Revert "Revert "cluster: Use python3 everywhere""

This reverts commit 7038338e0f.

cluster/gce/gci/configure-helper.sh

@@ -1781,7 +1781,7 @@ function start-kube-proxy {
 # $5: pod name, which should be either etcd or etcd-events
 function prepare-etcd-manifest {
   local host_name=${ETCD_HOSTNAME:-$(hostname -s)}
-  local -r host_ip=$(${PYTHON} -c "import socket;print(socket.gethostbyname(\"${host_name}\"))")
+  local -r host_ip=$(python3 -c "import socket;print(socket.gethostbyname(\"${host_name}\"))")
   local etcd_cluster=""
   local cluster_state="new"
   local etcd_protocol="http"
@@ -3288,24 +3288,6 @@ function main() {
   CONTAINERIZED_MOUNTER_HOME="${KUBE_HOME}/containerized_mounter"
   PV_RECYCLER_OVERRIDE_TEMPLATE="${KUBE_HOME}/kube-manifests/kubernetes/pv-recycler-template.yaml"
 
-  log-start 'SetPythonVersion'
-  if [[ "$(python -V 2>&1)" =~ "Python 2" ]]; then
-    # found python2, just use that
-    PYTHON="python"
-  elif [[ -f "/usr/bin/python2.7" ]]; then
-    # System python not defaulted to python 2 but using 2.7 during migration
-    PYTHON="/usr/bin/python2.7"
-  else
-    # No python2 either by default, let's see if we can find python3
-    PYTHON="python3"
-    if ! command -v ${PYTHON} >/dev/null 2>&1; then
-      echo "ERROR Python not found. Aborting."
-      exit 2
-    fi
-  fi
-  echo "Version :  $(${PYTHON} -V 2>&1)"
-  log-end 'SetPythonVersion'
-
   log-start 'SourceKubeEnv'
   if [[ ! -e "${KUBE_HOME}/kube-env" ]]; then
     echo "The ${KUBE_HOME}/kube-env file does not exist!! Terminate cluster initialization."

cluster/gce/gci/configure.sh

@@ -87,13 +87,9 @@ function download-kube-env {
       -o "${tmp_kube_env}" \
       http://metadata.google.internal/computeMetadata/v1/instance/attributes/kube-env
     # Convert the yaml format file into a shell-style file.
-    eval "$(${PYTHON} -c '''
+    eval "$(python3 -c '''
 import pipes,sys,yaml
-# check version of python and call methods appropriate for that version
+items = yaml.load(sys.stdin, Loader=yaml.BaseLoader).items()
-if sys.version_info[0] < 3:
-    items = yaml.load(sys.stdin).iteritems()
-else:
-    items = yaml.load(sys.stdin, Loader=yaml.BaseLoader).items()
 for k, v in items:
     print("readonly {var}={value}".format(var=k, value=pipes.quote(str(v))))
 ''' < "${tmp_kube_env}" > "${KUBE_HOME}/kube-env")"
@@ -131,13 +127,9 @@ function download-kube-master-certs {
       -o "${tmp_kube_master_certs}" \
       http://metadata.google.internal/computeMetadata/v1/instance/attributes/kube-master-certs
     # Convert the yaml format file into a shell-style file.
-    eval "$(${PYTHON} -c '''
+    eval "$(python3 -c '''
 import pipes,sys,yaml
-# check version of python and call methods appropriate for that version
+items = yaml.load(sys.stdin, Loader=yaml.BaseLoader).items()
-if sys.version_info[0] < 3:
-    items = yaml.load(sys.stdin).iteritems()
-else:
-    items = yaml.load(sys.stdin, Loader=yaml.BaseLoader).items()
 for k, v in items:
     print("readonly {var}={value}".format(var=k, value=pipes.quote(str(v))))
 ''' < "${tmp_kube_master_certs}" > "${KUBE_HOME}/kube-master-certs")"
@@ -160,7 +152,7 @@ function validate-hash {
 # Get default service account credentials of the VM.
 GCE_METADATA_INTERNAL="http://metadata.google.internal/computeMetadata/v1/instance"
 function get-credentials {
-  curl --fail --retry 5 --retry-delay 3 --retry-connrefused --silent --show-error "${GCE_METADATA_INTERNAL}/service-accounts/default/token" -H "Metadata-Flavor: Google" -s | ${PYTHON} -c \
+  curl --fail --retry 5 --retry-delay 3 --retry-connrefused --silent --show-error "${GCE_METADATA_INTERNAL}/service-accounts/default/token" -H "Metadata-Flavor: Google" -s | python3 -c \
     'import sys; import json; print(json.loads(sys.stdin.read())["access_token"])'
 }
 
@@ -861,25 +853,6 @@ log-wrap 'SetBrokenMotd' set-broken-motd
 
 KUBE_HOME="/home/kubernetes"
 KUBE_BIN="${KUBE_HOME}/bin"
-PYTHON="python"
-
-log-start 'SetPythonVersion'
-if [[ "$(python -V 2>&1)" =~ "Python 2" ]]; then
-  # found python2, just use that
-  PYTHON="python"
-elif [[ -f "/usr/bin/python2.7" ]]; then
-  # System python not defaulted to python 2 but using 2.7 during migration
-  PYTHON="/usr/bin/python2.7"
-else
-  # No python2 either by default, let's see if we can find python3
-  PYTHON="python3"
-  if ! command -v ${PYTHON} >/dev/null 2>&1; then
-    echo "ERROR Python not found. Aborting."
-    exit 2
-  fi
-fi
-echo "Version :  $(${PYTHON} -V 2>&1)"
-log-end 'SetPythonVersion'
 
 # download and source kube-env
 log-wrap 'DownloadKubeEnv' retry-forever 30 download-kube-env