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bring back Josh's docs from #1364
Signed-off-by: Sven Dowideit <SvenDowideit@home.org.au>
This commit is contained in:
Sven Dowideit
@@ -45,7 +45,6 @@
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<li><a href="{{site.baseurl}}/os/configuration/setting-up-docker-tls/">Setting up Docker TLS</a></li>
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<li><a href="{{site.baseurl}}/os/configuration/private-registries/">Private Registries</a></li>
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<li><a href="{{site.baseurl}}/os/configuration/switching-docker-versions/">Switching Docker Versions</a></li>
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<li><a href="{{site.baseurl}}/os/configuration/prepacking-docker-images/">Pre-packing Docker Images</a></li>
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<li><a href="{{site.baseurl}}/os/configuration/users/">Users</a></li>
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<li><a href="{{site.baseurl}}/os/configuration/resizing-device-partition/">Resizing a Device Partition</a></li>
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<li><a href="{{site.baseurl}}/os/configuration/sysctl/">sysctl Settings</a></li>
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@@ -60,11 +59,18 @@
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<a href="#">System Services<i class="pull-right fa fa-angle-down"></i></a>
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<ul>
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<li><a href="{{site.baseurl}}/os/system-services/adding-system-services/">System Services</a></li>
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<li><a href="{{site.baseurl}}/os/system-services/built-in-system-services/">Built-in System Services</a></li>
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<li><a href="{{site.baseurl}}/os/system-services/system-docker-volumes/">System Docker Volumes</a></li>
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<li><a href="{{site.baseurl}}/os/system-services/environment/">Environment</a></li>
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</ul>
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</li>
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<li>
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<a href="#">Boot Process<i class="pull-right fa fa-angle-down"></i></a>
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<ul>
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<li><a href="{{site.baseurl}}/os/boot-process/built-in-system-services/">Built-in System Services</a></li>
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<li><a href="{{site.baseurl}}/os/boot-process/cloud-init">Cloud-init</a></li>
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<li><a href="{{site.baseurl}}/os/boot-process/image-preloading">Image Preloading</a></li>
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</ul>
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</li>
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<li>
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<a href="#">Storage<i class="pull-right fa fa-angle-down"></i></a>
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<ul>
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@@ -1,22 +0,0 @@
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---
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title: Pre-packing Docker Images
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layout: os-default
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---
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## Pre-packing Docker Images
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---
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On boot, RancherOS scans `/var/lib/rancher/preload/docker` and `/var/lib/rancher/preload/system-docker` directories and tries to load container image archives it finds there, with `docker load` and `system-docker load`.
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The archives are `.tar` files, optionally compressed with `xz` or `gzip`. These can be produced by `docker save` command, e.g.:
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```
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$ docker save my-image1 my-image2 some-other/image3 | xz > my-images.tar.xz
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```
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The resulting files should be placed into `/var/lib/rancher/preload/docker` or `/var/lib/rancher/preload/system-docker` (depending on whether you want it preloaded into Docker or System Docker).
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Pre-loading process only reads each new archive once, so it won't take time on subsequent boots (`<archive>.done` files are created to mark the read archives). If you update the archive (place a newer archive with the same name) it'll get read on the next boot as well.
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Pre-packing docker images is handy when you're customizing your RancherOS distribution (perhaps, building cloud VM images for your infrastructure).
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---
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title: Built-in System Services in RancherOS
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layout: os-default
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---
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## Built-in System Services
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---
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To launch RancherOS, we have built-in system services. They are defined in the [Docker Compose](https://docs.docker.com/compose/compose-file/) format, and can be found in the default system config file, `/usr/share/ros/os-config.yml`. You can [add your own system services]({{site.baseurl}}/os/system-services/) or override services in the cloud-config.
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In start up order, here are the groups of services:
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1. Device and power management:
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- udev-cold
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- udev
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- acpid
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2. syslog
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3. System configuration and networking:
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- preload-system-images
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- cloud-init-pre
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- network-pre
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- ntp
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- cloud-init
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- network
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4. User interaction:
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- console
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- docker
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5. Post configuration:
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- preload-user-images
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### preload-system-images & preload-user-images
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Read more about [pre-packing Docker images]({{site.baseurl}}/os/configuration/prepacking-docker-images/).
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### cloud-init-pre
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User-data (i.e. [cloud-config]({{site.baseurl}}/os/configuration/#cloud-config)) and metadata from cloud provider, VM runtime, or a management service, is loaded in this service.
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The user-data is written to:
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* `/var/lib/rancher/conf/cloud-config.d/boot.yml` - If the user-data is a cloud-config, i.e. begins with `#cloud-config` and is YAML format.
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* `/var/lib/rancher/conf/cloud-config-script` - If the user-data is a script, i.e begins with `#!`.
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* `/var/lib/rancher/conf/metadata` - If it is serialized cloud provider metadata.
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It is configured by the `rancher.cloud_init.datasources` list in [cloud-config]({{site.baseurl}}/os/configuration/#cloud-config). It is pre-configured in cloud-provider specific images (e.g. AWS, GCE).
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### network-pre
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During this service, networking is set up, e.g. hostname, interfaces, and DNS.
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It is configured by `hostname` and `rancher.network`[settings]({{site.baseurl}}/os/networking/) in [cloud-config]({{site.baseurl}}/os/configuration/#cloud-config).
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### ntp
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Runs `ntpd` in a System Docker container.
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### cloud-init
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It does the same thing as cloud-init-pre, but in this step, it can also use the network to fetch user-data and metadata (e.g. in cloud providers).
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### network
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Completes setting up networking with configuration obtained by cloud-init.
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### console
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This service provides the RancherOS user interface by running `sshd` and `getty`. It completes the RancherOS configuration on start up:
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1. If the `rancher.password=<password>` kernel parameter exists, it sets `<password>` as the password for the `rancher` user.
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2. If there are no host SSH keys, it generates host SSH keys and saves them under `rancher.ssh.keys` in [cloud-config]({{site.baseurl}}/os/configuration/#cloud-config).
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3. Runs `cloud-init -execute`, which does the following:
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* Updates `.ssh/authorized_keys` in `/home/rancher` and `/home/docker` from [cloud-config]({{site.baseurl}}/os/configuration/ssh-keys/) and metadata.
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* Writes files specified by the `write_files` [cloud-config]({{site.baseurl}}/os/configuration/write-files/) setting.
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* Resizes the device specified by the `rancher.resize_device` [cloud-config]({{site.baseurl}}/os/configuration/resizing-device-partition/) setting.
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* Mount devices specified in the `mounts` [cloud-config]({{site.baseurl}}/os/configuration/additional-mounts/) setting.
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* Set sysctl parameters specified in the`rancher.sysctl` [cloud-config]({{site.baseurl}}/os/configuration/sysctl/) setting.
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4. If user-data contained a file that started with `#!`, then a file would be saved at `/var/lib/rancher/conf/cloud-config-script` during cloud-init and then executed. Any errors are ignored.
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5. Runs `/opt/rancher/bin/start.sh` if it exists and is executable. Any errors are ignored.
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6. Runs `/etc/rc.local` if it exists and is executable. Any errors are ignored.
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### docker
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This system service runs the user docker daemon. Normally it runs inside the console system container by running `docker-init` script which, in turn, looks for docker binaries in `/opt/bin`, `/usr/local/bin` and `/usr/bin`, adds the first found directory with docker binaries to PATH and runs `dockerlaunch docker daemon` appending the passed arguments.
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Docker daemon args are read from `rancher.docker.args` cloud-config property (followed by `rancher.docker.extra_args`).
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### RancherOS Configuration Load Order
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[Cloud-config]({{site.baseurl}}/os/configuration/#cloud-config/) is read by system services when they need to get configuration. Each additional file overwrites and extends the previous configuration file.
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1. `/usr/share/ros/os-config.yml` - This is the system default configuration, which should **not** be modified by users.
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2. `/usr/share/ros/oem/oem-config.yml` - This will typically exist by OEM, which should **not** be modified by users.
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3. Files in `/var/lib/rancher/conf/cloud-config.d/` ordered by filename. If a file is passed in through user-data, it is written by cloud-init and saved as `/var/lib/rancher/conf/cloud-config.d/boot.yml`.
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4. `/var/lib/rancher/conf/cloud-config.yml` - If you set anything with `ros config set`, the changes are saved in this file.
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5. Kernel parameters with names starting with `rancher`.
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6. `/var/lib/rancher/conf/metadata` - Metadata added by cloud-init.
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