Tomcat 7 aliases usage

[Skanus Meduoliai]

Hello, I would like to share some static images outside of web application WAR file. I found that Tomcat 7 have new functionality that allows to do that easily using new aliases system.

But for me it's not so easy to get it working as described in this site.

I am using Ubuntu 12.10 and Tomcat 7.0.32 version.

My uploaded images are stored like this:

/home/user/admin-images/-
                   -234bF5_image/image.jpg
                   -572d44_otherImage/otherImage.jpg
                   -12A4uR_otherImage/otherImage.jpg

In Tomcat configuration I have two context files: admin.xml and uploads.xml each of them looks like this:

admin.xml:

<Context path="/admin" 
        docBase="path/to/application/target" reloadable="false">
    <WatchedResource>WEB-INF/web.xml</WatchedResource>
    <Manager pathname="admin" />
</Context>

uploads.xml:

<?xml version="1.0" encoding="UTF-8"?>
<Context path="/admin" aliases="/images=/home/user/admin-images">

</Context>

Application starts but images is not accessible. I try to access them like this:

http//localhost:8080/admin/images/234bF5_image/image.jpg

Anybody knows how to properly use this aliases? Please?

[Tim Holloway]

Have you checked to see that Tomcat has read access rights to this directory?

Also, the docs say docBase has to point to a .war file or a directory. I'm not sure in the case of "directory" if they're being sloppy and mean that it, too has to be in WAR format.

[Skanus Meduoliai]

It have read access right to this directory. I have tried to make this directory WAR style by adding WEB-INF folder with web.xml file, but images were not reachable.

I found another way of getting access to static images outside web application.

You need define context in server.xml inside Tomcat configuration:

server.xml (this have to go into 'Host' tag):

...
...
<Host>
    ...
    ...
    <Context docBase="/home/user/admin-images/" path="/images" />
    ...
    ...
</Host>
...
...

That way I am able to reach static images like that:

http://localhost:8080/admin/images/234bF5_image/image.jpg

My new question would be:
This way to share static resources is safe? Does it have any disadvantages?

[Tim Holloway]

You should not define the Context in server.xml. That is a practice that has been discouraged since at least Tomcat4. Put it in a file named "admin.xml" in the TOMCAT_HOME/conf/Catalina/localhost directory.

[Skanus Meduoliai]

I was unable to do so, because admin.xml already contains <Context /> tag that points to web application. But I have created another context file images.xml and IT WORKED . Thanks

As I understand this is safe way to share static resources like that?

[Tim Holloway]

You are not actually "sharing static images". Web servers are not file servers. What you are really doing is creating a third webapp whose sole purpose is to serve up the images.

It is 100% safe/legal/valid for a webpage coming from one webapp to contain URLs (links and images) that are served by other apps - even other servers in other domains. It's what keeps doubleclick.net in business (among many others).