[Update 2015/03/15 I believe that as of 2.3 Nutch is no longer officially supporting MySQL as a storage backend. I am leaving this up for people who may need it for support purposes but if you are a new user starting with Nutch now don't use the MySQL backend]

Enough has changed from Nutch 2.1 to Nutch 2.2 to warrant an update to the installation instructions. These instructions assume Ubuntu 12.04 and Java 7 installed and JAVA_HOME configured.

Install MySQL Server and MySQL Client

using the Ubuntu software center or sudo apt-get install mysql-server mysql-client at the command line.

As MySQL defaults to latin we need to edit sudo vi /etc/mysql/my.cnf and under [mysqld] add

innodb_file_format=barracuda
innodb_file_per_table=true
innodb_large_prefix=true
character-set-server=utf8mb4
collation-server=utf8mb4_unicode_ci
max_allowed_packet=500M

The innodb options are to help deal with the small primary key size restriction of MySQL. The character and collation settings are to handle Unicode correctly.The max_allowed_packet settings is optional and only necessary for very large sizes. Restart your machine for the changes to take effect.

Check to make sure MySQL is running by typing sudo netstat -tap | grep mysql and you should see something like

tcp 0 0 localhost:mysql *:* LISTEN

We need to set up the nutch database manually as the current Nutch/Gora/MySQL generated db schema defaults to latin. Log into mysql at the command line using your previously set up MySQL id and password type

mysql -u xxxxx -p

then in the MySQL editor type the following:

CREATE DATABASE nutch DEFAULT CHARACTER SET utf8mb4 DEFAULT COLLATE utf8mb4_unicode_ci;

and enter followed by

use nutch;

and enter and then copy and paste the following altogether:

CREATE TABLE `webpage` (
`id` varchar(767) NOT NULL,
`headers` blob,
`text` longtext DEFAULT NULL,
`status` int(11) DEFAULT NULL,
`markers` blob,
`parseStatus` blob,
`modifiedTime` bigint(20) DEFAULT NULL,
`prevModifiedTime` bigint(20) DEFAULT NULL,
`score` float DEFAULT NULL,
`typ` varchar(32) CHARACTER SET latin1 DEFAULT NULL,
`batchId` varchar(32) CHARACTER SET latin1 DEFAULT NULL,
`baseUrl` varchar(767) DEFAULT NULL,
`content` longblob,
`title` varchar(2048) DEFAULT NULL,
`reprUrl` varchar(767) DEFAULT NULL,
`fetchInterval` int(11) DEFAULT NULL,
`prevFetchTime` bigint(20) DEFAULT NULL,
`inlinks` mediumblob,
`prevSignature` blob,
`outlinks` mediumblob,
`fetchTime` bigint(20) DEFAULT NULL,
`retriesSinceFetch` int(11) DEFAULT NULL,
`protocolStatus` blob,
`signature` blob,
`metadata` blob,
PRIMARY KEY (`id`)
) ENGINE=InnoDB
ROW_FORMAT=COMPRESSED
DEFAULT CHARSET=utf8mb4;

Then type enter. You are done setting up the MySQL database for Nutch.

Set up Nutch 2.2

by downloading the apache-nutch-2.2-src.tar.gz version from http://www.apache.org/dyn/closer.cgi/nutch/. Untar the contents of the file you just downloaded to a folder we will refer to going forward as ${APACHE_NUTCH_HOME}. In my particular case I prefer to use it with Eclipse so I untar it in the Eclipse workspace but this is not necessary.

From inside the nutch folder ensure the MySQL dependency for Nutch is available by editing the following in ${APACHE_NUTCH_HOME}/ivy/ivy.xml

change
<dependency org="org.apache.gora" name="gora-core" rev="0.3" conf="*->default"/>
to
<dependency org="org.apache.gora" name="gora-core" rev="0.2.1" conf="*->default"/>

and uncomment the gora-sql
<dependency org="org.apache.gora" name="gora-sql" rev="0.1.1-incubating" conf="*->default" />

and uncomment the mysql connector
<!-- Uncomment this to use MySQL as database with SQL as Gora store. -->
<dependency org="mysql" name="mysql-connector-java" rev="5.1.18" conf="*->default"/>



Edit the ${APACHE_NUTCH_HOME}/conf/gora.properties file either deleting or commenting out the Default SqlStore Properties using #. Then add the MySQL properties below replacing xxxxx with the user and password you set up when installing MySQL earlier.

###############################
# MySQL properties #
###############################
gora.sqlstore.jdbc.driver=com.mysql.jdbc.Driver
gora.sqlstore.jdbc.url=jdbc:mysql://localhost:3306/nutch?createDatabaseIfNotExist=true
gora.sqlstore.jdbc.user=xxxxx
gora.sqlstore.jdbc.password=xxxxx

Edit the ${APACHE_NUTCH_HOME}/conf/gora-sql-mapping.xml file changing the length of the primarykey from 512 to 767 in both places.
<primarykey column="id" length="767"/>

Configure ${APACHE_NUTCH_HOME}/conf/nutch-site.xml to put in a name in the value field under http.agent.name. It can be anything but cannot be left blank. Add additional languages if you want (I have added Japanese ja-jp below) and utf-8 as default as well. You must specify Sqlstore.

<property>
<name>http.agent.name</name>
<value>YourNutchSpider</value>
</property>

<property>
<name>http.accept.language</name>
<value>ja-jp, en-us,en-gb,en;q=0.7,*;q=0.3</value>
<description>Value of the "Accept-Language" request header field.
This allows selecting non-English language as default one to retrieve.
It is a useful setting for search engines build for certain national group.
</description>
</property>

<property>
<name>parser.character.encoding.default</name>
<value>utf-8</value>
<description>The character encoding to fall back to when no other information
is available</description>
</property>

<property>
<name>storage.data.store.class</name>
<value>org.apache.gora.sql.store.SqlStore</value>
<description>The Gora DataStore class for storing and retrieving data.
Currently the following stores are available: ....
</description>
</property>

Install ant using the Ubuntu software center or sudo apt-get install ant at the command line.

From the command line cd to your nutch folder

If you are using Eclipse type ant eclipse. When that is finished start up Eclipse and go to File -> Import -> Existing Projects into Workspace -> Browse and add ${APACHE_NUTCH_HOME}. Go to the new project in the Eclipse project explorer and scroll down until you find ant.xml. Right click on ant.xml and select run as -> 1 ant build. This may take a little while to compile.

If you are not using Eclipse after you have cd to ${APACHE_NUTCH_HOME} simply type ant runtime
This may take a few minutes to compile.

Start your first crawl

by typing the lines below at the terminal (replace 'http://nutch.apache.org/' with whatever site you want to crawl):
Inject a URL into the DB

cd ${APACHE_NUTCH_HOME}/runtime/local
mkdir -p urls
echo 'http://nutch.apache.org/' > urls/seed.txt

Start crawling (you will want to create your own script later but manually just to see what is happening type the following into the command line)

bin/nutch inject urls

bin/nutch generate -topN 20
bin/nutch fetch -all
bin/nutch parse -all
bin/nutch updatedb

Repeat the last four commands (generate, fetch, parse and updatedb) again.

For the generate command, topN is the max number of links you want to actually parse each time. The first time there is only one URL (the one we injected from seed.txt) but after that there are many more. Note, however, Nutch keeps track of all links it encounters in the webpage table. It just limits the amount it actually parses to TopN so don't be surprised by seeing many more rows in the webpage table than you expect by limiting with TopN.

Check your crawl results by looking at the webpage table in the nutch database.

mysql -u xxxxx -p
use nutch;
SELECT * FROM nutch.webpage;

You should see the results of your crawl (around 320 rows). It will be hard to read the columns so you may want to install MySQL Workbench via sudo apt-get install mysql-workbench and use that instead for viewing the data. You may also want to run the following SQL command select * from webpage where status = 2; to limit the rows in the webpage table to only urls that were actually parsed.

You can easily add more urls to search by hand in seed.txt if you want and then use the command bin/nutch inject urls .

Set up and index with Solr If you are using Nutch 2.2 at this time you are into the bleeding edge and probably want the latest version of Solr 4 as well. Untar it to to $HOME/apache-solr-4.X.X-XXXX. This folder will be now referred to as ${APACHE_SOLR_HOME}.
Download this link and use it to replace ${APACHE_SOLR_HOME}/example/solr/collection1/conf/schema.xml.

From the terminal start solr:
cd ${APACHE_SOLR_HOME}/example
java -jar start.jar

You can check this is running by opening http://localhost:8983/solr in your web browser. Select collection1 from the core selector.

Leave that terminal running and from a different terminal type the following:
cd ${APACHE_NUTCH_HOME}/runtime/local/
bin/nutch solrindex http://127.0.0.1:8983/solr/ -reindex

You can now run queries using Solr versus your crawled content. Open http://localhost:8983/solr/#/collection1/query and assuming you have crawled nutch.apache.org in the input box titled "q" you can do a search by inputting content:nutch 

There remains a lot to configure to get a good web search going but you are at least started.