flyway 无法连接到 docker-entrypoint-initdb.d 脚本中的 postgres 容器

Question

我正在尝试将postgres Docker映像扩展为可能（通过环境变量标志）在 DB init 上执行 flyway DB 迁移。我的 Dockerfile 在这里：

FROM postgres:9.6

# Install curl and java (for Flyway)
RUN set -x \
    && apt-get update \
    && apt-get install -y --no-install-recommends ca-certificates curl openjdk-8-jre 

# Install Flyway
ENV FLYWAY_VERSION 4.2.0
ENV FLYWAY_INSTALL_DIR /usr/src/flyway
ENV FLYWAY_CONF ${FLYWAY_INSTALL_DIR}/flyway-${FLYWAY_VERSION}/conf/flyway.conf
ENV FLYWAY_EXE ${FLYWAY_INSTALL_DIR}/flyway-${FLYWAY_VERSION}/flyway
RUN mkdir -p ${FLYWAY_INSTALL_DIR} && \
    curl -L https://repo1.maven.org/maven2/org/flywaydb/flyway-commandline/${FLYWAY_VERSION}/flyway-commandline-${FLYWAY_VERSION}.tar.gz | \
    tar -xzC ${FLYWAY_INSTALL_DIR} && \
    chmod +x ${FLYWAY_EXE}

# Copy migration scripts
ENV MIGRATIONS_LOCATION /flyway/migrations
COPY migrations $MIGRATIONS_LOCATION

COPY init_db.sh /docker-entrypoint-initdb.d/init_db.sh

使用我的init_db.sh启动脚本：

#!/bin/bash
set -e

RUN_MIGRATIONS="${RUN_MIGRATIONS:-false}"
DB_URL="jdbc:postgresql://localhost:5432/$DB_NAME"

psql -v ON_ERROR_STOP=1 --username "$POSTGRES_USER" <<-EOSQL
    CREATE DATABASE $DB_NAME;
EOSQL

if [ "$RUN_MIGRATIONS" == "true" ]; then
        echo "running migrations ..."
        ${FLYWAY_EXE} -user=$POSTGRES_USER -password=$POSTGRES_PASSWORD -url=$DB_URL -locations="filesystem:$MIGRATIONS_LOCATION" migrate
fi

但是，使用 运行容器时RUN_MIGRATIONS=true，flyway 无法连接到 postgres：

docker build . -t postgres-flyway && docker run -e DB_NAME=db -e RUN_MIGRATIONS=true -e POSTGRES_USER=postgres -e POSTGRES_PASSWORD=postgres postgres-flyway
The files belonging to this database system will be owned by user "postgres".
This user must also own the server process.

The database cluster will be initialized with locale "en_US.utf8".
The default database encoding has accordingly been set to "UTF8".
The default text search configuration will be set to "english".

Data page checksums are disabled.

fixing permissions on existing directory /var/lib/postgresql/data ... ok
creating subdirectories ... ok
selecting default max_connections ... 100
selecting default shared_buffers ... 128MB
selecting dynamic shared memory implementation ... posix
creating configuration files ... ok
running bootstrap script ... ok
performing post-bootstrap initialization ... ok
syncing data to disk ... ok

WARNING: enabling "trust" authentication for local connections
You can change this by editing pg_hba.conf or using the option -A, or
--auth-local and --auth-host, the next time you run initdb.

Success. You can now start the database server using:

    pg_ctl -D /var/lib/postgresql/data -l logfile start

waiting for server to start....LOG:  database system was shut down at 2018-08-06 02:19:32 UTC
LOG:  MultiXact member wraparound protections are now enabled
LOG:  autovacuum launcher started
LOG:  database system is ready to accept connections
 done
server started
ALTER ROLE


/usr/local/bin/docker-entrypoint.sh: sourcing /docker-entrypoint-initdb.d/init_db.sh
CREATE DATABASE
running migrations ...
Flyway 4.2.0 by Boxfuse

ERROR:
Unable to obtain Jdbc connection from DataSource (jdbc:postgresql://localhost:5432/db) for user 'postgres': Connection to localhost:5432 refused. Check that the hostname and port are correct and that the postmaster is accepting TCP/IP connections.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
SQL State  : 08001
Error Code : 0
Message    : Connection to localhost:5432 refused. Check that the hostname and port are correct and that the postmaster is accepting TCP/IP connections.

postgres 映像在端口 5432 上运行 postgres（像往常一样），所以我不知道为什么 flyway 无法通过localhost:5432.

我还注意到，在这种情况下，pg_isready声明 postgres 正在接受连接，但是当将主机名指定为时，localhost或者127.0.0.1它也无法访问 postgres。也就是说，通过pg_isready在我的init_db.sh脚本中插入一些命令：

...
pg_isready
pg_isready -p 5432
pg_isready -h localhost -p 5432
...

我在 postgres init 上看到以下日志输出：

...
/var/run/postgresql:5432 - accepting connections
/var/run/postgresql:5432 - accepting connections
localhost:5432 - no response
...

我怀疑我已经达到了 postgres 初始化上下文的限制，但我想了解为什么localhost/127.0.0.1:5432在初始化时无法访问 postgres 。

Answer 1

我在挖掘图像入口点脚本时发现了这个问题。最近对图像的更改限制 postgres 在内部初始化期间仅侦听 unix 域套接字上的连接：https://github.com/docker-library/postgres/pull/440