fix zk version

.travis.yml

@@ -21,6 +21,7 @@ env:
    - DISCOVERY_NODES=127.0.0.1:7171
    - HTTP_PERF=tcp://0.0.0.0:0
    - DOCKER_COMPOSE_VERSION=1.24.1
+   - ZK_VERSION=3.5.4-beta
 
 before_install:
   # docker-compose
@@ -30,7 +31,7 @@ before_install:
   - sudo mv docker-compose /usr/local/bin
   # zookeeper
   - wget "http://apache.cs.utah.edu/zookeeper/zookeeper-${ZK_VERSION}/zookeeper-3.5.4-beta.tar.gz"
-  - tar -xvf "zookeeper-3.5.4-beta.tar.gz"
+  - tar -xvf "zookeeper-${ZK_VERSION}.tar.gz"
 
 # Skip the install step. Don't `go get` dependencies. Only build with the code
 # in vendor/
@@ -46,7 +47,7 @@ before_script:
   - curl -sfL https://raw.githubusercontent.com/bilibili/discovery/master/cmd/discovery/discovery-example.toml -o $GOPATH/bin/discovery.toml
   - nohup bash -c "$GOPATH/bin/discovery -conf $GOPATH/bin/discovery.toml &"
   # zookeeper
-  - ./zookeeper-3.5.4-beta/bin/zkServer.sh start ./zk/conf/zoo_sample.cfg 1> /dev/null
+  - ./zookeeper-${ZK_VERSION}/bin/zkServer.sh start ./zk/conf/zoo_sample.cfg 1> /dev/null
 
 script:
   - go build ./...