Replace --collectors.enabled with per-collector flags (#640)

* Move NodeCollector into package collector

* Refactor collector enabling

* Update README with new collector enabled flags

* Fix out-of-date inline flag reference syntax

* Use new flags in end-to-end tests

* Add flag to disable all default collectors

* Track if a flag has been set explicitly

* Add --collectors.disable-defaults to README

* Revert disable-defaults flag

* Shorten flags

* Fixup timex collector registration

* Fix end-to-end tests

* Change procfs and sysfs path flags

* Fix review comments

end-to-end-test.sh

@@ -2,7 +2,7 @@
 
 set -euf -o pipefail
 
-collectors=$(cat << COLLECTORS
+enabled_collectors=$(cat << COLLECTORS
   arp
   bcache
   buddyinfo
@@ -36,6 +36,14 @@ collectors=$(cat << COLLECTORS
   zfs
 COLLECTORS
 )
+disabled_collectors=$(cat << COLLECTORS
+  filesystem
+  time
+  timex
+  uname
+  vmstat
+COLLECTORS
+)
 cd "$(dirname $0)"
 
 port="$((10000 + (RANDOM % 10000)))"
@@ -74,13 +82,14 @@ then
 fi
 
 ./node_exporter \
-  --collector.procfs="collector/fixtures/proc" \
-  --collector.sysfs="collector/fixtures/sys" \
-  --collectors.enabled="$(echo ${collectors} | tr ' ' ',')" \
+  --path.procfs="collector/fixtures/proc" \
+  --path.sysfs="collector/fixtures/sys" \
+  $(for c in ${enabled_collectors}; do echo --collector.${c}  ; done) \
+  $(for c in ${disabled_collectors}; do echo --no-collector.${c}  ; done) \
   --collector.textfile.directory="collector/fixtures/textfile/two_metric_files/" \
   --collector.megacli.command="collector/fixtures/megacli" \
-  --collector.wifi="collector/fixtures/wifi" \
-  --collector.qdisc="collector/fixtures/qdisc/" \
+  --collector.wifi.fixtures="collector/fixtures/wifi" \
+  --collector.qdisc.fixtures="collector/fixtures/qdisc/" \
   --web.listen-address "127.0.0.1:${port}" \
   --log.level="debug" > "${tmpdir}/node_exporter.log" 2>&1 &