Add un/register container IP

basic/srv/vm/cli.py

@@ -44,6 +44,14 @@ parser_disable_autostart.add_argument('app', help='Application name')
 parser_rebuild_issue = subparsers.add_parser('rebuild-issue', help='Rebuilds /etc/issue using current settings - used on VM startup')
 parser_rebuild_issue.set_defaults(action='rebuild-issue')
 
+parser_register_container = subparsers.add_parser('register-container', help='Register and assigns IP to an application container. Intended to be used with LXC hooks')
+parser_register_container.add_argument('lxc', nargs=argparse.REMAINDER)
+parser_register_container.set_defaults(action='register-container')
+
+parser_unregister_container = subparsers.add_parser('unregister-container', help='Removes IP assignment for an application container. Intended to be used with LXC hooks')
+parser_unregister_container.add_argument('lxc', nargs=argparse.REMAINDER)
+parser_unregister_container.set_defaults(action='unregister-container')
+
 parser_register_proxy = subparsers.add_parser('register-proxy', help='Rebuilds nginx proxy target for an application container')
 parser_register_proxy.set_defaults(action='register-proxy')
 parser_register_proxy.add_argument('app', help='Application name')
@@ -94,6 +102,10 @@ elif args.action == 'disable-autostart':
     mgr.disable_autostart(args.app)
 elif args.action == 'rebuild-issue':
     mgr.rebuild_issue()
+elif args.action == 'register-container':
+    mgr.register_container()
+elif args.action == 'unregister-container':
+    mgr.unregister_container()
 elif args.action == 'register-proxy':
     mgr.register_proxy(args.app)
 elif args.action == 'unregister-proxy':

basic/srv/vm/mgr/__init__.py

@@ -208,6 +208,19 @@ class VMMgr:
             raise validator.InvalidValueException('app', app)
         subprocess.run(['/sbin/rc-update', 'del', app])
 
+    def register_container(self):
+        # Set IP of a container based on values given via lxc.hook.start-host hook
+        app = os.environ['LXC_NAME']
+        pid = os.environ['LXC_PID']
+        ip = tools.get_unused_ip()
+        tools.update_hosts_lease(ip, app)
+        tools.set_container_ip(pid, ip)
+
+    def unregister_container(self):
+        # Unset IP of a container based on values given via lxc.hook.post-stop hook
+        app = os.environ['LXC_NAME']
+        tools.update_hosts_lease(None, app)
+
     def register_proxy(self, app):
         # Rebuild nginx configuration using IP of referenced app container and reload nginx
         if not validator.is_valid_app(app, self.conf):

basic/srv/vm/mgr/tools.py

@@ -16,13 +16,6 @@ def compile_url(domain, port, proto='https'):
     host = '{}{}'.format(domain, port)
     return '{}://{}'.format(proto, host) if proto is not None else host
 
-def get_container_ip(app):
-    # Return an IP address of a container. If the container is not running, return address from IPv6 discard prefix instead
-    try:
-        return subprocess.run(['/usr/bin/docker', 'inspect', '-f', '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}', app], check=True, stdout=subprocess.PIPE).stdout.decode().strip()
-    except:
-        return NULL_IP
-
 def get_local_ipv4():
     # Return first routable IPv4 address
     try:
@@ -122,3 +115,41 @@ def shutdown_vm():
 
 def reboot_vm():
     subprocess.run(['/sbin/reboot'])
+
+def get_unused_ip():
+    # This is a poor man's DHCP server which uses /etc/hosts as lease database
+    # Leases the first unused IP from range 172.17.0.0/16
+    leased = []
+    with open('/etc/hosts', 'r') as fd:
+        for line in fd.read().splitlines():
+            if line.startswith('172.17'):
+                ip = line.split()[0].split('.')
+                leased.append(int(ip[2]) * 256 + int(ip[3]))
+    for i in range(1, 65534):
+        if i not in leased:
+            break
+    return '172.17.{}.{}'. format(i // 256, i % 256)
+
+def update_hosts_lease(ip, app):
+    hosts = []
+    with open('/etc/hosts', 'r') as fd:
+        for line in fd:
+            if not line.strip().endswith(' {}'.format(app)):
+                hosts.append(line)
+    if ip:
+        hosts.append('{} {}\n'.format(ip, app))
+    with open('/etc/hosts', 'w') as fd:
+        fd.writelines(hosts)
+
+def get_container_ip(app):
+    # Return an IP of a container. If the container doesn't exist, return address from IPv6 discard prefix instead
+    with open('/etc/hosts', 'r') as fd:
+        for line in fd:
+            if line.strip().endswith(' {}'.format(app)):
+                return line.split()[0]
+    return NULL_IP
+
+def set_container_ip(pid, ip):
+    # Set IP in container based on PID given via lxc.hook.start-host hook
+    cmd = 'ip addr add {}/16 broadcast 172.17.255.255 dev eth0 && ip route add default via 172.17.0.1'.format(ip)
+    subprocess.run(['nsenter', '-a', '-t', pid, '--', '/bin/sh', '-c', cmd])

lxc-build

@@ -13,8 +13,6 @@ lxc.uts.name = {name}
 lxc.net.0.type = veth
 lxc.net.0.link = lxcbr0
 lxc.net.0.flags = up
-lxc.net.0.ipv4.address = 172.17.0.254/16
-lxc.net.0.ipv4.gateway = auto
 
 # Volumes
 lxc.rootfs.path = {rootfs}
@@ -43,6 +41,8 @@ lxc.console.logfile = /var/log/lxc/{name}.log
 # Other
 lxc.arch = x86_64
 lxc.cap.drop = sys_admin
+lxc.hook.start-host = /usr/bin/vmmgr register-container
+lxc.hook.post-stop = /usr/bin/vmmgr unregister-container
 lxc.include = /usr/share/lxc/config/common.conf
 '''