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203 lines
6.5 KiB
Markdown
203 lines
6.5 KiB
Markdown
# Docker Stacks and Distributed Application Bundles
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## Overview
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Docker Stacks and Distributed Application Bundles are experimental features
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introduced in Docker 1.12 and Docker Compose 1.8, alongside the concept of
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swarm mode, and Nodes and Services in the Engine API.
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A Dockerfile can be built into an image, and containers can be created from
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that image. Similarly, a docker-compose.yml can be built into a **distributed
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application bundle**, and **stacks** can be created from that bundle. In that
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sense, the bundle is a multi-services distributable image format.
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As of Docker 1.12 and Compose 1.8, the features are experimental. Neither
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Docker Engine nor the Docker Registry supports distribution of bundles.
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## Producing a bundle
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The easiest way to produce a bundle is to generate it using `docker-compose`
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from an existing `docker-compose.yml`. Of course, that's just *one* possible way
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to proceed, in the same way that `docker build` isn't the only way to produce a
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Docker image.
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From `docker-compose`:
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```bash
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$ docker-compose bundle
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WARNING: Unsupported key 'network_mode' in services.nsqd - ignoring
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WARNING: Unsupported key 'links' in services.nsqd - ignoring
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WARNING: Unsupported key 'volumes' in services.nsqd - ignoring
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[...]
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Wrote bundle to vossibility-stack.dab
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```
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## Creating a stack from a bundle
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A stack is created using the `docker deploy` command:
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```bash
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$ docker deploy --help
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Usage: docker deploy [OPTIONS] STACK
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Deploy a new stack or update an existing stack
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Aliases:
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deploy, up
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Options:
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--bundle-file string Path to a Distributed Application Bundle file
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-c, --compose-file string Path to a Compose file
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--help Print usage
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--with-registry-auth Send registry authentication details to Swarm agents
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```
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Let's deploy the stack created before:
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```bash
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$ docker deploy --bundle-file vossibility-stack.dab vossibility-stack
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Loading bundle from vossibility-stack.dab
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Creating service vossibility-stack_elasticsearch
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Creating service vossibility-stack_kibana
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Creating service vossibility-stack_logstash
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Creating service vossibility-stack_lookupd
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Creating service vossibility-stack_nsqd
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Creating service vossibility-stack_vossibility-collector
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```
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We can verify that services were correctly created:
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```bash
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$ docker service ls
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ID NAME MODE REPLICAS IMAGE
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29bv0vnlm903 vossibility-stack_lookupd replicated 1/1 nsqio/nsq@sha256:eeba05599f31eba418e96e71e0984c3dc96963ceb66924dd37a47bf7ce18a662
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4awt47624qwh vossibility-stack_nsqd replicated 1/1 nsqio/nsq@sha256:eeba05599f31eba418e96e71e0984c3dc96963ceb66924dd37a47bf7ce18a662
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4tjx9biia6fs vossibility-stack_elasticsearch replicated 1/1 elasticsearch@sha256:12ac7c6af55d001f71800b83ba91a04f716e58d82e748fa6e5a7359eed2301aa
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7563uuzr9eys vossibility-stack_kibana replicated 1/1 kibana@sha256:6995a2d25709a62694a937b8a529ff36da92ebee74bafd7bf00e6caf6db2eb03
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9gc5m4met4he vossibility-stack_logstash replicated 1/1 logstash@sha256:2dc8bddd1bb4a5a34e8ebaf73749f6413c101b2edef6617f2f7713926d2141fe
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axqh55ipl40h vossibility-stack_vossibility-collector replicated 1/1 icecrime/vossibility-collector@sha256:f03f2977203ba6253988c18d04061c5ec7aab46bca9dfd89a9a1fa4500989fba
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```
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## Managing stacks
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Stacks are managed using the `docker stack` command:
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```bash
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# docker stack --help
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Usage: docker stack COMMAND
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Manage Docker stacks
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Options:
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--help Print usage
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Commands:
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deploy Deploy a new stack or update an existing stack
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ls List stacks
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ps List the tasks in the stack
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rm Remove the stack
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services List the services in the stack
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Run 'docker stack COMMAND --help' for more information on a command.
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```
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## Bundle file format
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Distributed application bundles are described in a JSON format. When bundles
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are persisted as files, the file extension is `.dab` (Docker 1.12RC2 tools use
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`.dsb` for the file extension—this will be updated in the next release client).
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A bundle has two top-level fields: `version` and `services`. The version used
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by Docker 1.12 and later tools is `0.1`.
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`services` in the bundle are the services that comprise the app. They
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correspond to the new `Service` object introduced in the 1.12 Docker Engine API.
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A service has the following fields:
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<dl>
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<dt>
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Image (required) <code>string</code>
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</dt>
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<dd>
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The image that the service will run. Docker images should be referenced
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with full content hash to fully specify the deployment artifact for the
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service. Example:
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<code>postgres@sha256:f76245b04ddbcebab5bb6c28e76947f49222c99fec4aadb0bb
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1c24821a 9e83ef</code>
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</dd>
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<dt>
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Command <code>[]string</code>
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</dt>
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<dd>
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Command to run in service containers.
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</dd>
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<dt>
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Args <code>[]string</code>
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</dt>
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<dd>
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Arguments passed to the service containers.
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</dd>
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<dt>
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Env <code>[]string</code>
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</dt>
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<dd>
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Environment variables.
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</dd>
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<dt>
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Labels <code>map[string]string</code>
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</dt>
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<dd>
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Labels used for setting meta data on services.
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</dd>
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<dt>
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Ports <code>[]Port</code>
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</dt>
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<dd>
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Service ports (composed of <code>Port</code> (<code>int</code>) and
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<code>Protocol</code> (<code>string</code>). A service description can
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only specify the container port to be exposed. These ports can be
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mapped on runtime hosts at the operator's discretion.
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</dd>
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<dt>
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WorkingDir <code>string</code>
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</dt>
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<dd>
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Working directory inside the service containers.
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</dd>
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<dt>
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User <code>string</code>
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</dt>
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<dd>
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Username or UID (format: <code><name|uid>[:<group|gid>]</code>).
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</dd>
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<dt>
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Networks <code>[]string</code>
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</dt>
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<dd>
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Networks that the service containers should be connected to. An entity
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deploying a bundle should create networks as needed.
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</dd>
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</dl>
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The following is an example of bundlefile with two services:
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```json
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{
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"Version": "0.1",
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"Services": {
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"redis": {
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"Image": "redis@sha256:4b24131101fa0117bcaa18ac37055fffd9176aa1a240392bb8ea85e0be50f2ce",
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"Networks": ["default"]
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},
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"web": {
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"Image": "dockercloud/hello-world@sha256:fe79a2cfbd17eefc344fb8419420808df95a1e22d93b7f621a7399fd1e9dca1d",
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"Networks": ["default"],
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"User": "web"
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}
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}
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}
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```
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