github.com/gondor/docker@v1.9.0-rc1/man/docker-run.1.md (about) 1 % DOCKER(1) Docker User Manuals 2 % Docker Community 3 % JUNE 2014 4 # NAME 5 docker-run - Run a command in a new container 6 7 # SYNOPSIS 8 **docker run** 9 [**-a**|**--attach**[=*[]*]] 10 [**--add-host**[=*[]*]] 11 [**--blkio-weight**[=*[BLKIO-WEIGHT]*]] 12 [**-c**|**--cpu-shares**[=*0*]] 13 [**--cap-add**[=*[]*]] 14 [**--cap-drop**[=*[]*]] 15 [**--cgroup-parent**[=*CGROUP-PATH*]] 16 [**--cidfile**[=*CIDFILE*]] 17 [**--cpu-period**[=*0*]] 18 [**--cpu-quota**[=*0*]] 19 [**--cpuset-cpus**[=*CPUSET-CPUS*]] 20 [**--cpuset-mems**[=*CPUSET-MEMS*]] 21 [**-d**|**--detach**[=*false*]] 22 [**--device**[=*[]*]] 23 [**--dns**[=*[]*]] 24 [**--dns-opt**[=*[]*]] 25 [**--dns-search**[=*[]*]] 26 [**-e**|**--env**[=*[]*]] 27 [**--entrypoint**[=*ENTRYPOINT*]] 28 [**--env-file**[=*[]*]] 29 [**--expose**[=*[]*]] 30 [**--group-add**[=*[]*]] 31 [**-h**|**--hostname**[=*HOSTNAME*]] 32 [**--help**] 33 [**-i**|**--interactive**[=*false*]] 34 [**--ipc**[=*IPC*]] 35 [**--kernel-memory**[=*KERNEL-MEMORY*]] 36 [**-l**|**--label**[=*[]*]] 37 [**--label-file**[=*[]*]] 38 [**--link**[=*[]*]] 39 [**--log-driver**[=*[]*]] 40 [**--log-opt**[=*[]*]] 41 [**--lxc-conf**[=*[]*]] 42 [**-m**|**--memory**[=*MEMORY*]] 43 [**--mac-address**[=*MAC-ADDRESS*]] 44 [**--memory-reservation**[=*MEMORY-RESERVATION*]] 45 [**--memory-swap**[=*MEMORY-SWAP*]] 46 [**--memory-swappiness**[=*MEMORY-SWAPPINESS*]] 47 [**--name**[=*NAME*]] 48 [**--net**[=*"bridge"*]] 49 [**--oom-kill-disable**[=*false*]] 50 [**-P**|**--publish-all**[=*false*]] 51 [**-p**|**--publish**[=*[]*]] 52 [**--pid**[=*[]*]] 53 [**--privileged**[=*false*]] 54 [**--read-only**[=*false*]] 55 [**--restart**[=*RESTART*]] 56 [**--rm**[=*false*]] 57 [**--security-opt**[=*[]*]] 58 [**--stop-signal**[=*SIGNAL*]] 59 [**--sig-proxy**[=*true*]] 60 [**-t**|**--tty**[=*false*]] 61 [**-u**|**--user**[=*USER*]] 62 [**-v**|**--volume**[=*[]*]] 63 [**--ulimit**[=*[]*]] 64 [**--uts**[=*[]*]] 65 [**--volumes-from**[=*[]*]] 66 [**-w**|**--workdir**[=*WORKDIR*]] 67 IMAGE [COMMAND] [ARG...] 68 69 # DESCRIPTION 70 71 Run a process in a new container. **docker run** starts a process with its own 72 file system, its own networking, and its own isolated process tree. The IMAGE 73 which starts the process may define defaults related to the process that will be 74 run in the container, the networking to expose, and more, but **docker run** 75 gives final control to the operator or administrator who starts the container 76 from the image. For that reason **docker run** has more options than any other 77 Docker command. 78 79 If the IMAGE is not already loaded then **docker run** will pull the IMAGE, and 80 all image dependencies, from the repository in the same way running **docker 81 pull** IMAGE, before it starts the container from that image. 82 83 # OPTIONS 84 **-a**, **--attach**=[] 85 Attach to STDIN, STDOUT or STDERR. 86 87 In foreground mode (the default when **-d** 88 is not specified), **docker run** can start the process in the container 89 and attach the console to the process’s standard input, output, and standard 90 error. It can even pretend to be a TTY (this is what most commandline 91 executables expect) and pass along signals. The **-a** option can be set for 92 each of stdin, stdout, and stderr. 93 94 **--add-host**=[] 95 Add a custom host-to-IP mapping (host:ip) 96 97 Add a line to /etc/hosts. The format is hostname:ip. The **--add-host** 98 option can be set multiple times. 99 100 **--blkio-weight**=0 101 Block IO weight (relative weight) accepts a weight value between 10 and 1000. 102 103 **-c**, **--cpu-shares**=0 104 CPU shares (relative weight) 105 106 By default, all containers get the same proportion of CPU cycles. This proportion 107 can be modified by changing the container's CPU share weighting relative 108 to the weighting of all other running containers. 109 110 To modify the proportion from the default of 1024, use the **-c** or **--cpu-shares** 111 flag to set the weighting to 2 or higher. 112 113 The proportion will only apply when CPU-intensive processes are running. 114 When tasks in one container are idle, other containers can use the 115 left-over CPU time. The actual amount of CPU time will vary depending on 116 the number of containers running on the system. 117 118 For example, consider three containers, one has a cpu-share of 1024 and 119 two others have a cpu-share setting of 512. When processes in all three 120 containers attempt to use 100% of CPU, the first container would receive 121 50% of the total CPU time. If you add a fourth container with a cpu-share 122 of 1024, the first container only gets 33% of the CPU. The remaining containers 123 receive 16.5%, 16.5% and 33% of the CPU. 124 125 On a multi-core system, the shares of CPU time are distributed over all CPU 126 cores. Even if a container is limited to less than 100% of CPU time, it can 127 use 100% of each individual CPU core. 128 129 For example, consider a system with more than three cores. If you start one 130 container **{C0}** with **-c=512** running one process, and another container 131 **{C1}** with **-c=1024** running two processes, this can result in the following 132 division of CPU shares: 133 134 PID container CPU CPU share 135 100 {C0} 0 100% of CPU0 136 101 {C1} 1 100% of CPU1 137 102 {C1} 2 100% of CPU2 138 139 **--cap-add**=[] 140 Add Linux capabilities 141 142 **--cap-drop**=[] 143 Drop Linux capabilities 144 145 **--cgroup-parent**="" 146 Path to cgroups under which the cgroup for the container will be created. If the path is not absolute, the path is considered to be relative to the cgroups path of the init process. Cgroups will be created if they do not already exist. 147 148 **--cidfile**="" 149 Write the container ID to the file 150 151 **--cpu-period**=0 152 Limit the CPU CFS (Completely Fair Scheduler) period 153 154 Limit the container's CPU usage. This flag tell the kernel to restrict the container's CPU usage to the period you specify. 155 156 **--cpuset-cpus**="" 157 CPUs in which to allow execution (0-3, 0,1) 158 159 **--cpuset-mems**="" 160 Memory nodes (MEMs) in which to allow execution (0-3, 0,1). Only effective on NUMA systems. 161 162 If you have four memory nodes on your system (0-3), use `--cpuset-mems=0,1` 163 then processes in your Docker container will only use memory from the first 164 two memory nodes. 165 166 **--cpu-quota**=0 167 Limit the CPU CFS (Completely Fair Scheduler) quota 168 169 Limit the container's CPU usage. By default, containers run with the full 170 CPU resource. This flag tell the kernel to restrict the container's CPU usage 171 to the quota you specify. 172 173 **-d**, **--detach**=*true*|*false* 174 Detached mode: run the container in the background and print the new container ID. The default is *false*. 175 176 At any time you can run **docker ps** in 177 the other shell to view a list of the running containers. You can reattach to a 178 detached container with **docker attach**. If you choose to run a container in 179 the detached mode, then you cannot use the **-rm** option. 180 181 When attached in the tty mode, you can detach from a running container without 182 stopping the process by pressing the keys CTRL-P CTRL-Q. 183 184 **--device**=[] 185 Add a host device to the container (e.g. --device=/dev/sdc:/dev/xvdc:rwm) 186 187 **--dns-search**=[] 188 Set custom DNS search domains (Use --dns-search=. if you don't wish to set the search domain) 189 190 **--dns-opt**=[] 191 Set custom DNS options 192 193 **--dns**=[] 194 Set custom DNS servers 195 196 This option can be used to override the DNS 197 configuration passed to the container. Typically this is necessary when the 198 host DNS configuration is invalid for the container (e.g., 127.0.0.1). When this 199 is the case the **--dns** flags is necessary for every run. 200 201 **-e**, **--env**=[] 202 Set environment variables 203 204 This option allows you to specify arbitrary 205 environment variables that are available for the process that will be launched 206 inside of the container. 207 208 **--entrypoint**="" 209 Overwrite the default ENTRYPOINT of the image 210 211 This option allows you to overwrite the default entrypoint of the image that 212 is set in the Dockerfile. The ENTRYPOINT of an image is similar to a COMMAND 213 because it specifies what executable to run when the container starts, but it is 214 (purposely) more difficult to override. The ENTRYPOINT gives a container its 215 default nature or behavior, so that when you set an ENTRYPOINT you can run the 216 container as if it were that binary, complete with default options, and you can 217 pass in more options via the COMMAND. But, sometimes an operator may want to run 218 something else inside the container, so you can override the default ENTRYPOINT 219 at runtime by using a **--entrypoint** and a string to specify the new 220 ENTRYPOINT. 221 222 **--env-file**=[] 223 Read in a line delimited file of environment variables 224 225 **--expose**=[] 226 Expose a port, or a range of ports (e.g. --expose=3300-3310) informs Docker 227 that the container listens on the specified network ports at runtime. Docker 228 uses this information to interconnect containers using links and to set up port 229 redirection on the host system. 230 231 **--group-add**=[] 232 Add additional groups to run as 233 234 **-h**, **--hostname**="" 235 Container host name 236 237 Sets the container host name that is available inside the container. 238 239 **--help** 240 Print usage statement 241 242 **-i**, **--interactive**=*true*|*false* 243 Keep STDIN open even if not attached. The default is *false*. 244 245 When set to true, keep stdin open even if not attached. The default is false. 246 247 **--ipc**="" 248 Default is to create a private IPC namespace (POSIX SysV IPC) for the container 249 'container:<name|id>': reuses another container shared memory, semaphores and message queues 250 'host': use the host shared memory,semaphores and message queues inside the container. Note: the host mode gives the container full access to local shared memory and is therefore considered insecure. 251 252 **-l**, **--label**=[] 253 Set metadata on the container (e.g., --label com.example.key=value) 254 255 **--kernel-memory**="" 256 Kernel memory limit (format: `<number>[<unit>]`, where unit = b, k, m or g) 257 258 Constrains the kernel memory available to a container. If a limit of 0 259 is specified (not using `--kernel-memory`), the container's kernel memory 260 is not limited. If you specify a limit, it may be rounded up to a multiple 261 of the operating system's page size and the value can be very large, 262 millions of trillions. 263 264 **--label-file**=[] 265 Read in a line delimited file of labels 266 267 **--link**=[] 268 Add link to another container in the form of <name or id>:alias or just <name or id> 269 in which case the alias will match the name 270 271 If the operator 272 uses **--link** when starting the new client container, then the client 273 container can access the exposed port via a private networking interface. Docker 274 will set some environment variables in the client container to help indicate 275 which interface and port to use. 276 277 **--lxc-conf**=[] 278 (lxc exec-driver only) Add custom lxc options --lxc-conf="lxc.cgroup.cpuset.cpus = 0,1" 279 280 **--log-driver**="|*json-file*|*syslog*|*journald*|*gelf*|*fluentd*|*awslogs*|*none*" 281 Logging driver for container. Default is defined by daemon `--log-driver` flag. 282 **Warning**: the `docker logs` command works only for the `json-file` and 283 `journald` logging drivers. 284 285 **--log-opt**=[] 286 Logging driver specific options. 287 288 **-m**, **--memory**="" 289 Memory limit (format: <number>[<unit>], where unit = b, k, m or g) 290 291 Allows you to constrain the memory available to a container. If the host 292 supports swap memory, then the **-m** memory setting can be larger than physical 293 RAM. If a limit of 0 is specified (not using **-m**), the container's memory is 294 not limited. The actual limit may be rounded up to a multiple of the operating 295 system's page size (the value would be very large, that's millions of trillions). 296 297 **--memory-reservation**="" 298 Memory soft limit (format: <number>[<unit>], where unit = b, k, m or g) 299 300 After setting memory reservation, when the system detects memory contention 301 or low memory, containers are forced to restrict their consumption to their 302 reservation. So you should always set the value below **--memory**, otherwise the 303 hard limit will take precedence. By default, memory reservation will be the same 304 as memory limit. 305 306 **--memory-swap**="" 307 Total memory limit (memory + swap) 308 309 Set `-1` to disable swap (format: <number>[<unit>], where unit = b, k, m or g). 310 This value should always larger than **-m**, so you should always use this with **-m**. 311 312 **--mac-address**="" 313 Container MAC address (e.g. 92:d0:c6:0a:29:33) 314 315 Remember that the MAC address in an Ethernet network must be unique. 316 The IPv6 link-local address will be based on the device's MAC address 317 according to RFC4862. 318 319 **--name**="" 320 Assign a name to the container 321 322 The operator can identify a container in three ways: 323 UUID long identifier (“f78375b1c487e03c9438c729345e54db9d20cfa2ac1fc3494b6eb60872e74778”) 324 UUID short identifier (“f78375b1c487”) 325 Name (“jonah”) 326 327 The UUID identifiers come from the Docker daemon, and if a name is not assigned 328 to the container with **--name** then the daemon will also generate a random 329 string name. The name is useful when defining links (see **--link**) (or any 330 other place you need to identify a container). This works for both background 331 and foreground Docker containers. 332 333 **--net**="bridge" 334 Set the Network mode for the container 335 'bridge': creates a new network stack for the container on the docker bridge 336 'none': no networking for this container 337 'container:<name|id>': reuses another container network stack 338 'host': use the host network stack inside the container. Note: the host mode gives the container full access to local system services such as D-bus and is therefore considered insecure. 339 340 **--oom-kill-disable**=*true*|*false* 341 Whether to disable OOM Killer for the container or not. 342 343 **-P**, **--publish-all**=*true*|*false* 344 Publish all exposed ports to random ports on the host interfaces. The default is *false*. 345 346 When set to true publish all exposed ports to the host interfaces. The 347 default is false. If the operator uses -P (or -p) then Docker will make the 348 exposed port accessible on the host and the ports will be available to any 349 client that can reach the host. When using -P, Docker will bind any exposed 350 port to a random port on the host within an *ephemeral port range* defined by 351 `/proc/sys/net/ipv4/ip_local_port_range`. To find the mapping between the host 352 ports and the exposed ports, use `docker port`. 353 354 **-p**, **--publish**=[] 355 Publish a container's port, or range of ports, to the host. 356 format: ip:hostPort:containerPort | ip::containerPort | hostPort:containerPort | containerPort 357 Both hostPort and containerPort can be specified as a range of ports. 358 When specifying ranges for both, the number of container ports in the range must match the number of host ports in the range. (e.g., `-p 1234-1236:1234-1236/tcp`) 359 (use 'docker port' to see the actual mapping) 360 361 **--pid**=host 362 Set the PID mode for the container 363 **host**: use the host's PID namespace inside the container. 364 Note: the host mode gives the container full access to local PID and is therefore considered insecure. 365 366 **--uts**=host 367 Set the UTS mode for the container 368 **host**: use the host's UTS namespace inside the container. 369 Note: the host mode gives the container access to changing the host's hostname and is therefore considered insecure. 370 371 **--privileged**=*true*|*false* 372 Give extended privileges to this container. The default is *false*. 373 374 By default, Docker containers are 375 “unprivileged” (=false) and cannot, for example, run a Docker daemon inside the 376 Docker container. This is because by default a container is not allowed to 377 access any devices. A “privileged” container is given access to all devices. 378 379 When the operator executes **docker run --privileged**, Docker will enable access 380 to all devices on the host as well as set some configuration in AppArmor to 381 allow the container nearly all the same access to the host as processes running 382 outside of a container on the host. 383 384 **--read-only**=*true*|*false* 385 Mount the container's root filesystem as read only. 386 387 By default a container will have its root filesystem writable allowing processes 388 to write files anywhere. By specifying the `--read-only` flag the container will have 389 its root filesystem mounted as read only prohibiting any writes. 390 391 **--restart**="no" 392 Restart policy to apply when a container exits (no, on-failure[:max-retry], always, unless-stopped). 393 394 **--rm**=*true*|*false* 395 Automatically remove the container when it exits (incompatible with -d). The default is *false*. 396 397 **--security-opt**=[] 398 Security Options 399 400 "label:user:USER" : Set the label user for the container 401 "label:role:ROLE" : Set the label role for the container 402 "label:type:TYPE" : Set the label type for the container 403 "label:level:LEVEL" : Set the label level for the container 404 "label:disable" : Turn off label confinement for the container 405 406 **--stop-signal**=SIGTERM 407 Signal to stop a container. Default is SIGTERM. 408 409 **--sig-proxy**=*true*|*false* 410 Proxy received signals to the process (non-TTY mode only). SIGCHLD, SIGSTOP, and SIGKILL are not proxied. The default is *true*. 411 412 **--memory-swappiness**="" 413 Tune a container's memory swappiness behavior. Accepts an integer between 0 and 100. 414 415 **-t**, **--tty**=*true*|*false* 416 Allocate a pseudo-TTY. The default is *false*. 417 418 When set to true Docker can allocate a pseudo-tty and attach to the standard 419 input of any container. This can be used, for example, to run a throwaway 420 interactive shell. The default is value is false. 421 422 The **-t** option is incompatible with a redirection of the docker client 423 standard input. 424 425 **-u**, **--user**="" 426 Sets the username or UID used and optionally the groupname or GID for the specified command. 427 428 The followings examples are all valid: 429 --user [user | user:group | uid | uid:gid | user:gid | uid:group ] 430 431 Without this argument the command will be run as root in the container. 432 433 ""--ulimit""=[] 434 Ulimit options 435 436 **-v**, **--volume**=[] Create a bind mount 437 (format: `[host-dir:]container-dir[:<suffix options>]`, where suffix options 438 are comma delimited and selected from [rw|ro] and [z|Z].) 439 440 (e.g., using -v /host-dir:/container-dir, bind mounts /host-dir in the 441 host to /container-dir in the Docker container) 442 443 If 'host-dir' is missing, then docker automatically creates the new volume 444 on the host. **This auto-creation of the host path has been deprecated in 445 Release: v1.9.** 446 447 The **-v** option can be used one or 448 more times to add one or more mounts to a container. These mounts can then be 449 used in other containers using the **--volumes-from** option. 450 451 The volume may be optionally suffixed with :ro or :rw to mount the volumes in 452 read-only or read-write mode, respectively. By default, the volumes are mounted 453 read-write. See examples. 454 455 Labeling systems like SELinux require that proper labels are placed on volume 456 content mounted into a container. Without a label, the security system might 457 prevent the processes running inside the container from using the content. By 458 default, Docker does not change the labels set by the OS. 459 460 To change a label in the container context, you can add either of two suffixes 461 `:z` or `:Z` to the volume mount. These suffixes tell Docker to relabel file 462 objects on the shared volumes. The `z` option tells Docker that two containers 463 share the volume content. As a result, Docker labels the content with a shared 464 content label. Shared volume labels allow all containers to read/write content. 465 The `Z` option tells Docker to label the content with a private unshared label. 466 Only the current container can use a private volume. 467 468 The `container-dir` must always be an absolute path such as `/src/docs`. 469 The `host-dir` can either be an absolute path or a `name` value. If you 470 supply an absolute path for the `host-dir`, Docker bind-mounts to the path 471 you specify. If you supply a `name`, Docker creates a named volume by that `name`. 472 473 A `name` value must start with start with an alphanumeric character, 474 followed by `a-z0-9`, `_` (underscore), `.` (period) or `-` (hyphen). 475 An absolute path starts with a `/` (forward slash). 476 477 For example, you can specify either `/foo` or `foo` for a `host-dir` value. 478 If you supply the `/foo` value, Docker creates a bind-mount. If you supply 479 the `foo` specification, Docker creates a named volume. 480 481 **--volumes-from**=[] 482 Mount volumes from the specified container(s) 483 484 Mounts already mounted volumes from a source container onto another 485 container. You must supply the source's container-id. To share 486 a volume, use the **--volumes-from** option when running 487 the target container. You can share volumes even if the source container 488 is not running. 489 490 By default, Docker mounts the volumes in the same mode (read-write or 491 read-only) as it is mounted in the source container. Optionally, you 492 can change this by suffixing the container-id with either the `:ro` or 493 `:rw ` keyword. 494 495 If the location of the volume from the source container overlaps with 496 data residing on a target container, then the volume hides 497 that data on the target. 498 499 **-w**, **--workdir**="" 500 Working directory inside the container 501 502 The default working directory for 503 running binaries within a container is the root directory (/). The developer can 504 set a different default with the Dockerfile WORKDIR instruction. The operator 505 can override the working directory by using the **-w** option. 506 507 # EXAMPLES 508 509 ## Exposing log messages from the container to the host's log 510 511 If you want messages that are logged in your container to show up in the host's 512 syslog/journal then you should bind mount the /dev/log directory as follows. 513 514 # docker run -v /dev/log:/dev/log -i -t fedora /bin/bash 515 516 From inside the container you can test this by sending a message to the log. 517 518 (bash)# logger "Hello from my container" 519 520 Then exit and check the journal. 521 522 # exit 523 524 # journalctl -b | grep Hello 525 526 This should list the message sent to logger. 527 528 ## Attaching to one or more from STDIN, STDOUT, STDERR 529 530 If you do not specify -a then Docker will attach everything (stdin,stdout,stderr) 531 . You can specify to which of the three standard streams (stdin, stdout, stderr) 532 you’d like to connect instead, as in: 533 534 # docker run -a stdin -a stdout -i -t fedora /bin/bash 535 536 ## Sharing IPC between containers 537 538 Using shm_server.c available here: https://www.cs.cf.ac.uk/Dave/C/node27.html 539 540 Testing `--ipc=host` mode: 541 542 Host shows a shared memory segment with 7 pids attached, happens to be from httpd: 543 544 ``` 545 $ sudo ipcs -m 546 547 ------ Shared Memory Segments -------- 548 key shmid owner perms bytes nattch status 549 0x01128e25 0 root 600 1000 7 550 ``` 551 552 Now run a regular container, and it correctly does NOT see the shared memory segment from the host: 553 554 ``` 555 $ docker run -it shm ipcs -m 556 557 ------ Shared Memory Segments -------- 558 key shmid owner perms bytes nattch status 559 ``` 560 561 Run a container with the new `--ipc=host` option, and it now sees the shared memory segment from the host httpd: 562 563 ``` 564 $ docker run -it --ipc=host shm ipcs -m 565 566 ------ Shared Memory Segments -------- 567 key shmid owner perms bytes nattch status 568 0x01128e25 0 root 600 1000 7 569 ``` 570 Testing `--ipc=container:CONTAINERID` mode: 571 572 Start a container with a program to create a shared memory segment: 573 ``` 574 $ docker run -it shm bash 575 $ sudo shm/shm_server & 576 $ sudo ipcs -m 577 578 ------ Shared Memory Segments -------- 579 key shmid owner perms bytes nattch status 580 0x0000162e 0 root 666 27 1 581 ``` 582 Create a 2nd container correctly shows no shared memory segment from 1st container: 583 ``` 584 $ docker run shm ipcs -m 585 586 ------ Shared Memory Segments -------- 587 key shmid owner perms bytes nattch status 588 ``` 589 590 Create a 3rd container using the new --ipc=container:CONTAINERID option, now it shows the shared memory segment from the first: 591 592 ``` 593 $ docker run -it --ipc=container:ed735b2264ac shm ipcs -m 594 $ sudo ipcs -m 595 596 ------ Shared Memory Segments -------- 597 key shmid owner perms bytes nattch status 598 0x0000162e 0 root 666 27 1 599 ``` 600 601 ## Linking Containers 602 603 The link feature allows multiple containers to communicate with each other. For 604 example, a container whose Dockerfile has exposed port 80 can be run and named 605 as follows: 606 607 # docker run --name=link-test -d -i -t fedora/httpd 608 609 A second container, in this case called linker, can communicate with the httpd 610 container, named link-test, by running with the **--link=<name>:<alias>** 611 612 # docker run -t -i --link=link-test:lt --name=linker fedora /bin/bash 613 614 Now the container linker is linked to container link-test with the alias lt. 615 Running the **env** command in the linker container shows environment variables 616 with the LT (alias) context (**LT_**) 617 618 # env 619 HOSTNAME=668231cb0978 620 TERM=xterm 621 LT_PORT_80_TCP=tcp://172.17.0.3:80 622 LT_PORT_80_TCP_PORT=80 623 LT_PORT_80_TCP_PROTO=tcp 624 LT_PORT=tcp://172.17.0.3:80 625 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin 626 PWD=/ 627 LT_NAME=/linker/lt 628 SHLVL=1 629 HOME=/ 630 LT_PORT_80_TCP_ADDR=172.17.0.3 631 _=/usr/bin/env 632 633 When linking two containers Docker will use the exposed ports of the container 634 to create a secure tunnel for the parent to access. 635 636 637 ## Mapping Ports for External Usage 638 639 The exposed port of an application can be mapped to a host port using the **-p** 640 flag. For example, a httpd port 80 can be mapped to the host port 8080 using the 641 following: 642 643 # docker run -p 8080:80 -d -i -t fedora/httpd 644 645 ## Creating and Mounting a Data Volume Container 646 647 Many applications require the sharing of persistent data across several 648 containers. Docker allows you to create a Data Volume Container that other 649 containers can mount from. For example, create a named container that contains 650 directories /var/volume1 and /tmp/volume2. The image will need to contain these 651 directories so a couple of RUN mkdir instructions might be required for you 652 fedora-data image: 653 654 # docker run --name=data -v /var/volume1 -v /tmp/volume2 -i -t fedora-data true 655 # docker run --volumes-from=data --name=fedora-container1 -i -t fedora bash 656 657 Multiple --volumes-from parameters will bring together multiple data volumes from 658 multiple containers. And it's possible to mount the volumes that came from the 659 DATA container in yet another container via the fedora-container1 intermediary 660 container, allowing to abstract the actual data source from users of that data: 661 662 # docker run --volumes-from=fedora-container1 --name=fedora-container2 -i -t fedora bash 663 664 ## Mounting External Volumes 665 666 To mount a host directory as a container volume, specify the absolute path to 667 the directory and the absolute path for the container directory separated by a 668 colon: 669 670 # docker run -v /var/db:/data1 -i -t fedora bash 671 672 When using SELinux, be aware that the host has no knowledge of container SELinux 673 policy. Therefore, in the above example, if SELinux policy is enforced, the 674 `/var/db` directory is not writable to the container. A "Permission Denied" 675 message will occur and an avc: message in the host's syslog. 676 677 678 To work around this, at time of writing this man page, the following command 679 needs to be run in order for the proper SELinux policy type label to be attached 680 to the host directory: 681 682 # chcon -Rt svirt_sandbox_file_t /var/db 683 684 685 Now, writing to the /data1 volume in the container will be allowed and the 686 changes will also be reflected on the host in /var/db. 687 688 ## Using alternative security labeling 689 690 You can override the default labeling scheme for each container by specifying 691 the `--security-opt` flag. For example, you can specify the MCS/MLS level, a 692 requirement for MLS systems. Specifying the level in the following command 693 allows you to share the same content between containers. 694 695 # docker run --security-opt label:level:s0:c100,c200 -i -t fedora bash 696 697 An MLS example might be: 698 699 # docker run --security-opt label:level:TopSecret -i -t rhel7 bash 700 701 To disable the security labeling for this container versus running with the 702 `--permissive` flag, use the following command: 703 704 # docker run --security-opt label:disable -i -t fedora bash 705 706 If you want a tighter security policy on the processes within a container, 707 you can specify an alternate type for the container. You could run a container 708 that is only allowed to listen on Apache ports by executing the following 709 command: 710 711 # docker run --security-opt label:type:svirt_apache_t -i -t centos bash 712 713 Note: 714 715 You would have to write policy defining a `svirt_apache_t` type. 716 717 # HISTORY 718 April 2014, Originally compiled by William Henry (whenry at redhat dot com) 719 based on docker.com source material and internal work. 720 June 2014, updated by Sven Dowideit <SvenDowideit@home.org.au> 721 July 2014, updated by Sven Dowideit <SvenDowideit@home.org.au>