840f113a4f
As there can be custom schedulers, including scheduler-specific information on the resource management page can be a disingenuous - the values don't map to kubernetes, for example - and thus we should call out to the scheduler docs (and underlying docker docs) to make the mapping more clear.
78 lines
4.3 KiB
Markdown
78 lines
4.3 KiB
Markdown
# Deployment Tasks
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> New as of 0.5.0
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Sometimes you need to run a command on at deployment time, but before an app is completely deployed. Common use cases include:
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* Checking a database is initialized
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* Running database migrations
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* Any commands required to set up the server (e.g. something like a Django `collectstatic`)
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To support this, Dokku provides support for a special `release` command within your app's `Procfile`, as well as a special `scripts.dokku` key inside of your app's `app.json` file. Be aware that all commands are run within the context of the built docker image - no commands affect the host unless there are volume mounts attached to your app.
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Each "phase" has different expectations and limitations:
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- `app.json`: `scripts.dokku.predeploy`
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- When to use: This should be used if your app does not support arbitrary build commands and you need to make changes to the built image.
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- Are changes committed to the image at this phase: Yes
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- Example use-cases
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- Bundling assets in a slightly different way
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- Installing a custom package from source or copying a binary into place
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- `app.json`: `scripts.dokku.postdeploy`
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- When to use: This should be used in conjunction with external systems to signal the completion of your deploy.
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- Are changes committed to the image at this phase: No
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- Example use-cases
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- Notifying slack that your app is deployed
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- Coordinating traffic routing with a central load balancer
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- `Procfile`: `release`
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- When to use: This should be used in conjunction with external systems to signal the completion of your app image build.
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- Are changes committed to the image at this phase: No
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- Example use-cases
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- Sending CSS, JS, and other assets from your app’s slug to a CDN or S3 bucket
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- Priming or invalidating cache stores
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- Running database migrations
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Please keep the above in mind when utilizing deployment tasks.
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> To execute commands on the host during a release phase, see the [plugin creation documentation](/docs/development/plugin-creation.md) docs for more information on building your own custom plugin.
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## `app.json` deployment tasks
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Dokku provides limited support for the `app.json` manifest from Heroku (documentation available [here](https://devcenter.heroku.com/articles/app-json-schema)). The keys available for use with Deployment Tasks are:
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- `scripts.dokku.predeploy`: This is run _after_ an app's docker image is built, but _before_ any containers are scheduled. Changes made to your image are committed at this phase.
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- `scripts.dokku.postdeploy`: This is run _after_ an app's containers are scheduled. Changes made to your image are *not* committed at this phase.
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For buildpack-based deployments, the location of the `app.json` file should be at the root of your repository. Dockerfile-based app deploys should have the `app.json` in the configured `WORKDIR` directory; otherwise Dokku defaults to the buildpack app behavior of looking in `/app`.
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> Warning: Any failed `app.json` deployment task will fail the deploy. In the case of either phase, a failure will not affect any running containers.
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The following is an example `app.json` file. Please note that only the `scripts.dokku.predeploy` and `scripts.dokku.postdeploy` tasks are supported by Dokku at this time. All other fields will be ignored and can be omitted.
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```json
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{
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"scripts": {
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"dokku": {
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"predeploy": "touch /app/predeploy.test",
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"postdeploy": "curl https://some.external.api.service.com/deployment?state=success"
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}
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}
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}
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```
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## Procfile Release command
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> New as of 0.14.0
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The `Procfile` also supports a special `release` command which acts in a similar way to the [Heroku Release Phase](https://devcenter.heroku.com/articles/release-phase). This command is executed _after_ an app's docker image is built, but _before_ any containers are scheduled. This is also run _after_ any command executed by `scripts.dokku.predeploy`.
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To use the `release` command, simply add a `release` stanza to your Procfile.
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```Procfile
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release: curl https://some.external.api.service.com/deployment?state=built
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```
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Unlike the `scripts.dokku.predeploy` command, changes made during by the `release` command are *not* persisted to disk.
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> Warning: scaling the release command up will likely result in unspecified issues within your deployment, and is highly discouraged.
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