DEV Community: SysUpTime

Monitor Amazon Price Changes

SysUpTime — Sun, 07 Jun 2020 22:59:12 +0000

This article demonstrates how to use the web site monitor to check a product's price on Amazon periodically and send email when price changes.

Amazon Page Info

Let's pick an Amazon Kindle as an example. The shopping URL is

https://www.amazon.com/All-new-Kindle-Oasis-now-with-adjustable-warm-light/dp/B07F81WWKP/ref=sr_1_9?dchild=1

Use Chrome browser to open the URL. Right click on the price area and select "Inspect" menu.

The HTML source is shown below:

So we can look for a "td" node with "id" being "priceblock_ourprice_lbl", and its text node value is "Price:", and the real price is in the subsequent "span" node with "id" being "priceblock_ourprice".

Configure SMTP server

SMTP server needs to be configured first for sending email on alarm

Select "Setting/SMTP Server" menu:
Enter SMTP server parameters. We use gmail as an example:

Then press "Send Test Mail" to check if the SMTP server has been configured successfully.

Configure SysUpTime

Add a web site monitor:

In the URL field, enter

  https://www.amazon.com/All-new-Kindle-Oasis-now-with-adjustable-warm-light/dp/B07F81WWKP/ref=sr_1_9?dchild=1

Press "Configure" button next to the "Threshold settings".

Move "body response time" to the left and move "content match" to the right panel.

Configure it to use simple content match, and choose "Line contains" radio button, enter.

  engine_daemon_container_states_containers{state="running"}

to the text field of "Line contains". In the token field, enter "2".
The value is the second token of the line.

In the threshold field, enter 340, so that an alarm will be raised when price drops below 340.

Press "Ok" buttons to go back to the screen at step 1.

In the following screen

Press "Configure" button next to the "Actions"

Enter your email address to receive email notification when price drops below threshold:
Press "Ok" buttons to save the monitor.
(Optional) In the "Manage Monitor" dialog, select the newly created monitor and press "Chart" button to see the real time chart.

Monitor Docker Engine

SysUpTime — Sun, 07 Jun 2020 13:18:58 +0000

Docker an open-source project that automates the deployment of software applications inside containers.

Configure Docker

To monitor a Docker engine, the first step is to specify the metrics-address. The best way to do this is via the daemon.json, which is located at one of the following locations by default. If the file does not exist, create it.

Linux: /etc/docker/daemon.json
Windows Server: C:\ProgramData\docker\config\daemon.json
Docker Desktop for Mac / Docker Desktop for Windows: Click the Docker icon in the toolbar, select Preferences, then select "Docker Engine".

If the file is currently empty, paste the following:

{
  "metrics-addr" : "0.0.0.0:9323",
  "experimental" : true
}

This will publish the metrics endpoint, in the port 9323 of the host.

After Docker restars, use web browser pointing to http://192.168.2.13:9323
(assuming the IP of the Docker engine's machine is 192.168.2.13). A sample result:

# HELP builder_builds_failed_total Number of failed image builds
# TYPE builder_builds_failed_total counter
builder_builds_failed_total{reason="build_canceled"} 0
builder_builds_failed_total{reason="build_target_not_reachable_error"} 0
builder_builds_failed_total{reason="command_not_supported_error"} 0
builder_builds_failed_total{reason="dockerfile_empty_error"} 0
builder_builds_failed_total{reason="dockerfile_syntax_error"} 0
builder_builds_failed_total{reason="error_processing_commands_error"} 0
builder_builds_failed_total{reason="missing_onbuild_arguments_error"} 0
builder_builds_failed_total{reason="unknown_instruction_error"} 0
# HELP builder_builds_triggered_total Number of triggered image builds
# TYPE builder_builds_triggered_total counter
builder_builds_triggered_total 0
# HELP engine_daemon_container_actions_seconds The number of seconds it takes to process each container action
# TYPE engine_daemon_container_actions_seconds histogram
engine_daemon_container_actions_seconds_bucket{action="changes",le="0.005"} 1
engine_daemon_container_actions_seconds_bucket{action="changes",le="0.01"} 1
engine_daemon_container_actions_seconds_bucket{action="changes",le="0.025"} 1
engine_daemon_container_actions_seconds_bucket{action="changes",le="0.05"} 1
engine_daemon_container_actions_seconds_bucket{action="changes",le="0.1"} 1
engine_daemon_container_actions_seconds_bucket{action="changes",le="0.25"} 1
engine_daemon_container_actions_seconds_bucket{action="changes",le="0.5"} 1
engine_daemon_container_actions_seconds_bucket{action="changes",le="1"} 1
engine_daemon_container_actions_seconds_bucket{action="changes",le="2.5"} 1

Configure SysUpTime

Add a web site monitor:

In the URL field, enter

http://192.168.2.13:9323/metrics
(Replace 192.168.2.13 with real docker engine's IP address)

Press "Configure" button next to the "Threshold settings".

Move "body response time" to the left and move "content match" to the right panel.

Configure it to use simple content match, and choose "Line contains" radio button, enter

engine_daemon_container_states_containers{state="running"}

to the text field of "Line contains". In the token field, enter "2".
The value is the second token of the line.

We don't need to check threshold, so uncheck "Enable threshold" on the top.
Press "Ok" buttons to save the monitor.
(Optional) In the "Manage Monitor" dialog, select the newly created monitor and press "Chart" button to see the real time chart.

Now we have created a monitor to check docker parameter:

engine_daemon_container_states_containers{state="running"}

Then we can create similar monitors for other parameters such as

engine_daemon_container_states_containers{state="paused"}
engine_daemon_container_states_containers{state="stopped"}
engine_daemon_health_checks_failed_total
swarm_node_manager

Monitor Zoom Services

SysUpTime — Fri, 05 Jun 2020 22:00:40 +0000

You can create web site monitors to monitor the status of Zoom services. Zoom
becomes ubiquitous nowadays and it's important to know when the zoom service
is down so that we can take alternative way to communicate.

Zoom provides an API for checking the status of the service.
We can use SysUpTime to create web site monitors to check the status. Here are the steps to
create the monitor.

Press "Add Monitor" button on toolbar to bring up a dialog and select "Web Site", and enter the following URL to the URL field: Zoom Status Page URL: https://status.zoom.us/api/v2/components.json The output of the status page is in JSON format. An example:

{
  "page": {
    "id": "14qjgk812kgk",
    "name": "Zoom",
    "url": "https://status.zoom.us",
    "time_zone": "America/Los_Angeles",
    "updated_at": "2020-06-04T08:36:42.450-07:00"
  },
  "components": [
    {
      "id": "jds2k69nx1t9",
      "name": "Web SDK",
      "status": "operational",
      "created_at": "2020-04-06T15:25:04.818-07:00",
      "updated_at": "2020-04-07T00:37:23.805-07:00",
      "position": 1,
      "description": null,
      "showcase": false,
      "group_id": "dhtlfcvrh3qh",
      "page_id": "14qjgk812kgk",
      "group": false,
      "only_show_if_degraded": false
    },
    {
      "id": "rhmrtnvc7xrt",
      "name": "Live Streaming",
      "status": "operational",
      "created_at": "2020-03-22T12:21:48.196-07:00",
      "updated_at": "2020-04-12T12:28:27.546-07:00",
      "position": 1,
      "description": null,
      "showcase": false,
      "group_id": "7kqrv6r1y1my",
      "page_id": "14qjgk812kgk",
      "group": false,
      "only_show_if_degraded": false
    },
    {
      "id": "cn1j8pttz0wy",
      "name": "Zoom Dashboard & Reporting",
      "status": "operational",
      "created_at": "2020-03-17T15:25:42.220-07:00",
      "updated_at": "2020-05-26T11:16:01.558-07:00",
      "position": 1,
      "description": null,
      "showcase": false,
      "group_id": "1ndlrnp6r9js",
      "page_id": "14qjgk812kgk",
      "group": false,
      "only_show_if_degraded": false
    },
    {
      "id": "3ml2fn8g0psv",
      "name": "Zoom Cloud Room Connector",
      "status": "operational",
      "created_at": "2015-01-26T15:08:04.212-08:00",
      "updated_at": "2020-05-27T07:21:19.349-07:00",
      "position": 1,
      "description": "Access for H.323/SIP endpoints",
      "showcase": false,
      "group_id": "b49qkwc1nk36",
      "page_id": "14qjgk812kgk",
      "group": false,
      "only_show_if_degraded": false
    },
    {
      "id": "3z7b6jks10hm",
      "name": "Zoom Meetings",
      "status": "operational",
      "created_at": "2015-01-26T15:04:39.101-08:00",
      "updated_at": "2020-05-17T08:39:54.325-07:00",
      "position": 1,
      "description": "Access to meetings",
      "showcase": false,
      "group_id": null,
      "page_id": "14qjgk812kgk",
      "group": false,
      "only_show_if_degraded": false
    },
    {
      "id": "wgnljdgkx9dw",
      "name": "Zoom Connector for Cisco",
      "status": "operational",
      "created_at": "2018-08-08T09:29:00.502-07:00",
      "updated_at": "2019-03-15T22:00:54.658-07:00",
      "position": 2,
      "description": null,
      "showcase": false,
      "group_id": "b49qkwc1nk36",
      "page_id": "14qjgk812kgk",
      "group": false,
      "only_show_if_degraded": false
    },
    {
      "id": "q4msk5dl4bhm",
      "name": "Zoom Video Webinars",
      "status": "operational",
      "created_at": "2015-01-26T15:04:39.115-08:00",
      "updated_at": "2020-05-17T08:39:54.343-07:00",
      "position": 2,
      "description": "Access to video webinars",
      "showcase": false,
      "group_id": null,
      "page_id": "14qjgk812kgk",
      "group": false,
      "only_show_if_degraded": false
    },
    {
      "id": "nyfqtg3bpllm",
      "name": "REST API",
      "status": "operational",
      "created_at": "2020-03-17T15:28:23.405-07:00",
      "updated_at": "2020-04-06T15:25:14.997-07:00",
      "position": 2,
      "description": null,
      "showcase": false,
      "group_id": "dhtlfcvrh3qh",
      "page_id": "14qjgk812kgk",
      "group": false,
      "only_show_if_degraded": false
    },
    {
      "id": "9skbqhkvk721",
      "name": "Download Center",
      "status": "operational",
      "created_at": "2018-05-17T11:29:26.349-07:00",
      "updated_at": "2020-03-17T15:27:40.414-07:00",
      "position": 2,
      "description": null,
      "showcase": false,
      "group_id": "1ndlrnp6r9js",
      "page_id": "14qjgk812kgk",
      "group": false,
      "only_show_if_degraded": false
    },
    {
      "id": "rmphw6f34qk9",
      "name": "Marketplace",
      "status": "operational",
      "created_at": "2020-04-06T15:25:48.555-07:00",
      "updated_at": "2020-04-06T15:25:48.555-07:00",
      "position": 3,
      "description": null,
      "showcase": false,
      "group_id": "dhtlfcvrh3qh",
      "page_id": "14qjgk812kgk",
      "group": false,
      "only_show_if_degraded": false
    },
    {
      "id": "jh6w5p8b9yv9",
      "name": "Zoom Phone",
      "status": "operational",
      "created_at": "2019-01-23T13:28:01.376-08:00",
      "updated_at": "2020-04-22T10:16:39.384-07:00",
      "position": 3,
      "description": null,
      "showcase": false,
      "group_id": null,
      "page_id": "14qjgk812kgk",
      "group": false,
      "only_show_if_degraded": false
    },
    {
      "id": "12cw0typ4wln",
      "name": "Zoom Connector for Polycom",
      "status": "operational",
      "created_at": "2018-08-08T09:29:25.667-07:00",
      "updated_at": "2019-03-15T22:00:54.705-07:00",
      "position": 3,
      "description": null,
      "showcase": false,
      "group_id": "b49qkwc1nk36",
      "page_id": "14qjgk812kgk",
      "group": false,
      "only_show_if_degraded": false
    },
    {
      "id": "t2jk6yrqbp4j",
      "name": "Zoom Chat",
      "status": "operational",
      "created_at": "2015-01-26T15:08:19.770-08:00",
      "updated_at": "2020-03-18T10:32:00.350-07:00",
      "position": 4,
      "description": "Access to Group Chats",
      "showcase": false,
      "group_id": null,
      "page_id": "14qjgk812kgk",
      "group": false,
      "only_show_if_degraded": false
    },
    {
      "id": "8gftm750nwzm",
      "name": "Web Portal",
      "status": "operational",
      "created_at": "2020-03-17T15:28:43.573-07:00",
      "updated_at": "2020-03-17T15:28:43.573-07:00",
      "position": 4,
      "description": null,
      "showcase": false,
      "group_id": "1ndlrnp6r9js",
      "page_id": "14qjgk812kgk",
      "group": false,
      "only_show_if_degraded": false
    },
    {
      "id": "4h0vkyt0jjnz",
      "name": "Web Client",
      "status": "operational",
      "created_at": "2020-04-03T00:42:50.563-07:00",
      "updated_at": "2020-04-05T09:52:27.031-07:00",
      "position": 5,
      "description": null,
      "showcase": false,
      "group_id": "1ndlrnp6r9js",
      "page_id": "14qjgk812kgk",
      "group": false,
      "only_show_if_degraded": false
    },
    {
      "id": "1ndlrnp6r9js",
      "name": "Zoom Website",
      "status": "operational",
      "created_at": "2020-03-17T15:25:42.214-07:00",
      "updated_at": "2020-03-17T15:29:04.202-07:00",
      "position": 5,
      "description": null,
      "showcase": false,
      "group_id": null,
      "page_id": "14qjgk812kgk",
      "group": true,
      "only_show_if_degraded": false,
      "components": [
        "cn1j8pttz0wy",
        "9skbqhkvk721",
        "8gftm750nwzm",
        "4h0vkyt0jjnz"
      ]
    },
    {
      "id": "b49qkwc1nk36",
      "name": "Conference Room Connector",
      "status": "operational",
      "created_at": "2018-08-08T09:28:24.725-07:00",
      "updated_at": "2020-03-17T15:29:04.216-07:00",
      "position": 6,
      "description": null,
      "showcase": false,
      "group_id": null,
      "page_id": "14qjgk812kgk",
      "group": true,
      "only_show_if_degraded": false,
      "components": [
        "3ml2fn8g0psv",
        "wgnljdgkx9dw",
        "12cw0typ4wln"
      ]
    },
    {
      "id": "gkx8x46kw77h",
      "name": "Cloud Recording",
      "status": "operational",
      "created_at": "2020-03-17T15:29:33.741-07:00",
      "updated_at": "2020-05-12T10:21:53.254-07:00",
      "position": 7,
      "description": null,
      "showcase": false,
      "group_id": null,
      "page_id": "14qjgk812kgk",
      "group": false,
      "only_show_if_degraded": false
    },
    {
      "id": "ntdt65v1f9rv",
      "name": "Meeting Telephony Services",
      "status": "operational",
      "created_at": "2015-01-26T15:08:50.964-08:00",
      "updated_at": "2020-06-03T11:01:02.347-07:00",
      "position": 8,
      "description": "Access to Telephony Services",
      "showcase": false,
      "group_id": null,
      "page_id": "14qjgk812kgk",
      "group": false,
      "only_show_if_degraded": false
    },
    {
      "id": "7kqrv6r1y1my",
      "name": "Integrations",
      "status": "operational",
      "created_at": "2020-03-22T12:21:48.183-07:00",
      "updated_at": "2020-03-22T12:21:48.183-07:00",
      "position": 9,
      "description": null,
      "showcase": false,
      "group_id": null,
      "page_id": "14qjgk812kgk",
      "group": true,
      "only_show_if_degraded": false,
      "components": [
        "rhmrtnvc7xrt"
      ]
    },
    {
      "id": "dhtlfcvrh3qh",
      "name": "Zoom Developer Platform",
      "status": "operational",
      "created_at": "2020-04-06T15:25:04.810-07:00",
      "updated_at": "2020-04-06T15:25:04.810-07:00",
      "position": 10,
      "description": null,
      "showcase": false,
      "group_id": null,
      "page_id": "14qjgk812kgk",
      "group": true,
      "only_show_if_degraded": false,
      "components": [
        "jds2k69nx1t9",
        "nyfqtg3bpllm",
        "rmphw6f34qk9"
      ]
    }
  ]
}

Press "Configure" button to configure "Threshold settings" and select "content match", then press "Edit" button, and we see the following screen:
Select "JSON format, and enter values, so we will monitor the status of "Live Streaming" service
In the threshold screen, enter "operational", which means if the value is not "operational", an alarm will be raised.

Now a monitor has been created for checking the status of "Live Streaming" service, the following is the graph:

We then can create more monitors to check the status of other zoom services.

Monitor NGINX

SysUpTime — Sun, 31 May 2020 02:53:54 +0000

Nginx status page can give us realtime information about the server's current status, such as number of connections and requests.

Configure Nginx

Run this command to check if your Nginx server support status page:

nginx -V 2>&1 | grep -o with-http_stub_status_module

Edit Nginx config file and add the following inside server{...} block:

 location /nginx_status {
          stub_status on;
          access_log   off;
          allow 1.1.1.1;
          deny all;
        }

Then reload Nginx config:

nginx -s reload

After reloading config, visit http://yourdomain.com/nginx_status and the output will be something like:

Active connections: 81 
server accepts handled requests
 12132 12132 15001 
Reading: 0 Writing: 3 Waiting: 5

Notes:

Active connections – Number of all open connections. This doesn’t mean number of users. A single user, for a single page view can open many concurrent connections to your server.
Server accepts handled requests – This shows three values.
1. First is total accepted connections.
2. Second is total handled connections. Usually first 2 values are same.
3. Third value is number of accepted and handles requests. This is usually greater than second value.
4. Dividing third-value by second-one will give you number of requests per connection handled by Nginx. In above example, 15001/12132, 1.24 requests per connections.
Reading – Nginx reads request header
Writing – Nginx reads request body, processes request, or writes response to a client
Waiting – keep-alive connections, actually it is active – (reading + writing).This value depends on keepalive-timeout. Do not confuse non-zero waiting value for poor performance. It can be ignored. Although, you can force zero waiting by setting keepalive_timeout 0;

Configure SysUpTime

Add a web site monitor:
Configure it to use simple content match, and choose the third token of first line of the http response, which is the value of active connections.
The chart of the monitor will be something like: