Add Telegram Support to Thold – Need Help Locating Graph Image Variable

[InsaneGriever]

Hi team,

I'm currently working on integrating Telegram notifications into Thold. So far, the basic functionality is working — messages are successfully sent with device information and threshold alerts. However, I'm stuck on one specific part: I can't figure out which variable contains the graph image, or how the image itself is generated.

Here is a relevant snippet where the email and Telegram message are sent:

if (trim($warning_emails) != '' && $thold_data['acknowledgment'] == '') {
    $message = get_thold_warning_text($thold_data['data_source_name'], $thold_data, $h, $thold_data['lastread'], $thold_data['local_graph_id']);

    thold_mail($warning_emails, $warning_bcc_emails, '', $subject, $message, $file_array, '', $notify_list_id, $h, $format_file, $thold_data['graph_timespan']);
    send_telegram($message, $subject, $h, $format_file, $thold_data['graph_timespan']);

And here’s an example of what I currently receive in Telegram:

NORMAL: 'Threshold name' restored to Normal Threshold with value 1.29 Ti

Device: 'host'
Hostname: 'ip'

A Threshold has returned to normal status. Device: 'host' ('IP')
URL: Link to Graph in Cacti
Message:

Graph: default.format (Last 7 days)

As you can see, there’s no actual image included — just the text.

Here’s the code of my send_telegram() function, in case it helps:

function send_telegram($tg_text, $subject = '', $host = array(), $format_file = '', $graph_timespan = 7) {
    $tg_text = strip_tags($tg_text);
    $TG_apiToken = ""; // your telegram apiToken
    $TG_chatid =""; // your telegram chatid

    $TG_message = '';
    if (!empty($subject)) {
        $TG_message .= "<b>" . htmlspecialchars($subject) . "</b>\n\n";
    }

    if (!empty($host)) {
        $TG_message .= "<b>Device:</b> " . htmlspecialchars($host['description']) . "\n";
        if (!empty($host['hostname'])) {
            $TG_message .= "<b>Hostname:</b> " . htmlspecialchars($host['hostname']) . "\n";
        }
        if (!empty($host['ip'])) {
            $TG_message .= "<b>IP:</b> " . htmlspecialchars($host['ip']) . "\n";
        }
        $TG_message .= "\n";
    }

    $TG_message .= $tg_text;

    if (!empty($format_file)) {
        $TG_message .= "\n\n<b>Graph:</b> " . htmlspecialchars($format_file);
        if ($graph_timespan > 0) {
            $TG_message .= " (Last " . $graph_timespan . " days)";
        }
    }

    $TG_message = urlencode($TG_message);

    $response = file_get_contents("https://api.telegram.org/bot$TG_apiToken/sendMessage?chat_id=$TG_chatid&text=$TG_message&parse_mode=HTML");
}

My question is:
How is the graph image actually generated and attached (e.g. in email), and where can I get the image file or URL so I can include it in the Telegram message (either as a link or as a photo)?

Thanks in advance for any guidance!

[xmacan]

thold_functions.php:

Image parameters:
$file_array = array(
'local_graph_id' => $thold_data['local_graph_id'],
'local_data_id' => $thold_data['local_data_id'],
'rra_id' => 0,
'file' => "$httpurl/graph_image.php?local_graph_id=" . $thold_data['local_graph_id'] . '&rra_id=0&view_type=tree',
'mimetype' => 'image/png',
'filename' => clean_up_name(thold_get_cached_name($thold_data))
);

And in function thold_email read part begins with:
if (is_array($filename) && sizeof($filename) && strstr($message, '') !== 0) {

[InsaneGriever]

Thanks! I was able to figure it out — this was very helpful.
Just posting the working solution here in case anyone else needs it in the future.

Here’s the updated send_telegram() function that also sends the graph image as a photo to Telegram:
functions.php:

function send_telegram($tg_text, $subject = '', $host = array(), $format_file = '', $graph_timespan = 7, $filename = array()) {
    $tg_text = strip_tags($tg_text);
    
    $TG_apiToken = ""; // your telegram apiToken
    $TG_chatid = "";   // your telegram chatid
    
    // Format the message
    $TG_message = '';
    if (!empty($subject)) {
        $TG_message .= "<b>" . htmlspecialchars($subject) . "</b>\n\n";
    }

    if (!empty($host)) {
        $TG_message .= "<b>Device:</b> " . htmlspecialchars($host['description']) . "\n";
        if (!empty($host['hostname'])) {
            $TG_message .= "<b>Hostname:</b> " . htmlspecialchars($host['hostname']) . "\n";
        }
        if (!empty($host['ip'])) {
            $TG_message .= "<b>IP:</b> " . htmlspecialchars($host['ip']) . "\n";
        }
        $TG_message .= "\n";
    }

    // Send image if available
    if (is_array($filename) && sizeof($filename)) {
        if (isset($filename['local_data_id'])) {
            $filename = array($filename); // Normalize to array
        }

        $time = time();
        $first_weekdayid = read_user_setting('first_weekdayid');
        $timespan = array();
        get_timespan($timespan, $time, $graph_timespan, $first_weekdayid);

        foreach ($filename as $val) {
            $graph_data_array = array(
                'graph_start'   => $timespan['begin_now'],
                'graph_end'     => $timespan['end_now'],
                'image_format'  => 'png',
                'graph_theme'   => 'modern',
                'output_flag'   => RRDTOOL_OUTPUT_STDOUT,
                'disable_cache' => true
            );

            $graph_image = rrdtool_function_graph($val['local_graph_id'], '', $graph_data_array, '');

            if ($graph_image !== false) {
                $temp_file = tempnam(sys_get_temp_dir(), 'tg_graph_');
                file_put_contents($temp_file, $graph_image);

                $post_fields = array(
                    'chat_id'    => $TG_chatid,
                    'photo'      => new CURLFile($temp_file, 'image/png', 'graph_' . $val['local_graph_id'] . '.png'),
                    'caption'    => $TG_message,
                    'parse_mode' => 'HTML'
                );

                $ch = curl_init();
                curl_setopt($ch, CURLOPT_URL, "https://api.telegram.org/bot$TG_apiToken/sendPhoto");
                curl_setopt($ch, CURLOPT_POST, 1);
                curl_setopt($ch, CURLOPT_POSTFIELDS, $post_fields);
                curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
                curl_exec($ch);
                curl_close($ch);

                unlink($temp_file);
                return; // Only send the first image
            }
        }
    } else {
        // Fallback to plain message
        $TG_message = urlencode($TG_message);
        file_get_contents("https://api.telegram.org/bot$TG_apiToken/sendMessage?chat_id=$TG_chatid&text=$TG_message&parse_mode=HTML");
    }
}

thold_functions.php after all thold_mail:

send_telegram($message, $subject, $h, $format_file, $thold_data['graph_timespan'], $file_array);

[TheWitness]

So, my comments here are for a purpose...

• Are there cases where there will be more than one bearer token for a single service?
• Does there need to be one more than one service (eg. Telegram, Slack, nasty ole Teams)?
• Can we just lock in on JSON POST or do we need other protocols?
• What about content, do we dictate the JSON format, or do the service providers?

I reopened as seeing code provides inspiration.

[TheWitness]

So, it looks like the service provider has requirements. Also, I'm not sure your fallback method is correct. It should use curl too, and file get contents or put? I guess it could be get, but does that expose you token in clear text?

[InsaneGriever]

Yes, curl can definitely be used for sending text messages as well.
Using POST instead of GET is a better and more secure practice, since it keeps sensitive data like tokens out of logs and URLs.
You’re also right about not hardcoding tokens and chat IDs. In a production setup, they should come from config files or environment variables. I kept them in the code here just for demonstration purposes.
For my use case, this implementation is sufficient, since the information being sent is not critical or sensitive — just notifications about thresholds going back to normal, etc.

Something like that

		$post_fields = array(
			'chat_id' => $TG_chatid,
			'text' => $TG_message,
			'parse_mode' => 'HTML'
		);
		
		$ch = curl_init();
		curl_setopt($ch, CURLOPT_URL, "https://api.telegram.org/bot$TG_apiToken/sendMessage");
		curl_setopt($ch, CURLOPT_POST, 1);
		curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($post_fields));
		curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
		curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: application/x-www-form-urlencoded'));
		
		$response = curl_exec($ch);
		$error = curl_error($ch);
		curl_close($ch);
		
		if ($error) {
			cacti_log("Telegram API Error (Message): " . $error, true, 'SYSTEM');
			return false;
		}
		return true;

[TheWitness]

So, I can see this as a feature. Basically, we would need to add a setting or two. For example:

Console > Settings > Alerting/Thold > Telegram Section > TokenID + ChatID

Then, add two columns in thold_template and thold_data:
telegram_enable char(2) default ''
telegram_chat_id varchar(20) default ''

Then do the underlying logic, a checkbox for telegram_enable, and an optional chat_id that would default to the global setting if not set.

Seems strait forward. We were looking at re-imagining notification, but not many of us on the team have the time right now.

Second approach would be to make this a part of the notification list. So, each notification list would have it's own telegram token and chat_id, defaulted to the global setting, and then you simply let thold know that this notification supports telegram.