1. docker
  2. Commit 6440cacd49226e97b2dcb64eb31cb32b87b1ff18
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update rolling update tutorial to reflect default parallelism and update on failure

Signed-off-by: Charles Smith <charles.smith@docker.com>

Charles Smith authored on 2016/07/26 01:04:15
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docs/swarm/swarm-tutorial/rolling-update.md
History View file @ 6440cac
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@@ -29,7 +29,6 @@ update delay:
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       --replicas 3 \
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       --name redis \
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       --update-delay 10s \
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-      --update-parallelism 1 \
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       redis:3.0.6
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     0u6a4s31ybk7yw2wyvtikmu50
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@@ -37,18 +36,21 @@ update delay:
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     You configure the rolling update policy at service deployment time.
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-    The `--update-parallelism` flag configures the number of service tasks that
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-    the scheduler can update simultaneously. When updates to individual tasks
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-    return a state of `RUNNING` or `FAILED`, the scheduler schedules another
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-    task to update until all tasks are updated.
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-
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     The `--update-delay` flag configures the time delay between updates to a
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-    service task or sets of tasks.
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+    service task or sets of tasks. You can describe the time `T` as a
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+    combination of the number of seconds `Ts`, minutes `Tm`, or hours `Th`. So
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+    `10m30s` indicates a 10 minute 30 second delay.
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-    You can describe the time `T` as a combination of the number of seconds
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-    `Ts`, minutes `Tm`, or hours `Th`. So `10m30s` indicates a 10 minute 30
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-    second delay.
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+    By default the scheduler updates 1 task at a time. You can pass the
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+    `--update-parallelism` flag to configure the maximum number of service tasks
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+    that the scheduler updates simultaneously.
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+    By default, when an update to an individual task returns a state of
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+    `RUNNING`, the scheduler schedules another task to update until all tasks
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+    are updated. If, at any time during an update a task returns `FAILED`, the
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+    scheduler pauses the update. You can control the behavior using the
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+    `--update-failure-action` flag for `docker service create` or
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+    `docker service update`.
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 3. Inspect the `redis` service:
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@@ -77,13 +79,15 @@ applies the update to nodes according to the `UpdateConfig` policy:
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     redis
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     ```
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-    The scheduler applies rolling updates as follows:
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+    The scheduler applies rolling updates as follows by default:
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-    * Stop the initial number of tasks according to `--update-parallelism`.
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-    * Schedule updates for the stopped tasks.
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-    * Start the containers for the updated tasks.
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-    * After an update to a task completes, wait for the specified delay
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-    period before stopping the next task.
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+    * Stop the first task.
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+    * Schedule update for the stopped task.
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+    * Start the container for the updated task.
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+    * If the update to a task returns `RUNNING`, wait for the
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+    specified delay period then stop the next task.
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+    * If, at any time during the update, a task returns `FAILED`, pause the
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+    update.
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 5. Run `docker service inspect --pretty redis` to see the new image in the
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 desired state:
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@@ -105,7 +109,31 @@ desired state:
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     Resources:
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     ```
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-6. Run `docker service tasks <TASK-ID>` to watch the rolling update:
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+    The output of `service inspect` shows if your update paused due to failure:
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+
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+    ```bash
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+    $ docker service inspect --pretty redis
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+
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+    ID:             0u6a4s31ybk7yw2wyvtikmu50
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+    Name:           redis
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+    ...snip...
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+    Update status:
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+     State:      paused
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+     Started:    11 seconds ago
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+     Message:    update paused due to failure or early termination of task 9p7ith557h8ndf0ui9s0q951b
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+    ...snip...
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+    ```
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+
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+    To restart a paused update run `docker service update <SERVICE-ID>`. For example:
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+
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+    ```bash
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+    docker service update redis
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+    ```
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+
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+    To avoid repeating certain update failures, you may need to reconfigure the
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+    service by passing flags to `docker service update`.
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+
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+6. Run `docker service tasks <SERVICE-ID>` to watch the rolling update:
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     ```bash
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     $ docker service tasks redis