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dagger/docs/core-concepts/1202-plan.md
Gerhard Lazu 5fe04d22e9
Revise Europa Docs - Core Concepts - It all starts with a plan
Thank you Tanguy for the "fresh pair of eyes" perspective.

Thank you Tom for the link suggestions.

Supersedes https://github.com/dagger/dagger/pull/1847

Signed-off-by: Gerhard Lazu <gerhard@lazu.co.uk>
2022-03-25 16:25:24 +00:00

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---
slug: /1202/plan
displayed_sidebar: europa
---
# It all starts with a plan
## Plan structure
A config declared in Dagger starts with a plan, specifically `dagger.#Plan`
Within this plan we can:
- interact with the `client` filesystem
- read files, usually the current directory as `.`
- write files, usually the build output as `_build`
- read `env` variables, such as `NETLIFY_TEAM` in our example
- declare a few `actions`, e.g. `deps`, `test` & `build`
This is our **Getting Started** todoapp plan structure:
```cue file=../tests/core-concepts/plan/structure.cue.fragment
```
When the above plan gets executed via `dagger do build`, it produces the following output:
```shell
[✔] client.filesystem.".".read 0.0s
[✔] actions.deps 1.1s
[✔] actions.test.script 0.0s
[✔] actions.test 0.0s
[✔] actions.build.run.script 0.0s
[✔] actions.build.run 0.0s
[✔] actions.build.contents 0.0s
[✔] client.filesystem."./_build".write 0.1s
```
Since these actions have run before, they are cached and take less than 2 seconds to complete.
While the names used for the actions above - `deps`, `test` & `build` - are short and descriptive,
any other names would have worked. Put differently, action naming does not affect plan execution.
Lastly, notice that even if the `deploy` action is defined, we did not run it.
Similar to Makefile targets, we have the option of running specific actions.
We ran the `dagger do build` command, which only runs the `build` action (and all its dependent actions).
This Dagger property enables us to keep the entire CI/CD config in a single file, while keeping the integration execution separate from the deployment one.
Separating CI & CD concerns becomes essential as our pipelines grow in complexity, and we learn about operational and security constraints specific to our systems.
## Packages & imports
In order to understand the correlation between actions, definitions and packages, let us focus on the following fragment from our **Getting Started** todoapp config:
```cue
package todoapp
import (
"dagger.io/dagger"
"universe.dagger.io/netlify"
)
dagger.#Plan & {
// ...
actions: {
// ...
deploy: netlify.#Deploy & {
// ...
}
// ...
}
}
```
We start by declaring the package name, `package todoapp` above.
Next, we import the packages that we use in our plan.
The first import is needed for the `dagger.#Plan` definition to be available.
The second import is for `netlify.#Deploy` to work.
:::info
Which other imports we are missing?
Look at all the actions in the plan structure at the top of this page.
Now check all the available packages in [universe.dagger.io](https://github.com/dagger/dagger/tree/v0.2.0/pkg/universe.dagger.io).
:::
We now understand that the `deploy` action is the deploy definition from the netlify package, written as `deploy: netlify.#Deploy`
Each definition has default values that can be modified via curly brackets. This is what that looks like in practice for our deploy action:
```cue
// ...
deploy: netlify.#Deploy & {
contents: build.contents.output
site: client.env.APP_NAME
token: client.env.NETLIFY_TOKEN
team: client.env.NETLIFY_TEAM
}
// ...
```
We can build complex pipelines efficiently by referencing any definition, from any package in our actions.
This is one of the fundamental concepts that makes Dagger a powerful language for building CI/CD pipelines.
If you want to learn more packages in the context of CUE, the config language used by Dagger configs, check out the [Packages](1215-what-is-cue.md#packages) section on the **What is CUE?** page.
:::tip
Now that we understand the basics of a Dagger plan, we are ready to learn more about how to interact with the client environment.
We can read the env (including secrets), run commands, use local sockets, etc.
:::