psql: 致命错误: 用户 "postgres" Ident 认证失败

修改认证文件/var/lib/pgsql/data/pg_hba.conf，登陆使用密码。

#vi /var/lib/pgsql/data/pg_hba.conf

把这个配置文件中的认证 METHOD的ident修改为trust，可以实现用账户和密码来访问数据库，

即解决psql: 致命错误: 用户 "postgres" Ident 认证失败 这个问题）

第五步：重启postgresql服务器使设置生效

#service postgresql-9.4 restart

或者

#systemctl restart postgresql.service

这样问题就解决了，数据库可以正常被rails项目访问了

pg_hba.conf这个文件的完整代码如下：

#=========================================

# PostgreSQL Client Authentication Configuration File

# ===================================================

#

# Refer to the "Client Authentication" section in the PostgreSQL

# documentation for a complete description of this file. A short

# synopsis follows.

#

# This file controls: which hosts are allowed to connect, how clients

# are authenticated, which PostgreSQL user names they can use, which

# databases they can access. Records take one of these forms:

#

# local DATABASE USER METHOD [OPTIONS]

# host DATABASE USER ADDRESS METHOD [OPTIONS]

# hostssl DATABASE USER ADDRESS METHOD [OPTIONS]

# hostnossl DATABASE USER ADDRESS METHOD [OPTIONS]

#

# (The uppercase items must be replaced by actual values.)

#

# The first field is the connection type: "local" is a Unix-domain

# socket, "host" is either a plain or SSL-encrypted TCP/IP socket,

# "hostssl" is an SSL-encrypted TCP/IP socket, and "hostnossl" is a

# plain TCP/IP socket.

#

# DATABASE can be "all", "sameuser", "samerole", "replication", a

# database name, or a comma-separated list thereof. The "all"

# keyword does not match "replication". Access to replication

# must be enabled in a separate record (see example below).

#

# USER can be "all", a user name, a group name prefixed with "+", or a

# comma-separated list thereof. In both the DATABASE and USER fields

# you can also write a file name prefixed with "@" to include names

# from a separate file.

#

# ADDRESS specifies the set of hosts the record matches. It can be a

# host name, or it is made up of an IP address and a CIDR mask that is

# an integer (between 0 and 32 (IPv4) or 128 (IPv6) inclusive) that

# specifies the number of significant bits in the mask. A host name

# that starts with a dot (.) matches a suffix of the actual host name.

# Alternatively, you can write an IP address and netmask in separate

# columns to specify the set of hosts. Instead of a CIDR-address, you

# can write "samehost" to match any of the server's own IP addresses,

# or "samenet" to match any address in any subnet that the server is

# directly connected to.

#

# METHOD can be "trust", "reject", "md5", "password", "gss", "sspi",

# "krb5", "ident", "peer", "pam", "ldap", "radius" or "cert". Note that

# "password" sends passwords in clear text; "md5" is preferred since

# it sends encrypted passwords.

#

# OPTIONS are a set of options for the authentication in the format

# NAME=VALUE. The available options depend on the different

# authentication methods -- refer to the "Client Authentication"

# section in the documentation for a list of which options are

# available for which authentication methods.

#

# Database and user names containing spaces, commas, quotes and other

# special characters must be quoted. Quoting one of the keywords

# "all", "sameuser", "samerole" or "replication" makes the name lose

# its special character, and just match a database or username with

# that name.

#

# This file is read on server startup and when the postmaster receives

# a SIGHUP signal. If you edit the file on a running system, you have

# to SIGHUP the postmaster for the changes to take effect. You can

# use "pg_ctl reload" to do that.

# Put your actual configuration here

# ----------------------------------

#

# If you want to allow non-local connections, you need to add more

# "host" records. In that case you will also need to make PostgreSQL

# listen on a non-local interface via the listen_addresses

# configuration parameter, or via the -i or -h command line switches.

# TYPE DATABASE USER ADDRESS METHOD

# "local" is for Unix domain socket connections only

local all all trust

# IPv4 local connections:

host all all 127.0.0.1/32 trust

# IPv6 local connections:

host all all ::1/128 trust

# Allow replication connections from localhost, by a user with the

# replication privilege.

#local replication postgres peer

#host replication postgres 127.0.0.1/32 ident

#host replication postgres ::1/128 ident

#=========================================