Tabs in config file causes service not to start

[markwalkom]

Here is a sample file where spaces are used to pad a config setting;

root@vagrant-ubuntu-trusty-64:/etc/elasticsearch# cat -T elasticsearch.yml
node:
        name: test
root@vagrant-ubuntu-trusty-64:/etc/elasticsearch# service elasticsearch start
 * Starting Elasticsearch Server                                                                                                                                                                                                                                    [ OK ]
root@vagrant-ubuntu-trusty-64:/etc/elasticsearch# ps -fe|grep java
elastic+  1761     1 99 07:31 ?        00:00:02 /usr/bin/java -Xms256m -Xmx1g -Xss256k -Djava.awt.headless=true -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:CMSInitiatingOccupancyFraction=75 -XX:+UseCMSInitiatingOccupancyOnly -XX:+HeapDumpOnOutOfMemoryError -XX:+DisableExplicitGC -Dfile.encoding=UTF-8 -Delasticsearch -Des.pidfile=/var/run/elasticsearch.pid -Des.path.home=/usr/share/elasticsearch -cp :/usr/share/elasticsearch/lib/elasticsearch-1.4.2.jar:/usr/share/elasticsearch/lib/*:/usr/share/elasticsearch/lib/sigar/* -Des.default.config=/etc/elasticsearch/elasticsearch.yml -Des.default.path.home=/usr/share/elasticsearch -Des.default.path.logs=/var/log/elasticsearch -Des.default.path.data=/var/lib/elasticsearch -Des.default.path.work=/tmp/elasticsearch -Des.default.path.conf=/etc/elasticsearch org.elasticsearch.bootstrap.Elasticsearch
root      1775  1635  0 07:31 pts/0    00:00:00 grep --color=auto java

And here is similar with a tab;

root@vagrant-ubuntu-trusty-64:/etc/elasticsearch# cat -T elasticsearch.yml
node:
^Iname: test
root@vagrant-ubuntu-trusty-64:/etc/elasticsearch# service elasticsearch start
 * Starting Elasticsearch Server                                                                                                                                                                                                                                    [ OK ]
root@vagrant-ubuntu-trusty-64:/etc/elasticsearch# ps -ef|grep java
root      1913  1635  0 07:33 pts/0    00:00:00 grep --color=auto java

The tab is confirmed as the problem when you call the binary with it's arguments manually;

root@vagrant-ubuntu-trusty-64:/etc/elasticsearch# /usr/bin/java -Xms256m -Xmx1g -Xss256k -Djava.awt.headless=true -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:CMSInitiatingOccupancyFraction=75 -XX:+UseCMSInitiatingOccupancyOnly -XX:+HeapDumpOnOutOfMemoryError -XX:+DisableExplicitGC -Dfile.encoding=UTF-8 -Delasticsearch -Des.pidfile=/var/run/elasticsearch.pid -Des.path.home=/usr/share/elasticsearch -cp :/usr/share/elasticsearch/lib/elasticsearch-1.4.2.jar:/usr/share/elasticsearch/lib/*:/usr/share/elasticsearch/lib/sigar/* -Des.default.config=/etc/elasticsearch/elasticsearch.yml -Des.default.path.home=/usr/share/elasticsearch -Des.default.path.logs=/var/log/elasticsearch -Des.default.path.data=/var/lib/elasticsearch -Des.default.path.work=/tmp/elasticsearch -Des.default.path.conf=/etc/elasticsearch org.elasticsearch.bootstrap.Elasticsearch
{1.4.2}: Setup Failed ...
- SettingsException[Failed to load settings from [file:/etc/elasticsearch/elasticsearch.yml]]
    IOException[Tabs are illegal in YAML.  Did you mean to use whitespace character instead?]
org.elasticsearch.common.settings.SettingsException: Failed to load settings from [file:/etc/elasticsearch/elasticsearch.yml]
    at org.elasticsearch.common.settings.ImmutableSettings$Builder.loadFromStream(ImmutableSettings.java:947)
    at org.elasticsearch.common.settings.ImmutableSettings$Builder.loadFromUrl(ImmutableSettings.java:931)
    at org.elasticsearch.node.internal.InternalSettingsPreparer.prepareSettings(InternalSettingsPreparer.java:63)
    at org.elasticsearch.bootstrap.Bootstrap.initialSettings(Bootstrap.java:106)
    at org.elasticsearch.bootstrap.Bootstrap.main(Bootstrap.java:177)
    at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:32)
Caused by: java.io.IOException: Tabs are illegal in YAML.  Did you mean to use whitespace character instead?
    at org.elasticsearch.common.settings.loader.YamlSettingsLoader.load(YamlSettingsLoader.java:44)
    at org.elasticsearch.common.settings.ImmutableSettings$Builder.loadFromStream(ImmutableSettings.java:944)
    ... 5 more

I think this is important to address as some of the config examples we have on the site are spaced similar to this, and someone may inadvertently use tabs and wonder why things don't start.

[clintongormley]

Tabs are illegal in YAML. Previously we used to treat them as two spaces, but if you happen to use a different indentation level that could result in incorrect configuration. It is safer to just throw an exception (which I think is pretty self-explanatory).

See #8355