Add PuppetDB service discovery

We have been Puppet user for 10 years and we are users of
https://github.com/camptocamp/prometheus-puppetdb-sd

However, that file_sd implementation contains business logic and
assumptions around e.g. the modules which you are using.

This pull request adds a simple PuppetDB service discovery, which will
enable more use cases than the upstream sd.

Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu>

config/config_test.go

@@ -45,6 +45,7 @@ import (
 	"github.com/prometheus/prometheus/discovery/marathon"
 	"github.com/prometheus/prometheus/discovery/moby"
 	"github.com/prometheus/prometheus/discovery/openstack"
+	"github.com/prometheus/prometheus/discovery/puppetdb"
 	"github.com/prometheus/prometheus/discovery/scaleway"
 	"github.com/prometheus/prometheus/discovery/targetgroup"
 	"github.com/prometheus/prometheus/discovery/triton"
@@ -790,6 +791,34 @@ var expectedConf = &Config{
 				}},
 			},
 		},
+		{
+			JobName: "service-puppetdb",
+
+			HonorTimestamps: true,
+			ScrapeInterval:  model.Duration(15 * time.Second),
+			ScrapeTimeout:   DefaultGlobalConfig.ScrapeTimeout,
+
+			MetricsPath:      DefaultScrapeConfig.MetricsPath,
+			Scheme:           DefaultScrapeConfig.Scheme,
+			HTTPClientConfig: config.DefaultHTTPClientConfig,
+
+			ServiceDiscoveryConfigs: discovery.Configs{&puppetdb.SDConfig{
+				URL:               "https://puppetserver/",
+				Query:             "resources { type = \"Package\" and title = \"httpd\" }",
+				IncludeParameters: true,
+				Port:              80,
+				RefreshInterval:   model.Duration(60 * time.Second),
+				HTTPClientConfig: config.HTTPClientConfig{
+					FollowRedirects: true,
+					TLSConfig: config.TLSConfig{
+						CAFile:   "testdata/valid_ca_file",
+						CertFile: "testdata/valid_cert_file",
+						KeyFile:  "testdata/valid_key_file",
+					},
+				},
+			},
+			},
+		},
 		{
 			JobName:         "hetzner",
 			HonorTimestamps: true,
@@ -1262,6 +1291,22 @@ var expectedErrors = []struct {
 		filename: "empty_static_config.bad.yml",
 		errMsg:   "empty or null section in static_configs",
 	},
+	{
+		filename: "puppetdb_no_query.bad.yml",
+		errMsg:   "query missing",
+	},
+	{
+		filename: "puppetdb_no_url.bad.yml",
+		errMsg:   "url missing",
+	},
+	{
+		filename: "puppetdb_bad_url.bad.yml",
+		errMsg:   "host is missing in URL",
+	},
+	{
+		filename: "puppetdb_no_scheme.bad.yml",
+		errMsg:   "url scheme must be http or https",
+	},
 	{
 		filename: "hetzner_role.bad.yml",
 		errMsg:   "unknown role",

config/testdata/conf.good.yml

@@ -307,6 +307,18 @@ scrape_configs:
           cert_file: valid_cert_file
           key_file: valid_key_file
 
+  - job_name: service-puppetdb
+    puppetdb_sd_configs:
+      - url: https://puppetserver/
+        query: 'resources { type = "Package" and title = "httpd" }'
+        include_parameters: true
+        port: 80
+        refresh_interval: 1m
+        tls_config:
+          ca_file: valid_ca_file
+          cert_file: valid_cert_file
+          key_file: valid_key_file
+
   - job_name: hetzner
     hetzner_sd_configs:
       - role: hcloud

config/testdata/puppetdb_bad_url.bad.yml

@@ -0,0 +1,4 @@
+scrape_configs:
+  - puppetdb_sd_configs:
+      - url: http://
+        query: 'resources { type = "Package" and title = "httpd" }'

config/testdata/puppetdb_no_query.bad.yml

@@ -0,0 +1,3 @@
+scrape_configs:
+  - puppetdb_sd_configs:
+      - url: http://puppetserver/

config/testdata/puppetdb_no_scheme.bad.yml

@@ -0,0 +1,4 @@
+scrape_configs:
+  - puppetdb_sd_configs:
+      - url: ftp://puppet
+        query: 'resources { type = "Package" and title = "httpd" }'

config/testdata/puppetdb_no_url.bad.yml

@@ -0,0 +1,3 @@
+scrape_configs:
+  - puppetdb_sd_configs:
+      - query: 'resources { type = "Package" and title = "httpd" }'

discovery/install/install.go

@@ -31,6 +31,7 @@ import (
 	_ "github.com/prometheus/prometheus/discovery/marathon"     // register marathon
 	_ "github.com/prometheus/prometheus/discovery/moby"         // register moby
 	_ "github.com/prometheus/prometheus/discovery/openstack"    // register openstack
+	_ "github.com/prometheus/prometheus/discovery/puppetdb"     // register puppetdb
 	_ "github.com/prometheus/prometheus/discovery/scaleway"     // register scaleway
 	_ "github.com/prometheus/prometheus/discovery/triton"       // register triton
 	_ "github.com/prometheus/prometheus/discovery/xds"          // register xds

discovery/puppetdb/fixtures/vhosts.json

@@ -0,0 +1,49 @@
+[
+   {
+      "certname": "edinburgh.example.com",
+      "environment": "prod",
+      "exported": false,
+      "file": "/etc/puppetlabs/code/environments/prod/modules/upstream/apache/manifests/init.pp",
+      "line": 384,
+      "parameters": {
+         "access_log": true,
+         "access_log_file": "ssl_access_log",
+         "additional_includes": [ ],
+         "directoryindex": "",
+         "docroot": "/var/www/html",
+         "ensure": "absent",
+         "options": [
+            "Indexes",
+            "FollowSymLinks",
+            "MultiViews"
+         ],
+         "php_flags": { },
+         "labels": {
+            "alias": "edinburgh"
+         },
+         "scriptaliases": [
+            {
+               "alias": "/cgi-bin",
+               "path": "/var/www/cgi-bin"
+            }
+         ]
+      },
+      "resource": "49af83866dc5a1518968b68e58a25319107afe11",
+      "tags": [
+         "roles::hypervisor",
+         "apache",
+         "apache::vhost",
+         "class",
+         "default-ssl",
+         "profile_hypervisor",
+         "vhost",
+         "profile_apache",
+         "hypervisor",
+         "__node_regexp__edinburgh",
+         "roles",
+         "node"
+      ],
+      "title": "default-ssl",
+      "type": "Apache::Vhost"
+   }
+]