Probes

Probes are the heart of the monitoring requests. Probes are arrays of request objects defined in the config file monika.yml like so.

1 probes:
2   - id: '1'
3     name: Name of the probe
4     description: Probe to check GET time
5     interval: 10
6     requests:
7       - {}
8     alerts: []
9   - id: '2'
10     name: Name of the probe 2
11     description: Probe to check GET health
12     interval: 10
13     requests:
14       - {}
15     alerts: []

Monika goes through each probe object, sends it out, and determines whether an alert or notification needs to be sent out.

Probe Request Anatomy

An actual probe request may be something like below.

1 probes: [
2     id: '1'
3     name: 'Example: get Time'
4     description: Probe
5     interval: 10
6     requests:
7     - method: POST
8       url: https://mybackend.org/user/login
9       timeout: 7000
10       saveBody: true
11       headers:
12         Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkhlbGxvIGZyb20gSHlwZXJqdW1wIiwiaWF0IjoxNTE2MjM5MDIyfQ.T2SbP1G39CMD4MMfkOZYGFgNIQgNkyi0sPdiFi_DfVA
13       body:
14         username: someusername
15         password: somepassword
16       alerts: ARRAY-HERE
17     incidentThreshold: 3
18     recoveryThreshold: 3
19     alerts:
20     - query: response.status != 200
21       message: HTTP response status is {{ response.status }}, expecting 200
22   ]

Details of the field are given in the table below.

PING

You can send an ICMP echo request to a specific url by enabling the ping: true field. In this mode the http method is ignored and a PING echo request is sent to the specified url.

1 probes:
2   - id: 'ping_test'
3     name: ping_test
4     description: requesting icmp ping
5     interval: 10
6     requests:
7       - url: http://google.com
8         ping: true

TCP

You can send a TCP request to a specific host and port with data by using the socket field.

1 probes:
2   - id: 'tcp-example'
3     socket:
4       host: localhost
5       port: 3333
6       data: Hello from Monika

Probe Response Anatomy

The default shape of a response when Monika has successfully fetched a request is as the following.

1 status: 200
2 statusText: OK
3 headers:
4   test-header: ...
5 config:
6   url: https://reqres.in/api/users
7   method: GET
8   data:
9     mydata: value
10   headers:
11     Accept: application/json, text/plain, */*
12     User-Agent: axios/0.21.1
13 data: ...

Details of the fields are shown in the table below.

Probe response data could be used for Request Chaining.

Execution order

In a configuration with multiple probes, Monika will load the requests in the order that they are entered, one after another. However, probes may be performed out of sequence depending on their interval setting, network latency and response times. By default Monika loops through all the probe configurations in the order they are entered, but you can use the --id or the --repeat flags to specify or repeat a particular sequence. See the cli options here for more information.

In general, Monika will sleep until the next interval timer to repeat a probe. If no interval time is specified for a probe, the default value will be used. If the configured probe interval is shorter than the amount of time to dispatch all the requests, then Monika will immediately repeat after the last response and any notification alerts sent.

Content-Type header

Currently, Monika only supports Content-Type value application/x-www-form-urlencoded and application/json with UTF-8 encoding.

Request Body

By default, the request body will be treated as-is. If the request header's Content-Type is set to application/x-www-form-urlencoded, it will be serialized into URL-safe string in UTF-8 encoding.

Postman JSON file support

NOTE: We only support Postman collection v2.0 and v2.1 files.

To run monika using a Postman JSON file, use --postman flag as follows:

 monika --postman <path_to_postman_file>

Insomnia file support

Monika supports Insomnia collection file in version 4 format. Both json and yaml files are supported. To run Monika using an Insomnia collection file, use --insomnia flag as follows:

 monika --insomnia <path_to_insomnia_file>

HAR file support

HAR HTTP-Archive format was created by the Web Performance Working Group and has become the standard in browser archive request data definition. To run monika using a HAR file, use --har flag as follows:

 monika --har <path_to_HAR_file>

Further reading

1. Alerts
2. Notifications