194 lines
6.3 KiB
Markdown
194 lines
6.3 KiB
Markdown
# Process and Container Management
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> New as of 0.3.14, Enhanced in 0.7.0
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```
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ps <app> # List processes running in app container(s)
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ps:rebuild <app> # Rebuild an app from source
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ps:rebuildall # Rebuild all apps from source
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ps:report [<app>] [<flag>] # Displays a process report for one or more apps
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ps:restart <app> # Restart app container(s)
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ps:restart-policy <app> # Shows the restart-policy for an app
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ps:restartall # Restart all deployed app containers
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ps:scale <app> <proc>=<count> [<proc>=<count>] # Get/Set how many instances of a given process to run
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ps:set-restart-policy <app> <policy> # Sets app restart-policy
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ps:start <app> # Start app container(s)
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ps:stop <app> # Stop app container(s)
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```
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By default, Dokku will only start a single `web` process - if defined - though process scaling can be managed by the `ps` plugin or [via a custom `DOKKU_SCALE` file](/docs/deployment/process-management.md#manually-managing-process-scaling).
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> The `web` proctype is the only proctype that will invoke custom checks as defined by a CHECKS file. It is also the only process type that will be launched in a container that is either proxied via nginx or bound to an external port.
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## Usage
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### Listing processes running in an app container
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To find out if your application's containers are running the commands you expect, simply run the `ps` command against that application.
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```shell
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dokku ps node-js-app
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```
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### Rebuilding applications
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There are some Dokku commands which will not automatically rebuild an application's environment, or which can be told to skip a rebuild. For instance, you may wish to run multiple `config:set` commands without a restart so as to speed up configuration. In these cases, you can ultimately trigger an application rebuild using `ps:rebuild`
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```shell
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dokku ps:rebuild node-js-app
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```
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You may also rebuild all applications at once, which is useful when enabling/disabling a plugin that modifies all applications:
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```shell
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dokku ps:rebuildall
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```
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> The `ps:rebuild` and `ps:rebuildall` commands only work for applications for which there is a source, and thus
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> will only always work deterministically for git-deployed application. Please see
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> the [images documentation](/docs/deployment/methods/images.md) and [tar documentation](/docs/deployment/methods/tar.md)
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> in for more information concerning rebuilding those applications.
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### Restarting applications
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Applications can be restarted, which is functionally identical to calling the `release_and_deploy` function on an application. Please not that any linked containers *must* be started before the application in order to have a successful boot.
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```shell
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dokku ps:restart node-js-app
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```
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You may also trigger a restart on all applications at one time:
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```shell
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dokku ps:restartall
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```
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### `ps:scale` command
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Dokku can also manage scaling itself via the `ps:scale` command. This command can be used to scale multiple process types at the same time.
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```shell
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dokku ps:scale node-js-app web=1
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```
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Multiple process types can be scaled at once:
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```shell
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dokku ps:scale node-js-app web=1 worker=1
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```
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Issuing the `ps:scale` command with no process type argument will output the current scaling settings for an application:
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```shell
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dokku ps:scale node-js-app
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```
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```
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-----> Scaling for node-js-app
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-----> proctype qty
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-----> -------- ---
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-----> web 1
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-----> worker 1
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```
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### Stopping applications
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Deployed applications can be stopped using the `ps:stop` command. This turns off all running containers for an application, and will result in a `502 Bad Gateway` response for the default nginx proxy implementation.
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```shell
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dokku ps:stop node-js-app
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```
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### Starting applications
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All stopped containers can be started using the `ps:start` command. This is similar to running `ps:restart`, except no action will be taken if the application containers are running.
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```shell
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dokku ps:start node-js-app
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```
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## Restart Policies
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> New as of 0.7.0
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By default, Dokku will automatically restart containers that exit with a non-zero status up to 10 times via the [on-failure Docker restart policy](https://docs.docker.com/engine/reference/run/#restart-policies-restart).
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### Showing the current restart policy
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The `ps:restart-policy` command will show the currently configured restart policy for an application. The default policy is `on-failure:10`
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```shell
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dokku ps:restart-policy node-js-app
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```
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```
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=====> node-js-app restart-policy:
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on-failure:10
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```
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### Setting the restart policy
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You can configure this via the `ps:set-restart-policy` command:
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```shell
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# always restart an exited container
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dokku ps:set-restart-policy node-js-app always
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```
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```
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-----> Setting restart policy: always
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```
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```shell
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# never restart an exited container
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dokku ps:set-restart-policy node-js-app no
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```
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```
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-----> Setting restart policy: no
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```
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```shell
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# only restart it on Docker restart if it was not manually stopped
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dokku ps:set-restart-policy node-js-app unless-stopped
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```
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```
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-----> Setting restart policy: unless-stopped
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```
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```shell
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# restart only on non-zero exit status
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dokku ps:set-restart-policy node-js-app on-failure
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```
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```
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-----> Setting restart policy: on-failure
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```
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```shell
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# restart only on non-zero exit status up to 20 times
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dokku ps:set-restart-policy node-js-app on-failure:20
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```
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```
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-----> Setting restart policy: on-failure:20
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```
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Restart policies have no bearing on server reboot, and Dokku will always attempt to restart your applications at that point unless they were manually stopped.
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## Manually managing process scaling
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You can optionally _commit_ a `DOKKU_SCALE` file to the root of your repository - *not* to the /home/dokku/APP directory. Dokku expects this file to contain one line for every process defined in your Procfile.
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Example:
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```Procfile
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web=1
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worker=2
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```
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If it is not committed to the repository, the `DOKKU_SCALE` file will otherwise be automatically generated based on your `ps:scale` settings.
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> *NOTE*: Dokku will always use the DOKKU_SCALE file that ships with the repo to override any local settings.
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