Add an end-to-end test.

This test runs a selection of collectors against the fixtures and
compares the output to a reference.

The uname and filesystem collectors are disabled because they use system
calls that cannot be fixtured easily.

.travis.yml

@@ -11,3 +11,5 @@ install:
 
 script:
   - go test -v ./...
+  - go build
+  - ./end-to-end-test.sh -v

collector/fixtures/megacli

@@ -1,3 +1,3 @@
 #!/usr/bin/env bash
 
-cat fixtures/megacli_disks.txt
+cat "$(dirname "$0")/megacli_disks.txt"

collector/mdadm.go

@@ -226,6 +226,7 @@ func (c *mdadmCollector) Update(ch chan<- prometheus.Metric) (err error) {
 	_, err = os.Stat(statusfile)
 	if os.IsNotExist(err) {
 		// no such file or directory, nothing to do, just return
+		log.Debugf("Not collecting mdstat, file does not exist: %s", statusfile)
 		return nil
 	}
 

end-to-end-test.sh

@@ -0,0 +1,91 @@
+#!/usr/bin/env bash
+
+set +euf +o pipefail
+
+cd "$(dirname $0)"
+
+port="$((10000 + (RANDOM % 10000)))"
+tmpdir=$(mktemp -d /tmp/node_exporter_e2e_test.XXXXXX)
+
+skip_re="^(go_|node_exporter_|process_|node_textfile_mtime)"
+
+keep=0; update=0; verbose=0
+while getopts 'hkuv' opt
+do
+  case "$opt" in
+    k)
+      keep=1
+      ;;
+    u)
+      update=1
+      ;;
+    v)
+      verbose=1
+      set -x
+      ;;
+    *)
+      echo "Usage: $0 [-k] [-u] [-v]"
+      echo "  -k: keep temporary files and leave node_exporter running"
+      echo "  -u: update fixture"
+      echo "  -v: verbose output"
+      exit 1
+      ;;
+  esac
+done
+
+
+./node_exporter \
+  -collector.procfs="collector/fixtures/proc" \
+  -collector.sysfs="collector/fixtures/sys" \
+  -collectors.enabled="diskstats,filefd,loadavg,mdadm,meminfo,netdev,netstat,sockstat,stat,textfile,bonding,megacli" \
+  -collector.textfile.directory="collector/fixtures/textfile/two_metric_files/" \
+  -collector.megacli.command="collector/fixtures/megacli" \
+  -web.listen-address "127.0.0.1:${port}" \
+  -log.level="debug" > "${tmpdir}/node_exporter.log" 2>&1 &
+
+echo $! > "${tmpdir}/node_exporter.pid"
+
+finish() {
+  if [ ${verbose} -ne 0 ]
+  then
+    echo "LOG ====================="
+    cat "${tmpdir}/node_exporter.log"
+    echo "========================="
+  fi
+
+  if [ ${update} -ne 0 ]
+  then
+    cp "${tmpdir}/e2e-output.txt" "collector/fixtures/e2e-output.txt"
+  fi
+
+  if [ ${keep} -eq 0 ]
+  then
+    kill -9 "$(cat ${tmpdir}/node_exporter.pid)"
+    # This silences the "Killed" message
+    wait "$(cat ${tmpdir}/node_exporter.pid)" > /dev/null 2>&1
+    rm -rf "${tmpdir}"
+  fi
+}
+
+trap finish EXIT
+
+get() {
+  if which curl > /dev/null 2>&1
+  then
+    curl -s -f "$@"
+  elif which wget > /dev/null 2>&1
+  then
+    wget -O - "$@"
+  else
+    echo "Neither curl nor wget found"
+    exit 1
+  fi
+}
+
+sleep 1
+
+get "127.0.0.1:${port}/metrics" > "${tmpdir}/e2e-output.txt"
+
+diff -u \
+  <(grep -E -v "${skip_re}" "collector/fixtures/e2e-output.txt") \
+  <(grep -E -v "${skip_re}" "${tmpdir}/e2e-output.txt")