collector: Implement uname collector for FreeBSD (#1239)

* collector: Implement uname collector for FreeBSD

Signed-off-by: David O'Rourke <david.orourke@gmail.com>

5 files changed, 144 insertions, 40 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 28cefae..c445503 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,7 @@ The cpufreq metrics now separate the `cpufreq` and `scaling` data based on what
 * [ENHANCEMENT] Add Infiniband counters #1120
 * [FEATURE] Add a flag to disable exporter metrics #1148
 * [FEATURE] Add kstat-based Solaris metrics for boottime, cpu and zfs collectors #1197
+* [FEATURE] Add uname collector for FreeBSD #1239
 
 ## 0.17.0 / 2018-11-30
 
diff --git a/README.md b/README.md
index 9066d85..187e275 100644
--- a/README.md
+++ b/README.md
@@ -54,7 +54,7 @@ stat | Exposes various statistics from `/proc/stat`. This includes boot time, fo
 textfile | Exposes statistics read from local disk. The `--collector.textfile.directory` flag must be set. | _any_
 time | Exposes the current system time. | _any_
 timex | Exposes selected adjtimex(2) system call stats. | Linux
-uname | Exposes system information as provided by the uname system call. | Linux
+uname | Exposes system information as provided by the uname system call. | FreeBSD, Linux
 vmstat | Exposes statistics from `/proc/vmstat`. | Linux
 xfs | Exposes XFS runtime statistics. | Linux (kernel 4.4+)
 zfs | Exposes [ZFS](http://open-zfs.org/) performance statistics. | [Linux](http://zfsonlinux.org/), Solaris
diff --git a/collector/uname.go b/collector/uname.go
new file mode 100644
index 0000000..e9a633f
--- /dev/null
+++ b/collector/uname.go
@@ -0,0 +1,72 @@
+// Copyright 2019 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build freebsd linux
+// +build !nouname
+
+package collector
+
+import (
+        "github.com/prometheus/client_golang/prometheus"
+)
+
+var unameDesc = prometheus.NewDesc(
+        prometheus.BuildFQName(namespace, "uname", "info"),
+        "Labeled system information as provided by the uname system call.",
+        []string{
+                "sysname",
+                "release",
+                "version",
+                "machine",
+                "nodename",
+                "domainname",
+        },
+        nil,
+)
+
+type unameCollector struct{}
+type uname struct {
+        SysName    string
+        Release    string
+        Version    string
+        Machine    string
+        NodeName   string
+        DomainName string
+}
+
+func init() {
+        registerCollector("uname", defaultEnabled, newUnameCollector)
+}
+
+// NewUnameCollector returns new unameCollector.
+func newUnameCollector() (Collector, error) {
+        return &unameCollector{}, nil
+}
+
+func (c unameCollector) Update(ch chan<- prometheus.Metric) error {
+        uname, err := getUname()
+        if err != nil {
+                return err
+        }
+
+        ch <- prometheus.MustNewConstMetric(unameDesc, prometheus.GaugeValue, 1,
+                uname.SysName,
+                uname.Release,
+                uname.Version,
+                uname.Machine,
+                uname.NodeName,
+                uname.DomainName,
+        )
+
+        return nil
+}
diff --git a/collector/uname_freebsd.go b/collector/uname_freebsd.go
new file mode 100644
index 0000000..9e4a8ba
--- /dev/null
+++ b/collector/uname_freebsd.go
@@ -0,0 +1,57 @@
+// Copyright 2019 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build !nouname
+
+package collector
+
+import (
+        "bytes"
+        "strings"
+
+        "golang.org/x/sys/unix"
+)
+
+func getUname() (uname, error) {
+        var utsname unix.Utsname
+        if err := unix.Uname(&utsname); err != nil {
+                return uname{}, err
+        }
+
+        // We do a little bit of work here to emulate what happens in the Linux
+        // uname calls since FreeBSD uname doesn't have a Domainname.
+        nodename := string(utsname.Nodename[:bytes.IndexByte(utsname.Nodename[:], 0)])
+        split := strings.SplitN(nodename, ".", 2)
+
+        // We'll always have at least a single element in the array. We assume this
+        // is the hostname.
+        hostname := split[0]
+
+        // If we have more than one element, we assume this is the domainname.
+        // Otherwise leave it to "(none)" like Linux.
+        domainname := "(none)"
+        if len(split) > 1 {
+                domainname = split[1]
+        }
+
+        output := uname{
+                SysName:    string(utsname.Sysname[:bytes.IndexByte(utsname.Sysname[:], 0)]),
+                Release:    string(utsname.Release[:bytes.IndexByte(utsname.Release[:], 0)]),
+                Version:    string(utsname.Version[:bytes.IndexByte(utsname.Version[:], 0)]),
+                Machine:    string(utsname.Machine[:bytes.IndexByte(utsname.Machine[:], 0)]),
+                NodeName:   hostname,
+                DomainName: domainname,
+        }
+
+        return output, nil
+}
diff --git a/collector/uname_linux.go b/collector/uname_linux.go
index 090180d..65de629 100644
--- a/collector/uname_linux.go
+++ b/collector/uname_linux.go
@@ -18,49 +18,23 @@ package collector
 import (
         "bytes"
 
-        "github.com/prometheus/client_golang/prometheus"
-
         "golang.org/x/sys/unix"
 )
 
-var unameDesc = prometheus.NewDesc(
-        prometheus.BuildFQName(namespace, "uname", "info"),
-        "Labeled system information as provided by the uname system call.",
-        []string{
-                "sysname",
-                "release",
-                "version",
-                "machine",
-                "nodename",
-                "domainname",
-        },
-        nil,
-)
-
-type unameCollector struct{}
-
-func init() {
-        registerCollector("uname", defaultEnabled, newUnameCollector)
-}
-
-// NewUnameCollector returns new unameCollector.
-func newUnameCollector() (Collector, error) {
-        return &unameCollector{}, nil
-}
+func getUname() (uname, error) {
+        var utsname unix.Utsname
+        if err := unix.Uname(&utsname); err != nil {
+                return uname{}, err
+        }
 
-func (c unameCollector) Update(ch chan<- prometheus.Metric) error {
-        var uname unix.Utsname
-        if err := unix.Uname(&uname); err != nil {
-                return err
+        output := uname{
+                SysName:    string(utsname.Sysname[:bytes.IndexByte(utsname.Sysname[:], 0)]),
+                Release:    string(utsname.Release[:bytes.IndexByte(utsname.Release[:], 0)]),
+                Version:    string(utsname.Version[:bytes.IndexByte(utsname.Version[:], 0)]),
+                Machine:    string(utsname.Machine[:bytes.IndexByte(utsname.Machine[:], 0)]),
+                NodeName:   string(utsname.Nodename[:bytes.IndexByte(utsname.Nodename[:], 0)]),
+                DomainName: string(utsname.Domainname[:bytes.IndexByte(utsname.Domainname[:], 0)]),
         }
 
-        ch <- prometheus.MustNewConstMetric(unameDesc, prometheus.GaugeValue, 1,
-                string(uname.Sysname[:bytes.IndexByte(uname.Sysname[:], 0)]),
-                string(uname.Release[:bytes.IndexByte(uname.Release[:], 0)]),
-                string(uname.Version[:bytes.IndexByte(uname.Version[:], 0)]),
-                string(uname.Machine[:bytes.IndexByte(uname.Machine[:], 0)]),
-                string(uname.Nodename[:bytes.IndexByte(uname.Nodename[:], 0)]),
-                string(uname.Domainname[:bytes.IndexByte(uname.Domainname[:], 0)]),
-        )
-        return nil
+        return output, nil
 }