[mesh] sidecar egress supports routing by request domain

[benja-wu]

EaseMesh sidecar egress enhancement:

• Add egress HTTPServer rules for domain routing in DNS-based RPC scenario
• Domain matching by using exactly matching and regular expression.

[megaeasex]

[TASK:easegress-pr-test SUCCESS]megaease/easegress Pull Request 299 Deploy Test Success

[codecov-commenter]

Codecov Report

Merging #299 (b6ec6a5) into main (12f3379) will increase coverage by 0.22%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #299      +/-   ##
==========================================
+ Coverage   80.23%   80.45%   +0.22%     
==========================================
  Files          53       53              
  Lines        5888     5888              
==========================================
+ Hits         4724     4737      +13     
+ Misses        905      895      -10     
+ Partials      259      256       -3     

Impacted Files	Coverage Δ
pkg/object/mqttproxy/topic.go	100.00% <0.00%> (+0.46%)	⬆️
pkg/cluster/cluster.go	50.88% <0.00%> (+2.11%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update bc90a63...b6ec6a5. Read the comment docs.

[localvar]

propose to not using Sprintf to avoid double escaping which make the regexp hard to read.
and, is the regexp correct?

Suggested change

	return fmt.Sprintf("^(|(\\w+\\.)+)%s\\.(\\w+)\\.svc\\..+", serviceName)
	return `^(|(\w+\.)+)` + serviceName + `\.(\w+)\.svc\..+`

[benja-wu]

I use this program to test the regexp locally, it works.

package main

import (
	"fmt"
	"regexp"
)

func main() {
	hostRE, err := regexp.Compile(`^(|(\w+\.)+)vet-services\.(\w+)\.svc\..+`)
	if err != nil {
		fmt.Printf("gen regexp failed: %v", err)
		return
	}

	pass := func() bool {
		host := "_tcp._zip.vet-services.easemesh.svc.cluster.local"
		if (hostRE.MatchString(host)) != true {
			fmt.Printf("failed at %s\n", host)
			return false
		}

		host = "_zip.vet-services.easemesh.svc.cluster.local"
		if hostRE.Match([]byte(host)) != true {
			fmt.Printf("failed at %s\n", host)
			return false
		}

		host = "_udp.vet-services.easemesh.svc.local"
		if hostRE.Match([]byte(host)) != true {
			fmt.Printf("failed at %s\n", host)
			return false
		}

		host = "vet-services.easemesh.svc.local"
		if hostRE.MatchString(host) != true {
			fmt.Printf("failed at %s\n", host)
			return false
		}

		host = "_tcp._zip.vetservices.easemesh.svc.cluster.local"
		if hostRE.MatchString(host) != false {
			fmt.Printf("failed at %s\n", host)
			return false
		}

		host = "_tcp._zip.vet-services.easemesh.cluster.local"
		if hostRE.MatchString(host) != false {
			fmt.Printf("failed at %s\n", host)
			return false
		}

		host = "_tcp._zip.vet-services.easemesh.svk.cluster.local"
		if hostRE.MatchString(host) != false {
			fmt.Printf("failed at %s\n", host)
			return false
		}

		host = "_tcp._zip.vet-services.easemesh.svc"
		if hostRE.MatchString(host) != false {
			fmt.Printf("failed at %s\n", host)
			return false
		}
		return true
	}()

	if pass {
		fmt.Println("ok")
		return
	}
	fmt.Println("failed")
}

[megaeasex]

[TASK:easegress-pr-test SUCCESS]megaease/easegress Pull Request 299 Deploy Test Success

[megaeasex]

[TASK:easegress-pr-test SUCCESS]megaease/easegress Pull Request 299 Deploy Test Success