http_agent lld missing Convert to Json (output_format) option

[gchalmers_aus]

Hello forum,
In low level discovery I have created a http agent rule to return data from a REST API.
It connects and returns data successfully however without a "data" tag on the front.

If I create an item directly I have the option to "convert to JSON" which works as expect, however this option is not available when creating a lld.

It is documented in api/reference/discoveryrule/object as output_format with a value of 0 or 1


Troubleshooting:
Versions:
I have tried on both 4.05 and 4.2-1.el7 (latest).

Export/Import:
I have tried exporting the template adding the "output_format" and importing it back in however that errors with a message about the unknown tag "output_format".

API:
I have tried using the api to get the discovery rule - success but no output_format tag,
Using the api to get the item with the convert to json ticked returns the item with the output_format tag

updating the discovery rule with output_format
{
"jsonrpc": "2.0",
"method": "discoveryrule.update",
"params": {
"itemid": "237182",
"output_format": "1"

},
"id": 1,
"auth": "xxxxxx"
}

success:

{
"jsonrpc": "2.0",
"result": {
"itemids": [
"237182"
]
},
"id": 1
}

however the discovery rule does not convert to json as expected.



Is this by design or a bug that low level discovery using http_agent does not allow convert to json?

[mariusl]

Stumbeled upon the same issue in Zabbix 7.2. Trying to create a LLD rule from an URL that is returning clear text data, but don't have the convert to JSON option so i get an error

> Invalid discovery rule value: cannot parse as a valid JSON object: invalid object format, expected opening character '{' or '[' at: '0'

[cyber]

Stumbeled upon the same issue in Zabbix 7.2. Trying to create a LLD rule from an URL that is returning clear text data, but don't have the convert to JSON option so i get an error

> Invalid discovery rule value: cannot parse as a valid JSON object: invalid object format, expected opening character '{' or '[' at: '0'

Is there by any chance some headers in output? Something like

HTTP/1.1 200 OK
Connection: close
Content-Length: 86944
Content-Type: application/json
X-Content-Type-Options: nosniff

you should run some preprocessing, to get rid of that...

[mariusl]

Is there by any chance some headers in output? Something like

you should run some preprocessing, to get rid of that...

Thanks for your reply. It doesn't seem to be headers that are the problem. The returned data is simply "mydata=0" which is not in JSON format. This is what the error message indicates.
Our problem is that the function "Convert to JSON" on HTTP agent is missing when using it in a discovery rule.

This item is present and available when creating a regular item:


But missing from when HTTP agent is used in a discovery rule:


Only workaround i have found it to create a regular item converting to JSON, then use that as a master item a dependent discovery rule.
However, my next problem is that the converted JSON is in wrong format as there is no array. Have tried using multiple different JSONPaths:
* $..body
* $.body
* $.. (terminates unexpectedly)

Returned data from the item before converting to JSON is "mydata=0" in clear text. After using the "convert to JSON" function i get this, without an array:

{"body":"mydata=0"}

I should probably create a new thread about this though.

[cyber]

You could submit a bug about htis... I dont see any reason why this should be different if used in discovery vs used in normal item.

[mariusl]

Bug report submitted in [ZBX-26022]