尝试使用Docker Compose实现Flask + PostgreSQL + Nginx的简单设置，如果我删除数据库连接逻辑，一切似乎都可以工作，但是如果不删除，它会无法解析服务名称而无法连接到数据库：
来自Flask的错误：
来自Flask的错误：
app_1 | {for debug, conn string used} postgresql://postgres:kftxx2h9mvOqhz3zyLIL-NG7RiUabFEzdCQCNtska-OmeASaSFk3frbKJMVqsZ@postgres:5432/postgres
app_1 | {for debug, start timestamp of first attempt to connect} 2018-03-25 18:38:48.898683
app_1 | Error: (psycopg2.OperationalError) could not translate host name "postgres" to address: Name or service not known
app_1 | (Background on this error at: http://sqlalche.me/e/e3q8)
That last error repeats bunch of times, since I'm making multiple attempts to connect until it succeeds.
postgres_1 | 2018-03-25 18:38:38.871 UTC [1] LOG: listening on IPv4 address "0.0.0.0", port 5432
postgres_1 | 2018-03-25 18:38:38.871 UTC [1] LOG: listening on IPv6 address "::", port 5432
postgres_1 | 2018-03-25 18:38:38.875 UTC [1] LOG: listening on Unix socket "/var/run/postgresql/.s.PGSQL.5432"
postgres_1 | 2018-03-25 18:38:38.891 UTC [19] LOG: database system was shut down at 2018-03-25 18:38:37 UTC
postgres_1 | 2018-03-25 18:38:38.896 UTC [1] LOG: database system is ready to accept connections
请注意，问题并不是当我尝试建立连接时Postgres还没有准备好（请检查时间戳+如果失败则在Python中尝试多次建立连接，并在每个连接之间设置小的延迟）。
Compose：
version: '2'
services:
data:
image: postgres:latest
volumes:
- /var/lib/postgresql
command: "true"
postgres:
restart: always
image: postgres:latest
env_file:
- db_env_file
volumes_from:
- data
ports:
- "5432:5432"
expose:
- "5432"
app:
restart: always
build: ./app
env_file:
- app_env_file
networks:
- mainnet
depends_on:
- "postgres"
links:
- postgres:postgres
volumes:
- ./app:/usr/src/app
nginx:
restart: always
build: ./nginx
networks:
- mainnet
links:
- app
volumes:
- ./app/static:/usr/share/nginx/html
ports:
- "80:8080"
networks:
mainnet:
db_env_file
POSTGRES_USER=postgres
POSTGRES_DB=postgres
POSTGRES_PASSWORD=kftxx2h9mvOqhz3zyLIL-NG7RiUabFEzdCQCNtska-OmeASaSFk3frbKJMVqsZ
PGDATA=/var/lib/postgresql/data/app_db_data
app_env_file
PYTHONUNBUFFERED=1 APP_DB_CONNECT_STRING=postgresql://postgres:kftxx2h9mvOqhz3zyLIL-NG7RiUabFEzdCQCNtska-OmeASaSFk3frbKJMVqsZ@app_db:5432/postgres
这是一个名为“app_env_file”的变量，其中包含两个参数：PYTHONUNBUFFERED和APP_DB_CONNECT_STRING。其中，APP_DB_CONNECT_STRING是一个PostgreSQL数据库连接字符串，用于连接应用程序与数据库。DEBUG_ENABLE=true
APP_SECRET=5:G[m+^]`^a|>^F^t8@5r/?$}S'S$(3q"{0qZN%JH!wYlwp"~"Gcw{Wd7CP]=K&P=R6klvzcg1]"!j+EY!lYJBtR:HLlXIqg#h$Uimb8ZycZg`>(1KvdNAxV16o62sF~_$Spo1+G-c-/k"Nlv(:>d5<~=X!M2iz0kc(5xZg^*MR$S.cp^^d7osHBsz<6Xsov8-X&1]LTzscCv1G}]RUsWP@v
DB_NAME=postgres
DB_USER=postgres
DB_PASS=kftxx2h9mvOqhz3zyLIL-NG7RiUabFEzdCQCNtska-OmeASaSFk3frbKJMVqsZ
DB_SERVICE=postgres
DB_PORT=5432
连接逻辑：
print("Connecting...", file=sys.stderr)
print(self.db_connect_string)
print(datetime.datetime.now())
connected = False
connectCount = 0
while not connected:
if connectCount > 0:
sleep(1.0)
connectCount += 1
try:
conn = self.engine.connect()
conn.close()
connected = True
except OperationalError as e:
if connectCount > 100:
raise
print("Error: " + str(e), file=sys.stderr)
尝试将连接URI更改为本地主机，同时在PostgreSQL中添加'expose: 5432'，但并没有真正帮助解决问题。