collectd-5.12.0/src/write_sensu.c

/**
 * collectd - src/write_sensu.c
 * Copyright (C) 2015 Fabrice A. Marie
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 *
 * Authors:
 *   Fabrice A. Marie <fabrice at kibinlabs.com>
 */

#define _GNU_SOURCE

#include "collectd.h"

#include "plugin.h"
#include "utils/common/common.h"
#include "utils_cache.h"
#include <arpa/inet.h>
#include <errno.h>
#include <inttypes.h>
#include <netdb.h>
#include <stddef.h>

#include <stdlib.h>
#define SENSU_HOST "localhost"
#define SENSU_PORT "3030"

#ifdef HAVE_ASPRINTF
#define my_asprintf asprintf
#define my_vasprintf vasprintf
#else
/*
 * asprintf() is available from Solaris 10 update 11.
 * For older versions, use asprintf() portable implementation from
 * https://github.com/littlstar/asprintf.c/blob/master/
 * copyright (c) 2014 joseph werle <joseph.werle@gmail.com> under MIT license.
 */

static int my_vasprintf(char **str, const char *fmt, va_list args) {
  int size = 0;
  va_list tmpa;
  // copy
  va_copy(tmpa, args);
  // apply variadic arguments to
  // sprintf with format to get size
  size = vsnprintf(NULL, size, fmt, tmpa);
  // toss args
  va_end(tmpa);
  // return -1 to be compliant if
  // size is less than 0
  if (size < 0) {
    return -1;
  }
  // alloc with size plus 1 for `\0'
  *str = (char *)malloc(size + 1);
  // return -1 to be compliant
  // if pointer is `NULL'
  if (NULL == *str) {
    return -1;
  }
  // format string with original
  // variadic arguments and set new size
  size = vsprintf(*str, fmt, args);
  return size;
}

static int my_asprintf(char **str, const char *fmt, ...) {
  int size = 0;
  va_list args;
  // init variadic argumens
  va_start(args, fmt);
  // format and get size
  size = my_vasprintf(str, fmt, args);
  // toss args
  va_end(args);
  return size;
}

#endif

struct str_list {
  int nb_strs;
  char **strs;
};

struct sensu_host {
  char *name;
  char *event_service_prefix;
  struct str_list metric_handlers;
  struct str_list notification_handlers;
#define F_READY 0x01
  uint8_t flags;
  pthread_mutex_t lock;
  bool notifications;
  bool metrics;
  bool store_rates;
  bool always_append_ds;
  bool include_source;
  char *separator;
  char *node;
  char *service;
  int s;
  struct addrinfo *res;
  int reference_count;
};

static char *sensu_tags;
static char **sensu_attrs;
static size_t sensu_attrs_num;

static int add_str_to_list(struct str_list *strs,
                           const char *str_to_add) /* {{{ */
{
  char **old_strs_ptr = strs->strs;
  char *newstr = strdup(str_to_add);
  if (newstr == NULL) {
    ERROR("write_sensu plugin: Unable to alloc memory");
    return -1;
  }
  strs->strs = realloc(strs->strs, strs->nb_strs + 1);
  if (strs->strs == NULL) {
    strs->strs = old_strs_ptr;
    free(newstr);
    ERROR("write_sensu plugin: Unable to alloc memory");
    return -1;
  }
  strs->strs[strs->nb_strs] = newstr;
  strs->nb_strs++;
  return 0;
}
/* }}} int add_str_to_list */

static void free_str_list(struct str_list *strs) /* {{{ */
{
  for (int i = 0; i < strs->nb_strs; i++)
    free(strs->strs[i]);
  free(strs->strs);
}
/* }}} void free_str_list */

static int sensu_connect(struct sensu_host *host) /* {{{ */
{
  int e;
  char const *node;
  char const *service;

  // Resolve the target if we haven't done already
  if (!(host->flags & F_READY)) {
    memset(&service, 0, sizeof(service));
    host->res = NULL;

    node = (host->node != NULL) ? host->node : SENSU_HOST;
    service = (host->service != NULL) ? host->service : SENSU_PORT;

    struct addrinfo ai_hints = {.ai_family = AF_INET,
                                .ai_flags = AI_ADDRCONFIG,
                                .ai_socktype = SOCK_STREAM};

    if ((e = getaddrinfo(node, service, &ai_hints, &(host->res))) != 0) {
      ERROR("write_sensu plugin: Unable to resolve host \"%s\": %s", node,
            gai_strerror(e));
      return -1;
    }
    DEBUG("write_sensu plugin: successfully resolved host/port: %s/%s", node,
          service);
    host->flags |= F_READY;
  }

  struct linger so_linger;
  host->s = -1;
  for (struct addrinfo *ai = host->res; ai != NULL; ai = ai->ai_next) {
    // create the socket
    if ((host->s = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol)) ==
        -1) {
      continue;
    }

    // Set very low close() lingering
    so_linger.l_onoff = 1;
    so_linger.l_linger = 3;
    if (setsockopt(host->s, SOL_SOCKET, SO_LINGER, &so_linger,
                   sizeof so_linger) != 0)
      WARNING("write_sensu plugin: failed to set socket close() lingering");

    set_sock_opts(host->s);

    // connect the socket
    if (connect(host->s, ai->ai_addr, ai->ai_addrlen) != 0) {
      close(host->s);
      host->s = -1;
      continue;
    }
    DEBUG("write_sensu plugin: connected");
    break;
  }

  if (host->s < 0) {
    WARNING("write_sensu plugin: Unable to connect to sensu client");
    return -1;
  }
  return 0;
} /* }}} int sensu_connect */

static void sensu_close_socket(struct sensu_host *host) /* {{{ */
{
  if (host->s != -1)
    close(host->s);
  host->s = -1;

} /* }}} void sensu_close_socket */

static char *build_json_str_list(const char *tag,
                                 struct str_list const *list) /* {{{ */
{
  int res;
  char *ret_str = NULL;
  char *temp_str;
  if (list->nb_strs == 0) {
    ret_str = malloc(1);
    if (ret_str == NULL) {
      ERROR("write_sensu plugin: Unable to alloc memory");
      return NULL;
    }
    ret_str[0] = '\0';
  }

  res = my_asprintf(&temp_str, "\"%s\": [\"%s\"", tag, list->strs[0]);
  if (res == -1) {
    ERROR("write_sensu plugin: Unable to alloc memory");
    free(ret_str);
    return NULL;
  }
  for (int i = 1; i < list->nb_strs; i++) {
    res = my_asprintf(&ret_str, "%s, \"%s\"", temp_str, list->strs[i]);
    free(temp_str);
    if (res == -1) {
      ERROR("write_sensu plugin: Unable to alloc memory");
      return NULL;
    }
    temp_str = ret_str;
  }
  res = my_asprintf(&ret_str, "%s]", temp_str);
  free(temp_str);
  if (res == -1) {
    ERROR("write_sensu plugin: Unable to alloc memory");
    return NULL;
  }

  return ret_str;
} /* }}} char *build_json_str_list*/

static int sensu_format_name2(char *ret, int ret_len, const char *hostname,
                              const char *plugin, const char *plugin_instance,
                              const char *type, const char *type_instance,
                              const char *separator) {
  char *buffer;
  size_t buffer_size;

  buffer = ret;
  buffer_size = (size_t)ret_len;

#define APPEND(str)                                                            \
  do {                                                                         \
    size_t l = strlen(str);                                                    \
    if (l >= buffer_size)                                                      \
      return ENOBUFS;                                                          \
    memcpy(buffer, (str), l);                                                  \
    buffer += l;                                                               \
    buffer_size -= l;                                                          \
  } while (0)

  assert(plugin != NULL);
  assert(type != NULL);

  APPEND(hostname);
  APPEND(separator);
  APPEND(plugin);
  if ((plugin_instance != NULL) && (plugin_instance[0] != 0)) {
    APPEND("-");
    APPEND(plugin_instance);
  }
  APPEND(separator);
  APPEND(type);
  if ((type_instance != NULL) && (type_instance[0] != 0)) {
    APPEND("-");
    APPEND(type_instance);
  }
  assert(buffer_size > 0);
  buffer[0] = 0;

#undef APPEND
  return 0;
} /* int sensu_format_name2 */

static void in_place_replace_sensu_name_reserved(char *orig_name) /* {{{ */
{
  size_t len = strlen(orig_name);
  for (size_t i = 0; i < len; i++) {
    // some plugins like ipmi generate special characters in metric name
    switch (orig_name[i]) {
    case '(':
      orig_name[i] = '_';
      break;
    case ')':
      orig_name[i] = '_';
      break;
    case ' ':
      orig_name[i] = '_';
      break;
    case '"':
      orig_name[i] = '_';
      break;
    case '\'':
      orig_name[i] = '_';
      break;
    case '+':
      orig_name[i] = '_';
      break;
    }
  }
} /* }}} char *replace_sensu_name_reserved */

static char *sensu_value_to_json(struct sensu_host const *host, /* {{{ */
                                 data_set_t const *ds, value_list_t const *vl,
                                 size_t index, gauge_t const *rates) {
  char name_buffer[5 * DATA_MAX_NAME_LEN];
  char service_buffer[6 * DATA_MAX_NAME_LEN];
  char *ret_str;
  char *temp_str;
  char *value_str;
  int res;
  // First part of the JSON string
  const char *part1 = "{\"name\": \"collectd\", \"type\": \"metric\"";

  char *handlers_str =
      build_json_str_list("handlers", &(host->metric_handlers));
  if (handlers_str == NULL) {
    ERROR("write_sensu plugin: Unable to alloc memory");
    return NULL;
  }

  // incorporate the handlers
  if (strlen(handlers_str) == 0) {
    free(handlers_str);
    ret_str = strdup(part1);
    if (ret_str == NULL) {
      ERROR("write_sensu plugin: Unable to alloc memory");
      return NULL;
    }
  } else {
    res = my_asprintf(&ret_str, "%s, %s", part1, handlers_str);
    free(handlers_str);
    if (res == -1) {
      ERROR("write_sensu plugin: Unable to alloc memory");
      return NULL;
    }
  }

  if (host->include_source) {
    res = my_asprintf(&temp_str, "%s, \"source\": \"%s\"", ret_str, vl->host);
    free(ret_str);
    if (res == -1) {
      ERROR("write_sensu plugin: Unable to alloc memory");
      return NULL;
    }
    ret_str = temp_str;
  }

  // incorporate the plugin name information
  res = my_asprintf(&temp_str, "%s, \"collectd_plugin\": \"%s\"", ret_str,
                    vl->plugin);
  free(ret_str);
  if (res == -1) {
    ERROR("write_sensu plugin: Unable to alloc memory");
    return NULL;
  }
  ret_str = temp_str;

  // incorporate the plugin type
  res = my_asprintf(&temp_str, "%s, \"collectd_plugin_type\": \"%s\"", ret_str,
                    vl->type);
  free(ret_str);
  if (res == -1) {
    ERROR("write_sensu plugin: Unable to alloc memory");
    return NULL;
  }
  ret_str = temp_str;

  // incorporate the plugin instance if any
  if (vl->plugin_instance[0] != 0) {
    res = my_asprintf(&temp_str, "%s, \"collectd_plugin_instance\": \"%s\"",
                      ret_str, vl->plugin_instance);
    free(ret_str);
    if (res == -1) {
      ERROR("write_sensu plugin: Unable to alloc memory");
      return NULL;
    }
    ret_str = temp_str;
  }

  // incorporate the plugin type instance if any
  if (vl->type_instance[0] != 0) {
    res =
        my_asprintf(&temp_str, "%s, \"collectd_plugin_type_instance\": \"%s\"",
                    ret_str, vl->type_instance);
    free(ret_str);
    if (res == -1) {
      ERROR("write_sensu plugin: Unable to alloc memory");
      return NULL;
    }
    ret_str = temp_str;
  }

  // incorporate the data source type
  if ((ds->ds[index].type != DS_TYPE_GAUGE) && (rates != NULL)) {
    char ds_type[DATA_MAX_NAME_LEN];
    snprintf(ds_type, sizeof(ds_type), "%s:rate",
             DS_TYPE_TO_STRING(ds->ds[index].type));
    res = my_asprintf(&temp_str, "%s, \"collectd_data_source_type\": \"%s\"",
                      ret_str, ds_type);
    free(ret_str);
    if (res == -1) {
      ERROR("write_sensu plugin: Unable to alloc memory");
      return NULL;
    }
    ret_str = temp_str;
  } else {
    res = my_asprintf(&temp_str, "%s, \"collectd_data_source_type\": \"%s\"",
                      ret_str, DS_TYPE_TO_STRING(ds->ds[index].type));
    free(ret_str);
    if (res == -1) {
      ERROR("write_sensu plugin: Unable to alloc memory");
      return NULL;
    }
    ret_str = temp_str;
  }

  // incorporate the data source name
  res = my_asprintf(&temp_str, "%s, \"collectd_data_source_name\": \"%s\"",
                    ret_str, ds->ds[index].name);
  free(ret_str);
  if (res == -1) {
    ERROR("write_sensu plugin: Unable to alloc memory");
    return NULL;
  }
  ret_str = temp_str;

  // incorporate the data source index
  {
    char ds_index[DATA_MAX_NAME_LEN];
    snprintf(ds_index, sizeof(ds_index), "%" PRIsz, index);
    res = my_asprintf(&temp_str, "%s, \"collectd_data_source_index\": %s",
                      ret_str, ds_index);
    free(ret_str);
    if (res == -1) {
      ERROR("write_sensu plugin: Unable to alloc memory");
      return NULL;
    }
    ret_str = temp_str;
  }

  // add key value attributes from config if any
  for (size_t i = 0; i < sensu_attrs_num; i += 2) {
    res = my_asprintf(&temp_str, "%s, \"%s\": \"%s\"", ret_str, sensu_attrs[i],
                      sensu_attrs[i + 1]);
    free(ret_str);
    if (res == -1) {
      ERROR("write_sensu plugin: Unable to alloc memory");
      return NULL;
    }
    ret_str = temp_str;
  }

  // incorporate sensu tags from config if any
  if ((sensu_tags != NULL) && (strlen(sensu_tags) != 0)) {
    res = my_asprintf(&temp_str, "%s, %s", ret_str, sensu_tags);
    free(ret_str);
    if (res == -1) {
      ERROR("write_sensu plugin: Unable to alloc memory");
      return NULL;
    }
    ret_str = temp_str;
  }

  // calculate the value and set to a string
  if (ds->ds[index].type == DS_TYPE_GAUGE) {
    res = my_asprintf(&value_str, GAUGE_FORMAT, vl->values[index].gauge);
    if (res == -1) {
      free(ret_str);
      ERROR("write_sensu plugin: Unable to alloc memory");
      return NULL;
    }
  } else if (rates != NULL) {
    res = my_asprintf(&value_str, GAUGE_FORMAT, rates[index]);
    if (res == -1) {
      free(ret_str);
      ERROR("write_sensu plugin: Unable to alloc memory");
      return NULL;
    }
  } else {
    if (ds->ds[index].type == DS_TYPE_DERIVE) {
      res = my_asprintf(&value_str, "%" PRIi64, vl->values[index].derive);
      if (res == -1) {
        free(ret_str);
        ERROR("write_sensu plugin: Unable to alloc memory");
        return NULL;
      }
    } else if (ds->ds[index].type == DS_TYPE_ABSOLUTE) {
      res = my_asprintf(&value_str, "%" PRIu64, vl->values[index].absolute);
      if (res == -1) {
        free(ret_str);
        ERROR("write_sensu plugin: Unable to alloc memory");
        return NULL;
      }
    } else {
      res = my_asprintf(&value_str, "%" PRIu64,
                        (uint64_t)vl->values[index].counter);
      if (res == -1) {
        free(ret_str);
        ERROR("write_sensu plugin: Unable to alloc memory");
        return NULL;
      }
    }
  }

  // Generate the full service name
  sensu_format_name2(name_buffer, sizeof(name_buffer), vl->host, vl->plugin,
                     vl->plugin_instance, vl->type, vl->type_instance,
                     host->separator);
  if (host->always_append_ds || (ds->ds_num > 1)) {
    if (host->event_service_prefix == NULL)
      snprintf(service_buffer, sizeof(service_buffer), "%s.%s", name_buffer,
               ds->ds[index].name);
    else
      snprintf(service_buffer, sizeof(service_buffer), "%s%s.%s",
               host->event_service_prefix, name_buffer, ds->ds[index].name);
  } else {
    if (host->event_service_prefix == NULL)
      sstrncpy(service_buffer, name_buffer, sizeof(service_buffer));
    else
      snprintf(service_buffer, sizeof(service_buffer), "%s%s",
               host->event_service_prefix, name_buffer);
  }

  // Replace collectd sensor name reserved characters so that time series DB is
  // happy
  in_place_replace_sensu_name_reserved(service_buffer);

  // finalize the buffer by setting the output and closing curly bracket
  res = my_asprintf(&temp_str, "%s, \"output\": \"%s %s %lld\"}\n", ret_str,
                    service_buffer, value_str,
                    (long long)CDTIME_T_TO_TIME_T(vl->time));
  free(ret_str);
  free(value_str);
  if (res == -1) {
    ERROR("write_sensu plugin: Unable to alloc memory");
    return NULL;
  }
  ret_str = temp_str;

  DEBUG("write_sensu plugin: Successfully created json for metric: "
        "host = \"%s\", service = \"%s\"",
        vl->host, service_buffer);
  return ret_str;
} /* }}} char *sensu_value_to_json */

/*
 * Uses replace_str2() implementation from
 * http://creativeandcritical.net/str-replace-c/
 * copyright (c) Laird Shaw, under public domain.
 */
static char *replace_str(const char *str, const char *old, /* {{{ */
                         const char *new) {
  char *ret, *r;
  const char *p, *q;
  size_t oldlen = strlen(old);
  size_t count = strlen(new);
  size_t retlen;
  size_t newlen = count;
  int samesize = (oldlen == newlen);

  if (!samesize) {
    for (count = 0, p = str; (q = strstr(p, old)) != NULL; p = q + oldlen)
      count++;
    /* This is undefined if p - str > PTRDIFF_MAX */
    retlen = p - str + strlen(p) + count * (newlen - oldlen);
  } else
    retlen = strlen(str);

  ret = calloc(1, retlen + 1);
  if (ret == NULL)
    return NULL;
  // added to original: not optimized, but keeps valgrind happy.

  r = ret;
  p = str;
  while (1) {
    /* If the old and new strings are different lengths - in other
     * words we have already iterated through with strstr above,
     * and thus we know how many times we need to call it - then we
     * can avoid the final (potentially lengthy) call to strstr,
     * which we already know is going to return NULL, by
     * decrementing and checking count.
     */
    if (!samesize && !count--)
      break;
    /* Otherwise i.e. when the old and new strings are the same
     * length, and we don't know how many times to call strstr,
     * we must check for a NULL return here (we check it in any
     * event, to avoid further conditions, and because there's
     * no harm done with the check even when the old and new
     * strings are different lengths).
     */
    if ((q = strstr(p, old)) == NULL)
      break;
    /* This is undefined if q - p > PTRDIFF_MAX */
    ptrdiff_t l = q - p;
    memcpy(r, p, l);
    r += l;
    memcpy(r, new, newlen);
    r += newlen;
    p = q + oldlen;
  }
  sstrncpy(r, p, retlen + 1);

  return ret;
} /* }}} char *replace_str */

static char *replace_json_reserved(const char *message) /* {{{ */
{
  char *msg = replace_str(message, "\\", "\\\\");
  if (msg == NULL) {
    ERROR("write_sensu plugin: Unable to alloc memory");
    return NULL;
  }
  char *tmp = replace_str(msg, "\"", "\\\"");
  free(msg);
  if (tmp == NULL) {
    ERROR("write_sensu plugin: Unable to alloc memory");
    return NULL;
  }
  msg = replace_str(tmp, "\n", "\\\n");
  free(tmp);
  if (msg == NULL) {
    ERROR("write_sensu plugin: Unable to alloc memory");
    return NULL;
  }
  return msg;
} /* }}} char *replace_json_reserved */

static char *sensu_notification_to_json(struct sensu_host *host, /* {{{ */
                                        notification_t const *n) {
  char service_buffer[6 * DATA_MAX_NAME_LEN];
  char const *severity;
  char *ret_str;
  char *temp_str;
  int status;
  size_t i;
  int res;
  // add the severity/status
  switch (n->severity) {
  case NOTIF_OKAY:
    severity = "OK";
    status = 0;
    break;
  case NOTIF_WARNING:
    severity = "WARNING";
    status = 1;
    break;
  case NOTIF_FAILURE:
    severity = "CRITICAL";
    status = 2;
    break;
  default:
    severity = "UNKNOWN";
    status = 3;
  }
  res = my_asprintf(&temp_str, "{\"status\": %d", status);
  if (res == -1) {
    ERROR("write_sensu plugin: Unable to alloc memory");
    return NULL;
  }
  ret_str = temp_str;

  // incorporate the timestamp
  res = my_asprintf(&temp_str, "%s, \"timestamp\": %lld", ret_str,
                    (long long)CDTIME_T_TO_TIME_T(n->time));
  free(ret_str);
  if (res == -1) {
    ERROR("write_sensu plugin: Unable to alloc memory");
    return NULL;
  }
  ret_str = temp_str;

  if (host->include_source) {
    res = my_asprintf(&temp_str, "%s, \"source\": \"%s\"", ret_str, n->host);
    free(ret_str);
    if (res == -1) {
      ERROR("write_sensu plugin: Unable to alloc memory");
      return NULL;
    }
    ret_str = temp_str;
  }

  char *handlers_str =
      build_json_str_list("handlers", &(host->notification_handlers));
  if (handlers_str == NULL) {
    ERROR("write_sensu plugin: Unable to alloc memory");
    free(ret_str);
    return NULL;
  }
  // incorporate the handlers
  if (strlen(handlers_str) != 0) {
    res = my_asprintf(&temp_str, "%s, %s", ret_str, handlers_str);
    free(ret_str);
    free(handlers_str);
    if (res == -1) {
      ERROR("write_sensu plugin: Unable to alloc memory");
      return NULL;
    }
    ret_str = temp_str;
  } else {
    free(handlers_str);
  }

  // incorporate the plugin name information if any
  if (n->plugin[0] != 0) {
    res = my_asprintf(&temp_str, "%s, \"collectd_plugin\": \"%s\"", ret_str,
                      n->plugin);
    free(ret_str);
    if (res == -1) {
      ERROR("write_sensu plugin: Unable to alloc memory");
      return NULL;
    }
    ret_str = temp_str;
  }

  // incorporate the plugin type if any
  if (n->type[0] != 0) {
    res = my_asprintf(&temp_str, "%s, \"collectd_plugin_type\": \"%s\"",
                      ret_str, n->type);
    free(ret_str);
    if (res == -1) {
      ERROR("write_sensu plugin: Unable to alloc memory");
      return NULL;
    }
    ret_str = temp_str;
  }

  // incorporate the plugin instance if any
  if (n->plugin_instance[0] != 0) {
    res = my_asprintf(&temp_str, "%s, \"collectd_plugin_instance\": \"%s\"",
                      ret_str, n->plugin_instance);
    free(ret_str);
    if (res == -1) {
      ERROR("write_sensu plugin: Unable to alloc memory");
      return NULL;
    }
    ret_str = temp_str;
  }

  // incorporate the plugin type instance if any
  if (n->type_instance[0] != 0) {
    res =
        my_asprintf(&temp_str, "%s, \"collectd_plugin_type_instance\": \"%s\"",
                    ret_str, n->type_instance);
    free(ret_str);
    if (res == -1) {
      ERROR("write_sensu plugin: Unable to alloc memory");
      return NULL;
    }
    ret_str = temp_str;
  }

  // add key value attributes from config if any
  for (i = 0; i < sensu_attrs_num; i += 2) {
    res = my_asprintf(&temp_str, "%s, \"%s\": \"%s\"", ret_str, sensu_attrs[i],
                      sensu_attrs[i + 1]);
    free(ret_str);
    if (res == -1) {
      ERROR("write_sensu plugin: Unable to alloc memory");
      return NULL;
    }
    ret_str = temp_str;
  }

  // incorporate sensu tags from config if any
  if ((sensu_tags != NULL) && (strlen(sensu_tags) != 0)) {
    res = my_asprintf(&temp_str, "%s, %s", ret_str, sensu_tags);
    free(ret_str);
    if (res == -1) {
      ERROR("write_sensu plugin: Unable to alloc memory");
      return NULL;
    }
    ret_str = temp_str;
  }

  // incorporate the service name
  sensu_format_name2(service_buffer, sizeof(service_buffer),
                     /* host */ "", n->plugin, n->plugin_instance, n->type,
                     n->type_instance, host->separator);
  // replace sensu event name chars that are considered illegal
  in_place_replace_sensu_name_reserved(service_buffer);
  res = my_asprintf(&temp_str, "%s, \"name\": \"%s\"", ret_str,
                    &service_buffer[1]);
  free(ret_str);
  if (res == -1) {
    ERROR("write_sensu plugin: Unable to alloc memory");
    return NULL;
  }
  ret_str = temp_str;

  // incorporate the check output
  if (n->message[0] != 0) {
    char *msg = replace_json_reserved(n->message);
    if (msg == NULL) {
      ERROR("write_sensu plugin: Unable to alloc memory");
      free(ret_str);
      return NULL;
    }
    res = my_asprintf(&temp_str, "%s, \"output\": \"%s - %s\"", ret_str,
                      severity, msg);
    free(ret_str);
    free(msg);
    if (res == -1) {
      ERROR("write_sensu plugin: Unable to alloc memory");
      return NULL;
    }
    ret_str = temp_str;
  }

  // Pull in values from threshold and add extra attributes
  for (notification_meta_t *meta = n->meta; meta != NULL; meta = meta->next) {
    if (strcasecmp("CurrentValue", meta->name) == 0 &&
        meta->type == NM_TYPE_DOUBLE) {
      res = my_asprintf(&temp_str, "%s, \"current_value\": \"%.8f\"", ret_str,
                        meta->nm_value.nm_double);
      free(ret_str);
      if (res == -1) {
        ERROR("write_sensu plugin: Unable to alloc memory");
        return NULL;
      }
      ret_str = temp_str;
    }
    if (meta->type == NM_TYPE_STRING) {
      res = my_asprintf(&temp_str, "%s, \"%s\": \"%s\"", ret_str, meta->name,
                        meta->nm_value.nm_string);
      free(ret_str);
      if (res == -1) {
        ERROR("write_sensu plugin: Unable to alloc memory");
        return NULL;
      }
      ret_str = temp_str;
    }
  }

  // close the curly bracket
  res = my_asprintf(&temp_str, "%s}\n", ret_str);
  free(ret_str);
  if (res == -1) {
    ERROR("write_sensu plugin: Unable to alloc memory");
    return NULL;
  }
  ret_str = temp_str;

  DEBUG("write_sensu plugin: Successfully created JSON for notification: "
        "host = \"%s\", service = \"%s\", state = \"%s\"",
        n->host, service_buffer, severity);
  return ret_str;
} /* }}} char *sensu_notification_to_json */

static int sensu_send_msg(struct sensu_host *host, const char *msg) /* {{{ */
{
  int status = 0;
  size_t buffer_len;

  status = sensu_connect(host);
  if (status != 0)
    return status;

  buffer_len = strlen(msg);

  status = (int)swrite(host->s, msg, buffer_len);
  sensu_close_socket(host);

  if (status != 0) {
    ERROR("write_sensu plugin: Sending to Sensu at %s:%s failed: %s",
          (host->node != NULL) ? host->node : SENSU_HOST,
          (host->service != NULL) ? host->service : SENSU_PORT, STRERRNO);
    return -1;
  }

  return 0;
} /* }}} int sensu_send_msg */

static int sensu_send(struct sensu_host *host, char const *msg) /* {{{ */
{
  int status = 0;

  status = sensu_send_msg(host, msg);
  if (status != 0) {
    host->flags &= ~F_READY;
    if (host->res != NULL) {
      freeaddrinfo(host->res);
      host->res = NULL;
    }
    return status;
  }

  return 0;
} /* }}} int sensu_send */

static int sensu_write(const data_set_t *ds, /* {{{ */
                       const value_list_t *vl, user_data_t *ud) {
  int status = 0;
  int statuses[vl->values_len];
  struct sensu_host *host = ud->data;
  gauge_t *rates = NULL;
  char *msg;

  pthread_mutex_lock(&host->lock);
  memset(statuses, 0, vl->values_len * sizeof(*statuses));

  if (host->store_rates) {
    rates = uc_get_rate(ds, vl);
    if (rates == NULL) {
      ERROR("write_sensu plugin: uc_get_rate failed.");
      pthread_mutex_unlock(&host->lock);
      return -1;
    }
  }
  for (size_t i = 0; i < vl->values_len; i++) {
    msg = sensu_value_to_json(host, ds, vl, (int)i, rates);
    if (msg == NULL) {
      sfree(rates);
      pthread_mutex_unlock(&host->lock);
      return -1;
    }
    status = sensu_send(host, msg);
    free(msg);
    if (status != 0) {
      ERROR("write_sensu plugin: sensu_send failed with status %i", status);
      pthread_mutex_unlock(&host->lock);
      sfree(rates);
      return status;
    }
  }
  sfree(rates);
  pthread_mutex_unlock(&host->lock);
  return status;
} /* }}} int sensu_write */

static int sensu_notification(const notification_t *n,
                              user_data_t *ud) /* {{{ */
{
  int status;
  struct sensu_host *host = ud->data;
  char *msg;

  pthread_mutex_lock(&host->lock);

  msg = sensu_notification_to_json(host, n);
  if (msg == NULL) {
    pthread_mutex_unlock(&host->lock);
    return -1;
  }

  status = sensu_send(host, msg);
  free(msg);
  if (status != 0)
    ERROR("write_sensu plugin: sensu_send failed with status %i", status);
  pthread_mutex_unlock(&host->lock);

  return status;
} /* }}} int sensu_notification */

static void sensu_free(void *p) /* {{{ */
{
  struct sensu_host *host = p;

  if (host == NULL)
    return;

  pthread_mutex_lock(&host->lock);

  host->reference_count--;
  if (host->reference_count > 0) {
    pthread_mutex_unlock(&host->lock);
    return;
  }

  sensu_close_socket(host);
  if (host->res != NULL) {
    freeaddrinfo(host->res);
    host->res = NULL;
  }
  sfree(host->service);
  sfree(host->event_service_prefix);
  sfree(host->name);
  sfree(host->node);
  sfree(host->separator);
  free_str_list(&(host->metric_handlers));
  free_str_list(&(host->notification_handlers));

  pthread_mutex_unlock(&host->lock);
  pthread_mutex_destroy(&host->lock);

  sfree(host);
} /* }}} void sensu_free */

static int sensu_config_node(oconfig_item_t *ci) /* {{{ */
{
  struct sensu_host *host = NULL;
  int status = 0;
  oconfig_item_t *child;
  char callback_name[DATA_MAX_NAME_LEN];

  if ((host = calloc(1, sizeof(*host))) == NULL) {
    ERROR("write_sensu plugin: calloc failed.");
    return ENOMEM;
  }
  pthread_mutex_init(&host->lock, NULL);
  host->reference_count = 1;
  host->node = NULL;
  host->service = NULL;
  host->notifications = false;
  host->metrics = false;
  host->store_rates = true;
  host->always_append_ds = false;
  host->include_source = false;
  host->metric_handlers.nb_strs = 0;
  host->metric_handlers.strs = NULL;
  host->notification_handlers.nb_strs = 0;
  host->notification_handlers.strs = NULL;
  host->separator = strdup("/");
  if (host->separator == NULL) {
    ERROR("write_sensu plugin: Unable to alloc memory");
    sensu_free(host);
    return -1;
  }

  status = cf_util_get_string(ci, &host->name);
  if (status != 0) {
    WARNING("write_sensu plugin: Required host name is missing.");
    sensu_free(host);
    return -1;
  }

  for (int i = 0; i < ci->children_num; i++) {
    child = &ci->children[i];
    status = 0;

    if (strcasecmp("Host", child->key) == 0) {
      status = cf_util_get_string(child, &host->node);
      if (status != 0)
        break;
    } else if (strcasecmp("Notifications", child->key) == 0) {
      status = cf_util_get_boolean(child, &host->notifications);
      if (status != 0)
        break;
    } else if (strcasecmp("Metrics", child->key) == 0) {
      status = cf_util_get_boolean(child, &host->metrics);
      if (status != 0)
        break;
    } else if (strcasecmp("EventServicePrefix", child->key) == 0) {
      status = cf_util_get_string(child, &host->event_service_prefix);
      if (status != 0)
        break;
    } else if (strcasecmp("Separator", child->key) == 0) {
      status = cf_util_get_string(child, &host->separator);
      if (status != 0)
        break;
    } else if (strcasecmp("MetricHandler", child->key) == 0) {
      char *temp_str = NULL;
      status = cf_util_get_string(child, &temp_str);
      if (status != 0)
        break;
      status = add_str_to_list(&(host->metric_handlers), temp_str);
      free(temp_str);
      if (status != 0)
        break;
    } else if (strcasecmp("NotificationHandler", child->key) == 0) {
      char *temp_str = NULL;
      status = cf_util_get_string(child, &temp_str);
      if (status != 0)
        break;
      status = add_str_to_list(&(host->notification_handlers), temp_str);
      free(temp_str);
      if (status != 0)
        break;
    } else if (strcasecmp("Port", child->key) == 0) {
      status = cf_util_get_service(child, &host->service);
      if (status != 0)
        break;
    } else if (strcasecmp("StoreRates", child->key) == 0) {
      status = cf_util_get_boolean(child, &host->store_rates);
      if (status != 0)
        break;
    } else if (strcasecmp("AlwaysAppendDS", child->key) == 0) {
      status = cf_util_get_boolean(child, &host->always_append_ds);
      if (status != 0)
        break;
    } else if (strcasecmp("IncludeSource", child->key) == 0) {
      status = cf_util_get_boolean(child, &host->include_source);
      if (status != 0)
        break;
    } else {
      WARNING("write_sensu plugin: ignoring unknown config "
              "option: \"%s\"",
              child->key);
    }
  }
  if (status != 0) {
    sensu_free(host);
    return status;
  }

  if (host->metrics && (host->metric_handlers.nb_strs == 0)) {
    sensu_free(host);
    WARNING("write_sensu plugin: metrics enabled but no MetricHandler defined. "
            "Giving up.");
    return -1;
  }

  if (host->notifications && (host->notification_handlers.nb_strs == 0)) {
    sensu_free(host);
    WARNING("write_sensu plugin: notifications enabled but no "
            "NotificationHandler defined. Giving up.");
    return -1;
  }

  if ((host->notification_handlers.nb_strs > 0) &&
      (host->notifications == false)) {
    WARNING("write_sensu plugin: NotificationHandler given so forcing "
            "notifications to be enabled");
    host->notifications = 1;
  }

  if ((host->metric_handlers.nb_strs > 0) && (host->metrics == false)) {
    WARNING("write_sensu plugin: MetricHandler given so forcing metrics to be "
            "enabled");
    host->metrics = true;
  }

  if (!(host->notifications || host->metrics)) {
    WARNING("write_sensu plugin: neither metrics nor notifications enabled. "
            "Giving up.");
    sensu_free(host);
    return -1;
  }

  snprintf(callback_name, sizeof(callback_name), "write_sensu/%s", host->name);

  user_data_t ud = {.data = host, .free_func = sensu_free};

  pthread_mutex_lock(&host->lock);

  if (host->metrics) {
    status = plugin_register_write(callback_name, sensu_write, &ud);
    if (status != 0)
      WARNING("write_sensu plugin: plugin_register_write (\"%s\") "
              "failed with status %i.",
              callback_name, status);
    else /* success */
      host->reference_count++;
  }

  if (host->notifications) {
    status =
        plugin_register_notification(callback_name, sensu_notification, &ud);
    if (status != 0)
      WARNING("write_sensu plugin: plugin_register_notification (\"%s\") "
              "failed with status %i.",
              callback_name, status);
    else
      host->reference_count++;
  }

  if (host->reference_count <= 1) {
    /* Both callbacks failed => free memory.
     * We need to unlock here, because sensu_free() will lock.
     * This is not a race condition, because we're the only one
     * holding a reference. */
    pthread_mutex_unlock(&host->lock);
    sensu_free(host);
    return -1;
  }

  host->reference_count--;
  pthread_mutex_unlock(&host->lock);

  return status;
} /* }}} int sensu_config_node */

static int sensu_config(oconfig_item_t *ci) /* {{{ */
{
  oconfig_item_t *child;
  int status;
  struct str_list sensu_tags_arr;

  sensu_tags_arr.nb_strs = 0;
  sensu_tags_arr.strs = NULL;

  for (int i = 0; i < ci->children_num; i++) {
    child = &ci->children[i];

    if (strcasecmp("Node", child->key) == 0) {
      sensu_config_node(child);
    } else if (strcasecmp(child->key, "attribute") == 0) {
      if (child->values_num != 2) {
        WARNING("sensu attributes need both a key and a value.");
        continue;
      }
      if (child->values[0].type != OCONFIG_TYPE_STRING ||
          child->values[1].type != OCONFIG_TYPE_STRING) {
        WARNING("sensu attribute needs string arguments.");
        continue;
      }

      strarray_add(&sensu_attrs, &sensu_attrs_num,
                   child->values[0].value.string);
      strarray_add(&sensu_attrs, &sensu_attrs_num,
                   child->values[1].value.string);

      DEBUG("write_sensu plugin: New attribute: %s => %s",
            child->values[0].value.string, child->values[1].value.string);
    } else if (strcasecmp(child->key, "tag") == 0) {
      char *tmp = NULL;
      status = cf_util_get_string(child, &tmp);
      if (status != 0)
        continue;

      status = add_str_to_list(&sensu_tags_arr, tmp);
      DEBUG("write_sensu plugin: Got tag: %s", tmp);
      sfree(tmp);
      if (status != 0)
        continue;
    } else {
      WARNING("write_sensu plugin: Ignoring unknown "
              "configuration option \"%s\" at top level.",
              child->key);
    }
  }
  if (sensu_tags_arr.nb_strs > 0) {
    sfree(sensu_tags);
    sensu_tags = build_json_str_list("tags", &sensu_tags_arr);
    free_str_list(&sensu_tags_arr);
    if (sensu_tags == NULL) {
      ERROR("write_sensu plugin: Unable to alloc memory");
      return -1;
    }
  }
  return 0;
} /* }}} int sensu_config */

void module_register(void) {
  plugin_register_complex_config("write_sensu", sensu_config);
}