在 Dockerfile 中运行“manage.py compilemessages”会给出“django.db.utils.OperationalError: could not connect to server: No such file or directory”答案

【问题标题】：Running "manage.py compilemessages" in Dockerfile gives "django.db.utils.OperationalError: could not connect to server: No such file or directory"在 Dockerfile 中运行“manage.py compilemessages”会给出“django.db.utils.OperationalError: could not connect to server: No such file or directory”
【发布时间】：2018-03-22 09:34:46
【问题描述】：

我有一个带有 django 项目的 repo，并想从中创建一个 Docker 映像。我也不想在 git 中存储任何已编译的文件，因此我尝试在 Docker 映像创建期间自动创建所有工件。如果我插入： RUN python manage.py compilemessages -l en 在我的 Dockerfile 中我得到（注意所有依赖项都安装在主机上）：

Traceback (most recent call last):
  File "manage.py", line 13, in <module>
    execute_from_command_line(sys.argv)
  File "/usr/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 338, in execute_from_command_line
    utility.execute()
  File "/usr/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 312, in execute
    django.setup()
  File "/usr/local/lib/python2.7/site-packages/django/__init__.py", line 18, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/usr/local/lib/python2.7/site-packages/django/apps/registry.py", line 115, in populate
    app_config.ready()
  File "/src/playpilot/apps.py", line 21, in ready
    for ct in ContentType.objects.all():
  File "/usr/local/lib/python2.7/site-packages/django/db/models/query.py", line 162, in __iter__
    self._fetch_all()
  File "/usr/local/lib/python2.7/site-packages/django/db/models/query.py", line 965, in _fetch_all
    self._result_cache = list(self.iterator())
...

File "/usr/local/lib/python2.7/site-packages/psycopg2/__init__.py", line 164, in connect
    conn = _connect(dsn, connection_factory=connection_factory, async=async)
django.db.utils.OperationalError: could not connect to server: No such file or directory
    Is the server running locally and accepting
    connections on Unix domain socket "/tmp/.s.PGSQL.5432"?

我通过在构建脚本中运行 docker-compose 来解决这个问题（带有整个运行环境）

docker-compose up -d
docker-compose exec web ./manage.py compilemessages -l en
docker commit proj_web_1 image_name
docker-compose down

但这会增加构建时间，而且看起来是一个非常丑陋的解决方案。

manage.py 不需要连接到数据库来执行此特定任务。有没有办法运行manage.py 这样它就不会调用数据库后端？

django 版本：1.8

【问题讨论】：

标签： python django docker django-manage.py manage.py

【解决方案1】：

使用django-admin 代替manage.py：

RUN django-admin compilemessages -l en

【讨论】：

【解决方案2】：

您的问题是，当您运行 collectstatic postgres 容器已启动但 postgres 本身尚未启动时。阅读https://docs.docker.com/compose/startup-order/了解更多信息

您基本上需要做的是设置 ENTRYPOINT 以检查 postgres 是否准备好接受连接，这是我在项目中如何做的示例

#!/bin/sh
# NOTE: if there is no bash can cause
# standard_init_linux.go:190: exec user process caused "no such file or directory"

# https://docs.docker.com/compose/startup-order/
set -euo pipefail

WAIT_FOR_POSTGRES=${WAIT_FOR_POSTGRES:-true}

if [[ "$WAIT_FOR_POSTGRES" = true ]]; then
    DATABASE_URL=${DATABASE_URL:-postgres://postgres:postgres@postgres:5432/postgres}

    # convert to connection string
    # https://www.postgresql.org/docs/current/static/libpq-connect.html#LIBPQ-CONNSTRING
    POSTGRES_URL=${DATABASE_URL%%\?*}
    # https://www.gnu.org/software/bash/manual/bash.html#Shell-Parameter-Expansion
    POSTGRES_URL=${POSTGRES_URL/#postgis:/postgres:}

    # let postgres and other services (e.g. elasticsearch) to warm up...
    # https://www.caktusgroup.com/blog/2017/03/14/production-ready-dockerfile-your-python-django-app/
    until psql $POSTGRES_URL -c '\q'; do
        >&2 echo "Postgres is not available - sleeping"
        sleep 1
    done
    # >&2 echo "Postgres is up - executing command"
fi

if [[ $# -ge 1 ]]; then
    exec "$@"
else
    echo "Applying migrations"
    python manage.py migrate --noinput -v 0
    echo "Generate translations"
    python manage.py compilemessages --locale ru -v 0
    echo "Starting server"
    exec python manage.py runserver 0.0.0.0:8000
fi

【讨论】：