Implement JSON parsing in the external module.

docs/config/modules/external.xml

@@ -227,7 +227,7 @@
               </listitem>
             </varlistentry>
           </variablelist>
-          <para>This is a regular expression that is globally applied to the stdout of the command.  Each match is turned into a metric. It is a requirement to used named capturing in the regular expression where "key" is the named match of the metric name and "value" is the named match for the matric value.  A sample for extracting performance data from Nagios commands would be: (?&lt;key&gt;\S+)=(?&lt;value&gt;[^;\s]+)(?=[;\s]). "NAGIOS" may also be specified as a value, which will configure the external check to do Nagios parsing based on the nagios_regex module configuration parameter.</para>
+          <para>This is a regular expression that is globally applied to the stdout of the command.  Each match is turned into a metric. It is a requirement to used named capturing in the regular expression where "key" is the named match of the metric name and "value" is the named match for the matric value.  A sample for extracting performance data from Nagios commands would be: (?&lt;key&gt;\S+)=(?&lt;value&gt;[^;\s]+)(?=[;\s]). "NAGIOS" may also be specified as a value, which will configure the external check to do Nagios parsing based on the nagios_regex module configuration parameter. "JSON" may be specified to instruct the output to be parsed as a JSON document using the same methodology as the HTTPTrap check.</para>
         </listitem>
       </varlistentry>
     </variablelist>

src/modules/external.c

@@ -57,6 +57,7 @@
 #include "noit_check.h"
 #include "noit_check_tools.h"
 #include "noit_mtev_bridge.h"
+#include "mtev_json.h"
 #include "external_proc.h"
 
 typedef enum {
@@ -75,6 +76,7 @@ struct check_info {
   char **envs;
   noit_check_t *check;
   int exit_code;
+  external_special_t type;
 
   int errortype;
   int written;
@@ -163,13 +165,27 @@ static void external_log_results(noit_module_t *self, noit_check_t *check) {
   }
 
   /* Hack the output into metrics */
-  if(ci->output && ci->matcher) {
+  if(ci->output && ci->type == EXTERNAL_JSON_TYPE) {
+    int len, cnt;
+    len = strlen(ci->output);
+    cnt = noit_check_stats_from_json_str(check, ci->output, len);
+    if(cnt <= 0) {
+      noit_stats_set_state(check, NP_BAD);
+      noit_stats_set_status(check, "command produced invalid or empty JSON");
+    }
+    else {
+      char buf[64];
+      snprintf(buf, sizeof(buf), "%d stats", cnt);
+      noit_stats_set_status(check, buf);
+    }
+  }
+  else if(ci->output && ci->matcher) {
     int rc, len, startoffset = 0;
     int ovector[30];
     char* output = ci->output;
     len = strlen(output);
     mtevL(data->nldeb, "going to match output at %d/%d\n", startoffset, len);
-    if (data->type == EXTERNAL_NAGIOS_TYPE) {
+    if (ci->type == EXTERNAL_NAGIOS_TYPE) {
       pcre *matcher;
       const char *error;
       char* pch;
@@ -225,7 +241,7 @@ static void external_log_results(noit_module_t *self, noit_check_t *check) {
          pcre_copy_named_substring(ci->matcher, output, ovector, rc,
                                    "value", value, sizeof(value)) > 0) {
         /* We're able to extract something... */
-        if (data->type == EXTERNAL_NAGIOS_TYPE) {
+        if (ci->type == EXTERNAL_NAGIOS_TYPE) {
           /* We only care about metrics after the pipe - get check status from the
            * pre-pipe data, then only match on post-pipe data */
           char uom[128];
@@ -246,10 +262,10 @@ static void external_log_results(noit_module_t *self, noit_check_t *check) {
       mtevL(data->nldeb, "going to match output at %d/%d\n", startoffset, len);
     }
     mtevL(data->nldeb, "match failed.... %d\n", rc);
+    if (ci->output)
+      noit_stats_set_status(check, ci->output);
   }
 
-  if (ci->output)
-    noit_stats_set_status(check, ci->output);
   noit_check_set_stats(check);
 
   /* If we didn't exit normally, or we core, or we have stderr to report...
@@ -688,15 +704,18 @@ static int external_invoke(noit_module_t *self, noit_check_t *check,
                         &value) != 0) {
     const char *error;
     int erroffset;
-    if (!strcmp(value, "NAGIOS")) {
-      data->type = EXTERNAL_NAGIOS_TYPE;
+    if (!strcmp(value, "JSON")) {
+      ci->type = EXTERNAL_JSON_TYPE;
+    }
+    else if (!strcmp(value, "NAGIOS")) {
+      ci->type = EXTERNAL_NAGIOS_TYPE;
       ci->matcher = pcre_compile(data->nagios_regex, 0, &error, &erroffset, NULL);
     }
     else {
-      data->type = EXTERNAL_DEFAULT_TYPE;
+      ci->type = EXTERNAL_DEFAULT_TYPE;
       ci->matcher = pcre_compile(value, 0, &error, &erroffset, NULL);
     }
-    if(!ci->matcher) {
+    if(ci->type != EXTERNAL_JSON_TYPE && !ci->matcher) {
       mtevL(data->nlerr, "external pcre /%s/ failed @ %d: %s\n",
             value, erroffset, error);
     }

src/modules/external.xml

@@ -34,7 +34,7 @@
                allowed=".+">These parameters allow the setting of environment variables for the command execution.  The text following env_ is the key and the parameter value is the value of the environment variable to be set via execve.</parameter>
     <parameter name="output_extract"
                required="optional"
-               allowed=".+">This is a regular expression that is globally applied to the stdout of the command.  Each match is turned into a metric. It is a requirement to used named capturing in the regular expression where "key" is the named match of the metric name and "value" is the named match for the matric value.  A sample for extracting performance data from Nagios commands would be: <![CDATA[(?<key>\S+)=(?<value>[^;\s]+)(?=[;\s])]]>. "NAGIOS" may also be specified as a value, which will configure the external check to do Nagios parsing based on the nagios_regex module configuration parameter.</parameter>
+               allowed=".+">This is a regular expression that is globally applied to the stdout of the command.  Each match is turned into a metric. It is a requirement to used named capturing in the regular expression where "key" is the named match of the metric name and "value" is the named match for the matric value.  A sample for extracting performance data from Nagios commands would be: <![CDATA[(?<key>\S+)=(?<value>[^;\s]+)(?=[;\s])]]>. "NAGIOS" may also be specified as a value, which will configure the external check to do Nagios parsing based on the nagios_regex module configuration parameter. "JSON" may be specified to instruct the output to be parsed as a JSON document using the same methodology as the HTTPTrap check.</parameter>
   </checkconfig>
   <examples>
     <example>

src/modules/external_proc.h

@@ -41,7 +41,8 @@
 
 typedef enum {
   EXTERNAL_DEFAULT_TYPE = 0,
-  EXTERNAL_NAGIOS_TYPE = 1
+  EXTERNAL_NAGIOS_TYPE = 1,
+  EXTERNAL_JSON_TYPE = 2
 } external_special_t;
 
 struct external_response {
@@ -62,7 +63,6 @@ typedef struct {
   int pipe_e2n[2];
   char* path;
   char* nagios_regex;
-  external_special_t type;
   eventer_jobq_t *jobq;
   mtev_atomic64_t check_no_seq;
   mtev_hash_table external_checks;