Py-node-exporter

**Breaking changes**

* Renamed `interface` label to `device` in netclass collector for consistency with
other network metrics 1224
* The cpufreq metrics now separate the `cpufreq` and `scaling` data based on what the driver provides. 1248
* The labels for the network_up metric have changed, see issue 1236
* Bonding collector now uses `mii_status` instead of `operstatus` 1124
* Several systemd metrics have been turned off by default to improve performance 1254
These include unit_tasks_current, unit_tasks_max, service_restart_total, and unit_start_time_seconds
* The systemd collector blacklist now includes automount, device, mount, and slice units by default. 1255

Changes

* [CHANGE] Bonding state uses mii_status 1124
* [CHANGE] Add a limit to the number of in-flight requests 1166
* [CHANGE] Renamed `interface` label to `device` in netclass collector 1224
* [CHANGE] Add separate cpufreq and scaling metrics 1248
* [CHANGE] Several systemd metrics have been turned off by default to improve performance 1254
* [CHANGE] Expand systemd collector blacklist 1255
* [CHANGE] Split cpufreq metrics into a separate collector 1253
* [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
* [FEATURE] Add diskstats collector for OpenBSD 1250
* [FEATURE] Add pressure collector exposing pressure stall information for Linux 1174
* [FEATURE] Add perf exporter for Linux 1274
* [ENHANCEMENT] Add Infiniband counters 1120
* [ENHANCEMENT] Add TCPSynRetrans to netstat default filter 1143
* [ENHANCEMENT] Move network_up labels into new metric network_info 1236
* [ENHANCEMENT] Use 64-bit counters for Darwin netstat
* [BUGFIX] Add fallback for missing /proc/1/mounts 1172
* [BUGFIX] Fix node_textfile_mtime_seconds to work properly on symlinks 1326

Build note: Linux builds can now be built without CGO.

**Breaking changes**

supvervisord collector reports `start_time_seconds` rather than `uptime` 952

The wifi collector is disabled by default due to suspected caching issues and goroutine leaks.
* https://github.com/prometheus/node_exporter/issues/870
* https://github.com/prometheus/node_exporter/issues/1008

Darwin meminfo metrics have been renamed to match Prometheus conventions. 1060

Changes

* [CHANGE] Use /proc/mounts instead of statfs(2) for ro state 1002
* [CHANGE] Exclude only subdirectories of /var/lib/docker 1003
* [CHANGE] Filter out non-installed units when collecting all systemd units 1011
* [CHANGE] `service_restart_total` and `socket_refused_connections_total` will not be reported if you're running an older version of systemd
* [CHANGE] collector/timex: remove cgo dependency 1079
* [CHANGE] filesystem: Ignore Docker netns mounts 1047
* [CHANGE] Ignore additional virtual filesystems 1104
* [FEATURE] Add netclass collector 851
* [FEATURE] Add processes collector 950
* [FEATURE] Collect start time for systemd units 952
* [FEATURE] Add socket unit stats to systemd collector 968
* [FEATURE] Collect NRestarts property for systemd service units 992
* [FEATURE] Collect NRefused property for systemd socket units (available as of systemd v239) 995
* [FEATURE] Allow removal of rootfs prefix for run in docker 1058
* [ENHANCEMENT] Support for octal characters in mountpoints 954
* [ENHANCEMENT] Update wifi stats to support multiple stations 980
* [ENHANCEMENT] Add transmit/receive bytes total for wifi stations 1150
* [ENHANCEMENT] Handle stuck NFS mounts 997
* [ENHANCEMENT] infiniband: Handle iWARP RDMA modules N/A 974
* [ENHANCEMENT] Update diskstats for linux kernel 4.19 1109
* [ENHANCEMENT] Collect TasksCurrent, TasksMax per systemd unit 1098

* [BUGFIX] Fix FreeBSD CPU temp 965
* [BUGFIX] Fix goroutine leak in supervisord collector 978
* [BUGFIX] Fix mdadm collector issues 985
* [BUGFIX] Fix ntp collector thread safety 1014
* [BUGFIX] Systemd units will not be ignored if you're running older versions of systemd 1039
* [BUGFIX] Handle vanishing PIDs 1043
* [BUGFIX] Correctly cast Darwin memory info 1060
* [BUGFIX] Filter systemd units in Go for compatibility with older versions 1083
* [BUGFIX] Update cpu collector for OpenBSD 6.4 1094
* [BUGFIX] Fix typo on HELP of `read_time_seconds_total` 1057
* [BUGFIX] collector/diskstats: don't fail if there are extra stats 1125
* [BUGFIX] collector/hwmon\_linux: handle temperature sensor file 1123
* [BUGFIX] collector/filesystem: add bounds check 1133
* [BUGFIX] Fix dragonfly's CPU counting frequency 1140
* [BUGFIX] Add fallback for missing /proc/1/mounts 1172

**Breaking changes**

This release contains major breaking changes to metric names. Many metrics have new names, labels, and label values in order to conform to current naming conventions.
* Linux node_cpu metrics now break out `guest` values into separate metrics. See Issue 737
* Many counter metrics have been renamed to include `_total`.
* Many metrics have been renamed/modified to include base units, for example `node_cpu` is now `node_cpu_seconds_total`.

In order to help with the transition we have an [upgrade guide](docs/V0_16_UPGRADE_GUIDE.md).

Other breaking changes:
* The megacli collector has been removed, is now replaced by the storcli.py textfile helper.
* The gmond collector has been removed.
* The textfile collector will now treat timestamps as errors.

* [CHANGE] Split out guest cpu metrics on Linux. 744
* [CHANGE] Exclude Linux proc from filesystem type regexp 774
* [CHANGE] Ignore more virtual filesystems 775
* [CHANGE] Remove obsolete megacli collector. 798
* [CHANGE] Ignore /var/lib/docker by default. 814
* [CHANGE] Cleanup NFS metrics 834
* [CHANGE] Only report core throttles per core, not per cpu 836
* [CHANGE] Treat custom textfile metric timestamps as errors 769
* [CHANGE] Use lowercase cpu label name in interrupts 849
* [CHANGE] Enable bonding collector by default. 872
* [CHANGE] Greatly reduce the metrics vmstat returns by default. 874
* [CHANGE] Greatly trim what netstat collector exposes by default 876
* [CHANGE] Drop `exec_` prefix and move `node_boot_time_seconds` from `exec` to new `boottime` collector and enable for Darwin/Dragonfly/FreeBSD/NetBSD/OpenBSD. 839, 901
* [CHANGE] Remove deprecated gmond collector 852
* [CHANGE] align Darwin disk stat names with Linux 930
* [FEATURE] Add `collect[]` parameter 699
* [FEATURE] Add text collector conversion for ipmitool output. 746
* [FEATURE] Add openbsd meminfo 724
* [FEATURE] Add systemd summary metrics 765
* [FEATURE] Add OpenBSD CPU collector 805
* [FEATURE] Add NFS Server metrics collector. 803
* [FEATURE] add sample directory size exporter 789
* [ENHANCEMENT] added Wear_Leveling_Count attribute to smartmon.sh script 707
* [ENHANCEMENT] Simplify Utsname string conversion 716
* [ENHANCEMENT] apt.sh: handle multiple origins in apt-get output 757
* [ENHANCEMENT] Export systemd timers last trigger seconds. 807
* [ENHANCEMENT] updates for zfsonlinux 0.7.5 779
* [BUGFIX] Fix smartmon.sh textfile script 700
* [BUGFIX] netdev: Change valueType to CounterValue 749
* [BUGFIX] textfile: fix duplicate metrics error 738
* [BUGFIX] Fix panic by updating github.com/ema/qdisc dependency 778
* [BUGFIX] Use uint64 in the ZFS collector 714
* [BUGFIX] multiply page size after float64 coercion to avoid signed integer overflow 780
* [BUGFIX] smartmon: Escape double quotes in device model family 772
* [BUGFIX] Fix log level regression in 533 815
* [BUGFIX] Correct the ClocksPerSec scaling factor on Darwin 846
* [BUGFIX] Count core throttles per core and per package 871
* [BUGFIX] Fix netdev collector for linux 890 910
* [BUGFIX] Fix memory corruption when number of filesystems > 16 on FreeBSD 900
* [BUGFIX] Fix parsing of interface aliases in netdev linux 904

* [BUGFIX] cpu: Support processor-less (memory-only) NUMA nodes 734

* [BUGFIX] xfs: expose correct fields, fix metric names 708
* [BUGFIX] Correct buffer_bytes > INT_MAX on BSD/amd64. 712
* [BUGFIX] netstat: return nothing when /proc/net/snmp6 not found 718
* [BUGFIX] Fix off by one in Linux interrupts collector 721
* [BUGFIX] Add and use sysReadFile in hwmon collector 728

**Breaking changes**

This release contains major breaking changes to flag handling.
* The flag library has been changed, all flags now require double-dashs. (`-foo` becomes `--foo`).
* The collector selection flag has been replaced by individual boolean flags.
* The `-collector.procfs` and `-collector.sysfs` flags have been renamed to `--path.procfs` and `--path.sysfs` respectively.

The `ntp` collector has been replaced with a new NTP-based check that is designed to expose the state of a localhost NTP server rather than provide the offset of the node to a remote NTP server. By default the `ntp` collector is now locked to localhost. This is to avoid accidental spamming of public internet NTP pools.

Windows support is now removed, the [wmi_exporter](https://github.com/martinlindhe/wmi_exporter) is recommended as a replacement.

* [CHANGE] `node_cpu` metrics moved from `stats` to `cpu` collector on linux (enabled by default). 548
* [CHANGE] Blacklist systemd scope units 534
* [CHANGE] Remove netbsd/arm 551
* [CHANGE] Remove Windows support 549
* [CHANGE] Enable IPVS collector by default 623
* [CHANGE] Switch to kingpin flags 639
* [CHANGE] Replace --collectors.enabled with per-collector flags 640
* [FEATURE] Add ARP collector for Linux 540
* [FEATURE] Add XFS colector for Linux 568, 575
* [FEATURE] Add qdisc collector for Linux 580
* [FEATURE] Add cpufreq stats for Linux 548
* [FEATURE] Add diskstats for Darwin 593
* [FEATURE] Add bcache collector for Linux 597
* [FEATURE] Add parsing /proc/net/snmp6 file for Linux 615
* [FEATURE] Add timex collector for Linux 664
* [ENHANCEMENT] Include overall health status in smartmon.sh example script 546
* [ENHANCEMENT] Include `guest_nice` in CPU collector 554
* [ENHANCEMENT] Add exec_boot_time for freebsd, dragonfly 550
* [ENHANCEMENT] Get full resolution for node_time 555
* [ENHANCEMENT] infiniband: Multiply port data XMIT/RCV metrics by 4 579
* [ENHANCEMENT] cpu: Metric 'package_throttles_total' is per package. 657
* [BUGFIX] Fix stale device error metrics 533
* [BUGFIX] edac: Fix typo in node_edac_csrow_uncorrectable_errors_total 564
* [BUGFIX] Use int64 throughout the ZFS collector 653
* [BUGFIX] Silently ignore nonexisting bonding_masters file 569
* [BUGFIX] Change raid0 status line regexp for mdadm collector (bug 618) 619
* [BUGFIX] Ignore wifi collector permission errors 646
* [BUGFIX] Always try to return smartmon_device_info metric 663