LinuxBootConfiguration.java

package hudson.plugins.pxe;

import hudson.Util;
import hudson.util.VariableResolver;
import org.apache.commons.io.IOUtils;
import org.apache.commons.jexl.ExpressionFactory;
import org.apache.commons.jexl.context.HashMapContext;
import org.jvnet.hudson.tftpd.Data;
import org.kohsuke.loopy.FileEntry;
import org.kohsuke.loopy.iso9660.ISO9660FileSystem;
import org.kohsuke.stapler.StaplerResponse;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.util.Locale;
import java.util.TimeZone;

public abstract class LinuxBootConfiguration extends IsoBasedBootConfiguration {
    protected LinuxBootConfiguration(File iso) {
        super(iso);
    }

    /**
     * Directs the user to the OS specific submenu.
     */
    public String getPxeLinuxConfigFragment() throws IOException {
        return String.format("LABEL %1$s\n" +
                "    MENU LABEL %2$s\n" +
                "    KERNEL vesamenu.c32\n" +
                "    APPEND %1$s/menu.txt \n",
                getId(), getRelease());
    }

    /**
     * Serves menu.txt by replacing variables.
     */
    public Data tftp(String fileName) throws IOException {
        if(fileName.equals("menu.txt")) {
            // pxelinux boot menu
            String template = IOUtils.toString(getResourceAsStream("menu.txt"));
            return Data.from(Util.replaceMacro(template,createResolver()));
        }

        // look them up in the ISO file
        ISO9660FileSystem fs = new ISO9660FileSystem(iso,false);
        FileEntry dir = getTftpIsoMountDir(fs);
        if(dir!=null) {
            FileEntry f = dir.get(fileName);
            if(f!=null)
                return new FileEntryData(f);
        }

        return null;
    }

    /**
     * Directory inside the ISO file that gets "mounted" to TFTP. Used normally to serve
     * kernel and initrd.
     *
     * @return
     *      null if no directory from ISO is mount to tftp. 
     */
    protected abstract FileEntry getTftpIsoMountDir(ISO9660FileSystem fs) throws IOException;


    /**
     * Creates a variable resolver that looks up properties on this class.
     */
    protected VariableResolver<String> createResolver() {
        final HashMapContext context = new HashMapContext();
        context.put("it", this);
        // these are commonly used values
        context.put("timeZone", TimeZone.getDefault().getID());
        context.put("locale", Locale.getDefault().toString());

        return new VariableResolver<String>() {
            public String resolve(String name) {
                try {
                    if (context.containsKey(name)) return context.get(name).toString();
                    Object o = ExpressionFactory.createExpression("it." + name).evaluate(context);
                    if(o==null) return "";
                    return String.valueOf(o);
                } catch (Exception e) {
                    throw new Error(e); // tunneling. this must indicate a programming error
                }
            }
        };
    }

    /**
     * Serves the static text resource after expanding macro variables.
     */
    protected void serveMacroExpandedResource(StaplerResponse rsp, String resourceName) throws IOException {
        rsp.setContentType("text/plain");
        rsp.getWriter().println(
                Util.replaceMacro(IOUtils.toString(getResourceAsStream(resourceName)), createResolver()));
    }

}