import: add new minimal tool "systemd-import" for pulling down foreign containers and install them locally

This adds a simply but powerful tool for downloading container images
from the most popular container solution used today. Use it like
this:

       # systemd-import pull-dck mattdm/fedora
       # systemd-nspawn -M fedora

This will donwload the layers for "mattdm/fedora", and make them
available locally as /var/lib/container/fedora.

The tool is pretty complete, as long as it's only about pulling down
images, or updating them. Pushing or searching is not supported yet.

1 files changed, 213 insertions, 0 deletions

diff --git a/src/import/import.c b/src/import/import.c
new file mode 100644
index 0000000000..9bade38c3a
--- /dev/null
+++ b/src/import/import.c
@@ -0,0 +1,213 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2014 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <getopt.h>
+
+#include "sd-event.h"
+#include "event-util.h"
+#include "verbs.h"
+#include "build.h"
+#include "import-dck.h"
+
+static bool arg_force = false;
+
+static void on_finished(DckImport *import, int error, void *userdata) {
+        sd_event *event = userdata;
+        assert(import);
+
+        if (error == 0)
+                log_info("Operation completed successfully.");
+        else
+                log_info_errno(error, "Operation failed: %m");
+
+        sd_event_exit(event, error);
+}
+
+static int pull_dck(int argc, char *argv[], void *userdata) {
+        _cleanup_(dck_import_unrefp) DckImport *import = NULL;
+        _cleanup_event_unref_ sd_event *event = NULL;
+        const char *name, *tag, *local;
+        int r;
+
+        tag = strchr(argv[1], ':');
+        if (tag) {
+                name = strndupa(argv[1], tag - argv[1]);
+                tag++;
+        } else {
+                name = argv[1];
+                tag = "latest";
+        }
+
+        if (argc >= 3)
+                local = argv[2];
+        else {
+                local = strchr(name, '/');
+                if (local)
+                        local++;
+                else
+                        local = name;
+        }
+
+        if (streq(local, "-") || isempty(local))
+                local = NULL;
+
+        if (!dck_name_is_valid(name)) {
+                log_error("Remote name '%s' is not valid.", name);
+                return -EINVAL;
+        }
+
+        if (!dck_tag_is_valid(tag)) {
+                log_error("Tag name '%s' is not valid.", tag);
+                return -EINVAL;
+        }
+
+        if (local) {
+                const char *p;
+
+                if (!machine_name_is_valid(tag)) {
+                        log_error("Local image name '%s' is not valid.", local);
+                        return -EINVAL;
+                }
+
+                p = strappenda("/var/lib/container/", local);
+                if (laccess(p, F_OK) >= 0) {
+                        if (!arg_force) {
+                                log_info("Image '%s' already exists.", local);
+                                return 0;
+                        }
+                } else if (errno != ENOENT)
+                        return log_error_errno(errno, "Can't check if image '%s' already exists: %m", local);
+
+                log_info("Pulling '%s' with tag '%s', saving as '%s'.", name, tag, local);
+        } else
+                log_info("Pulling '%s' with tag '%s'.", name, tag);
+
+        r = sd_event_default(&event);
+        if (r < 0)
+                return log_error_errno(r, "Failed to allocate event loop: %m");
+
+        assert_se(sigprocmask_many(SIG_BLOCK, SIGTERM, SIGINT, -1) == 0);
+        sd_event_add_signal(event, NULL, SIGTERM, NULL,  NULL);
+        sd_event_add_signal(event, NULL, SIGINT, NULL, NULL);
+
+        r = dck_import_new(&import, event, on_finished, event);
+        if (r < 0)
+                return log_error_errno(r, "Failed to allocate importer: %m");
+
+        r = dck_import_pull(import, name, tag, local, arg_force);
+        if (r < 0)
+                return log_error_errno(r, "Failed to pull image: %m");
+
+        r = sd_event_loop(event);
+        if (r < 0)
+                return log_error_errno(r, "Failed to run event loop: %m");
+
+        log_info("Exiting.");
+
+        return 0;
+}
+
+static int help(int argc, char *argv[], void *userdata) {
+
+        printf("%s [OPTIONS...] {COMMAND} ...\n\n"
+               "Import container or virtual machine image.\n\n"
+               "  -h --help                   Show this help\n"
+               "     --version                Show package version\n"
+               "     --force                  Force creation of image\n\n"
+               "Commands:\n"
+               "  pull-dck REMOTE [NAME]      Download an image\n",
+               program_invocation_short_name);
+
+        return 0;
+}
+
+static int parse_argv(int argc, char *argv[]) {
+
+        enum {
+                ARG_VERSION = 0x100,
+                ARG_FORCE,
+        };
+
+        static const struct option options[] = {
+                { "help",            no_argument,       NULL, 'h'                 },
+                { "version",         no_argument,       NULL, ARG_VERSION         },
+                { "force",           no_argument,       NULL, ARG_FORCE           },
+                {}
+        };
+
+        int c;
+
+        assert(argc >= 0);
+        assert(argv);
+
+        while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0)
+
+                switch (c) {
+
+                case 'h':
+                        return help(argc, argv, NULL);
+
+                case ARG_VERSION:
+                        puts(PACKAGE_STRING);
+                        puts(SYSTEMD_FEATURES);
+                        return 0;
+
+                case ARG_FORCE:
+                        arg_force = true;
+                        break;
+
+                case '?':
+                        return -EINVAL;
+
+                default:
+                        assert_not_reached("Unhandled option");
+                }
+
+        return 1;
+}
+
+static int import_main(int argc, char *argv[]) {
+
+        const Verb verbs[] = {
+                { "help",     VERB_ANY, VERB_ANY, 0, help     },
+                { "pull-dck", 2,        3,        0, pull_dck },
+                {}
+        };
+
+        return dispatch_verb(argc, argv, verbs, NULL);
+}
+
+int main(int argc, char *argv[]) {
+        int r;
+
+        setlocale(LC_ALL, "");
+        log_parse_environment();
+        log_open();
+
+        r = parse_argv(argc, argv);
+        if (r <= 0)
+                goto finish;
+
+        r = import_main(argc, argv);
+
+finish:
+        return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
+}