ci: Optimize Travis waiting for ES

.travis.yml

@@ -18,13 +18,15 @@ addons:
 services:
 - docker
 before_install:
+- if [[ "$TRAVIS_OS_NAME" == "linux" && ! $(which nc)     ]] ; then sudo apt-get install -y netcat ; fi
 - sudo sysctl -w vm.max_map_count=262144
 # - docker run -d --rm -p 9200:9200  -e "http.host=0.0.0.0" -e "transport.host=127.0.0.1" -e "bootstrap.memory_lock=true" -e "ES_JAVA_OPTS=-Xms1g -Xmx1g" docker.elastic.co/elasticsearch/elasticsearch:6.3.2 elasticsearch -Enetwork.host=_local_,_site_ -Enetwork.publish_host=_local_
 - docker-compose pull
 - docker-compose up -d
-- sleep 15
 - go get -u github.com/fortytw2/leaktest
 - go get . ./config ./aws ./trace/...
+- while ! nc -z localhost 9200; do sleep 1; done
+- while ! nc -z localhost 9210; do sleep 1; done
 install: true # ignore the go get -t -v ./...
 script:
 - go test -race -v . ./config ./aws ./trace/...