Dockerfile执行Python迁移脚本异常：容器正常退出但无输出

我在完成大学作业时，需要将Postgres备份迁移至Couchbase，全程通过Docker Compose部署。目前Postgres与Couchbase初始化均正常，但执行迁移的Python脚本服务容器始终以状态码0退出，却无任何输出，容器日志为空，我怀疑脚本未被正确执行。我已将迁移脚本替换为检查Couchbase运行状态的代码，但仍无输出。

工作目录 #

Dockerfile #

FROM python:3.9

# Set the working directory in the container to /app
WORKDIR /app

# Copy the current directory contents into the container at /app
COPY . /app

# Install any needed packages specified in requirements.txt
RUN pip install --no-cache-dir -r requirements.txt

# Run script when the container launches
CMD ["python", "./migration_script.py"]

docker-compose.yml #

version: "3.9"

networks:
    backend:
        external: true

services:
  postgres_db:
    container_name: postgresdb
    image: postgres:13

    environment:
      POSTGRES_USER: "postgres"
      POSTGRES_PASSWORD: "1234"
      POSTGRES_DB: "dvdrental"

    ports:
      - "5432:5432"
    networks:
      - "backend"

  postgres_seed:
    container_name: postgresseed
    image: postgres:13
    environment:
        POSTGRES_HOST_AUTH_METHOD: "trust"
        PGPASSWORD: "1234"
    volumes:
        - ./postgres/dvdrental.tar:/tmp/dvdrental.tar:ro
    entrypoint: [ "bash", "-c", "sleep 10 && pg_restore -h postgresdb -U postgres -d dvdrental /tmp/dvdrental.tar" ]
    restart: "no"
    networks:
      - "backend"
    depends_on:
      - "postgres_db"

  adminer:
    container_name: adminer
    image: adminer
    networks:
      - "backend"
    ports:
      - "${UI_PORT?}:8080"

  couchbase_server:
    container_name: couchbase
    image: couchbase:7.1.3
    ports:
      - "8091-8094:8091-8094"
      - "11210:11210"
    networks:
      - backend

  couchbase_init:
    container_name: couchbase_init
    image: couchbase:7.1.3
    volumes:
      - ./init-couchbase.sh:/opt/init-couchbase.sh
    depends_on:
      - couchbase_server
    networks:
      - backend
    command: /bin/sh -c "chmod +x /opt/init-couchbase.sh && /opt/init-couchbase.sh"

  data_migration_service:
    container_name: data_migration
    image: alpine
    build: .
    depends_on:
      - couchbase_init
    networks:
      - backend

migration_script.py #

import time
import requests

COUCHBASE_HOST = "couchbase"  # or the appropriate host
COUCHBASE_PORT = "8091"
COUCHBASE_URL = f"http://{COUCHBASE_HOST}:{COUCHBASE_PORT}/pools"

print("Waiting for Couchbase Server to start...")

while True:
    try:
        response = requests.get(COUCHBASE_URL)
        if response.status_code == 200:
            print("Couchbase Server is up and running.")
            break
    except requests.ConnectionError:
        print("Couchbase Server is not available yet, waiting...")
    time.sleep(1)

requirements.txt #

psycopg2-binary==2.9.3
couchbase==4.1.8
requests==2.31.0

运行docker compose up的日志 #

[+] Building 0.0s (0/0)                                                                  docker:desktop-linux
[+] Running 6/6
 ✔ Container couchbase       Created                                                                     0.0s 
 ✔ Container postgresdb      Created                                                                     0.0s 
 ✔ Container adminer         Created                                                                     0.0s 
 ✔ Container couchbase_init  Created                                                                     0.0s 
 ✔ Container postgresseed    Created                                                                     0.0s 
 ✔ Container data_migration  Created                                                                     0.0s 
Attaching to adminer, couchbase, couchbase_init, data_migration, postgresdb, postgresseed
couchbase       | Starting Couchbase Server -- Web UI available at http://<ip>:8091
couchbase       | and logs available in /opt/couchbase/var/lib/couchbase/logs
adminer         | [Thu Nov 30 09:09:08 2023] PHP 7.4.33 Development Server (http://[::]:8080) started
postgresdb      | The files belonging to this database system will be owned by user "postgres".
postgresdb      | This user must also own the server process.
postgresdb      | 
postgresdb      | The database cluster will be initialized with locale "en_US.utf8".
postgresdb      | The default database encoding has accordingly been set to "UTF8".
postgresdb      | The default text search configuration will be set to "english".
postgresdb      | 
postgresdb      | Data page checksums are disabled.
postgresdb      | 
postgresdb      | fixing permissions on existing directory /var/lib/postgresql/data ... ok
postgresdb      | creating subdirectories ... ok
postgresdb      | selecting dynamic shared memory implementation ... posix
postgresdb      | selecting default max_connections ... 100
postgresdb      | selecting default shared_buffers ... 128MB
postgresdb      | selecting default time zone ... Etc/UTC
postgresdb      | creating configuration files ... ok
couchbase_init  | Waiting for Couchbase Server to start...
couchbase_init  |   % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
couchbase_init  |                                  Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
couchbase_init  | curl: (7) Failed to connect to couchbase port 8091 after 1 ms: Connection refused
postgresdb      | running bootstrap script ... ok
data_migration exited with code 0
postgresdb      | performing post-bootstrap initialization ... ok
postgresdb      | syncing data to disk ... ok
postgresdb      | 
postgresdb      | initdb: warning: enabling "trust" authentication for local connections
postgresdb      | You can change this by editing pg_hba.conf or using the option -A, or
postgresdb      | --auth-local and --auth-host, the next time you run initdb.
postgresdb      | 
postgresdb      | Success. You can now start the database server using:
postgresdb      | 
postgresdb      |     pg_ctl -D /var/lib/postgresql/data -l logfile start
postgresdb      | 
postgresdb      | waiting for server to start....2023-11-30 09:09:09.088 UTC [48] LOG:  starting PostgreSQL 13.12 (Debian 13.12-1.pgdg120+1) on aarch64-unknown-linux-gnu, compiled by gcc (Debian 12.2.0-14) 12.2.0, 64-bit
postgresdb      | 2023-11-30 09:09:09.088 UTC [48] LOG:  listening on Unix socket "/var/run/postgresql/.s.PGSQL.5432"
postgresdb      | 2023-11-30 09:09:09.091 UTC [49] LOG:  database system was shut down at 2023-11-30 09:09:08 UTC
postgresdb      | 2023-11-30 09:09:09.093 UTC [48] LOG:  database system is ready to accept connections
postgresdb      |  done
postgresdb      | server started
postgresdb      | CREATE DATABASE
postgresdb      | 
postgresdb      | 
postgresdb      | /usr/local/bin/docker-entrypoint.sh: ignoring /docker-entrypoint-initdb.d/*
postgresdb      | 
postgresdb      | waiting for server to shut down...2023-11-30 09:09:09.273 UTC [48] LOG:  received fast shutdown request
postgresdb      | .2023-11-30 09:09:09.273 UTC [48] LOG:  aborting any active transactions
postgresdb      | 2023-11-30 09:09:09.275 UTC [48] LOG:  background worker "logical replication launcher" (PID 55) exited with exit code 1
postgresdb      | 2023-11-30 09:09:09.275 UTC [50] LOG:  shutting down
postgresdb      | 2023-11-30 09:09:09.281 UTC [48] LOG:  database system is shut down
postgresdb      |  done
postgresdb      | server stopped
postgresdb      | 
postgresdb      | PostgreSQL init process complete; ready for start up.
postgresdb      | 
postgresdb      | 2023-11-30 09:09:09.393 UTC [1] LOG:  starting PostgreSQL 13.12 (Debian 13.12-1.pgdg120+1) on aarch64-unknown-linux-gnu, compiled by gcc (Debian 12.2.0-14) 12.2.0, 64-bit
postgresdb      | 2023-11-30 09:09:09.393 UTC [1] LOG:  listening on IPv4 address "0.0.0.0", port 5432
postgresdb      | 2023-11-30 09:09:09.393 UTC [1] LOG:  listening on IPv6 address "::", port 5432
postgresdb      | 2023-11-30 09:09:09.394 UTC [1] LOG:  listening on Unix socket "/var/run/postgresql/.s.PGSQL.5432"
postgresdb      | 2023-11-30 09:09:09.396 UTC [63] LOG:  database system was shut down at 2023-11-30 09:09:09 UTC
postgresdb      | 2023-11-30 09:09:09.399 UTC [1] LOG:  database system is ready to accept connections
couchbase_init  |   % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
couchbase_init  |                                  Dload  Upload   Total   Spent    Left  Speed
100   551  100   551    0     0   103k      0 --:--:-- --:--:-- --:--:--  107k
couchbase_init  | {"isAdminCreds":true,"isROAdminCreds":false,"isEnterprise":true,"allowedServices":["kv","n1ql","index","fts","cbas","eventing","backup"],"isDeveloperPreview":false,"packageVariant":"linux/docker","pools":[],"settings":[],"uuid":[],"implementationVersion":"7.1.3-3479-enterprise","componentsVersion":{"asn1":"5.0.18","os_mon":"2.7.1","lhttpc":"1.3.0","chronicle":"0.0.1","ns_server":"7.1.3-3479-enterprise","kernel":"8.3.2.1","public_key":"1.12.0.1","sasl":"4.1.2","crypto":"5.0.6.3","inets":"7.5.3.1","ssl":"10.7.3.3","stdlib":"3.17.2","ale":"0.0.0"}}SUCCESS: Cluster initialized
couchbase_init  | SUCCESS: Bucket created
couchbase_init exited with code 0
postgresseed exited with code 0

我知道脚本可能在Couchbase初始化完成前执行，但这不应导致脚本无任何输出。

内容的提问来源于stack exchange，提问作者ms_7192