x0800), length 320: 10.128.0.4.50486 > 192.168.249.4.dec-notes: Flags [P.], seq 2715923852:2715924104, ack 2576249027, win 511, options [nop,nop,TS val 1194424180 ecr 1250876], length 252
19:47:02.405870  In 1e:3d:5b:13:d8:fe (oui Unknown) ethertype IPv4 (0x0800), length 320: 10.128.0.4.50488 > 192.168.249.4.dec-notes: Flags [P.], seq 680803294:680803546, ack 3839769659, win 511, options [nop,nop,TS val 1194425218 ecr 1251136], length 252
19:47:04.139458  In 1e:3d:5b:13:d8:fe (oui Unknown) ethertype IPv4 (0x0800), length 320: 10.128.0.4.50490 > 192.168.249.4.dec-notes: Flags [P.], seq 3963338234:3963338486, ack 1760248652, win 511, options [nop,nop,TS val 1194426952 ecr 1251569], length 252

r1#show management api gnmi 
Enabled:            Yes
Server:             running on port 3333, in MGMT VRF
SSL Profile:        none
QoS DSCP:           none
r1#

!
management api gnmi
   transport grpc GRPC
      port 3333
      vrf MGMT
!