prometheus plugin: support get scrape urls from consul

.gitignore

@@ -2,4 +2,4 @@
 .vscode
 /categraf*
 *.log
-vendor
+/vendor

conf/input.prometheus/prometheus.toml

@@ -1,11 +1,24 @@
 # # collect interval
 # interval = 15
 
-# [[instances]]
+[[instances]]
 # urls = [
 #     "http://localhost:9104/metrics"
 # ]
 
+## Scrape Services available in Consul Catalog
+[instances.consul]
+  enabled = false
+  agent = "http://localhost:8500"
+  query_interval = "5m"
+
+  [[instances.consul.query]]
+    name = "a service name"
+    tag = "a service tag"
+    url = 'http://{{if ne .ServiceAddress ""}}{{.ServiceAddress}}{{else}}{{.Address}}{{end}}:{{.ServicePort}}/{{with .ServiceMeta.metrics_path}}{{.}}{{else}}metrics{{end}}'
+    [instances.consul.query.tags]
+      host = "{{.Node}}"
+
 # bearer_token_string = ""
 
 # e.g. /run/secrets/kubernetes.io/serviceaccount/token

go.mod

@@ -15,6 +15,7 @@ require (
 	github.com/gogo/protobuf v1.3.2
 	github.com/golang/protobuf v1.5.2
 	github.com/golang/snappy v0.0.4
+	github.com/hashicorp/consul/api v1.13.0
 	github.com/influxdata/line-protocol/v2 v2.2.1
 	github.com/jmoiron/sqlx v1.3.5
 	github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51
@@ -38,13 +39,15 @@ require (
 	github.com/BurntSushi/toml v1.1.0 // indirect
 	github.com/Microsoft/go-winio v0.5.2 // indirect
 	github.com/alouca/gologger v0.0.0-20120904114645-7d4b7291de9c // indirect
+	github.com/armon/go-metrics v0.0.0-20180917152333-f0300d1749da // indirect
 	github.com/cespare/xxhash/v2 v2.1.2 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f // indirect
 	github.com/docker/distribution v2.8.1+incompatible // indirect
 	github.com/docker/go-connections v0.4.0 // indirect
 	github.com/docker/go-units v0.4.0 // indirect
 	github.com/fatih/camelcase v1.0.0 // indirect
+	github.com/fatih/color v1.9.0 // indirect
 	github.com/fatih/structs v1.1.0 // indirect
 	github.com/freedomkk-qfeng/go-fastping v0.0.0-20160109021039-d7bb493dee3e // indirect
 	github.com/go-logfmt/logfmt v0.5.1 // indirect
@@ -53,7 +56,17 @@ require (
 	github.com/godror/knownpb v0.1.0 // indirect
 	github.com/google/uuid v1.2.0 // indirect
 	github.com/grpc-ecosystem/grpc-gateway v1.16.0 // indirect
+	github.com/hashicorp/go-cleanhttp v0.5.1 // indirect
+	github.com/hashicorp/go-hclog v0.12.0 // indirect
+	github.com/hashicorp/go-immutable-radix v1.0.0 // indirect
+	github.com/hashicorp/go-rootcerts v1.0.2 // indirect
+	github.com/hashicorp/golang-lru v0.5.1 // indirect
+	github.com/hashicorp/serf v0.9.6 // indirect
 	github.com/lufia/plan9stats v0.0.0-20211012122336-39d0f177ccd0 // indirect
+	github.com/mattn/go-colorable v0.1.6 // indirect
+	github.com/mattn/go-isatty v0.0.12 // indirect
+	github.com/mitchellh/go-homedir v1.1.0 // indirect
+	github.com/mitchellh/mapstructure v1.1.2 // indirect
 	github.com/moby/term v0.0.0-20210619224110-3f7ff695adc6 // indirect
 	github.com/morikuni/aec v1.0.0 // indirect
 	github.com/opencontainers/go-digest v1.0.0 // indirect