作者：nanxiao

本文使用docker搭建Spark环境，使用的image文件是sequenceiq提供的1.3.0版本。

首先pull Spark image文件：

docker pull sequenceiq/spark:1.3.0

pull成功后，运行Spark：

docker run -i -t -h sandbox sequenceiq/spark:1.3.0 bash

测试Spark是否工作正常：

bash-4.1# spark-shell --master yarn-client --driver-memory 1g --executor-memory 1g --executor-cores 1
......
scala> sc.parallelize(1 to 1000).count()
......
res0: Long = 1000

输出1000，OK！

（1）启动spark-shell，输出log很多，解决方法如下：
a）把/usr/local/spark/conf文件夹下的log4j.properties.template文件复制生成一份log4j.properties文件：

bash-4.1# cd /usr/local/spark/conf
bash-4.1# cp log4j.properties.template log4j.properties

b）把log4j.properties文件里的“log4j.rootCategory=INFO, console”改成“log4j.rootCategory=WARN, console”即可。

（2）启动spark-shell会有以下warning：

15/05/25 04:49:28 WARN NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable

提示找不到hadoop的库文件，解决办法如下：

export LD_LIBRARY_PATH=/usr/local/hadoop/lib/native/:$LD_LIBRARY_PATH

请参考stackoverflow的相关讨论：
a）Hadoop “Unable to load native-hadoop library for your platform” error on CentOS；
b）Hadoop “Unable to load native-hadoop library for your platform” error on docker-spark?。

（3）在Quick Start中提到如下例子：

scala> val textFile = sc.textFile("README.md")
......
scala> textFile.count() // Number of items in this RDD

执行会有错误：

scala> textFile.count()
org.apache.hadoop.mapred.InvalidInputException: Input path does not exist: hdfs://sandbox:9000/user/root/README.md
        at org.apache.hadoop.mapred.FileInputFormat.singleThreadedListStatus(FileInputFormat.java:285)
        at org.apache.hadoop.mapred.FileInputFormat.listStatus(FileInputFormat.java:228)
        at org.apache.hadoop.mapred.FileInputFormat.getSplits(FileInputFormat.java:304)
        at org.apache.spark.rdd.HadoopRDD.getPartitions(HadoopRDD.scala:203)
        at org.apache.spark.rdd.RDD$$anonfun$partitions$2.apply(RDD.scala:219)
        at org.apache.spark.rdd.RDD$$anonfun$partitions$2.apply(RDD.scala:217)
        at scala.Option.getOrElse(Option.scala:120)
        at org.apache.spark.rdd.RDD.partitions(RDD.scala:217)

可以看到程序尝试从hdfs中寻找文件，所以报错。

解决方法有两种：
a） 指定本地文件系统：

scala> val textFile = sc.textFile("file:///usr/local/spark/README.md")
textFile: org.apache.spark.rdd.RDD[String] = file:///usr/local/spark/README.md MapPartitionsRDD[3] at textFile at <console>:21

scala> textFile.count()
res1: Long = 98

b）上传文件到hdfs上：

bash-4.1# hadoop fs -put /usr/local/spark/README.md README.md

接着运行spark-shell:

bash-4.1# spark-shell --master yarn-client --driver-memory 1g --executor-memory 1g --executor-cores 1
Spark assembly has been built with Hive, including Datanucleus jars on classpath
Welcome to
      ____              __
     / __/__  ___ _____/ /__
    _\ \/ _ \/ _ `/ __/  '_/
   /___/ .__/\_,_/_/ /_/\_\   version 1.3.0
      /_/

Using Scala version 2.10.4 (Java HotSpot(TM) 64-Bit Server VM, Java 1.7.0_51)
Type in expressions to have them evaluated.
Type :help for more information.
15/05/25 05:22:15 WARN Client: SPARK_JAR detected in the system environment. This variable has been deprecated in favor of the spark.yarn.jar configuration variable.
15/05/25 05:22:15 WARN Client: SPARK_JAR detected in the system environment. This variable has been deprecated in favor of the spark.yarn.jar configuration variable.
Spark context available as sc.
SQL context available as sqlContext.

scala> val textFile = sc.textFile("README.md")
textFile: org.apache.spark.rdd.RDD[String] = README.md MapPartitionsRDD[1] at textFile at <console>:21

scala> textFile.count()
res0: Long = 98

参考邮件：
Spark Quick Start – call to open README.md needs explicit fs prefix。

P.S.在主机（非docker环境）下载spark（https://spark.apache.org/downloads.html）运行时，会有以下warning：

log4j:WARN No appenders could be found for logger (org.apache.hadoop.metrics2.lib.MutableMetricsFactory).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.

解决办法是把/path/to/spark/conf文件夹下的log4j.properties.template文件复制生成一份log4j.properties文件即可。

参考stackoverflow的讨论：
log4j:WARN No appenders could be found for logger (running jar file, not web app)。