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End-to-End Testing for Developers

Document updated on Nov 10, 2023

In addition to checking the syntax of your KrakenD configuration and ensuring that the gateway can start, an essential step in any CI/CD strategy is including end-to-end tests to guarantee that all the active software components from beginning to end have the expected flow and that the gateway returns what you planned when working together with your upstream services.

How E2E testing works

The end-to-end testing definition is quite simple. You must create a folder to hold all the test cases you want to execute (e.g., specs). Inside the folder, you make a file per test case. Each test case is a JSON file containing the input request you will send to the gateway ( in) and the form of the expected output ( out). The test file has a structure supported by a JSON schema definition.

With a folder full of test cases, the krakend e2e command starts a gateway with the provided configuration and launches all the test cases in the folder. You are creating real traffic to the gateway and the backends and analyzing their responses through the gateway to validate the behavior before setting a configuration online.

Creating e2e test files

Tests must be deterministic
Make sure tests are deterministic and reproducible with a consistent output in different executions. If the output of a call varies over time, consider using the schema property to describe the properties rather than checking their exact values.

For instance, you could have the following contents on your disk:

Contents of E2E testing 
$tree /etc/krakend
├── krakend.json
└── specs
    ├── test-foo.json
    ├── test-bar.json
    └── some-other-test.json

KrakenD will run all the tests declared in the folder alphabetically (according to the file sorting of the OS).

Test Case files

Each test case is a simple .json file containing an object with an in (the input request you want to do to KrakenD) and an out (the output you expect in the response).

Sometimes, a test case needs to have multiple calls to validate a scenario. When this happens, you can add a next entry, an array containing couples of in and out objects that will be executed and analyzed in the declared order. The next does not evaluate until the tool has already processed the siblings in and out.

The test case file must follow the e2e schema (explained below) to work correctly, but the tool does not validate the JSON format of each test case during runtime (this makes processing faster).

Here’s an example of test you can save under specs/test1.json and run it with any KrakenD configuration (debug_endpoint set to true required):

{
    "$schema": "https://www.krakend.io/schema/v2.5/e2e.json",
    "@comment": "Makes sure that the debug endpoint returns a status ok",
    "in": {
        "method": "GET",
        "url": "http://localhost:8080/__debug/something",
        "header": {
            "User-Agent": "krakend-e2e-tool"
        }
    },
    "out": {
        "status_code": 200,
        "body": {
          "status": "ok"
        },
        "header": {
            "content-type": ["application/json; charset=utf-8"],
            "X-Krakend-Completed": ["true"],
            "Cache-Control": [""]
        }
    }
}

The test above connects to the URL http://localhost:8080/__debug/something and analyzes its response output, and checks that:

  • It returns an HTTP status_code equal to 200
  • That the body is literally {"status": "ok"}, and the entirety of the payload.
  • It also makes sure that there are three header conditions:
    • The content-type and X-Krakend-Completed have the specified values
    • The Cache-Control header cannot be present (we compare it to an empty string).

Any other headers that are not mapped here are ignored, so the response could have more.

Finally, the $schema you see at the top of the file points to the E2E JSON Schema that helps you autocomplete and validate from your IDE (provided that it has automatic JSON-schema validation). The value can be either of:

  • https://www.krakend.io/schema/v2.5/e2e.json (minor version)
  • https://www.krakend.io/schema/e2e.json (latest version)

See the format of the test cases below.

Test Case format

Test cases must be in JSON format and might contain two or three top-level attributes:

Fields of Schema validation for End To End testing specs
* required fields
in  *

object		The input request definition. At least you should define the URL used to connect to KrakenD
body

object, array, string		If you want to add a payload in the request, set its body here

object		An optional map of headers you want to include in the request.
Example: {"User-Agent":"krakend e2e tool"}
method

string		The method sent in the request
Possible values are: "GET" , "POST" , "PUT" , "PATCH" , "DELETE"
Defaults to "GET"
url  *

string		The full URL you want to use in the request, including schema, host, port, path, and any additional query string parameters you might need.
Example: "http://localhost:8080/__debug/something"
next

array		Additional checks, in sequential order, of in and out definitions. The outter in and out are always executed first.
Example: {"next":[{"in":{},"out":{}},{"in":{},"out":{}}]} Each item is an object with the following properties:
in  *

object		The input request definition. At least you should define the URL used to connect to KrakenD
body

object, array, string		If you want to add a payload in the request, set its body here

object		An optional map of headers you want to include in the request.
Example: {"User-Agent":"krakend e2e tool"}
method

string		The method sent in the request
Possible values are: "GET" , "POST" , "PUT" , "PATCH" , "DELETE"
Defaults to "GET"
url  *

string		The full URL you want to use in the request, including schema, host, port, path, and any additional query string parameters you might need.
Example: "http://localhost:8080/__debug/something"
out  *

object		The expected response from the server
* Required any of: ( status_code ) , or ( status_code + body ) , or ( status_code + schema )
body

string, object		The expected returned body by the response as a string or JSON object. Remove this body field when you don’t want to check its contents, when the response does not have a body, or when you want to use the schema instead.
Example: "http://localhost:8080/__debug/something"

object		Checks that all headers included in the response match the provided values. You only need to declare the relevant headers you want, as the rest are ignored. As headers, by RFC definition, can be multiple, you must always use an array to express the values you want to check. You can also check that a specific header does not exist in the response declaring an empty value [""].
Example: {"Cache-Control":[""],"X-Krakend-Completed":["true"],"content-type":["application/json; charset=utf-8"]}

Properties of header can use a name matching the pattern .*, and their content is an array

schema

object		A JSON Schema object that validates the response. This option allows you to work with responses that the literal value is not that important and you want to check the structure of the returned document instead. If the response matches the schema definition, the test passes. If you define a schema and a body simultaneously only the schema is validated.
status_code

integer		The integer value of the HTTP status code returned by the server.
Example: 200
out  *

object		The expected response from the server
* Required any of: ( status_code ) , or ( status_code + body ) , or ( status_code + schema )
body

string, object		The expected returned body by the response as a string or JSON object. Remove this body field when you don’t want to check its contents, when the response does not have a body, or when you want to use the schema instead.
Example: "http://localhost:8080/__debug/something"

object		Checks that all headers included in the response match the provided values. You only need to declare the relevant headers you want, as the rest are ignored. As headers, by RFC definition, can be multiple, you must always use an array to express the values you want to check. You can also check that a specific header does not exist in the response declaring an empty value [""].
Example: {"Cache-Control":[""],"X-Krakend-Completed":["true"],"content-type":["application/json; charset=utf-8"]}

Properties of header can use a name matching the pattern .*, and their content is an array

schema

object		A JSON Schema object that validates the response. This option allows you to work with responses that the literal value is not that important and you want to check the structure of the returned document instead. If the response matches the schema definition, the test passes. If you define a schema and a body simultaneously only the schema is validated.
status_code

integer		The integer value of the HTTP status code returned by the server.
Example: 200
Schema: https://www.krakend.io/schema/v2.5/e2e.json

Testing non-deterministic responses

When the response of your backend is not deterministic, instead of checking the response against a body trying to find an exact payload, you can test it against a JSON Schema, using the schema attribute.

For instance, our health endpoint returns the date after every request. It would be impossible to test it literally, as the date changes between executions. The following test would make sure that it works by comparing the response with a schema:

{
    "$schema": "https://www.krakend.io/schema/v2.5/e2e.json",
    "@comment": "Makes sure that the health endpoint contains three fields with the right types",
    "in": {
        "url": "http://localhost:8080/__health"
    },
    "out": {
        "status_code": 200,
        "schema": {
          "$schema": "http://json-schema.org/draft-07/schema#",
          "required": ["agents","now","status"],
          "properties": {
            "agents": {
                "type": "object"
            },
            "now": {
                "type": "string"
            },
            "status": {
                "type": "string",
                "enum": ["ok"]
            }
          }
        }
    }
}

The content inside the schema property is JSON Schema syntax up to a Draft-07 response.

Running the e2e tests

The e2e command can run without additional flags if you use the default naming, but it has several run options. It looks like this:

Term 
$krakend e2e -h

╓▄█                          ▄▄▌                               ╓██████▄µ
▐███  ▄███╨▐███▄██H╗██████▄  ║██▌ ,▄███╨ ▄██████▄  ▓██▌█████▄  ███▀╙╙▀▀███╕
▐███▄███▀  ▐█████▀"╙▀▀"╙▀███ ║███▄███┘  ███▀""▀███ ████▀╙▀███H ███     ╙███
▐██████▌   ▐███⌐  ,▄████████M║██████▄  ║██████████M███▌   ███H ███     ,███
▐███╨▀███µ ▐███   ███▌  ,███M║███╙▀███  ███▄```▄▄` ███▌   ███H ███,,,╓▄███▀
▐███  ╙███▄▐███   ╙█████████M║██▌  ╙███▄`▀███████╨ ███▌   ███H █████████▀
                     ``                     `'`

Version: 2.5

Executes an end-to-end test for the gateway based on the configuration file and a set of specs.

Usage:
  krakend e2e [flags]

Examples:
krakend e2e -c config.json -s specs

Flags:
  -c, --config string    Path to the krakend configuration file. (default "./krakend.json")
  -d, --delay duration   The delay for the delayed backend endpoint. (default 200ms)
  -e, --envar string     Comma separated list of patterns to use to filter the envars to pass (set to ".*" to pass everything).
  -h, --help             help for e2e
  -l, --log string       Path for storing the server logs. (default "./e2e.log")
  -r, --no-redirect      Disable redirects at the http client.
  -p, --port int         The port for the mocked backend api. (default 8081)
  -s, --specs string     Path to the specs folder. (default "./specs")

When you run the tests, KrakenD will tell you the failing ones with a [KO] and the working ones with an [OK]. For instance:

Term 
$krakend e2e
[OK] test1
1 test(s) completed
Total time: 1.102928274s

The e2e command starts and shuts down two services during the tests:

  • A KrakenD instance running on port 8080 or the port you have defined in your configuration, on which all test requests are sent.
  • An additional backend service on port 8081 (or the one you define with krakend e2e -p) with a few utility endpoints that you can use to complement your testing (see below)

Skipping tests

Only files ending with a .json extension are taken into account.

If you want to skip a test temporarily, rename the test to a non .json extension. For instance, you can rename test1.json to test1.json.skip.

Using mock data

The main point of integration tests is to test KrakenD configurations (not necessarily the backend content itself). Therefore, all tests expect reproducible outputs.

Part of a testing strategy is using mocked data. An easy way to have fake data is to create a mock folder with static JSON content and offer it via the static-filesystem.

By using static files, you could, for instance, create /mock/ endpoints that return the static files inside your mock folder folder.

E2E utility backend service

In addition to the KrakenD service used to test the configuration, the command e2e will start on port 8081(by default) an additional backend service with the following endpoints you can include in your tests.

You can see the code of these endpoints below here.

In addition to the endpoints below, you can also use the echo and debug endpoints of KrakenD (not this service)

Endpoint /param_forwarding/*

An echo endpoint that returns an object containing a map with the request details:

  • path: The URL requested to the backend
  • query: The different query strings passed to the backend
  • headers: All the headers that reached the backend
  • foo: An additional object with a hardcoded value 42
  • body: A string with the data passed in the request’s body. Only dumped when you call the backend with the query string ?dump_body=1.

For example, a call to http://localhost:8081/param_forwarding/hey/yo?a=1&b=1&dumb_body=1 produces the response:

{
    "path": "/param_forwarding/hey/yo",
    "query": {
        "a": 1,
        "b": 2,
        "dump_body": 1
    },
    "headers": {
        "Accept-Encoding": [
            "gzip"
        ],
        "User-Agent": [
            "KrakenD Version 2.5"
        ],
        "X-Forwarded-Host": [
            "localhost:8080"
        ]
    },
    "foo": 42,
    "body": {}
}

Endpoint /xml

Returns hardcoded content in XML format. Useful to test a mix of JSON and XML encodings:

<?xml version="1.0" encoding="UTF-8"?>
<user type="admin">
  <name>Elliot</name>
  <social>
    <facebook>https://facebook.com</facebook>
    <twitter>https://twitter.com</twitter>
    <youtube>https://youtube.com</youtube>
  </social>
</user>

Endpoint /collection/*

Returns a collection of 10 objects (an array) with the number of iteration (i) and the path used. For instance, calling http://localhost:8081/collection/hi-there produces:

[
    {
        "i": 0,
        "path": "/collection/hi-there"
    },
    {
        "i": 1,
        "path": "/collection/hi-there"
    },
    {
        "i": 2,
        "path": "/collection/hi-there"
    },
    {
        "i": 3,
        "path": "/collection/hi-there"
    },
    {
        "i": 4,
        "path": "/collection/hi-there"
    },
    {
        "i": 5,
        "path": "/collection/hi-there"
    },
    {
        "i": 6,
        "path": "/collection/hi-there"
    },
    {
        "i": 7,
        "path": "/collection/hi-there"
    },
    {
        "i": 8,
        "path": "/collection/hi-there"
    },
    {
        "i": 9,
        "path": "/collection/hi-there"
    }
]

Endpoint /delayed/*

Returns an echo endpoint (as in /param_forwarding), but it delays the response for 200ms or any other value you pass using the -d flag when running the tests.

Endpoint /redirect/*

Returns an HTTP redirection to /param_forwarding/ using the status code passed by query string with ?status=301. For instance, http://localhost:8081/redirect/hi-there?status=302`.

Endpoint /jwk/symmetric

Returns a fake signing key that validates demo JWT tokens. To be used when you set the jwk_url if you don’t want to issue real tokens

{
  "keys": [
    {
      "kty": "oct",
      "alg": "A128KW",
      "k": "GawgguFyGrWKav7AX4VKUg",
      "kid": "sim1"
    },
    {
      "kty": "oct",
      "k": "AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow",
      "kid": "sim2",
      "alg": "HS256"
    }
  ]
}

The key above validates the following Authorization: Beaerer demo token:

bearer eyJhbGciOiJIUzI1NiIsImtpZCI6InNpbTIifQ.eyJhdWQiOiJodHRwOi8vYXBpLmV4YW1wbGUuY29tIiwiZXhwIjoxNzM1Njg5NjAwLCJpc3MiOiJodHRwczovL2tyYWtlbmQuaW8iLCJqdGkiOiJtbmIyM3Zjc3J0NzU2eXVpb21uYnZjeDk4ZXJ0eXVpb3AiLCJyb2xlcyI6WyJyb2xlX2EiLCJyb2xlX2IiXSwic3ViIjoiMTIzNDU2Nzg5MHF3ZXJ0eXVpbyJ9.htgbhantGcv6zrN1i43Rl58q1sokh3lzuFgzfenI0Rk
Scarf

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