在前面几部分的基础上, 我们更新一下代码，实现一个简单容器 sdocker.
sdocker目录构成
linux: # tree . ├── Makefile ├── cpu-test.c # 由cpu.c重命名 ├── memory-test.cpp # 由memory.cpp重命名 ├── resource.c # 新增用于资源管理 ├── resource.h ├── sdocker_exec.c # 模拟 docker exec └── sdocker_run.c # 由namespace.c更新而来, 模拟 docker run 0 directories, 7 files linux: #
修改点
1. 更新rootfs: a) 拷贝cpu-test/memory-test到rootfs/bin目录下, 对应的依赖库也按照先前文章介绍的方法拷贝到rootfs对应路径，方便后续进行cpu和memory测试; b) rootfs增加拷贝top命令, 方便查看cpu使用率; c) 增加rootfs/root/.bashrc, 用于设置容器的提示符, 内容如下所示: linux:~ # cat /var/lib/sdocker/rootfs/root/.bashrc export PS1="h:w $ " linux:~ # sdocker启动后的终端提示符如下所示(主机名@容器id: 路径)： sdocker@11041:/ $ 2. 增加sdocker_run程序: a) 增加cgroup资源管理文件resource.c, 可以设置memory.limit_in_bytes, memory.swappiness, cpu.cfs_period_us, cpu.cfs_quota_us. 资源管理会在启动容器进程后在/sys/fs/cgroup/{cpu,memory}下建立目录名为容器id的目录, 程序结束后删除. b) 增加信号量和共享内存, 用于主进程和容器进程间传递数据(比如容器id和rootfs路径);
c) 把proc, sys, dev, dev/pts这些都挂载到容器;
d) 默认启动的容器mount-propagation type是MS_SHARED, 容器进程mount操作在主机可见, 为了让容器mount操作主机不可见, 设置容器的propagation type为MS_PRIVATE; 3. 增加sdocker_exec程序, 通过注入namespace方式实现类似docker exec功能
基础验证
########### 启动容器, 默认执行bash ########### linux: # ./sdocker_run -h Usage: sdocker [OPTIONS] IMAGE Start a container using bash default Options: -c, --cpu-test start cpu test with high cpu program -m, --memory-test start memory test with high memory program -n, --hostname string docker hostname, default is sdocker --memory-limit bytes Memory limit, file: memory.limit_in_bytes --memory-swappiness int Tune container memory swappiness (0 to 100) , file: memory.swappiness --cpu-period int Limit CPU CFS (Completely Fair Scheduler) period, file: cpu.cfs_period_us --cpu-quota int Limit CPU CFS (Completely Fair Scheduler) quota, file: cpu.cfs_quota_us -h, --help show help linux: # ./sdocker_run /var/lib/sdocker/rootfs/ [+] start container with id 11275 sdocker@11275:/ $ ps -ef UID PID PPID C STIME TTY TIME CMD 0 1 0 0 07:47 pts/0 00:00:00 /bin/bash 0 2 1 0 07:47 pts/0 00:00:00 ps -ef sdocker@11275:/ $ ########### 启动另一个终端查看 ########### linux: # ls /sys/fs/cgroup/{cpu,memory} /sys/fs/cgroup/cpu: 11275 cpu.cfs_period_us cpu.shares cpuacct.usage_percpu cgroup.clone_children cpu.cfs_quota_us cpu.stat notify_on_release cgroup.procs cpu.rt_period_us cpuacct.stat release_agent cgroup.sane_behavior cpu.rt_runtime_us cpuacct.usage tasks /sys/fs/cgroup/memory: 11275 memory.low_limit_in_bytes memory.swappiness cgroup.clone_children memory.max_usage_in_bytes memory.usage_in_bytes cgroup.event_control memory.move_charge_at_immigrate memory.use_hierarchy cgroup.procs memory.numa_stat notify_on_release cgroup.sane_behavior memory.oom_control release_agent memory.failcnt memory.pressure_level tasks memory.force_empty memory.soft_limit_in_bytes memory.limit_in_bytes memory.stat linux: # ./sdocker_exec 11275 /var/lib/sdocker/rootfs/ sdocker@11275:/ $ ps -ef UID PID PPID C STIME TTY TIME CMD 0 1 0 0 07:47 pts/0 00:00:00 /bin/bash 0 3 0 0 07:48 pts/1 00:00:00 bash 0 4 3 0 07:48 pts/1 00:00:00 ps -ef sdocker@11275:/ $ exit exit linux: #
无资源限制测试cpu-test
########### 启动容器执行cpu-test, 理论cpu占用要到100% ########### linux: # ./sdocker_run -c /var/lib/sdocker/rootfs/ [+] start container with id 11293 ########### 启动另一个终端查看 ########### linux: # ./sdocker_exec 11293 /var/lib/sdocker/rootfs/ sdocker@11293:/ $ ps -ef UID PID PPID C STIME TTY TIME CMD 0 1 0 99 07:54 pts/0 00:00:22 /bin/cpu-test 0 2 0 0 07:54 pts/1 00:00:00 bash 0 3 2 0 07:54 pts/1 00:00:00 ps -ef $sdocker@11293:/ $ top top - 07:57:04 up 1 day, 27 min, 0 users, load average: 0.96, 0.47, 0.19 Tasks: 3 total, 2 running, 1 sleeping, 0 stopped, 0 zombie %Cpu(s): 0.1 us, 0.0 sy, 0.0 ni, 99.9 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem: 32689888 total, 1003220 used, 31686668 free, 2204 buffers KiB Swap: 33551356 total, 0 used, 33551356 free. 500328 cached Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1 0 20 0 4052 172 136 R 100.00 0.001 3:03.84 cpu-test 2 0 20 0 11576 2916 2548 S 0.000 0.009 0:00.00 bash 4 0 20 0 11348 1924 1712 R 0.000 0.006 0:00.00 top sdocker@11293:/ $ exit exit linux: #
有资源限制测试cpu-test, 限制cpu使用率20%
########### 启动容器执行cpu-test, 设置cpu占用率不超过20% ########### linux: # ./sdocker_run -c --cpu-quota 20000 /var/lib/sdocker/rootfs/ [+] start container with id 11362 ########### 启动另一个终端查看 ########### linux: # ./sdocker_exec 11362 /var/lib/sdocker/rootfs/ sdocker@11362:/ $ ps -ef UID PID PPID C STIME TTY TIME CMD 0 1 0 20 08:02 pts/0 00:00:03 /bin/cpu-test 0 2 0 0 08:03 pts/1 00:00:00 bash 0 3 2 0 08:03 pts/1 00:00:00 ps -ef sdocker@11362:/ $ top top - 08:03:26 up 1 day, 33 min, 0 users, load average: 0.31, 0.66, 0.40 Tasks: 3 total, 2 running, 1 sleeping, 0 stopped, 0 zombie %Cpu(s): 1.2 us, 0.0 sy, 0.0 ni, 98.7 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem: 32689888 total, 1004588 used, 31685300 free, 2204 buffers KiB Swap: 33551356 total, 0 used, 33551356 free. 500372 cached Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1 0 20 0 4052 180 140 R 20.333 0.001 0:06.46 cpu-test 2 0 20 0 11576 2856 2492 S 0.000 0.009 0:00.00 bash 4 0 20 0 11320 2100 1800 R 0.000 0.006 0:00.00 top sdocker@11362:/ $ exit exit linux: #
有资源限制测试memory-test, 设置内存使用上限10M, 并关闭 swap
########### 启动容器执行memory-test, 设置memory使用不超过10M, 一段时间后容器触发oom退出 ########### linux: # ./sdocker_run --memory-test --memory-limit 10485760 --memory-swappiness 0 /var/lib/sdocker/rootfs/ [+] start container with id 14673 [+] malloc size: 1048576 [+] malloc size: 2097152 [+] malloc size: 3145728 [+] malloc size: 4194304 [+] malloc size: 5242880 [+] malloc size: 6291456 [+] malloc size: 7340032 [+] malloc size: 8388608 [+] malloc size: 9437184 linux: # ps -ef | grep sdocker | grep -v grep linux: # ########### 启动另一个终端查看, 一段时间后容器退出 ########### linux: # ./sdocker_exec 14673 /var/lib/sdocker/rootfs/ sdocker@14673:/ $ ps -ef UID PID PPID C STIME TTY TIME CMD 0 1 0 0 00:52 pts/0 00:00:00 /bin/memory-test 0 2 0 0 00:52 pts/1 00:00:00 bash 0 3 2 0 00:52 pts/1 00:00:00 ps -ef sdocker@14673:/ $