com.microkubes.tools.gateway.KongServiceRegistry Maven / Gradle / Ivy

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Java integration library for Microkubes platform.
There is a newer version: 0.2.0.RELEASE
package com.microkubes.tools.gateway;

import com.mashape.unirest.http.HttpResponse;
import com.mashape.unirest.http.JsonNode;
import com.mashape.unirest.http.Unirest;
import com.mashape.unirest.http.exceptions.UnirestException;
import org.json.JSONObject;

import java.util.Map;

/**
 * {@link ServiceRegistry} for Kong Gateway.
 * Registers microservices as APIs on the Kong API Gateway.
 */
public class KongServiceRegistry implements ServiceRegistry {
    private String kongAdminUrl;

    /**
     * Builds new empty {@link KongServiceRegistry}.
     */
    public KongServiceRegistry() {
    }

    /**
     * Builds new {@link KongServiceRegistry} with the given URL to the Admin port on the Kong Gateway.
     *
     * @param kongAdminUrl the URL to the admin port on the Kong Gateway.
     */
    public KongServiceRegistry(String kongAdminUrl) {
        this.kongAdminUrl = kongAdminUrl;
    }

    /**
     * Registers the service as an API on Kong API Gateway.
     * A preliminary check is performed for the existence of the API. If it exists and it has already been registered,
     * then the API definition will be updated. Otherwise, new API is added to the list of APIs on Kong Gateway.
     *
     * @param service the definition of the service contained in {@link ServiceInfo}
     */
    @Override
    public void register(ServiceInfo service) {
        try {
            service.validate();
            addOrUpdateApi(service.getName(), toKongAPIBody(service));
        } catch (ValidationException e) {
            throw new ServiceRegistryException(e);
        }
    }

    private JSONObject toKongAPIBody(ServiceInfo service) throws ValidationException {
        JSONObject obj = new JSONObject();

        obj.put("name", service.getName());
        obj.put("upstream_url", getUpstreamUrl(service));
        obj.put("uris", String.join(",", service.getPaths()));

        for (Map.Entry entry : service.getProperties().entrySet()) {
            obj.put(entry.getKey(), entry.getValue());
        }

        return obj;
    }

    private String getUpstreamUrl(ServiceInfo service) throws ValidationException {
        if (service.getHost() == null || service.getPort() <= 0 || service.getPort() > 65535) {
            throw new ValidationException("Service host or port missing");
        }
        return String.format("http://%s:%s", service.getHost(), service.getPort());
    }

    private boolean apiAlreadyExists(String apiName) {
        try {
            HttpResponse response = Unirest.get(getKongUrl("/apis/" + apiName)).asString();
            if (response.getStatus() == 200) {
                return true;
            }
            if (response.getStatus() == 404) {
                return false;
            }
            throw new ServiceRegistryException(response.getBody());
        } catch (UnirestException e) {
            throw new ServiceRegistryException(e);
        }
    }

    private JsonNode addApi(JSONObject apiDef) {
        try {
            HttpResponse response = Unirest.post(getKongUrl("/apis/"))
                    .header("Content-Type", "application/json")
                    .body(apiDef.toString())
                    .asJson();
            if (response.getStatus() != 201) {
                throw new ServiceRegistryException(response.getBody().toString());
            }
            return response.getBody();
        } catch (UnirestException e) {
            throw new ServiceRegistryException(e);
        }
    }

    private JsonNode updateApi(String apiName, JSONObject apiDef) {
        try {
            HttpResponse response = Unirest.patch(getKongUrl("/apis/" + apiName))
                    .header("Content-Type", "application/json")
                    .body(apiDef.toString())
                    .asJson();
            if (response.getStatus() != 200) {
                throw new ServiceRegistryException(response.getBody().toString());
            }
            return response.getBody();
        } catch (UnirestException e) {
            throw new ServiceRegistryException(e);
        }
    }

    /**
     * Implements the logic for adding or updating an exiting API on Kong API Gateway.
     *
     * @param apiName the name of the API. This is extracted from the {@link ServiceInfo#getName()}.
     * @param apiDef  the API definition as JSON ojbect to be send to Kong.
     * @return the response as JSON received from Kong.
     */
    protected JsonNode addOrUpdateApi(String apiName, JSONObject apiDef) {
        if (apiAlreadyExists(apiName)) {
            return updateApi(apiName, apiDef);
        }
        return addApi(apiDef);
    }

    /**
     * Gets an URL to a path on the admin endpoint on Kong.
     * Basically a helper method for appendig and constructing URLs to specific admin endpoints on Kong.
     *
     * @param path the path to the admin endpoint for which the whole URL is constructed.
     * @return the constructed URL.
     */
    protected String getKongUrl(String path) {
        return kongAdminUrl + path;
    }

    public String getKongAdminUrl() {
        return kongAdminUrl;
    }

    public void setKongAdminUrl(String kongAdminUrl) {
        this.kongAdminUrl = kongAdminUrl;
    }
}