yegor256#1041 added docker dameon auto restarter

src/main/java/com/rultor/agents/daemons/ShellCommand.java

@@ -43,7 +43,7 @@
  * @since 1.62
  */
 @Immutable
-final class ShellCommand {
+public final class ShellCommand {
 
     /**
      * Join shell commands with this string.
@@ -71,7 +71,7 @@ final class ShellCommand {
      * @param dir String working directory
      * @param cmd String command to run
      */
-    ShellCommand(final Shell shll, final String dir, final String cmd) {
+    public ShellCommand(final Shell shll, final String dir, final String cmd) {
         this.shell = shll;
         this.directory = dir;
         this.command = cmd;

src/main/java/com/rultor/agents/daemons/StartsDaemon.java

@@ -39,6 +39,7 @@
 import com.jcabi.xml.XML;
 import com.rultor.Time;
 import com.rultor.agents.AbstractAgent;
+import com.rultor.agents.docker.DockerDaemon;
 import com.rultor.agents.shells.TalkShells;
 import com.rultor.spi.Profile;
 import java.io.ByteArrayInputStream;
@@ -115,6 +116,10 @@ public Iterable<Directive> process(final XML xml) {
     public String run(final XML xml) throws IOException {
         final XML daemon = xml.nodes("/talk/daemon").get(0);
         final Shell shell = new TalkShells(xml).get();
+        final DockerDaemon docker = new DockerDaemon(shell);
+        if (!docker.running()) {
+            docker.restart();
+        }
         final ByteArrayOutputStream baos = new ByteArrayOutputStream();
         new Shell.Safe(shell).exec(
             "mktemp -d -t rultor-XXXX",

src/main/java/com/rultor/agents/docker/DockerDaemon.java

@@ -0,0 +1,103 @@
+/**
+ * Copyright (c) 2009-2016, rultor.com
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met: 1) Redistributions of source code must retain the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer. 2) Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer in the documentation and/or other materials provided
+ * with the distribution. 3) Neither the name of the rultor.com nor
+ * the names of its contributors may be used to endorse or promote
+ * products derived from this software without specific prior written
+ * permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT
+ * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package com.rultor.agents.docker;
+
+import com.jcabi.aspects.Immutable;
+import com.jcabi.ssh.Shell;
+import com.rultor.agents.daemons.ShellCommand;
+import java.io.IOException;
+import org.apache.commons.lang3.StringUtils;
+
+/**
+ * Docker daemon.
+ *
+ * @author Armin Braun (me@obrown.io)
+ * @version $Id$
+ * @since 1.62
+ */
+@Immutable
+public final class DockerDaemon {
+
+    /**
+     * Shell to use.
+     */
+    private final transient Shell shell;
+
+    /**
+     * Ctor.
+     * @param ssh Shell of the Docker daemon host
+     */
+    public DockerDaemon(final Shell ssh) {
+        this.shell = ssh;
+    }
+
+    /**
+     * Checks if the Docker daemon is running.
+     * Uses the return status of executing `docker info` in the Docker host's
+     * root shell to determine the status of the daemon.
+     * @return True if the Docker daemon is running
+     * @throws IOException on error
+     */
+    public boolean running() throws IOException {
+        return "1\n".equals(
+            this.exec(
+                StringUtils.join(
+                    "if pgrep \"docker\" > /dev/null;",
+                    "then echo \"1\"; else; echo \"0\"; fi;"
+                )
+            )
+        );
+    }
+
+    /**
+     * Restarts the Docker daemon.
+     * @throws IOException if restarting the Docker daemon fails
+     */
+    public void restart() throws IOException {
+        try {
+            this.exec("sudo service docker restart");
+        } catch (final IOException | IllegalArgumentException ex) {
+            throw new IOException("Restarting the Docker daemon failed", ex);
+        }
+    }
+
+    /**
+     * Runs a given command on the Docker daemon's host.
+     * @param cmd String of the command to be run
+     * @return String of the command's output
+     * @throws IOException on error in communicating with the SSH shell
+     * @throws IllegalArgumentException on error in the executed command
+     */
+    private String exec(final String cmd)
+        throws IOException, IllegalArgumentException {
+        return new ShellCommand(this.shell, "/", cmd).exec();
+    }
+
+}