Docker

注意

Docker 在创建新网络时，会从一组默认的私有网段池里“挑”一个未用的范围（172.17.0.0/16 开始，依次递增）。

告诉 Docker 不要用 172.18.0.0/16，换成别的网段

networks:
redis_net:
driver: bridge
ipam:
config:
- subnet: 172.30.0.0/16
gateway: 172.30.0.1

出现这种问题可以使用 ip route show 查看ip路由

排查

docker run -it --entrypoint /bin/sh docker-image

Docker compose

environment variables

Dockerfile

DockerCompose

Composefile

• remove none image

docker image prune

• Docker 的缓存机制

COPY requirements.txt .
RUN pip install -r requirements.txt

## RUN pip install "..."   替换这个 可以使用缓存

RUN pip install "..." 就像每次都在写一篇新文章，哪怕内容一样，文件名都不同，系统不认缓存。

COPY requirements.txt && pip install -r 就像你上传一份清单，只有清单变了才重新下载。

entrypoint and cmd

Great question! The difference between `ENTRYPOINT` and `CMD` in Docker is subtle but important, especially for how the container runs and how you can override commands.

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### Why use `ENTRYPOINT` vs `CMD`?

#### 1. `ENTRYPOINT`

* Defines the **main executable** that always runs when the container starts.
* You can **append arguments** to the `docker run` command, and those will be passed as parameters to the entrypoint.
* Useful when you want the container to behave like a specific program or tool, but still accept flexible arguments.

Example:

```Dockerfile
ENTRYPOINT ["python", "bin/datax.py"]

If you run:

docker run datax-image /opt/datax/job/job.json

It executes:

python bin/datax.py /opt/datax/job/job.json

---

2. CMD

• Provides default arguments to the container’s command.
• Can be overridden entirely by passing a new command in docker run.
• If you use CMD alone without ENTRYPOINT, the entire command can be replaced.

Example:

CMD ["python", "bin/datax.py"]

If you run:

docker run datax-image /opt/datax/job/job.json

Docker will ignore the CMD and try to run /opt/datax/job/job.json as a command, which will fail.

---

Which one to use for DataX?

• Using ENTRYPOINT for python bin/datax.py makes the container act like the DataX executable.
• You then just pass the job JSON file as an argument when running the container.
• If you used CMD, running the container with extra arguments would replace the entire command, which is usually not what you want.

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TL;DR

• Use ENTRYPOINT when you want a fixed executable and flexible arguments.
• Use CMD when you want default commands/args but allow full override.

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Want me to help you adjust your Dockerfile to work perfectly with your workflow?