将项目连接到Postgresql数据库时遇到问题(服务器是否在本地运行并接受连接？)

Question

我正在尝试连接一个ruby on rails项目来拥有一个postgresql数据库，这样我就可以在完成后部署到heroku上。我试着自己挖掘答案，对postgresql和如何调试的知识非常有限，所以如果你有任何想法，我可以做什么来解决这个问题，请非常具体。

背景信息:我做过一个项目，没有问题，但这是一个新项目，我不得不卸载并重新安装postgresql，因为另一个错误，我现在有PostgreSQL12，我相信。

我刚开始一个新项目，当运行$rake db:create时，我得到了以下错误：

Database 'gachamons_backend_development' already exists
could not connect to server: No such file or directory
        Is the server running locally and accepting
        connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?
Couldn't create 'gachamons_backend_test' database. Please check your configuration.
rails aborted!
ActiveRecord::NoDatabaseError: could not connect to server: No such file or directory
        Is the server running locally and accepting
        connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?
/mnt/c/users/adam/desktop/flatiron/gachamons-backend/bin/rails:5:in `<top (required)>'
/mnt/c/users/adam/desktop/flatiron/gachamons-backend/bin/spring:10:in `require'
/mnt/c/users/adam/desktop/flatiron/gachamons-backend/bin/spring:10:in `block in <top (required)>'
/mnt/c/users/adam/desktop/flatiron/gachamons-backend/bin/spring:7:in `tap'
/mnt/c/users/adam/desktop/flatiron/gachamons-backend/bin/spring:7:in `<top (required)>'

Caused by:
PG::ConnectionBad: could not connect to server: No such file or directory
        Is the server running locally and accepting
        connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?
/mnt/c/users/adam/desktop/flatiron/gachamons-backend/bin/rails:5:in `<top (required)>'
/mnt/c/users/adam/desktop/flatiron/gachamons-backend/bin/spring:10:in `require'
/mnt/c/users/adam/desktop/flatiron/gachamons-backend/bin/spring:10:in `block in <top (required)>'
/mnt/c/users/adam/desktop/flatiron/gachamons-backend/bin/spring:7:in `tap'
/mnt/c/users/adam/desktop/flatiron/gachamons-backend/bin/spring:7:in `<top (required)>'
Tasks: TOP => db:create
(See full trace by running task with --trace)

当我尝试使用$service postgresql status查看服务器是否已关闭时：

12/main (port 5432): down

$psql：

psql: error: could not connect to server: could not connect to server: No such file or directory
        Is the server running locally and accepting
        connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"? 

我在另一篇关于运行$dpkg -l | grep postgres的文章中看到，它产生了这个我不知道如何调试的输出：

ii  postgresql                        12+214                             all          object-relational SQL database (supported version)
ii  postgresql-12                     12.2-4                             amd64        object-relational SQL database, version 12 server
ii  postgresql-client-12              12.2-4                             amd64        front-end programs for PostgreSQL 12
ii  postgresql-client-common          214                                all          manager for multiple PostgreSQL client versions
ii  postgresql-common                 214                                all          PostgreSQL database-cluster manager
ii  postgresql-contrib                12+214                             all          additional facilities for PostgreSQL (supported version)

然后我运行了$pg_lsclusters：

12 main 5432 down postgres /var/lib/postgresql/12/main /var/log/postgresql/postgresql-12-main.log

最后是$sudo service postgresql restart

* Restarting PostgreSQL 12 database server           * Error: /usr/lib/postgresql/12/bin/pg_ctl /usr/lib/postgresql/12/bin/pg_ctl start -D /var/lib/postgresql/12/main -l /var/log/postgresql/postgresql-12-main.log -s -o  -c config_file="/etc/postgresql/12/main/postgresql.conf"  exited with status 1: 
2021-08-24 15:48:39.458 EDT [4148] LOG:  starting PostgreSQL 12.2 (Ubuntu 12.2-4) on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 9.3.0-8ubuntu1) 9.3.0, 64-bit
2021-08-24 15:48:39.460 EDT [4148] LOG:  could not bind IPv4 address "127.0.0.1": Permission denied
2021-08-24 15:48:39.460 EDT [4148] HINT:  Is another postmaster already running on port 5432? If not, wait a few seconds and retry.
2021-08-24 15:48:39.460 EDT [4148] WARNING:  could not create listen socket for "localhost"
2021-08-24 15:48:39.460 EDT [4148] FATAL:  could not create any TCP/IP sockets
2021-08-24 15:48:39.461 EDT [4148] LOG:  database system is shut down
pg_ctl: could not start server
Examine the log output. 

编辑以包含database.yml：

default: &default
  adapter: postgresql
  encoding: unicode
  # For details on connection pooling, see Rails configuration guide
  # https://guides.rubyonrails.org/configuring.html#database-pooling
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>

development:
  <<: *default
  database: gachamons_backend_development
  host: localhost
  port: 5432
  user: postgres
  password: postgres

test:
  <<: *default
  database: gachamons_backend_test
  port: 5432
  user: postgres
  password: postgres

production:
  <<: *default
  url: <%= ENV['MY_APP_DATABASE_URL'] %>

这些都是我试图调试的东西，但我还不够熟悉，无法理解输出的含义。任何详细的解释，以便我可以理解下一次将不胜感激，让我从a到b。非常感谢。

Answer 1

从上面的输出可以看出，postgresql数据库已关闭。在postgresql配置文件(/etc/postgresql/12/main/postgresql.conf)中，输入: listen_addresses='*‘

然后重启postgresql。

Answer 2

user @engineersmnky指出，database.yml中的测试环境没有主机，在尝试创建数据库时会产生多个错误。