# Exercise — writing YAML

Let's write YAML manifests for the wordsmith app!

It can be a single YAML file or multiple files in a directory.

See next slides for testing instructions and hints.

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## How to test our YAML

If `XYZ` is that YAML file (or directory with YAML files), we should be able to:

1. Create a new namespace, e.g. `foo123`

2. Deploy wordsmith with a single command

   (e.g. `kubectl apply --namespace foo123 -f XYZ`)

3. Find out the connection information for `web`

   (e.g. `kubectl get service web --namespace`)

4. Connect to it and see the wordsmith app

See next slide for hints.

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## Strategies

There are at least three methods to write our YAML.

1. Dump the YAML of existing wordsmith deployments and services.

   (we can dump YAML with `kubectl get -o yaml ...`)

2. Adapt existing YAML (from the docs or dockercoins).

   (for reference, kubercoins is at https://github.com/jpetazzo/kubercoins)

3. Write it entirely from scratch.

See next slide for more hints.

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## Adapting YAML

*Scroll one slide at a time to see hints.*

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One option is to start with the YAML from kubercoins.

(see https://github.com/jpetazzo/kubercoins)

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Adapt the YAML of a deployment (e.g. worker) to run "web".

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We need to change the name, labels, selectors, and image.

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Then adapt the YAML of a service (e.g. webui).

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We need to change the name, labels, selectors, possibly port number.

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Repeat for the other components.