KrakenD API Gateway

https://www.krakend.io/docs
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KrakenD is an open-source, high-performance API Gateway that simplifies microservices integration,...
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### Install KrakenD Enterprise on Fedora (dnf)

Source: https://www.krakend.io/docs/enterprise/overview/installing/

Installs the repo package, installs krakend-ee, and starts the service using dnf.

```bash
$rpm -Uvh https://download.krakend.io/rpm/krakend-ee-repo-2.1-0.x86_64.rpm
dnf install -y krakend-ee
systemctl start krakend-ee
```

--------------------------------

### Install KrakenD on Fedora (dnf)

Source: https://www.krakend.io/docs/overview/installing/

Installs the repo package, the KrakenD package, and starts the KrakenD service using dnf.

```bash
$rpm -Uvh https://repo.krakend.io/rpm/krakend-repo-0.2-0.x86_64.rpm
dnf install -y krakend
systemctl start krakend
```

--------------------------------

### Install KrakenD on CentOS, Oracle Linux, and Redhat (yum)

Source: https://www.krakend.io/docs/overview/installing/

Installs the repo package, the KrakenD package, and starts the KrakenD service using yum.

```bash
$rpm -Uvh https://repo.krakend.io/rpm/krakend-repo-0.2-0.x86_64.rpm
yum install -y krakend
systemctl start krakend
```

--------------------------------

### GraphQL query for POST and GET examples

Source: https://www.krakend.io/docs/backends/graphql/

The GraphQL query used in both POST and GET examples. It fetches a hero's name and optionally friends based on the withFriends variable.

```graphql
query Hero($episode: Episode, $withFriends: Boolean!) {
  hero(episode: $episode) {
    name
    friends @include(if: $withFriends) {
      name
    }
  }
}
```

--------------------------------

### Create and initialize the krakend-client-example Go project

Source: https://www.krakend.io/docs/enterprise/extending/http-client-plugins/

Commands to create a new directory, navigate into it, and initialize a Go module named krakend-client-example.

```bash
mkdir krakend-client-example
cd krakend-client-example
go mod init krakend-client-example
```

--------------------------------

### Create Go project krakend-server-example

Source: https://www.krakend.io/docs/enterprise/extending/http-server-plugins/

Commands to create a new Go project directory and initialize the module named krakend-server-example.

```bash
mkdir krakend-server-example
cd krakend-server-example
go mod init krakend-server-example
```

--------------------------------

### GET + mutation: KrakenD configuration

Source: https://www.krakend.io/docs/backends/graphql/

KrakenD configuration for the GET + mutation example, using a GET endpoint and variables with placeholders.

```json
{
    "endpoint": "/review/{stars}",
    "method": "GET",
    "backend": [
        {
            "timeout": "4100ms",
            "url_pattern": "/graphql?timeout=4s",
            "extra_config": {
                "backend/graphql": {
                    "type":  "mutation",
                    "query_path": "./graphql/mutations/review.graphql",
                    "variables": {
                        "review": {
                            "stars": "{stars}"
                        },
                        "ep": "JEDI",
                        "id_show": "1500"
                    },
                    "operationName": "CreateReviewForEpisode"
                }
            }
        }
    ]
}
```

--------------------------------

### Example base configuration file (base_krakend.json)

Source: https://www.krakend.io/docs/enterprise/developer/openapi/

Shows a sample base configuration file that can be used with the `-b` flag. It includes version, name, logging configuration, and an example endpoint.

```json
{
  "version": 4,
  "name": "Master configuration",
  "extra_config": {
    "telemetry/logging": {
      "level": "DEBUG",
      "prefix": "[KRAKEND]",
      "stdout": true,
      "syslog": false
    },
    "endpoints": [
      {
        "endpoint": "/health",
        "backend": [
          {
            "url_pattern": "/infra/health"
          }
        ]
      }
    ]
  }
}
```

--------------------------------

### Create initial directory structure

Source: https://www.krakend.io/docs/enterprise/configuration/flexible-config/

Create the initial directory structure reflecting the `paths` set in the configuration. This example creates `partials`, `settings`, and `templates` directories.

```bash
$mkdir -p {partials,settings,templates}
```

--------------------------------

### Install KrakenD Enterprise on CentOS/RockyLinux/Oracle/Redhat (yum)

Source: https://www.krakend.io/docs/enterprise/overview/installing/

Installs the repo package, installs krakend-ee, and starts the service using yum.

```bash
$rpm -Uvh https://download.krakend.io/rpm/krakend-ee-repo-2.1-0.x86_64.rpm
yum install -y krakend-ee
systemctl start krakend-ee
```

--------------------------------

### GET + mutation: cURL request to KrakenD

Source: https://www.krakend.io/docs/backends/graphql/

Example of a GET request to KrakenD with an empty body, as required for mutations.

```bash
$curl -d '' -G http://krakend/review/5
```

--------------------------------

### File structure for flexible configuration example

Source: https://www.krakend.io/docs/deploying/docker/

This shows the expected directory structure for the multi-stage Dockerfile example. It includes the config folder with partials, settings (prod and test), templates, the Dockerfile, and krakend.tmpl.

```text
.
├── config
│   ├── partials
│   ├── settings
│   │   ├── prod
│   │   │   └── env.json
│   │   └── test
│   │       └── env.json
│   └── templates
│       └── some.tmpl
├── Dockerfile
└── krakend.tmpl
```

--------------------------------

### indexOf function examples

Source: https://www.krakend.io/docs/enterprise/security-policies/advanced-policy-macros/

JavaScript examples demonstrating 'indexOf' with optional start position and error on out-of-range position.

```js
'hello mellow'.indexOf('')         // returns 0
'hello mellow'.indexOf('ello')     // returns 1
'hello mellow'.indexOf('jello')    // returns -1
'hello mellow'.indexOf('', 2)      // returns 2
'hello mellow'.indexOf('ello', 2)  // returns 7
'hello mellow'.indexOf('ello', 20) // error
```

--------------------------------

### Settings paths configuration example

Source: https://www.krakend.io/docs/enterprise/configuration/flexible-config/

Shows how to define multiple paths for settings directories and files. Directories are loaded recursively and in order, with contents merged at the root level of the settings tree.

```json
{
    "settings": {
        "paths": [
            "./settings/common",
            "./settings/production",
            "override.yaml"
        ]
    }
}
```

--------------------------------

### Example: Backend configuration with multiple hosts

Source: https://www.krakend.io/docs/enterprise/backends/

Shows how to configure an endpoint with multiple backend hosts for load balancing.

```json
{
    "endpoints": [
        {
            "endpoint": "/v1/products",
            "method": "GET",
            "backend": [
                {
                    "url_pattern": "/products",
                    "host": [
                        "https://products-01.myapi.com:8000",
                        "https://products-02.myapi.com:8000",
                        "https://products-03.myapi.com:8000"
                    ]
                }
            ]
        }
    ]
}
```

--------------------------------

### Redis-backed rate limit configuration example

Source: https://www.krakend.io/docs/enterprise/throttling/global-rate-limit/

Shows the required two namespaces: 'redis' for the connection pool and 'qos/ratelimit/service/redis' for rate limit settings. The example uses a shared Redis instance and a header-based strategy with a key of 'x-client-id'.

```json
{
  "$schema": "https://www.krakend.io/schema/v3.0/krakend.json",
  "version": 4,
  "extra_config": {
    "redis": {
      "connection_pools": [
        {
          "name": "shared_instance",
          "address": "redis:6379"
        }
      ]
    },
    "qos/ratelimit/service/redis": {
      "connection_pool": "shared_instance",
      "on_failure_allow": false,
      "max_rate": 10,
      "capacity": 10,
      "client_max_rate": 10,
      "client_capacity": 10,
      "every": "1m",
      "strategy": "header",
      "key": "x-client-id"
    }
  }
}
```

--------------------------------

### Start the environment (Vagrant commands)

Source: https://www.krakend.io/docs/benchmarks/api-gateway-benchmark/

Commands to start the Vagrant environment, SSH into the webserver, gateway, and consumer VMs, deploy the dummy API and KrakenD gateway, and run the benchmark tests (test00 and test01).

```bash
$cd deployment/vagrant
$ vagrant up

$ vagrant ssh webserver
[vagrant@webserver ~]$ cd /opt/benchmarks/webservers/dummy-api
[vagrant@webserver dummy-api]$ sudo ./deploy
[vagrant@webserver dummy-api]$ exit

$ vagrant ssh gateway
[vagrant@gateway ~]$ cd /opt/benchmarks/gateways/krakend
[vagrant@gateway krakend]$ sudo ./deploy
[vagrant@gateway krakend]$ exit

$ vagrant ssh consumer
[vagrant@consumer ~]$ cd /opt/benchmarks/consumers/boom
[vagrant@consumer boom]$ sudo ./deploy
[vagrant@consumer boom]$ /usr/local/bin/test00
[vagrant@consumer boom]$ /usr/local/bin/test01
```

--------------------------------

### GET /status - Get revoker status

Source: https://www.krakend.io/docs/enterprise/authentication/revoke-server/

Returns the status of the internal Revoker's bloom filter and the selected settings. The example shows the configuration and percentage_consumed.

```bash
$curl -iH'Authorization: bearer 639ee23f-f4c5-40c4-855c-912bf01fae87' http://localhost:8081/status
HTTP/1.1 200 OK
Content-Type: application/json; charset=utf-8
Date: Mon, 24 Oct 2022 11:47:46 GMT
Content-Length: 166

{"config":{"Seed":"","N":10000000,"P":1e-7,"HashName":"optimal","TTL":1500,"Workers":5,"PingInterval":30000000000,"CN":"c2d1f2a3-8fc2-4278-b1c1-c002557b6b45","MaxRetries":3},"percentage_consumed":0}
```

--------------------------------

### getDayOfYear function syntax and examples

Source: https://www.krakend.io/docs/enterprise/security-policies/built-in-functions/

Returns the day of the year. Starts with index 0. The syntax is <timestamp>.getDayOfYear() -> <int>. Examples show usage with a timestamp.

```plaintext
<timestamp>.getDayOfYear() -> <int>
```

```javascript
timestamp(now).getDayOfYear() // returns 0 on January 1st
timestamp(now).getDayOfYear() // returns 10 on January 11th
```

--------------------------------

### getDate function syntax and example

Source: https://www.krakend.io/docs/enterprise/security-policies/built-in-functions/

Returns the day of the month. Index starts at 1. The syntax is <timestamp>.getDate() -> <int>. Example shows usage with a timestamp.

```plaintext
<timestamp>.getDate() -> <int>
```

```javascript
// Given it's February 1st
timestamp(now).getDate() // returns 1
```

--------------------------------

### Load markdown intro file in OpenAPI configuration

Source: https://www.krakend.io/docs/enterprise/endpoints/openapi/

Use flexible configuration to include a markdown file in the OpenAPI introduction. The example loads partials/openapi/intro.md and assigns it to the description field using the include and toJson template functions.

```go-text-template
{
  "version": 4,
  "name": "Your KrakenD API",
  "extra_config": {
    "documentation/openapi": {
      "description": {{include "openapi/intro.md" | toJson }}
    }
  }
}
```

--------------------------------

### startsWith function syntax and examples

Source: https://www.krakend.io/docs/enterprise/security-policies/built-in-functions/

Checks if a substring is the start of a string. The syntax is <string>.startsWith(<string>) -> <bool>. Examples show usage with a path variable.

```plaintext
<string>.startsWith(<string>) -> <bool>
```

```javascript
// Given a path /testing
req_path.startsWith('/test') // returns true
req_path.startsWith('/toast') // returns false
```

--------------------------------

### Start KrakenD with krakend run

Source: https://www.krakend.io/docs/enterprise/overview/run/

Command to start the KrakenD server using a configuration file.

```bash
$krakend run -c krakend.json
```

--------------------------------

### getDayOfMonth function syntax and example

Source: https://www.krakend.io/docs/enterprise/security-policies/built-in-functions/

Returns the day of the month. The first month starts at index 0. The syntax is <timestamp>.getDayOfMonth() -> <int>. Example shows usage with a timestamp.

```plaintext
<timestamp>.getDayOfMonth() -> <int>
```

```javascript
// Given it's February 1st
timestamp(now).getDayOfMonth() // returns 0
```

--------------------------------

### Flexible configuration file structure

Source: https://www.krakend.io/docs/configuration/templates/

Shows the directory layout for the flexible configuration example, including the base template, partials, and settings directories.

```text
.
├── krakend.tmpl
├── partials
│   └── all_backends_extra_config.json
└── settings
    ├── endpoint.json
    └── service.json

```

--------------------------------

### getMonth function syntax and example

Source: https://www.krakend.io/docs/enterprise/security-policies/built-in-functions/

Returns the month from the date. Starts with index 0 on January and ends at 11. The syntax is <timestamp>.getMonth() -> <int>. Example shows usage with a timestamp.

```plaintext
<timestamp>.getMonth() -> <int>
```

```javascript
timestamp(now).getMonth() // returns 2 on March
```
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