wen Docker-Java限制cpu和内存及浅析源码解决docker磁盘挂载失效问题
需求
之前工作流的运行都是用的docker-java提供的api拉起的docker容器直接跑服务，但是最新线上的新业务资源消耗较大，单个容器如果不加控制，CPU和内存都会拉满，导致服务器莫名宕机事故的发生，所以Docker限制cpu使用率和内存限制就得安排上
实施
HostConfig构建
自定义HostConfig，设置cpu和内存限制，pipeline配置了就按照配置来，如果没有就走默认配置
public void setUp() {
this.dockerHostConfig = new HostConfig();
Double memoryValue = this.pipeline.getMemory() != null
? this.pipeline.getMemory() * 1024 * 1024 * 1024
: this.config.getDefaultMemoryLimitInGb() * 1024 * 1024 * 1024;
this.dockerHostConfig.withMemory(memoryValue.longValue());
double cpu = StringUtils.isNotBlank(this.pipeline.getCpu())
? Double.parseDouble(this.pipeline.getCpu())
: this.config.getDefaultCpuCoreLimit();
// 单个 CPU 为 1024，两个为 2048，以此类推
this.dockerHostConfig.withCpuShares((int)(cpu * 1024));
}
CreateContainerCmd 构建
public String startContainer(String image,
String name,
List<ContainerPortBind> portBinds,
List<ContainerVolumeBind> volumeBinds,
List<String> extraHosts,
List<String> envs,
List<String> entrypoints,
HostConfig hostConfig,
String... cmds) {
List<Volume> volumes = new ArrayList<>();
List<Bind> volumesBinds = new ArrayList<>();
……
……
……
CreateContainerCmd cmd = this.client.createContainerCmd(image)
.withName(name)
.withVolumes(volumes)
.withBinds(volumesBinds);
if (portBinds != null && portBinds.size() > 0) {
cmd = cmd.withPortBindings(portBindings);
}
if (cmds != null && cmds.length > 0) {
cmd = cmd.withCmd(cmds);
}
if (extraHosts != null && extraHosts.size() > 0) {
cmd.withExtraHosts(extraHosts);
}
if (envs != null) {
cmd.withEnv(envs);
}
if (entrypoints != null) {
cmd.withEntrypoint(entrypoints);
}
// 这一句是重点
cmd.withHostConfig(hostConfig);
CreateContainerResponse container = cmd.exec();
this.client.startContainerCmd(container.getId()).exec();
return container.getId();
}
docker inspect containerId
执行 docker inspect a436678ccb0c 结果如下
"HostConfig": {
"Binds": [],
"ContainerIDFile": "",
"LogConfig": {
"Type": "json-file",
"Config": {
"max-file": "3",
"max-size": "10m"
}
},
"NetworkMode": "default",
"PortBindings": null,
"RestartPolicy": {
"Name": "",
"MaximumRetryCount": 0
}
"CpuShares": 2048,
"Memory": 6442450944,
"NanoCpus": 0,
"CgroupParent": "",
"BlkioWeight": 0,
"BlkioWeightDevice": null
}
CpuShares和Memory已经是我们设置的默认值，API生效，我们再来看下执行的日志
proc "pipeline_task_4b86c7830e4c4e39a77c454589c9e7e9_1" starting 2021-09-22 17:30:15 logPath:/mnt/xx/xx/logs/2021/09/22/bfbadf65-ac41-459d-a96d-3dc9a0105c25/job.log
+ java -jar /datavolume/xxx/xx.jar --spring.profiles.active=test
STDERR: Error: Unable to access jarfile /datavolume/xxx/xx.jar
5c494aeacb87af3a46a4fedc6e695ae888d4d2b9d7e603f24ef7fe114956c782 finished!
proc "pipeline_task_4b86c7830e4c4e39a77c454589c9e7e9_1" exited with status 1
proc "新增节点" error
start to kill all pipeline task
pipeline exit with error
执行文件没有找到，向上看Binds为空，所以挂载丢了，可以为什么了？明明 withVolumes() 和 withBinds() 两个方法逻辑都没有动，还是看下源码分析一下吧
问题定位与解决
看源码之前我们先了解一下docker的hostConfig，文件路径在：/var/lib/docker/containers//hostconfig.json
其实这个就是容器运行的宿主机配置，磁盘绑定，cpu、内存限制、DNS、网络以及种种配置都在这个文件中，docker-java中HostConfig对象其实就是这个json对应的model，我们自定义了HostConfig对象，问题应当是出在 cmd.withHostConfig(hostConfig); 这一句代码上
以前的绑定逻辑
之前没有限制，所以在实例化CreateContainerCmd时候没有定制HostConfig参数
CreateContainerCmd cmd = this.client.createContainerCmd(image)
.withName(name)
.withVolumes(volumes)
.withBinds(volumesBinds);
CreateContainerCmd withBinds
/**
*
* @deprecated see {@link #getHostConfig()}
*/
@Deprecated
default CreateContainerCmd withBinds(Bind... binds) {
Objects.requireNonNull(binds, "binds was not specified");
getHostConfig().setBinds(binds);
return this;
}
getHostConfig() 方法追溯到实现类 CreateContainerCmdImpl hostConfig是直接在类实例化的时候new出来的一个新对象
@JsonProperty("HostConfig")
private HostConfig hostConfig = new HostConfig();
我们再看下 CreateContainerCmd 的 withHostConfig() 方法，代码也是在实现类里面
@Override
public CreateContainerCmd withHostConfig(HostConfig hostConfig) {
this.hostConfig = hostConfig;
return this;
}
直接覆盖了对象中原来的hostConfig, 我们的withHostConfig又在最后调用的可不就把挂载丢了吗，正好CreateContainerCmd 的 withBinds 方法也被 @Deprecated 修饰了，我们就来调整一下代码
public String startContainer(String image,
String name,
List<ContainerPortBind> portBinds,
List<ContainerVolumeBind> volumeBinds,
List<String> extraHosts,
List<String> envs,
List<String> entrypoints,
HostConfig hostConfig,
String... cmds) {
List<Volume> volumes = new ArrayList<>();
List<Bind> volumesBinds = new ArrayList<>();
……
//这一行很关键
hostConfig.withBinds(volumesBinds);
if (portBinds != null && portBinds.size() > 0) {
hostConfig.withPortBindings(portBindings);
}
if (extraHosts != null && extraHosts.size() > 0) {
hostConfig.withExtraHosts(extraHosts.toArray(new String[extraHosts.size()]));
}
CreateContainerCmd cmd = this.client.createContainerCmd(image).withHostConfig(hostConfig)
.withName(name)
.withVolumes(volumes);
if (cmds != null && cmds.length > 0) {
cmd = cmd.withCmd(cmds);
}
if (envs != null) {
cmd.withEnv(envs);
}
if (entrypoints != null) {
cmd.withEntrypoint(entrypoints);
}
CreateContainerResponse container = cmd.exec();
this.client.startContainerCmd(container.getId()).exec();
return container.getId();
};
OK，搞定，docker stats 查看容器的cpu占用，始终不会超过200%
参考链接
https://github.com/docker-java/docker-java
