容器的缓存数据

容器的缓存数据

许多构建工具都会下载外部依赖并将它们缓存到本地以便于将来的使用。 由于容器最初是由 "干净的" 文件系统构建的, 这导致流水线速度变慢, 因为它们不会利用后续流水线运行的磁盘缓存。 on-disk caches between subsequent Pipeline runs.

流水线支持 向Docker中添加自定义的参数, 允许用户指定自定义的 Docker Volumes 装在, 这可以用于在流水线运行之间的 agent上缓存数据。下面的示例将会在 流水线运行期间使用 maven container缓存 ~/.m2, 从而避免了在流水线的后续运行中重新下载依赖的需求。
Jenkinsfile (Declarative Pipeline)

pipeline {
    agent {
        docker {
            image 'maven:3-alpine'
            args '-v $HOME/.m2:/root/.m2'
        }
    }
    stages {
        stage('Build') {
            steps {
                sh 'mvn -B'
            }
        }
    }
}

Reusing the Maven local repository

The local Maven repository can be reused across containers by creating a volume and mounting it in /root/.m2.

$ docker volume create --name maven-repo
$ docker run -it -v maven-repo:/root/.m2 maven mvn archetype:generate # will download artifacts
$ docker run -it -v maven-repo:/root/.m2 maven mvn archetype:generate # will reuse downloaded artifacts

Or you can just use your home .m2 cache directory that you share e.g. with your Eclipse/IDEA:

$ docker run -it --rm -v "$PWD":/usr/src/mymaven -v "$HOME/.m2":/root/.m2 -v "$PWD/target:/usr/src/mymaven/target" -w /usr/src/mymaven maven mvn clean package

Create and manage volumes

Unlike a bind mount, you can create and manage volumes outside the scope of any container.

Create a volume:

$ docker volume create my-vol

List volumes:

$ docker volume ls

local my-vol

Inspect a volume:

$ docker volume inspect my-vol
[
    {
        "Driver": "local",
        "Labels": {},
        "Mountpoint": "/var/lib/docker/volumes/my-vol/_data",
        "Name": "my-vol",
        "Options": {},
        "Scope": "local"
    }
]

Remove a volume:

$ docker volume rm my-vol

Start a container with a volume

If you start a container with a volume that does not yet exist, Docker creates the volume for you. The following example mounts the volume myvol2 into /app/ in the container.

The -v and --mount examples below produce the same result. You can’t run them both unless you remove the devtest container and the myvol2 volume after running the first one.

$ docker run -d \
  --name devtest \
  --mount source=myvol2,target=/app \
  nginx:latest
$ docker run -d \
  --name devtest \
  -v myvol2:/app \
  nginx:latest

Use docker inspect devtest to verify that the volume was created and mounted correctly. Look for the Mounts section:

"Mounts": [
    {
        "Type": "volume",
        "Name": "myvol2",
        "Source": "/var/lib/docker/volumes/myvol2/_data",
        "Destination": "/app",
        "Driver": "local",
        "Mode": "",
        "RW": true,
        "Propagation": ""
    }
],

This shows that the mount is a volume, it shows the correct source and destination, and that the mount is read-write.

Stop the container and remove the volume. Note volume removal is a separate step.

$ docker container stop devtest
$ docker container rm devtest
$ docker volume rm myvol2