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226 lines
4.3 KiB
Markdown
226 lines
4.3 KiB
Markdown
## Adding nodes using the Docker API
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- We don't have to SSH into the other nodes, we can use the Docker API
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- If you are using Play-With-Docker:
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- the nodes expose the Docker API over port 2375/tcp, without authentication
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- we will connect by setting the `DOCKER_HOST` environment variable
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- Otherwise:
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- the nodes expose the Docker API over port 2376/tcp, with TLS mutual authentication
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- we will use Docker Machine to set the correct environment variables
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<br/>(the nodes have been suitably pre-configured to be controlled through `node1`)
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---
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# Docker Machine
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- Docker Machine has two primary uses:
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- provisioning cloud instances running the Docker Engine
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- managing local Docker VMs within e.g. VirtualBox
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- Docker Machine is purely optional
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- It makes it easy to create, upgrade, manage... Docker hosts:
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- on your favorite cloud provider
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- locally (e.g. to test clustering, or different versions)
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- across different cloud providers
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---
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class: self-paced
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## If you're using Play-With-Docker ...
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- You won't need to use Docker Machine
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- Instead, to "talk" to another node, we'll just set `DOCKER_HOST`
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- You can skip the exercises telling you to do things with Docker Machine!
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---
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## Docker Machine basic usage
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- We will learn two commands:
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- `docker-machine ls` (list existing hosts)
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- `docker-machine env` (switch to a specific host)
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.exercise[
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- List configured hosts:
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```bash
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docker-machine ls
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```
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]
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You should see your 5 nodes.
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---
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class: in-person
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## How did we make our 5 nodes show up there?
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*For the curious...*
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- This was done by our VM provisioning scripts
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- After setting up everything else, `node1` adds the 5 nodes
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to the local Docker Machine configuration
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(located in `$HOME/.docker/machine`)
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- Nodes are added using [Docker Machine generic driver](https://docs.docker.com/machine/drivers/generic/)
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(It skips machine provisioning and jumps straight to the configuration phase)
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- Docker Machine creates TLS certificates and deploys them to the nodes through SSH
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---
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## Using Docker Machine to communicate with a node
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- To select a node, use `eval $(docker-machine env nodeX)`
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- This sets a number of environment variables
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- To unset these variables, use `eval $(docker-machine env -u)`
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.exercise[
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- View the variables used by Docker Machine:
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```bash
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docker-machine env node3
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```
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]
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(This shows which variables *would* be set by Docker Machine; but it doesn't change them.)
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---
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## Getting the token
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- First, let's store the join token in a variable
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- This must be done from a manager
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.exercise[
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- Make sure we talk to the local node, or `node1`:
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```bash
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eval $(docker-machine env -u)
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```
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- Get the join token:
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```bash
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TOKEN=$(docker swarm join-token -q worker)
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```
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]
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---
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## Change the node targeted by the Docker CLI
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- We need to set the right environment variables to communicate with `node3`
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.exercise[
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- If you're using Play-With-Docker:
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```bash
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export DOCKER_HOST=tcp://node3:2375
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```
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- Otherwise, use Docker Machine:
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```bash
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eval $(docker-machine env node3)
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```
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]
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---
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## Checking which node we're talking to
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- Let's use the Docker API to ask "who are you?" to the remote node
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.exercise[
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- Extract the node name from the output of `docker info`:
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```bash
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docker info | grep ^Name
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```
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]
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This should tell us that we are talking to `node3`.
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Note: it can be useful to use a [custom shell prompt](
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https://github.com/jpetazzo/orchestration-workshop/blob/master/prepare-vms/scripts/postprep.rc#L68)
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reflecting the `DOCKER_HOST` variable.
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---
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## Adding a node through the Docker API
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- We are going to use the same `docker swarm join` command as before
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.exercise[
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- Add `node3` to the Swarm:
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```bash
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docker swarm join --token $TOKEN node1:2377
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```
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]
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---
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## Going back to the local node
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- We need to revert the environment variable(s) that we had set previously
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.exercise[
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- If you're using Play-With-Docker, just clear `DOCKER_HOST`:
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```bash
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unset DOCKER_HOST
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```
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- Otherwise, use Docker Machine to reset all the relevant variables:
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```bash
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eval $(docker-machine env -u)
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```
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]
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From that point, we are communicating with `node1` again.
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---
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## Checking the composition of our cluster
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- Now that we're talking to `node1` again, we can use management commands
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.exercise[
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- Check that the node is here:
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```bash
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docker node ls
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```
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]
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