Replace sequential container indexes with randomly generated IDs

Signed-off-by: Joffrey F <joffrey@docker.com>

compose/cli/main.py

@@ -474,15 +474,16 @@ def exec_command(self, options):
             -u, --user USER   Run the command as this user.
             -T                Disable pseudo-tty allocation. By default `docker-compose exec`
                               allocates a TTY.
-            --index=index     index of the container if there are multiple
-                              instances of a service [default: 1]
+            --index=index     "index" of the container if there are multiple
+                              instances of a service. If missing, Compose will pick an
+                              arbitrary container.
             -e, --env KEY=VAL Set environment variables (can be used multiple times,
                               not supported in API < 1.25)
             -w, --workdir DIR Path to workdir directory for this command.
         """
         environment = Environment.from_env_file(self.project_dir)
         use_cli = not environment.get_boolean('COMPOSE_INTERACTIVE_NO_CLI')
-        index = int(options.get('--index'))
+        index = options.get('--index')
         service = self.project.get_service(options['SERVICE'])
         detach = options.get('--detach')
 
@@ -659,10 +660,11 @@ def port(self, options):
 
         Options:
             --protocol=proto  tcp or udp [default: tcp]
-            --index=index     index of the container if there are multiple
-                              instances of a service [default: 1]
+            --index=index     "index" of the container if there are multiple
+                              instances of a service. If missing, Compose will pick an
+                              arbitrary container.
         """
-        index = int(options.get('--index'))
+        index = options.get('--index')
         service = self.project.get_service(options['SERVICE'])
         try:
             container = service.get_container(number=index)

compose/container.py

@@ -10,6 +10,7 @@
 from .const import LABEL_PROJECT
 from .const import LABEL_SERVICE
 from .const import LABEL_VERSION
+from .utils import truncate_id
 from .version import ComposeVersion
 
 
@@ -80,7 +81,7 @@ def service(self):
     @property
     def name_without_project(self):
         if self.name.startswith('{0}_{1}'.format(self.project, self.service)):
-            return '{0}_{1}'.format(self.service, self.number)
+            return '{0}_{1}'.format(self.service, self.short_number)
         else:
             return self.name
 
@@ -90,7 +91,11 @@ def number(self):
         if not number:
             raise ValueError("Container {0} does not have a {1} label".format(
                 self.short_id, LABEL_CONTAINER_NUMBER))
-        return int(number)
+        return number
+
+    @property
+    def short_number(self):
+        return truncate_id(self.number)
 
     @property
     def ports(self):

compose/service.py

@@ -1,7 +1,6 @@
 from __future__ import absolute_import
 from __future__ import unicode_literals
 
-import itertools
 import logging
 import os
 import re
@@ -49,9 +48,11 @@
 from .parallel import parallel_execute
 from .progress_stream import stream_output
 from .progress_stream import StreamOutputError
+from .utils import generate_random_id
 from .utils import json_hash
 from .utils import parse_bytes
 from .utils import parse_seconds_float
+from .utils import truncate_id
 
 
 log = logging.getLogger(__name__)
@@ -215,13 +216,17 @@ def containers(self, stopped=False, one_off=False, filters={}, labels=None):
             )
         )
 
-    def get_container(self, number=1):
+    def get_container(self, number=None):
         """Return a :class:`compose.container.Container` for this service. The
         container must be active, and match `number`.
         """
-
-        for container in self.containers(labels=['{0}={1}'.format(LABEL_CONTAINER_NUMBER, number)]):
-            return container
+        if number is not None and len(number) == 64:
+            for container in self.containers(labels=['{0}={1}'.format(LABEL_CONTAINER_NUMBER, number)]):
+                return container
+        else:
+            for container in self.containers():
+                if number is None or container.number.startswith(number):
+                    return container
 
         raise ValueError("No container found for %s_%s" % (self.name, number))
 
@@ -426,7 +431,6 @@ def _containers_have_diverged(self, containers):
         return has_diverged
 
     def _execute_convergence_create(self, scale, detached, start, project_services=None):
-            i = self._next_container_number()
 
             def create_and_start(service, n):
                 container = service.create_container(number=n, quiet=True)
@@ -437,7 +441,9 @@ def create_and_start(service, n):
                 return container
 
             containers, errors = parallel_execute(
-                [ServiceName(self.project, self.name, index) for index in range(i, i + scale)],
+                [ServiceName(self.project, self.name, number) for number in [
+                    self._next_container_number() for _ in range(scale)
+                ]],
                 lambda service_name: create_and_start(self, service_name.number),
                 lambda service_name: self.get_container_name(service_name.service, service_name.number),
                 "Creating"
@@ -568,7 +574,7 @@ def recreate_container(self, container, timeout=None, attach_logs=False, start_n
         container.rename_to_tmp_name()
         new_container = self.create_container(
             previous_container=container if not renew_anonymous_volumes else None,
-            number=container.labels.get(LABEL_CONTAINER_NUMBER),
+            number=container.number,
             quiet=True,
         )
         if attach_logs:
@@ -723,20 +729,8 @@ def get_link_names(self):
     def get_volumes_from_names(self):
         return [s.source.name for s in self.volumes_from if isinstance(s.source, Service)]
 
-    # TODO: this would benefit from github.com/docker/docker/pull/14699
-    # to remove the need to inspect every container
     def _next_container_number(self, one_off=False):
-        containers = itertools.chain(
-            self._fetch_containers(
-                all=True,
-                filters={'label': self.labels(one_off=one_off)}
-            ), self._fetch_containers(
-                all=True,
-                filters={'label': self.labels(one_off=one_off, legacy=True)}
-            )
-        )
-        numbers = [c.number for c in containers]
-        return 1 if not numbers else max(numbers) + 1
+        return generate_random_id()
 
     def _fetch_containers(self, **fetch_options):
         # Account for containers that might have been removed since we fetched
@@ -1370,7 +1364,7 @@ def build_container_name(project, service, number, one_off=False):
     bits = [project.lstrip('-_'), service]
     if one_off:
         bits.append('run')
-    return '_'.join(bits + [str(number)])
+    return '_'.join(bits + [truncate_id(number)])
 
 
 # Images

compose/utils.py

@@ -7,6 +7,7 @@
 import json.decoder
 import logging
 import ntpath
+import random
 
 import six
 from docker.errors import DockerException
@@ -151,3 +152,21 @@ def unquote_path(s):
     if s[0] == '"' and s[-1] == '"':
         return s[1:-1]
     return s
+
+
+def generate_random_id():
+    while True:
+        val = hex(random.getrandbits(32 * 8))[2:-1]
+        try:
+            int(truncate_id(val))
+            continue
+        except ValueError:
+            return val
+
+
+def truncate_id(value):
+    if ':' in value:
+        value = value[value.index(':') + 1:]
+    if len(value) > 12:
+        return value[:12]
+    return value