fully working config handling. support for multiple metrics of the same type. implement signal trapping

README.md

@@ -7,7 +7,7 @@ metrics.sh is a lightweight metrics collection and fowarding utility implemented
 ```
 $ ./metrics.sh --help
 
-  Usage: ./metrics.sh [-d] [-h] [-v] [-m metrics] [-r reporter] [-i interval]
+  Usage: ./metrics.sh [-d] [-h] [-v] [-c] [-m] [-r] [-i]
 
   Options:
 
@@ -54,8 +54,7 @@ TODO: how to write custom reporters
 ## TODO
 
 - README
-- config file support
+- config file docs
 - config file auto-generation
 - load custom/contrib metrics and reporters
-- same metric multiple times? (e.g. disk_usage for multiple devices)
 - allow multiple reporters?

lib/main.sh

@@ -28,9 +28,6 @@ main_load () {
     # register metric
     __AVAILABLE_METRICS=$(trim "$__AVAILABLE_METRICS $metric")
   done
-
-  load_metric_with_prefix __m_${metric}_ $file
-
 }
 
 main_init () {
@@ -41,12 +38,6 @@ main_init () {
   # create temp dir
   TEMP_DIR=$(make_temp_dir)
 
-  # register trap
-  trap '
-    main_terminate
-    trap - TERM && kill -- -$$ INT TERM EXIT
-  ' INT TERM EXIT
-
   # check if reporter exists
   if ! in_array $__REPORTER "$__AVAILABLE_REPORTERS"; then
     echo "Error: reporter '$__REPORTER' is not available"
@@ -63,78 +54,96 @@ main_init () {
   done
 
   # init reporter
+  if is_function __r_${__REPORTER}_config; then
+    __r_${__REPORTER}_config
+  fi
   if is_function __r_${__REPORTER}_init; then
     __r_${__REPORTER}_init
   fi
-
-  # init metrics
-  for metric in $__METRICS; do
-    local metric_name=$(get_name $metric)
-    local metric_alias=$(get_alias $metric)
-
-    load_metric_with_prefix __m_${metric_alias}_ ./metrics/${metric_name}.sh
-
-    if ! is_function __m_${metric_alias}_init; then
-      continue
-    fi
-
-    __m_${metric_alias}_init
-  done
 }
 
 main_collect () {
-  # used by metrics to return results
+  # register trap
-  report () {
+  trap '
-    local _r_label _r_result
+    trap "" 13
-    if [ -z $2 ]; then
+    trap - INT TERM EXIT
-      _r_label=$metric
+    echo Exit signal received.
-      _r_result="$1"
+    kill -13 -$$
-    else
+  ' 13 INT TERM EXIT
-      _r_label="$metric.$1"
-      _r_result="$2"
-    fi
-    if is_number $_r_result; then
-      __r_${__REPORTER}_report $_r_label $_r_result
-    fi
-  }
 
   # collect metrics
   for metric in $__METRICS; do
-    metric=$(get_alias $metric)
+    # run in subshell to isolate scope
-    if ! is_function __m_${metric}_collect; then
+    (
-      continue
+      local metric_name=$(get_name $metric)
-    fi
+      local metric_alias=$(get_alias $metric)
+      # used by metrics to return results
+      report () {
+        local _r_label _r_result
+        if [ -z $2 ]; then
+          _r_label=$metric_alias
+          _r_result="$1"
+        else
+          _r_label="$metric_alias.$1"
+          _r_result="$2"
+        fi
+        if is_number $_r_result; then
+          __r_${__REPORTER}_report $_r_label $_r_result
+        fi
+      }
 
-    # fork
+      # init metric
-    (while true; do
+      if is_function __m_${metric_alias}_config; then
-      __m_${metric}_collect
+        __m_${metric_alias}_config
-      sleep $INTERVAL
+      fi
-    done) &
+
+      load_metric_with_prefix __m_${metric_alias}_ ./metrics/${metric_name}.sh
+
+      if is_function __m_${metric_alias}_init; then
+        __m_${metric_alias}_init
+      fi
+
+      if ! is_function __m_${metric_alias}_collect; then
+        continue
+      fi
+
+      # collect metrics
+      trap "
+        if is_function __m_${metric_alias}_terminate; then
+          verbose 'Stopping metric ${metric_alias}'
+          __m_${metric_alias}_terminate
+        fi
+        exit 0
+      " 13
+
+      while true; do
+        __m_${metric_alias}_collect
+        sleep $INTERVAL
+      done
+    ) &
   done
 
-  # run forever
+  # wait until interrupted
-  sleep 2147483647 # `sleep infinity` is not portable
+  wait
+  # then wait again for processes to end
+  wait
+
+  main_terminate
 }
 
 main_terminate () {
-  # terminate metrics
-  for metric in $__METRICS; do
-    metric=$(get_alias $metric)
-    if ! is_function __m_${metric}_terminate; then
-      continue
-    fi
-    __m_${metric}_terminate
-  done
-
   # terminate reporter
   if is_function __r_${__REPORTER}_terminate; then
+    verbose "Stopping reporter ${__REPORTER}"
     __r_${__REPORTER}_terminate
   fi
 
+  verbose -n "Cleaning up..."
   # delete temporary directory
   if [ -d $TEMP_DIR ]; then
     rmdir $TEMP_DIR
   fi
+  verbose "done"
 }
 
 main_docs () {

lib/utils/config.sh

@@ -24,7 +24,6 @@ parse_config () {
 
   local _group
   local _name
-  local _alias
   local _body
 
   end_section () {
@@ -34,20 +33,16 @@ parse_config () {
 
     local fn_name
     if [ "$_group" = "reporter" ]; then
-      __CFG_REPORTERS=$(trim "${__CFG_REPORTERS} ${_name}:${_alias}")
+      __CFG_REPORTERS=$(trim "${__CFG_REPORTERS} ${_name}")
       fn_name="__r_"
     elif [ "$_group" = "metric" ]; then
-      __CFG_METRICS=$(trim "${__CFG_METRICS} ${_name}:${_alias}")
+      __CFG_METRICS=$(trim "${__CFG_METRICS} ${_name}")
       fn_name="__m_"
     else
-      fn_name="global"
+      fn_name="main"
     fi
 
-    if [ -n "$_alias" ]; then
+    fn_name=${fn_name}$(get_alias $_name)
-      fn_name="${fn_name}${_alias}"
-    elif [ -n "$_name" ]; then
-      fn_name="${fn_name}${_name}"
-    fi
 
     if [ -z "$_body" ]; then
       return
@@ -68,7 +63,7 @@ parse_config () {
     local _section=$(echo $line | grep '^\[.*' | sed 's/\[\(.*\)\]/\1/')
     if [ -n "$_section" ]; then
       end_section
-      unset _group _name _alias _body
+      unset _group _name _body
 
       _group=$(echo $_section | awk '{ print $1 }')
 
@@ -78,13 +73,11 @@ parse_config () {
       fi
 
       if [ "$_group" = "metrics.sh" ]; then
-        _group="global"
+        _group="main"
         continue
       fi
 
-      _section=$(echo $_section | awk '{ print $2 }')
+      _name=$(echo $_section | awk '{ print $2 }')
-      _name=$(echo $_section | awk 'BEGIN { FS=":" } { print $1 }')
-      _alias=$(echo $_section | awk 'BEGIN { FS=":" } { print $2 }')
       continue
     fi
 

lib/utils/helpers.sh

@@ -16,4 +16,11 @@ in_array () {
 
 trim () {
   echo $1 | sed -e 's/^[[:space:]]*//g' -e 's/[[:space:]]*\$//g'
+}
+
+unique_id () {
+  RESTORE_LC_ALL=$LC_ALL
+  LC_ALL=C
+  echo __u_$(cat /dev/urandom | tr -dc 'A-Za-z0-9' | head -c 10)
+  LC_ALL=$RESTORE_LC_ALL
 }

metrics.sh

@@ -12,7 +12,7 @@ LANG=en_US.UTF-8
 LANGUAGE=en_US.UTF-8
 
 usage () {
-  echo "  Usage: $0 [-d] [-h] [-v] [-m metrics] [-r reporter] [-i interval]"
+  echo "  Usage: $0 [-d] [-h] [-v] [-c] [-m] [-r] [-i]"
 }
 
 help () {
@@ -82,10 +82,11 @@ done
 # run
 . ./lib/main.sh
 
-if [ $opt_verbose = "true" ]; then
+if [ $opt_verbose = true ]; then
   verbose_on
   verbose "Started in verbose mode"
 fi
+verbose "PID: $$"
 verbose "OS detected: $OS_TYPE"
 
 main_load
@@ -105,8 +106,8 @@ if [ -n "$CONFIG_FILE" ]; then
     exit 1
   fi
 
-  if is_function global_config; then
+  if is_function main_config; then
-    global_config
+    main_config
   fi
 
   configured_reporters=$(get_configured_reporters)

metrics/disk_io.sh

@@ -8,7 +8,7 @@ init () {
       DISK_IO_MOUNTPOINT="/dev/vda"
     fi
   fi
-  readonly __disk_io_fifo=$TEMP_DIR/disk_io
+  readonly __disk_io_fifo=$TEMP_DIR/$(unique_id)
   mkfifo $__disk_io_fifo
   __disk_io_bgproc &
 }