Extract Load Balancer IP address using regex nodejs-CodePudding

I'm not a regex wizard :P and I think asking for some help does not hurt.

I was wondering to extract an IP address from a k8s service (traefik), in order to use the IP Address string in my code.

An array of strings will be available and I just need the LoadBalancer Ingress IP address: 10.0.0.115 -- the rest, we can ignore it.

Here's a small example what I'm trying to perform:

const log = [
  'Name:                     traefik',
  'Namespace:                kube-system',
  'Labels:                   app.kubernetes.io/instance=traefik',
  '                          app.kubernetes.io/managed-by=Helm',
  '                          app.kubernetes.io/name=traefik',
  '                          helm.sh/chart=traefik-10.9.100',
  'Annotations:              meta.helm.sh/release-name: traefik',
  '                          meta.helm.sh/release-namespace: kube-system',
  'Selector:                 app.kubernetes.io/instance=traefik,app.kubernetes.io/name=traefik',
  'Type:                     LoadBalancer',
  'IP Family Policy:         SingleStack',
  'IP Families:              IPv4',
  'IP:                       10.43.251.46',
  'IPs:                      10.43.251.46',
  'LoadBalancer Ingress:     10.0.0.115',
  'Port:                     web  80/TCP',
  'TargetPort:               web/TCP',
  'NodePort:                 web  31729/TCP',
  'Endpoints:                10.42.0.20:8000',
  'Port:                     websecure  443/TCP',
  'TargetPort:               websecure/TCP',
  'NodePort:                 websecure  31708/TCP',
  'Endpoints:                10.42.0.20:8443',
  'Session Affinity:         None',
  'External Traffic Policy:  Cluster',
  'Events:                   <none>',
  ''
];
const regex = new RegExp(/(Ingress:)(\s.*\d)/g);
const result = regex.exec(log);

console.log(result[2]);

The regex actually matches, but it brings everything after the expected string:

"     10.0.0.115,Port:                     web  80/TCP,TargetPort:               web/TCP,NodePort:                 web  31729/TCP,Endpoints:                10.42.0.20:8000,Port:                     websecure  443/TCP,TargetPort:               websecure/TCP,NodePort:                 websecure  31708/TCP,Endpoints:                10.42.0.20:8443"

Expected output: 10.0.0.115

Update: Here's the regex test https://regex101.com/r/fKtMH7/1

I tried another methods to accomplish the same result, but regex seems to be the reliable one.

Any help will be very appreciated.

Thanks

CodePudding user response：

Well, since you want to do it with regex, one solution would be to find to group the Ingress: and then the IP address.

const log = [
  'Name:                     traefik',
  'Namespace:                kube-system',
  'Labels:                   app.kubernetes.io/instance=traefik',
  '                          app.kubernetes.io/managed-by=Helm',
  '                          app.kubernetes.io/name=traefik',
  '                          helm.sh/chart=traefik-10.9.100',
  'Annotations:              meta.helm.sh/release-name: traefik',
  '                          meta.helm.sh/release-namespace: kube-system',
  'Selector:                 app.kubernetes.io/instance=traefik,app.kubernetes.io/name=traefik',
  'Type:                     LoadBalancer',
  'IP Family Policy:         SingleStack',
  'IP Families:              IPv4',
  'IP:                       10.43.251.46',
  'IPs:                      10.43.251.46',
  'LoadBalancer Ingress:     10.0.0.115',
  'Port:                     web  80/TCP',
  'TargetPort:               web/TCP',
  'NodePort:                 web  31729/TCP',
  'Endpoints:                10.42.0.20:8000',
  'Port:                     websecure  443/TCP',
  'TargetPort:               websecure/TCP',
  'NodePort:                 websecure  31708/TCP',
  'Endpoints:                10.42.0.20:8443',
  'Session Affinity:         None',
  'External Traffic Policy:  Cluster',
  'Events:                   <none>',
  ''
];


serviceRegex = /(LoadBalancer Ingress:)\s /
ipRegex = /((?:[0-9]{1,3}\.){3}[0-9]{1,3})/

const regex = new RegExp(`${serviceRegex.source}${ipRegex.source}`);
const result = regex.exec(log);

console.log(result[2]);

Of course you can write a better regex for the IP address, this is just quick example

CodePudding user response：

const result = JSON.parse(log.join(','));
console.log(result['LoadBalancer Ingress']);

I haven't tested this; however, this is a solid direction to take.