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update doc 

Signed-off-by: Victor Vieux <victorvieux@gmail.com>
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Victor Vieux 2015-04-27 09:48:24 -07:00
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scheduler/filter/README.md
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@ -97,39 +97,55 @@ without specifying them when starting the node. Those tags are sourced from
* kernelversion
* operatingsystem
## Affinity Filter
## Affinity filter
#### Containers
You use an `--affinity:<filter>` to create "attractions" between containers. For
example, you can run a container and instruct it to locate and run next to
another container based on an identifier, an image, or a label. These
attractions ensure that containers run on the same network node &mdash; without
you having to know what each node is running.
You can schedule 2 containers and make the container #2 next to the container #1 using it's name or ID.
#### Container affinity
You can schedule a new container to run next to another based on a container
name or ID. For example, you can start a container called `frontend` running
`nginx`:
```bash
$ docker run -d -p 80:80 --name front nginx
87c4376856a8
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NODE NAMES
87c4376856a8 nginx:latest "nginx" Less than a second ago running 192.168.0.42:80->80/tcp node-1 front
```
Using `-e affinity:container==front` will schedule a container next to the container `front`.
You can also use IDs instead of name: `-e affinity:container==87c4376856a8`
Then, using `-e affinity:container==frontend` flag schedule a second container to
locate and run next to `frontend`.
```bash
$ docker run -d --name logger -e affinity:container==front logger
$ docker run -d --name logger -e affinity:container==frontend logger
87c4376856a8
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NODE NAMES
87c4376856a8 nginx:latest "nginx" Less than a second ago running 192.168.0.42:80->80/tcp node-1 front
87c4376856a8 nginx:latest "nginx" Less than a second ago running 192.168.0.42:80->80/tcp node-1 frontend
963841b138d8 logger:latest "logger" Less than a second ago running node-1 logger
```
The `logger` container ends up on `node-1` because its affinity with the container `front`.
Because of name affinity, the `logger` container ends up on `node-1` along with
the `frontend` container. Instead of the `frontend` name you could have supplied its
ID as follows:
#### Images
```bash
docker run -d --name logger -e affinity:container==87c4376856a8`
```
You can schedule a container only on nodes where a specific image is already pulled.
#### Image affinity
You can schedule a container to run only on nodes where a specific image is already pulled.
```bash
$ docker -H node-1:2375 pull redis
@ -137,8 +153,9 @@ $ docker -H node-2:2375 pull mysql
$ docker -H node-3:2375 pull redis
```
Here only `node-1` and `node-3` have the `redis` image. Using `-e affinity:image=redis` we can
schedule container only on these 2 nodes. You can also use the image ID instead of its name.
Only `node-1` and `node-3` have the `redis` image. Specify a `-e
affinity:image=redis` filter to schedule several additional containers to run on
these nodes.
```bash
$ docker run -d --name redis1 -e affinity:image==redis redis
@ -162,25 +179,37 @@ CONTAINER ID IMAGE COMMAND CREATED
963841b138d8 redis:latest "redis" Less than a second ago running node-1 redis8
```
As you can see here, the containers were only scheduled on nodes with the `redis` image already pulled.
#### Labels
You can schedule 2 containers and make the container #2 next to the container #1 using it's labels.
As you can see here, the containers were only scheduled on nodes that had the
`redis` image. Instead of the image name, you could have specified the image ID.
```bash
$ docker run -d -p 80:80 --label com.example.type=front nginx
$ docker images
REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE
redis latest 06a1f75304ba 2 days ago 111.1 MB
$ docker run -d --name redis1 -e affinity:image==06a1f75304ba redis
```
#### Label affinity
Label affinity allows you to set up an attraction based on a container's label.
For example, you can run a `nginx` container with the `com.example.type=frontend` label.
```bash
$ docker run -d -p 80:80 --label com.example.type=frontend nginx
87c4376856a8
$ docker ps
$ docker ps --filter "label=com.example.type=front"
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NODE NAMES
87c4376856a8 nginx:latest "nginx" Less than a second ago running 192.168.0.42:80->80/tcp node-1 trusting_yonath
```
Using `-e affinity:com.example.type==front` will schedule a container next to the container with label `front`.
Then, use `-e affinity:com.example.type==frontend` to schedule a container next to
the container with the `com.example.type==frontend` label.
```bash
$ docker run -d -e affinity:com.example.type==front logger
$ docker run -d -e affinity:com.example.type==frontend logger
87c4376856a8
$ docker ps
@ -189,7 +218,7 @@ CONTAINER ID IMAGE COMMAND CREATED
963841b138d8 logger:latest "logger" Less than a second ago running node-1 happy_hawking
```
The `logger` container ends up on `node-1` because its affinity with the container `front`.
The `logger` container ends up on `node-1` because its affinity with the `com.example.type==frontend` label.
#### Expression Syntax