Support chart labels in alerts (#13290)

* chart labels for alerts

* proper termination

* use strchr

* change if statement

* change label variable. add docs

* change doc

* assign buf to temp

* use new dictionary functions

* reduce variable scope

* reduce line length

* make sure rrdcalc updates labels after inserted

* reduce var scope

* add rrdcalc.c for cmocka tests

* Revert "add rrdcalc.c for cmocka tests"

This reverts commit 5fe122adcf7abcbe6d67fa2ebd7c4ff8620cf9c8.

* Fix cmocka unit tests

* valgrind errors

Co-authored-by: Vladimir Kobal <vlad@prokk.net>

4 files changed, 43 insertions, 53 deletions

diff --git a/health/REFERENCE.md b/health/REFERENCE.md
index d1af747676..90da4102a9 100644
--- a/health/REFERENCE.md
+++ b/health/REFERENCE.md
@@ -536,12 +536,48 @@ See our [simple patterns docs](/libnetdata/simple_pattern/README.md) for more ex
 
 #### Alarm line `info`
 
-The info field can contain a small piece of text describing the alarm or template. This will be rendered in notifications and UI elements whenever the specific alarm is in focus. An example for the `ram_available` alarm is:
+The info field can contain a small piece of text describing the alarm or template. This will be rendered in
+notifications and UI elements whenever the specific alarm is in focus. An example for the `ram_available` alarm is:
 
 ```yaml
 info: percentage of estimated amount of RAM available for userspace processes, without causing swapping
 ```
 
+info fields can contain special variables in their text that will be replaced during run-time to provide more specific
+alert information. Current variables supported are:
+
+| variable | description |
+| ---------| ----------- |
+| $family  | Will be replaced by the family instance for the alert (e.g. eth0) |
+| $label:  | Followed by a chart label name, this will replace the variable with the chart label's value |
+
+For example, an info field like the following:
+
+```yaml
+info: average inbound utilization for the network interface $family over the last minute
+```
+
+Will be rendered on the alert acting on interface `eth0` as:
+
+```yaml
+info: average inbound utilization for the network interface eth0 over the last minute
+```
+
+An alert acting on a chart that has a chart label named e.g. `target`, with a value of `https://netdata.cloud/`,
+can be enriched as follows:
+
+```yaml
+info: average ratio of HTTP responses with unexpected status over the last 5 minutes for the site $label:target
+```
+
+Will become:
+
+```yaml
+info: average ratio of HTTP responses with unexpected status over the last 5 minutes for the site https://netdata.cloud/
+```
+
+> Please note that variable names are case sensitive.
+
 ## Expressions
 
 Netdata has an internal [infix expression parser](/libnetdata/eval). This parses expressions and creates an internal
diff --git a/health/health_config.c b/health/health_config.c
index 7efa45486a..77b12fc183 100644
--- a/health/health_config.c
+++ b/health/health_config.c
@@ -942,6 +942,8 @@ static int health_readfile(const char *filename, void *data) {
                 }
                 rc->info = strdupz(value);
                 strip_quotes(rc->info);
+                rc->original_info = strdupz(value);
+                strip_quotes(rc->original_info);
             }
             else if(hash == hash_delay && !strcasecmp(key, HEALTH_DELAY_KEY)) {
                 alert_cfg->delay = strdupz(value);
diff --git a/health/health_json.c b/health/health_json.c
index 4e8f437613..a0dc55b612 100644
--- a/health/health_json.c
+++ b/health/health_json.c
@@ -96,22 +96,7 @@ void health_alarm_entry2json_nolock(BUFFER *wb, ALARM_ENTRY *ae, RRDHOST *host)
                    , (ae->flags & HEALTH_ENTRY_FLAG_SILENCED)?"true":"false"
     );
 
-    char *replaced_info = NULL;
-    if (likely(ae->info)) {
-        char *m = NULL;
-        replaced_info = strdupz(ae->info);
-        size_t pos = 0;
-        while ((m = strstr(replaced_info + pos, "$family"))) {
-            char *buf = NULL;
-            pos = m - replaced_info;
-            buf = find_and_replace(replaced_info, "$family", ae->family ? ae->family : "", m);
-            freez(replaced_info);
-            replaced_info = strdupz(buf);
-            freez(buf);
-        }
-    }
-
-    health_string2json(wb, "\t\t", "info", replaced_info?replaced_info:"", ",\n");
+    health_string2json(wb, "\t\t", "info", ae->info ? ae->info : "", ",\n");
 
     if(unlikely(ae->flags & HEALTH_ENTRY_FLAG_NO_CLEAR_NOTIFICATION)) {
         buffer_strcat(wb, "\t\t\"no_clear_notification\": true,\n");
@@ -127,7 +112,6 @@ void health_alarm_entry2json_nolock(BUFFER *wb, ALARM_ENTRY *ae, RRDHOST *host)
 
     buffer_strcat(wb, "\t}");
 
-    freez(replaced_info);
     freez(edit_command);
 }
 
@@ -182,21 +166,6 @@ static inline void health_rrdcalc2json_nolock(RRDHOST *host, BUFFER *wb, RRDCALC
     char value_string[100 + 1];
     format_value_and_unit(value_string, 100, rc->value, rc->units, -1);
 
-    char *replaced_info = NULL;
-    if (likely(rc->info)) {
-        char *m;
-        replaced_info = strdupz(rc->info);
-        size_t pos = 0;
-        while ((m = strstr(replaced_info + pos, "$family"))) {
-            char *buf = NULL;
-            pos = m - replaced_info;
-            buf = find_and_replace(replaced_info, "$family", (rc->rrdset && rc->rrdset->family) ? rc->rrdset->family : "", m);
-            freez(replaced_info);
-            replaced_info = strdupz(buf);
-            freez(buf);
-        }
-    }
-
     char hash_id[GUID_LEN + 1];
     uuid_unparse_lower(rc->config_hash_id, hash_id);
 
@@ -250,7 +219,7 @@ static inline void health_rrdcalc2json_nolock(RRDHOST *host, BUFFER *wb, RRDCALC
                    , rc->recipient?rc->recipient:host->health_default_recipient
                    , rc->source
                    , rc->units?rc->units:""
-                   , replaced_info?replaced_info:""
+                   , rc->info?rc->info:""
                    , rrdcalc_status2string(rc->status)
                    , (unsigned long)rc->last_status_change
                    , (unsigned long)rc->last_updated
@@ -322,8 +291,6 @@ static inline void health_rrdcalc2json_nolock(RRDHOST *host, BUFFER *wb, RRDCALC
     buffer_strcat(wb, "\n");
 
     buffer_strcat(wb, "\t\t}");
-
-    freez(replaced_info);
 }
 
 //void health_rrdcalctemplate2json_nolock(BUFFER *wb, RRDCALCTEMPLATE *rt) {
diff --git a/health/health_log.c b/health/health_log.c
index f0a05531d3..d880625e05 100644
--- a/health/health_log.c
+++ b/health/health_log.c
@@ -512,23 +512,8 @@ inline ALARM_ENTRY* health_create_alarm_entry(
     ae->old_value_string = strdupz(format_value_and_unit(value_string, 100, ae->old_value, ae->units, -1));
     ae->new_value_string = strdupz(format_value_and_unit(value_string, 100, ae->new_value, ae->units, -1));
 
-    char *replaced_info = NULL;
-    if (likely(info)) {
-        char *m;
-        replaced_info = strdupz(info);
-        size_t pos = 0;
-        while ((m = strstr(replaced_info + pos, "$family"))) {
-            char *buf = NULL;
-            pos = m - replaced_info;
-            buf = find_and_replace(replaced_info, "$family", (ae->family) ? ae->family : "", m);
-            freez(replaced_info);
-            replaced_info = strdupz(buf);
-            freez(buf);
-        }
-    }
-
-    if(replaced_info) ae->info = strdupz(replaced_info);
-    freez(replaced_info);
+    if (info)
+        ae->info = strdupz(info);
 
     ae->old_status = old_status;
     ae->new_status = new_status;