Servlet to download a resource subtree from AEM as a content-package

getpackage.java

/**
 * This is a servlet that enables to download a package of a JCR subtree without
 * having to create a package in the package manager. The package is
 * created on the fly, and not saved to disk / the repository, so this is
 * better suited to large content trees, but valuable also for quickly downloading
 * a page.
 *
 * CAUTION: not suitable for production, only for internal testing systems!
 *
 * Usage with curl e.g.
 * curl -s -S -o tmp.zip -u admin:admin http://localhost:6502/apps/net/stoerr/hpsx/getpackage.html/{path to download}
 *
 * Example Creates a package of this tool:
 * http://localhost:6502/apps/net/stoerr/hpsx/getpackage.html/apps/net/stoerr/hpsx
 *
 * Fragment of a bash script to download a path from another AEM system and install it locally on AEM:
 * path=$1
 * TMPFIL=`mktemp -u`.zip
 * trap "{ rm -f $TMPFIL; }" EXIT
 * PKG=$(basename $TMPFIL)
 * curl -S -o $TMPFIL -u ${OTHER_USER}:${OTHER_PWD} http://${OTHERIP}:4502/apps/netcentric/hpsx/getpackage.html${path}?packageName=$PKG
 * curl -u admin:admin -F file=@"$TMPFIL" -F name="tmp $path" -F force=true -F install=true http://localhost:6502/crx/packmgr/service.jsp
 * curl -u admin:admin -F cmd=delete http://localhost:6502/crx/packmgr/service/.json/etc/packages/my_packages/${PKG%%.zip}-1.zip
 */

package apps.net.stoerr.hpsx.getpackage;

import org.apache.commons.lang3.StringUtils;
import org.apache.jackrabbit.vault.fs.api.PathFilterSet;
import org.apache.jackrabbit.vault.fs.config.DefaultWorkspaceFilter;
import org.apache.jackrabbit.vault.packaging.*;
import org.apache.sling.api.SlingHttpServletRequest;
import org.apache.sling.api.SlingHttpServletResponse;
import org.apache.sling.api.request.RequestPathInfo;
import org.apache.sling.api.resource.Resource;
import org.apache.sling.api.resource.ResourceResolver;
import org.apache.sling.api.servlets.SlingSafeMethodsServlet;
import org.osgi.framework.BundleContext;
import org.osgi.framework.FrameworkUtil;
import org.osgi.framework.ServiceReference;

import javax.jcr.RepositoryException;
import javax.jcr.Session;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import java.io.IOException;

public class getpackage extends SlingSafeMethodsServlet {

    String PARAM_PACKAGENAME = "packageName";

    protected void doGet(SlingHttpServletRequest request, SlingHttpServletResponse response)
            throws ServletException, IOException {
        RequestPathInfo pathInfo = request.getRequestPathInfo();
        String resourcePath = pathInfo.getSuffix();
        ResourceResolver resolver = request.getResourceResolver();
        Resource resource = resolver.getResource(resourcePath);
        if (resource == null) {
            throw new IllegalArgumentException("Not found: " + resourcePath);
        }
        if (!resource.getPath().matches("/.*/.*/.*")) {
            throw new IllegalArgumentException("Path too short - package would probably be too large");
        }
        if (!"admin".equals(request.getResourceResolver().getUserID())) {
            throw new IllegalArgumentException("For security reasons only allowed for admin");
        }
        resourcePath = resource.getPath();
        String packageName = "tmp-" + resourcePath.replaceAll("[^a-zA-Z0-9_-]+", "_");
        if (StringUtils.isNotBlank(request.getParameter(PARAM_PACKAGENAME))) {
            packageName = request.getParameter(PARAM_PACKAGENAME);
        }

        response.setContentType("application/zip");
        response.addHeader("Content-Disposition", "attachment; filename=" +
                packageName + ".zip");

        BundleContext bundleContext = FrameworkUtil.getBundle(Packaging.class).getBundleContext();
        ServiceReference packagingRef = bundleContext.getServiceReference(Packaging.class.getName());
        Packaging packaging = (Packaging) bundleContext.getService(packagingRef);
        try {
            writePackage(resource, packageName, request, packaging, response.getOutputStream());
        } catch (RepositoryException | PackageException e) {
            throw new ServletException(e);
        } finally {
            bundleContext.ungetService(packagingRef);
            resolver.revert();
        }
    }

    private void writePackage(Resource resource, String packageName, SlingHttpServletRequest request, Packaging packaging, ServletOutputStream outputStream) throws IOException, RepositoryException, PackageException {

        JcrPackageManager pkgmgr = packaging.getPackageManager(request.getResourceResolver().adaptTo(Session.class));

        JcrPackage jcrPackage = pkgmgr.create("my_packages", packageName, "1");
        try {
            JcrPackageDefinition pkgdef = jcrPackage.getDefinition();
            DefaultWorkspaceFilter workspaceFilter = new DefaultWorkspaceFilter();
            workspaceFilter.add(new PathFilterSet(resource.getPath()));
            pkgdef.setFilter(workspaceFilter, false);

            pkgmgr.assemble(pkgdef, null, outputStream);
        } finally {
            try {
                pkgmgr.remove(jcrPackage);
            } catch (Exception e) {
                // ignore
            }
        }
    }

}