ballerina 学习二十二 弹性服务
主要包含断路器模式，负载均衡模式，故障转移，重试
Circuit Breaker
- 参考代码
import ballerina/http;
import ballerina/log;
import ballerina/runtime;
endpoint http:Client backendClientEP {
url: "http://localhost:8080",
circuitBreaker: {
rollingWindow: {
timeWindowMillis: 10000,
bucketSizeMillis: 2000
},
failureThreshold: 0.2,
resetTimeMillis: 10000,
statusCodes: [400, 404, 500]
}, timeoutMillis: 2000
};
@http:ServiceConfig {
basePath: "/cb"
}
service<http:Service> circuitbreaker bind { port: 9090 } {
@http:ResourceConfig {
methods: ["GET"],
path: "/"
}
invokeEndpoint(endpoint caller, http:Request request) {
var backendRes = backendClientEP->forward("/hello", request);
match backendRes { http:Response res => {
caller->respond(res) but {
error e => log:printError("Error sending response", err = e)
};
}
error responseError => {
http:Response response = new;
response.statusCode = 500;
response.setPayload(responseError.message);
caller->respond(response) but {
error e => log:printError("Error sending response", err = e)
};
}
}
}
}
public int counter = 1;
@http:ServiceConfig { basePath: "/hello" }
service<http:Service> helloWorld bind { port: 8080 } {
@http:ResourceConfig {
methods: ["GET"],
path: "/"
}
sayHello(endpoint caller, http:Request req) {
if (counter % 5 == 0) {
runtime:sleep(5000); counter = counter + 1;
http:Response res = new;
res.setPayload("Hello World!!!");
caller->respond(res) but {
error e => log:printError(
"Error sending response from mock service", err = e)
};
} else if (counter % 5 == 3) {
counter = counter + 1;
http:Response res = new;
res.statusCode = 500;
res.setPayload(
"Internal error occurred while processing the request.");
caller->respond(res) but {
error e => log:printError(
"Error sending response from mock service", err = e)
};
} else {
counter = counter + 1;
http:Response res = new;
res.setPayload("Hello World!!!");
caller->respond(res) but {
error e => log:printError(
"Error sending response from mock service", err = e)
};
}
}
}
Load Balancing(http)
- 参考代码
import ballerina/http;
import ballerina/log;
endpoint http:Listener backendEP {
port: 8080
};
endpoint http:LoadBalanceClient lbBackendEP {
targets: [
{ url: "http://localhost:8080/mock1" },
{ url: "http://localhost:8080/mock2" },
{ url: "http://localhost:8080/mock3" }
],
algorithm: http:ROUND_ROBIN,
timeoutMillis: 5000
};
@http:ServiceConfig {
basePath: "/lb"
}
service<http:Service> loadBalancerDemoService bind { port: 9090 } {
@http:ResourceConfig {
path: "/"
}
invokeEndpoint(endpoint caller, http:Request req) {
http:Request outRequest = new;
json requestPayload = { "name": "Ballerina" };
outRequest.setPayload(requestPayload);
var response = lbBackendEP->post("/", request = outRequest);
match response {
http:Response resp => {
caller->respond(resp) but {
error e => log:printError("Error sending response", err = e)
};
}
error responseError => {
http:Response outResponse = new;
outResponse.statusCode = 500;
outResponse.setPayload(responseError.message);
caller->respond(outResponse) but {
error e => log:printError("Error sending response", err = e)
};
}
}
}
}
@http:ServiceConfig { basePath: "/mock1" }
service mock1 bind backendEP {
@http:ResourceConfig {
path: "/"
}
mock1Resource(endpoint caller, http:Request req) {
http:Response outResponse = new;
outResponse.setPayload("Mock1 Resource is invoked.");
caller->respond(outResponse) but {
error e => log:printError(
"Error sending response from mock service", err = e)
};
}
}@http:ServiceConfig { basePath: "/mock2" }
service mock2 bind backendEP {
@http:ResourceConfig {
path: "/"
}
mock2Resource(endpoint caller, http:Request req) {
http:Response outResponse = new;
outResponse.setPayload("Mock2 Resource is Invoked.");
caller->respond(outResponse) but {
error e => log:printError(
"Error sending response from mock service", err = e)
};
}
}@http:ServiceConfig { basePath: "/mock3" }
service mock3 bind backendEP {
@http:ResourceConfig {
path: "/"
}
mock3Resource(endpoint caller, http:Request req) {
http:Response outResponse = new;
outResponse.setPayload("Mock3 Resource is Invoked.");
caller->respond(outResponse) but {
error e => log:printError(
"Error sending response from mock service", err = e)
};
}
}
Failover
- 参考代码
import ballerina/http;
import ballerina/log;
import ballerina/runtime;
endpoint http:Listener backendEP {
port: 8080
};
endpoint http:FailoverClient foBackendEP {
timeoutMillis: 5000,
failoverCodes: [501, 502, 503],
intervalMillis: 5000,
targets: [
{ url: "http://localhost:3000/mock1" },
{ url: "http://localhost:8080/echo" },
{ url: "http://localhost:8080/mock" }
]};
@http:ServiceConfig {
basePath: "/fo"
}
service<http:Service> failoverDemoService bind { port: 9090 } {
@http:ResourceConfig {
methods: ["GET", "POST"],
path: "/"
}
invokeEndpoint(endpoint caller, http:Request request) {
var backendRes = foBackendEP->get("/", request = request);
match backendRes {
http:Response response => {
caller->respond(response) but {
error e => log:printError("Error sending response", err = e)
};
}
error responseError => {
http:Response response = new;
response.statusCode = 500;
response.setPayload(responseError.message);
caller->respond(response) but {
error e => log:printError("Error sending response", err = e)
};
}
}
}
}
@http:ServiceConfig {
basePath: "/echo"
}
service echo bind backendEP {
@http:ResourceConfig {
methods: ["POST", "PUT", "GET"],
path: "/"
}
echoResource(endpoint caller, http:Request req) {
http:Response outResponse = new;
runtime:sleep(30000); outResponse.setPayload("echo Resource is invoked");
caller->respond(outResponse) but {
error e => log:printError(
"Error sending response from mock service", err = e)
};
}
}
@http:ServiceConfig {
basePath: "/mock"
}
service mock bind backendEP {
@http:ResourceConfig {
methods: ["POST", "PUT", "GET"],
path: "/"
}
mockResource(endpoint caller, http:Request req) {
http:Response outResponse = new;
outResponse.setPayload("Mock Resource is Invoked.");
caller->respond(outResponse) but {
error e => log:printError(
"Error sending response from mock service", err = e)
};
}
}
Retry
- 参考代码
import ballerina/http;
import ballerina/log;
import ballerina/runtime;
endpoint http:Client backendClientEP {
url: "http://localhost:8080",
retryConfig: {
interval: 3000,
count: 3,
backOffFactor: 0.5
}, timeoutMillis: 2000
};@http:ServiceConfig {
basePath: "/retry"
}
service<http:Service> retryDemoService bind { port: 9090 } {
@http:ResourceConfig {
methods: ["GET"],
path: "/"
}
invokeEndpoint(endpoint caller, http:Request request) {
var backendResponse = backendClientEP->get("/hello", request = request);
match backendResponse { http:Response response => {
caller->respond(response) but {
error e => log:printError("Error sending response", err = e)
}; }
error responseError => {
http:Response errorResponse = new;
errorResponse.statusCode = 500;
errorResponse.setPayload(responseError.message); caller->respond(errorResponse) but {
error e => log:printError("Error sending response", err = e)
};
}
}
}
}public int counter = 0;@http:ServiceConfig { basePath: "/hello" }
service<http:Service> mockHelloService bind { port: 8080 } {
@http:ResourceConfig {
methods: ["GET"],
path: "/"
}
sayHello(endpoint caller, http:Request req) {
counter = counter + 1;
if (counter % 4 != 0) {
log:printInfo(
"Request received from the client to delayed service.");
runtime:sleep(5000); http:Response res = new;
res.setPayload("Hello World!!!");
caller->respond(res) but {
error e => log:printError(
"Error sending response from mock service", err = e)
};
} else {
log:printInfo(
"Request received from the client to healthy service.");
http:Response res = new;
res.setPayload("Hello World!!!");
caller->respond(res) but {
error e => log:printError(
"Error sending response from mock service", err = e) };
}
}
}
参考资料
https://ballerina.io/learn/by-example/http-failover.html
https://ballerina.io/learn/by-example/http-circuit-breaker.html
https://ballerina.io/learn/by-example/http-load-balancer.html
https://ballerina.io/learn/by-example/http-retry.html
