[k8s]args指令案例-彻底理解docker entrypoint
需求:
搞个镜像,可以运行java -jar xxx.jar包,xxx.jar包名称要用参数传
- 思路1: 打对应运行jar包的jdk的image.
- 思路2: 打通用jdk
1, 运行指定jar的指定版的jdk
- k8s运行该image遇到的问题
- kubectl create -f sms.yaml时报
rpc error: code = 2 desc = failed to start container "cffbbc3d295f7b5a8d497c8147f7222636b51647387cda491a89d292437c7e47": Error response from daemon: {"message":"invalid header field value \"oci runtime error: container_linux.go:247: starting container process caused \\\"exec: \\\\\\\"/tmp/sms-xx.jar\\\\\\\": permission denied\\\"\\n\""} - 1
- 等了一会pod奔溃了,报错
failed to open log file "/var/log/pods/6533426e-aeec-11e7-b1c6-025622f1d9fa/sms-test_3.log": open /var/log/pods/6533426e-aeec-11e7-b1c6-025622f1d9fa/sms-test_3.log: no such file or directory - 1
gg了好一阵,没发现方法解决
- 这是我的yaml
sms.yaml
apiVersion: v1
kind: Pod
metadata:
name: sms-test
labels:
app: sms-test
spec:
containers:
- name: sms-test
image: sms
imagePullPolicy: IfNotPresent
command: ["/tmp/sms-xxx.jar"]
volumeMounts:
- mountPath: /tmp
name: test-volume
volumes:
- name: test-volume
hostPath:
path: /tmp报错问题见上!
- 但是我这样启镜像是正常的
#vm的tmp下放xxx.jar,挂到容器里
docker run -v /tmp:/tmp -itd sms ‘/tmp/sms-xxx.jar‘- 1
- 2
我一般处理容器化业务思路:
0,物理vm先打通该服务. 1. 打docker镜像.docker run先跑起来. 2.写yaml改造成k8s
- 我安装思路1定义运行jar包的jdk:的dockerfile
Dockerfile
FROM airdock/base:jessie
RUN mkdir -p /srv/java/
# Add java dynamic memory script
COPY java-dynamic-memory-opts /srv/java/
# Install Oracle JDK 8u25
RUN cd /tmp && curl -L -O "http://xxx/jdk-8u25-linux-x64.gz" && tar xf jdk-8u25-linux-x64.gz -C /srv/java && rm -f jdk-8u25-linux-x64.gz && ln -s /srv/java/jdk* /srv/java/jdk && ln -s /srv/java/jdk /srv/java/jvm && chown -R java:java /srv/java && /root/post-install
# Define commonly used JAVA_HOME variable
# Add /srv/java and jdk on PATH variable
ENV JAVA_HOME=/srv/java/jdk PATH=${PATH}:/srv/java/jdk/bin:/srv/java
COPY docker-entrypoint.sh /bin/
ENTRYPOINT ["docker-entrypoint.sh"]docker-entrypoint.sh
#!/bin/bash
java -jar $1嗯哼? 没毛病.
解决k8s运行定制jdk环境的问题:
方法: yaml里command换args指令即可.
sms.yaml
...
spec:
containers:
- name: sms-test
image: sms
imagePullPolicy: IfNotPresent
args: ["/tmp/sms-xxx.jar"]
...docker run -v /tmp:/tmp -itd sms ‘/tmp/sms-xxx.jar‘
这里args,而非commands- 1
- 2
2, 使jdk环境通用化
想想为了运行一个jar包,定义个运行jar的jdk环境,有点得不偿失.思路:为了通用性,搞个指定版本jdk image,管他运行什么呢.
Dockerfile
FROM airdock/base:jessie
RUN mkdir -p /srv/java/
# Add java dynamic memory script
COPY java-dynamic-memory-opts /srv/java/
# timezone 这里把时区改掉
COPY localtime /etc/localtime
# Install Oracle JDK 8u25
RUN cd /tmp && curl -L -O "http://xxx/jdk-8u25-linux-x64.gz" && tar xf jdk-8u25-linux-x64.gz -C /srv/java && rm -f jdk-8u25-linux-x64.gz && ln -s /srv/java/jdk* /srv/java/jdk && ln -s /srv/java/jdk /srv/java/jvm && chown -R java:java /srv/java && /root/post-install
# Define commonly used JAVA_HOME variable
# Add /srv/java and jdk on PATH variable
ENV JAVA_HOME=/srv/java/jdk PATH=${PATH}:/srv/java/jdk/bin:/srv/javaapiVersion: v1
kind: Pod
metadata:
name: sms-test
labels:
app: sms-test
spec:
containers:
- name: sms-test
image: jdk8u25-ori
imagePullPolicy: IfNotPresent
command: ["java","-jar","/tmp/sms-xxx.jar"]
volumeMounts:
- mountPath: /tmp
name: test-volume
volumes:
- name: test-volume
hostPath:
path: /data经过观察jar包运行良好.
可见理解k8s yaml指令还是有点必要的.不然天天闲的蛋疼,没事干. 人生最大的敌人是无聊.
彻底理解entrypiont-命令行揉搓挤捏
指定entrypiont
- 错误的姿势
docker run -itd -v /tmp/:/tmp/ jdk-ori ‘java -jar /tmp/sms.jar‘- 正确的姿势1
docker run -itd -v /tmp/:/tmp/ jdk-ori java -jar ‘/tmp/sms.jar‘- 正确姿势2:
docker run -it -itd -v /tmp/:/tmp/ --entrypoint /srv/java/jdk/bin/java jdk-ori -jar /tmp/sms.jar
--entrypoint "/srv/java/jdk/bin/java -jar" 这样是不支持的, 这个传参方式不能加参数 ,而dockerfile里则可以- 正确姿势3: 挂脚本方式
$ cat /tmp/entry.sh
#!/bin/bash
java -jar $1
docker run -it --rm -v /tmp/:/tmp/ --entrypoint "/tmp/entry.sh" jdk-ori /tmp/sms.jar也可以指定这些:
https://docs.docker.com/engine/reference/run/#entrypoint-default-command-to-execute-at-runtime
CMD (Default Command or Options)
ENTRYPOINT (Default Command to Execute at Runtime)
EXPOSE (Incoming Ports)
ENV (Environment Variables)
HEALTHCHECK
VOLUME (Shared Filesystems)
USER
WORKDIR如何在k8s里指定docker run -w 的workdir
思路: 可以通过env方式
[[email protected] ma]# cat centos.yaml
apiVersion: v1
kind: Pod
metadata:
name: my-centos
labels:
app: centos
spec:
containers:
- name: my-centos
image: centos:6.8
imagePullPolicy: IfNotPresent
command: ["top","-b"]
env:
- name: PWD
value: "/tmp"一个计时的pod
apiVersion: v1
kind: Pod
metadata:
name: counter
spec:
containers:
- name: count
image: busybox
args: [/bin/sh, -c,
‘i=0; while true; do echo "$i: $(date)"; i=$((i+1)); sleep 1; done‘]https://k8smeetup.github.io/docs/concepts/cluster-administration/logging/
原文地址：https://www.cnblogs.com/gaoyuechen/p/11811180.html
时间： 2024-08-25 06:06:25