started working on config loader

README.md

@@ -1,8 +1,6 @@
 # metrics.sh
 
-metrics.sh is a lightweight metrics collection and fowarding utility implemented in portable POSIX compliant shell scripts. A transparent interface based on hooks enables writing custom metric collectors and forwarders in an elegant way.
+metrics.sh is a lightweight metrics collection and fowarding utility implemented in portable POSIX compliant shell scripts. A transparent interface based on hooks enables writing custom metric collectors and reporters in an elegant way.
-
-Besides having a low impact on system resources, which makes metric.sh a suitable solution for running in virtual environments and servers with limited capacities, simplicty is the main goal of this project, hence its documentation shall fit in a single README.
 
 ## Usage
 
@@ -13,6 +11,7 @@ $ ./metrics.sh --help
 
   Options:
 
+    -c, --config   <file>      path to config file
     -m, --metrics  <metrics>   comma-separated list of metrics to collect
     -r, --reporter <reporter>  use specified reporter (default: stdout)
     -i, --interval <seconds>   collect metrics every n seconds (default: 2)
@@ -31,7 +30,7 @@ TODO: /etc/init.d
 
 ### Requirements
 
-metrics.sh has been tested on Ubuntu and Mac OS X but is supposed to run on most *NIX-line operating systems. Some of the provided metrics require [procfs](http://en.wikipedia.org/wiki/Procfs) to be available.
+metrics.sh has been tested on Ubuntu and Mac OS X but is supposed to run on most *NIX-like operating systems. Some of the provided metrics require [procfs](http://en.wikipedia.org/wiki/Procfs) to be available.
 
 ## Metrics
 

lib/utils/config.sh

@@ -0,0 +1,97 @@
+#!/bin/sh
+
+__CFG_REPORTERS=
+__CFG_METRICS=
+
+get_configured_reporters () {
+  echo $__CFG_REPORTERS
+}
+
+get_configured_metrics () {
+  echo $__CFG_METRICS
+}
+
+parse_config () {
+  if [ ! -f "$1" ]; then
+    echo "Error: unable to load config file: ${1}"
+    return 1
+  fi
+
+  RESTORE_IFS=$IFS
+  # dash compatibility :-(
+  IFS=$'
+'
+
+  local _group
+  local _name
+  local _alias
+  local _body
+
+  end_section () {
+    if [ -z "$_group" ]; then
+      return
+    fi
+
+    local fn_name
+    if [ "$_group" = "reporter" ]; then
+      __CFG_REPORTERS=$(trim "${__CFG_REPORTERS} ${_name}:${_alias}")
+      fn_name="__r_"
+    elif [ "$_group" = "metric" ]; then
+      __CFG_METRICS=$(trim "${__CFG_METRICS} ${_name}:${_alias}")
+      fn_name="__m_"
+    else
+      fn_name="global"
+    fi
+
+    if [ -n "$_alias" ]; then
+      fn_name="${fn_name}${_alias}"
+    elif [ -n "$_name" ]; then
+      fn_name="${fn_name}${_name}"
+    fi
+
+    if [ -z "$_body" ]; then
+      return
+    fi
+
+    #echo "${fn_name}_config () { ${_body}; }"
+    eval "${fn_name}_config () { ${_body}; }"
+  }
+
+  for line in $(cat $1); do
+    # handle comments / empty lines
+    line=$(echo $line | grep -v '^\(#\|;\)')
+
+    if [ -z "$line" ]; then
+      continue
+    fi
+
+    local _section=$(echo $line | grep '^\[.*' | sed 's/\[\(.*\)\]/\1/')
+    if [ -n "$_section" ]; then
+      end_section
+      unset _group _name _alias _body
+
+      _group=$(echo $_section | awk '{ print $1 }')
+
+      if echo " metrics.sh metric reporter " | grep -q -v " $_group "; then
+        echo "Warning: unknown section in configuration file: $_section"
+        continue
+      fi
+
+      if [ "$_group" = "metrics.sh" ]; then
+        _group="global"
+        continue
+      fi
+
+      _section=$(echo $_section | awk '{ print $2 }')
+      _name=$(echo $_section | awk 'BEGIN { FS=":" } { print $1 } ')
+      _alias=$(echo $_section | awk 'BEGIN { FS=":" } { print $2 } ')
+      continue
+    fi
+
+    _body=$(echo "${_body};${line}" | sed 's/^;//g')
+  done
+
+  end_section
+
+  IFS=$RESTORE_IFS
+}

metrics.sh

@@ -4,6 +4,7 @@
 INTERVAL=2
 REPORTER=stdout
 METRICS=cpu,disk_io,disk_usage,heartbeat,memory,network_io,swap
+CONFIG_FILE=
 
 # env
 LC_ALL=en_US.UTF-8
@@ -20,6 +21,7 @@ help () {
   echo
   echo "  Options: "
   echo
+  echo "    -c, --config   <file>      path to config file"
   echo "    -m, --metrics  <metrics>   comma-separated list of metrics to collect"
   echo "    -r, --reporter <reporter>  use specified reporter (default: stdout)"
   echo "    -i, --interval <seconds>   collect metrics every n seconds (default: 2)"
@@ -35,6 +37,11 @@ opt_verbose=false
 
 while [ $# -gt 0 ]; do
   case $1 in
+    -c|--config)
+      shift
+      CONFIG_FILE=$1
+      ;;
+
     -m|--metrics)
       shift
       METRICS=$1
@@ -90,6 +97,29 @@ if [ $opt_docs = true ]; then
   exit
 fi
 
+if [ -n "$CONFIG_FILE" ]; then
+  verbose "Loading configuration file: $CONFIG_FILE"
+
+  parse_config $CONFIG_FILE
+  if [ $? -ne 0 ]; then
+    exit 1
+  fi
+
+  if is_function global_config; then
+    global_config
+  fi
+
+  configured_reporters=$(get_configured_reporters)
+  if [ -n "$configured_reporters" ]; then
+    REPORTER=$configured_reporters
+  fi
+
+  configured_metrics=$(get_configured_metrics)
+  if [ -n "$configured_metrics" ]; then
+    METRICS=$configured_metrics
+  fi
+fi
+
 main_init $METRICS $REPORTER
 verbose "Using metrics: $__METRICS"
 verbose "Using reporter: $__REPORTER"