on single node kubernetes cluster i can expose a service with 'expose' cmd, but doing it via create -f <svc.json-file> fails -

i setting single node k8s cluster testing, , we've run confusing problem services. i've distilled example down 1 of deploying word press service, can kubectl create -f wordpress-rc.json followed expose. when follow create of rep controller kubectl create -f fails. show json file content below.

rep controller:

{   "kind": "replicationcontroller",   "apiversion": "v1",   "metadata": {     "name": "wordpress",     "labels": {       "app": "wordpress"     }   },   "spec": {     "replicas": 1,     "selector": {       "app": "wordpress"     },     "template": {       "metadata": {         "labels": {           "app": "wordpress"         }       },       "spec": {         "containers": [           {             "name": "wordpress",             "image": "tutum/wordpress",             "ports": [               {                 "containerport": 80,                 "name": "http-server",                 "protocol": "tcp"               }             ],             "imagepullpolicy": "ifnotpresent"            }         ],         "restartpolicy": "always",         "dnspolicy": "clusterfirst"       }     }   } } 

service:

{   "kind": "service",   "apiversion": "v1",   "metadata": {     "name": "wordpress",     "labels": {       "name": "wordpress"     }   },   "spec": {         "type": "loadbalancer",     "ports": [       {         "name":"wordpress1",         "protocol":"tcp",         "port": 80,         "targetport": 80       }     ],     "selector": {       "name": "wordpress"     }   } } 

working command sequence

 alias kk kubectl  kk create -f /tmp/wp-rc.json  kubectl expose rc wordpress --type=loadbalancer 

failed command sequence

  alias kk kubectl   kk create -f /tmp/wp-rc.json   kk create -f /tmp/wp-service.json 

my question why wouldn't service definition work, while expose command ?

for completeness.. here how start single node k8s cluster. running on centos 7, b.t.w:

#   magic selinux context set command required. details, see: http://stackoverflow.com/questions/34777111/cannot-create-a-shared-volume-mount-via-emptydir-on-single-node-kubernetes-on # sudo chcon -rt svirt_sandbox_file_t /var/lib/kubelet   docker run --net=host -d gcr.io/google_containers/etcd:2.0.12 /usr/local/bin/etcd --addr=127.0.0.1:4001 --bind-addr=0.0.0.0:4001 --data-dir=/var/etcd/data   docker run \     --volume=/:/rootfs:ro \     --volume=/sys:/sys:ro \     --volume=/dev:/dev \     --volume=/var/lib/docker/:/var/lib/docker:ro \     --volume=/var/lib/kubelet/:/var/lib/kubelet:rw \     --volume=/var/run:/var/run:rw \     --net=host \     --pid=host \     --privileged=true \     -d \     gcr.io/google_containers/hyperkube:v1.0.1 \     /hyperkube kubelet --containerized --hostname-override="127.0.0.1" --address="0.0.0.0" --api-servers=http://localhost:8080 --config=/etc/kubernetes/manifests  docker run -d --net=host --privileged gcr.io/google_containers/hyperkube:v1.0.1 /hyperkube proxy --master=http://127.0.0.1:8080 --v=2  sleep 20   # give time launch 

the service json file used label selector name: wordpress, different replication controller's label selector app: wordpress. means service created json file targeting pods name: wordpress label, replication controller targeting pod app: wordpress label. why service created json file didn't work expected.

you may use kubectl svc wordpress -o yaml compare both created services.

also, according config best practice, it's recommended create service first, , replication controller:

create service before corresponding replication controllers scheduler can spread pods comprising service. can create replication controller without specifying replicas, create service, scale replication controller, may work better in example using progressive disclosure , may have benefits in real scenarios also, such ensuring 1 replica works before creating lots of them)