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Refactoring the documentation to cover first the new backend system and at the end the legacy

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Signed-off-by: cmoulliard <cmoulliard@redhat.com>
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cmoulliard
2024-05-03 15:03:06 +02:00
parent b10a8cb578
commit 686e31b961
1 changed files with 30 additions and 34 deletions
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docs/features/software-templates/writing-templates.md
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@@ -744,51 +744,31 @@ The `projectSlug` filter generates a project slug from a repository URL
## Custom Filters
Whenever it is needed to extend the built-in filters with yours `${{ parameters.name | my-filter1 | my-filter2 | etc }}`, then you can add them
using the property `addTemplateFilters` that you typically define using the `createRouter()` function of the `Scaffolder plugin`
using the property `additionalTemplateFilters`.
```ts title="packages/backend/src/plugins/scaffolder.ts"
export default async function createPlugin({
logger,
config,
}: PluginEnvironment): Promise<Router> {
...
return await createRouter({
logger,
config,
additionalTemplateFilters: {
<YOUR_FILTERS>
}
});
```
The `addTemplateFilters` property accepts a `Record`
The `additionalTemplateFilters` property accepts as type a `Record`
```ts title="plugins/scaffolder-backend/src/service/Router.ts"
additionalTemplateFilters?: Record<string, TemplateFilter>;
```
where the first parameter is the name of the filter and the second `TemplateFilter` receives a list of `JSON value` arguments. The `templateFilter()` function must return a JsonValue (Json array, object or primitive).
where the first parameter is the name of the filter and the second receives a list of `JSON value` arguments. The `templateFilter()` function must return a JsonValue which is either a Json array, object or primitive.
```ts title="plugins/scaffolder-node/src/types.ts"
export type TemplateFilter = (...args: JsonValue[]) => JsonValue | undefined;
```
From a practical coding point of view, you will translate that into the following snippet code
From a practical coding point of view, you will translate that into the following snippet code handling 2 filters:
```ts title="packages/backend/src/plugins/scaffolder.ts"
```ts"
...
return await createRouter({
logger: env.logger,
config: env.config,
additionalTemplateFilters: {
base64: (...args: JsonValue[]) => btoa(args.join("")),
betterFilter: (...args: JsonValue[]) => { return `This is a much better string than "${args}", don't you think?` }
},
});
additionalTemplateFilters: {
base64: (...args: JsonValue[]) => btoa(args.join("")),
betterFilter: (...args: JsonValue[]) => { return `This is a much better string than "${args}", don't you think?` }
}
```
And within your template, you will be able to use the filters like this
And within your template, you will be able to use the filters using a parameter and the filter passed using the pipe symbol
```yaml
apiVersion: scaffolder.backstage.io/v1beta3
@@ -815,13 +795,11 @@ spec:
message: ${{ parameters.userName | betterFilter | base64 }}
```
### Register Custom Filters with the New Backend System
To register the custom filters using the new Backend System, you will have to create a [backend module](../../backend-system/architecture/06-modules.md) calling following extension point: `scaffolderTemplatingExtensionPoint`.
Next, you will have to register the property `addTemplateFilters` using the `scaffolderTemplatingExtensionPoint` of a new `BackendModule` [created](../../backend-system/architecture/06-modules.md).
Here is a very simplified example of how to do that:
```ts title="packages/backend/src/index.ts"
```ts title="packages/backend-next/src/index.ts"
/* highlight-add-start */
import { scaffolderTemplatingExtensionPoint } from '@backstage/plugin-scaffolder-node/alpha';
import { createBackendModule } from '@backstage/backend-plugin-api';
@@ -855,3 +833,21 @@ backend.add(import('@backstage/plugin-scaffolder-backend/alpha'));
/* highlight-add-next-line */
backend.add(scaffolderModuleCustomFilters());
```
If you still use the legacy backend system, then you will use the `createRouter()` function of the `Scaffolder plugin`
```ts title="packages/backend/src/plugins/scaffolder.ts"
export default async function createPlugin({
logger,
config,
}: PluginEnvironment): Promise<Router> {
...
return await createRouter({
logger,
config,
additionalTemplateFilters: {
<YOUR_FILTERS>
}
});
```