HDFS for Go
This is a native golang client for hdfs. It connects directly to the namenode using the protocol buffers API.
It tries to be idiomatic by aping the stdlib
os package, where possible, and
implements the interfaces from it, including
Here's what it looks like in action:
client, _ := hdfs.New("namenode:8020") file, _ := client.Open("/mobydick.txt") buf := make(byte, 59) file.ReadAt(buf, 48847) fmt.Println(string(buf)) // => Abominable are the tumblers into which he pours his poison.
For complete documentation, check out the Godoc.
Along with the library, this repo contains a commandline client for HDFS. Like the library, its primary aim is to be idiomatic, by enabling your favorite unix verbs:
$ hdfs --help Usage: hdfs COMMAND The flags available are a subset of the POSIX ones, but should behave similarly. Valid commands: ls [-lah] [FILE]... rm [-rf] FILE... mv [-fT] SOURCE... DEST mkdir [-p] FILE... touch [-amc] FILE... chmod [-R] OCTAL-MODE FILE... chown [-R] OWNER[:GROUP] FILE... cat SOURCE... head [-n LINES | -c BYTES] SOURCE... tail [-n LINES | -c BYTES] SOURCE... du [-sh] FILE... checksum FILE... get SOURCE [DEST] getmerge SOURCE DEST put SOURCE DEST
Since it doesn't have to wait for the JVM to start up, it's also a lot faster
$ time hadoop fs -ls / > /dev/null real 0m2.218s user 0m2.500s sys 0m0.376s $ time hdfs ls / > /dev/null real 0m0.015s user 0m0.004s sys 0m0.004s
Best of all, it comes with bash tab completion for paths!
Installing the commandline client
Grab a tarball from the releases page and unzip it wherever you like.
To configure the client, make sure one or both of these environment variables
point to your Hadoop configuration (
systems with Hadoop installed, they should already be set.
$ export HADOOP_HOME="/etc/hadoop" $ export HADOOP_CONF_DIR="/etc/hadoop/conf"
To install tab completion globally on linux, copy or link the
file which comes with the tarball into the right place:
$ ln -sT bash_completion /etc/bash_completion.d/gohdfs
By default on non-kerberized clusters, the HDFS user is set to the currently-logged-in user. You can override this with another environment variable:
$ export HADOOP_USER_NAME=username
Using the commandline client with Kerberos authentication
hadoop fs, the commandline client expects a
ccache file in the default
/tmp/krb5cc_<uid>. That means it should 'just work' to use
$ kinit [email protected] $ hdfs ls /
If that doesn't work, try setting the
KRB5CCNAME environment variable to
wherever you have the
This library uses "Version 9" of the HDFS protocol, which means it should work with hadoop distributions based on 2.2.x and above. The tests run against CDH 5.x and HDP 2.x.
This library is heavily indebted to snakebite.