MF-295 add mqtt benchmark tool

Gopkg.toml

@@ -118,3 +118,7 @@
 [prune]
   go-tests = true
   unused-packages = true
+
+[[constraint]]
+  revision = "ced62fe5104b907b6c16cb7e575c17b2e62ceddd"
+  name = "gonum.org/v1/gonum"

tools/mqtt-bench/README.md

@@ -0,0 +1,70 @@
+# MQTT benchmarking tool
+
+A simple MQTT (broker) benchmarking tool for Mainflux platform. ( based on github.com/krylovsk/mqtt-benchmark )
+
+
+The tool supports multiple concurrent clients, publishers and subscribers configurable message size, etc:
+
+```
+cd benchmark
+go build  -o mqtt-benchmark *.go
+
+> mqtt-benchmark --help
+Usage of mqtt-benchmark:
+  -broker="tcp://localhost:1883": MQTT broker endpoint as scheme://host:port
+  -clients=10: Number of clients to start
+  -count=100: Number of messages to send per client
+  -format="text": Output format: text|json
+  -password="": MQTT password (empty if auth disabled)
+  -qos=1: QoS for published messages
+  -quiet=false : Suppress logs while running (except errors and the result)
+  -size=100: Size of the messages payload (bytes
+  -subs=10 number of subscribers
+  -pubs=10 number of publishers
+  -config=connections.json , file with mainflux channels
+  -mtls=false, use mtls
+  -ca=ca.crt, use mqtts, pass ca to server validate certificate
+```
+
+Two output formats supported: human-readable plain text and JSON.
+
+Before use you need a channels.toml  you can use tools/provision/main.go to create
+channels for testing
+
+Example use and output:
+
+```
+go build -o mqtt-benchmark *.go
+
+without mtls
+./mqtt-benchmark --broker tcp://localhost:1883 --count 100 --size 100  --qos 0 --format text   --subs 100 --pubs 0 --channels channels.toml
+
+with mtls
+./mqtt-benchmark --broker tcps://localhost:8883 --count 100 --size 100  --qos 0 --format text   --subs 100 --pubs 0 --channels channels.toml --mtls -ca ca.crt
+```
+
+
+You can use config.toml to create tests with this tool
+./mqtt-benchmark --config config.toml it will read params from config.toml
+
+
+```
+broker_url = "tcp://localhost:1883"
+qos = 2
+message_size =100
+message_count =100
+publishers_num =3
+subscribers_num =1
+format = "text"
+quiet = true
+mtls = false
+skiptlsver = true
+ca_file = "ca.crt"
+channels_file = "channels.toml"
+```
+
+For Example
+
+```
+./mqtt-benchmark --config tests/fanin.toml
+```