Allow netdata plugins to expose functions for querying more information about specific charts (#13720)

* function renames and code cleanup in popen.c; no actual code changes

* netdata popen() now opens both child process stdin and stdout and returns FILE * for both

* pass both input and output to parser structures

* updated rrdset to call custom functions

* RRDSET FUNCTION leading calls for both sync and async operation

* put RRDSET functions to a separate file

* added format and timeout at function definition

* support for synchronous (internal plugins) and asynchronous (external plugins and children) functions

* /api/v1/function endpoint

* functions are now attached to the host and there is a dictionary view per chart

* functions implemented at plugins.d

* remove the defer until keyword hook from plugins.d when it is done

* stream sender implementation of functions

* sanitization of all functions so that certain characters are only allowed

* strictier sanitization

* common max size

* 1st working plugins.d example

* always init inflight dictionary

* properly destroy dictionaries to avoid parallel insertion of items

* add more debugging on disconnection reasons

* add more debugging on disconnection reasons again

* streaming receiver respects newlines

* dont use the same fp for both streaming receive and send

* dont free dbengine memory with internal checks

* make sender proceed in the buffer

* added timing info and garbage collection at plugins.d

* added info about routing nodes

* added info about routing nodes with delay

* added more info about delays

* added more info about delays again

* signal sending thread to wake up

* streaming version labeling and commented code to support capabilities

* added functions to /api/v1/data, /api/v1/charts, /api/v1/chart, /api/v1/info

* redirect top output to stdout

* address coverity findings

* fix resource leaks of popen

* log attempts to connect to individual destinations

* better messages

* properly parse destinations

* try to find a function from the most matching to the least matching

* log added streaming destinations

* rotate destinations bypassing a node in the middle that does not accept our connection

* break the loops properly

* use typedef to define callbacks

* capabilities negotiation during streaming

* functions exposed upstream based on capabilities; compression disabled per node persisting reconnects; always try to connect with all capabilities

* restore functionality to lookup functions

* better logging of capabilities

* remove old versions from capabilities when a newer version is there

* fix formatting

* optimization for plugins.d rrdlabels to avoid creating and destructing dictionaries all the time

* delayed health initialization for rrddim and rrdset

* cleanup health initialization

* fix for popen() not returning the right value

* add health worker jobs for initializing rrdset and rrddim

* added content type support for functions; apps.plugin permanent function to display all the processes

* fixes for functions parameters parsing in apps.plugin

* fix for process matching in apps.plugiin

* first working function for apps.plugin

* Dashboard ACL is disabled for functions; Function errors are all in JSON format

* apps.plugin function processes returns json table

* use json_escape_string() to escape message

* fix formatting

* apps.plugin exposes all its metrics to function processes

* fix json formatting when filtering out some rows

* reopen the internal pipe of rrdpush in case of errors

* misplaced statement

* do not use buffer->len

* support for GLOBAL functions (functions that are not linked to a chart

* added /api/v1/functions endpoint; removed format from the FUNCTIONS api;

* swagger documentation about the new api end points

* added plugins.d documentation about functions

* never re-close a file

* remove uncessesary ifdef

* fixed issues identified by codacy

* fix for null label value

* make edit-config copy-and-paste friendly

* Revert "make edit-config copy-and-paste friendly"

This reverts commit 54500c0e0a97f65a0c66c4d34e966f6a9056698e.

* reworked sender handshake to fix coverity findings

* timeout is zero, for both send_timeout() and recv_timeout()

* properly detect that parent closed the socket

* support caching of function responses; limit function response to 10MB; added protection from malformed function responses

* disabled excessive logging

* added units to apps.plugin function processes and normalized all values to be human readable

* shorter field names

* fixed issues reported

* fixed apps.plugin error response; tested that pluginsd can properly handle faulty responses

* use double linked list macros for double linked list management

* faster apps.plugin function printing by minimizing file operations

* added memory percentage

* fix compatibility issues with older compilers and FreeBSD

* rrdpush sender code cleanup; rrhost structure cleanup from sender flags and variables;

* fix letftover variable in ifdef

* apps.plugin: do not call detach from the thread; exit immediately when input is broken

* exclude AR charts from health

* flush cleaner; prefer sender output

* clarity

* do not fill the cbuffer if not connected

* fix

* dont enabled host->sender if streaming is not enabled; send host label updates to parent;

* functions are only available through ACLK

* Prepared statement reports only in dev mode

* fix AR chart detection

* fix for streaming not being enabling itself

* more cleanup of sender and receiver structures

* moved read-only flags and configuration options to rrdhost->options

* fixed merge with master

* fix for incomplete rename

* prevent service thread from working on charts that are being collected

Co-authored-by: Stelios Fragkakis <52996999+stelfrag@users.noreply.github.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/web/api/formatters/json_wrapper.c b/web/api/formatters/json_wrapper.c
index 3ebe42c99f..811afa8921 100644
--- a/web/api/formatters/json_wrapper.c
+++ b/web/api/formatters/json_wrapper.c
@@ -175,6 +175,25 @@ void rrdr_json_wrapper_begin(RRDR *r, BUFFER *wb, uint32_t format, RRDR_OPTIONS
         buffer_strcat(wb, "],\n");
     }
 
+    // functions
+    {
+        DICTIONARY *funcs = dictionary_create(DICT_OPTION_SINGLE_THREADED|DICT_OPTION_DONT_OVERWRITE_VALUE);
+        for (i = 0, rd = temp_rd ? temp_rd : r->st->dimensions; rd; rd = rd->next) {
+            chart_functions_to_dict(rd->rrdset, funcs);
+        }
+
+        buffer_sprintf(wb, "   %sfunctions%s: [", kq, kq);
+        void *t; (void)t;
+        dfe_start_read(funcs, t) {
+            const char *comma = "";
+            if(t_dfe.counter) comma = ", ";
+            buffer_sprintf(wb, "%s%s%s%s", comma, sq, t_dfe.name, sq);
+        }
+        dfe_done(t);
+        dictionary_destroy(funcs);
+        buffer_strcat(wb, "],\n");
+    }
+
     // Composite charts
     if (context_mode && temp_rd) {
         buffer_sprintf(