this.cluster = new ecs.Cluster(this, "MyCluster", {
            clusterName: cdk.PhysicalName.GENERATE_IF_NEEDED,
            vpc: this.vpc,
            defaultCloudMapNamespace: {
                name: "passmate.private",
                useForServiceConnect: true,
                type: cloudmap.NamespaceType.DNS_PRIVATE,
                vpc: this.vpc
            },
        });

keycloakContainer.addPortMappings({
            name: "keycloak_http",
            containerPort: this.webPort});
...
this.service = new ecs.FargateService(this, 'Service', {
            cluster: props.cluster,
           ...
            serviceConnectConfiguration: {
                services: [{
                    portMappingName: "keycloak_http",
                    dnsName: "keycloak",
                    port: _keycloakPublicPort,
                }]
            }
        });

Domain name       | Description | Instance discovery                           | Namespace ID
passmate.private | -                   | API calls and DNS queries in VPCs | ns-jfyvbvl33oocytvv
passmate.private | -                   | API calls                                             | ns-pge2n6bdb7z4k72x