如何防止 docker 在 postgres 启动后退出

Question

我正在尝试在 docker 中构建一个自定义的 postgres 复制集群。我使用postgres:9.6-alpine作为我的基本映像。 这是我用来构建从属容器的Dockerfile。

// Dockerfile
FROM postgres:9.6-alpine
ENV GOSU_VERSION 1.10
RUN set -ex; 

apk add --no-cache --virtual .gosu-deps 
dpkg 
gnupg 
openssl 
; 

dpkgArch="$(dpkg --print-architecture | awk -F- '{ print $NF }')"; 
wget -O /usr/local/bin/gosu "https://github.com/tianon/gosu/releases/download/$GOSU_VERSION/gosu-$dpkgArch"; 
wget -O /usr/local/bin/gosu.asc "https://github.com/tianon/gosu/releases/download/$GOSU_VERSION/gosu-$dpkgArch.asc"; 

# verify the signature
export GNUPGHOME="$(mktemp -d)"; 
gpg --keyserver ha.pool.sks-keyservers.net --recv-keys B42F6819007F00F88E364FD4036A9C25BF357DD4; 
gpg --batch --verify /usr/local/bin/gosu.asc /usr/local/bin/gosu; 
rm -r "$GNUPGHOME" /usr/local/bin/gosu.asc; 

chmod +x /usr/local/bin/gosu; 
# verify that the binary works
gosu nobody true; 

apk del .gosu-deps
RUN apk add --update iputils
RUN apk add --update htop
# COPY ./setup-slave.sh /docker-entrypoint-initdb.d
COPY ./docker-entrypoint.sh /docker-entrypoint.sh
RUN chmod +x /docker-entrypoint.sh
CMD ["gosu", "postgres", "pg_ctl", "-D/var/lib/postgresql/data", "start"]

这是我 docker-entrypoint.sh：

#!/bin/bash
if [ ! -s "$PGDATA/PG_VERSION" ]; then
echo '*:*:*:myuser:123456' > ~/.pgpass
chmod 0600 ~/.pgpass
until ping -c 1 -W 1 pg_master
do
echo "Waiting for master to ping..."
sleep 1s
done
until pg_basebackup -h pg_master -D ${PGDATA} -U arioo -vP -W
do
echo "Waiting for master to connect..."
sleep 1s
done
echo "host replication all 0.0.0.0/0 md5" >> "$PGDATA/pg_hba.conf"
set -e  
cat >> ${PGDATA}/postgresql.conf <<EOF
wal_level = hot_standby
max_wal_senders = 8
wal_keep_segments = 32
hot_standby = off
EOF
cat > ${PGDATA}/recovery.conf <<EOF
standby_mode = on
primary_conninfo = 'host=pg_master port=5432 user=rep password=123456'
trigger_file = '/tmp/touch_me_to_promote_to_me_master'
EOF
chown postgres. ${PGDATA} -R
chmod 700 ${PGDATA} -R
fi
exec "$@"

除了一件事之外，整个事情都很好。Docker 在启动时立即退出从属容器。据我了解pg_ctl start应该在前台开始发布。但是为什么 docker 仍然退出？

我使用docker-compose来运行群集。

我什至尝试在docker-entrypoint.sh末尾放置一个无限循环，就像下面的代码一样，无论我做什么，它仍然会退出：

while true; do
sleep 1s
done

Answer 1

似乎运行postgres而不是pg_ctl start是解决方案。pg_ctl实际上是一个控制 postgres 守护进程的实用程序，因此它在后台运行 postgres 是合乎逻辑的。