python - 无法从 Python 连接到 Docker Postgresql 实例

Question

我正在使用 Docker 来“容器化”一个 PostgreSQL 部署。我可以启动容器并通过命令行连接到 PostgreSQL，如下所示:

minime2@CEBERUS:~/Projects/skunkworks$ docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS               NAMES
dc176901052a        df:pg               "docker-entrypoint..."   About an hour ago   Up About an hour    5432/tcp            vigilant_agnesi

minime2@CEBERUS:~/Projects/skunkworks$ CONTAINER_ID=dc176901052a
minime2@CEBERUS:~/Projects/skunkworks$ IP=$(docker inspect -f '{{.NetworkSettings.Networks.bridge.IPAddress}}' $CONTAINER_ID)

minime2@CEBERUS:~/Projects/skunkworks$ echo $IP
172.17.0.2


minime2@CEBERUS:~/Projects/skunkworks$ docker exec -it vigilant_agnesi psql -U postgres -W cookiebox
Passwod for user postgres:
psql (9.6.5)
Type "help" for help

cookiebox#

现在正在尝试与 Python 连接:

Python 3.5.2 (default, Sep 14 2017, 22:51:06) 
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import psycopg2
>>> conn = psycopg2.connect("dbname='cookiebox' user='postgres' host='172.17.0.2' password='nunyabiznes'")                                     Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/minime2/Projects/skunkworks/archivers/env/lib/python3.5/site-packages/psycopg2/__init__.py", line 130, in connect
    conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
psycopg2.OperationalError: could not connect to server: Connection refused
        Is the server running on host "172.17.0.2" and accepting
        TCP/IP connections on port 5432?

>>> 

任何人都可以解释为什么我不能使用 Python 连接到 PostgreSQL - 即使我使用相同的参数/参数在命令行上启用成功连接(使用 docker exec？) .

[[附加信息]]

根据@Itvhillo 的建议，我尝试使用桌面应用程序连接到 PG 服务。我使用以下命令运行 docker 服务:

docker run -i -p 5432:5432 --name $CONTAINER_NAME $DOCKER_IMAGE

我正在使用 Db Visualizer连接到数据库，我已将主机名设置为“localhost”。我可以成功 ping 端口，但是当我尝试连接到数据库时仍然收到错误消息(可能与权限相关的错误):

An error occurred while establishing the connection:

Long Message:
The connection attempt failed.

Details:
   Type: org.postgresql.util.PSQLException
   SQL State: 08001

顺便说一下，这是 PG 服务实例的输出的尾部:

PostgreSQL init process complete; ready for start up.

LOG:  could not bind IPv6 socket: Cannot assign requested address
HINT:  Is another postmaster already running on port 5432? If not, wait a few seconds and retry.
LOG:  database system was shut down at 2018-01-30 16:21:59 UTC
LOG:  MultiXact member wraparound protections are now enabled
LOG:  database system is ready to accept connections
LOG:  autovacuum launcher started

[[附加信息2]]

这是我的 Dockerfile 的结尾:

# modified target locations (checked by login onto Docker container)
# show hba_file;
# show config_file;

#################################################################################
# From here: https://docs.docker.com/engine/examples/postgresql_service/
# Adjust PostgreSQL configuration so that remote connections to the
# database are possible.
RUN echo "host all  all    0.0.0.0/0  md5" >> /var/lib/postgresql/data/pg_hba.conf

# And add ``listen_addresses`` to ``/var/lib/postgresql/data/postgresql.conf``
RUN echo "listen_addresses='*'" >> /var/lib/postgresql/data/postgresql.conf
#################################################################################


EXPOSE 5432

# Add VOLUMEs to allow backup of config, logs and databases
VOLUME  ["/etc/postgresql", "/var/log/postgresql", "/var/lib/postgresql", "/usr/lib/postgresql/"]

Answer 1

如果你正在运行

$ docker run -i -p 5432:5432 --name $CONTAINER_NAME $DOCKER_IMAGE

然后你应该能够从主机连接到 localhost:5432。检查端口 5432 是否正在监听的最简单方法是使用 netcat。如果成功，您应该得到:

$ nc -zv localhost 5432 
Connection to localhost 5432 port [tcp/postgresql] succeeded!

在这种情况下，您应该可以使用以下方式进行连接:

>>> psycopg2.connect("dbname='cookiebox' user='postgres' host='localhost' password='nunyabiznes'") 

另一方面，如果你得到类似的东西:

$ nc -zv localhost 5432 
nc: connect to localhost port 5432 (tcp) failed: Connection refused

那么这意味着 PostgreSQL 没有监听，因此您的 Dockerfile 中有问题，您需要在 Dockerfile 上发布更多详细信息来诊断它。