20755: Merge branch 'main' into 20755-ec2-multiple-subnets

[arvados.git] / lib / config / config.default.yml

diff --git a/lib/config/config.default.yml b/lib/config/config.default.yml
index 1df8f1310dbec93392c9cb8a70f6d488cf44cbe9..8260224ab7183225be6e28ec7f66680ec1c4671a 100644 (file)
--- a/lib/config/config.default.yml
+++ b/lib/config/config.default.yml
@@ -1413,10 +1413,30 @@ Clusters:
         # down.
         MaxInstances: 64
 
-        # Maximum fraction of CloudVMs.MaxInstances allowed to run
-        # "supervisor" containers at any given time. A supervisor is a
-        # container whose purpose is mainly to submit and manage other
-        # containers, such as arvados-cwl-runner workflow runner.
+        # The minimum number of instances expected to be runnable
+        # without reaching a provider-imposed quota.
+        #
+        # This is used as the initial value for the dispatcher's
+        # dynamic instance limit, which increases (up to MaxInstances)
+        # as containers start up successfully and decreases in
+        # response to high API load and cloud quota errors.
+        #
+        # Setting this too high creates a risk that the dispatcher
+        # will cause deadlock by starting so many supervisor
+        # containers (based on SupervisorFraction and MaxInstances)
+        # that the cloud quota prevents them from running any child
+        # containers.
+        #
+        # Setting this too low causes the dispatcher to be
+        # unnecessarily slow to start up new instances after a
+        # restart.
+        InitialQuotaEstimate: 16
+
+        # Maximum fraction of available instance capacity allowed to
+        # run "supervisor" containers at any given time. A supervisor
+        # is a container whose purpose is mainly to submit and manage
+        # other containers, such as arvados-cwl-runner workflow
+        # runner.
         #
         # If there is a hard limit on the amount of concurrent
         # containers that the cluster can run, it is important to
@@ -1511,10 +1531,23 @@ Clusters:
           SecretAccessKey: ""
 
           # (ec2) Instance configuration.
+
+          # (ec2) Region, like "us-east-1".
+          Region: ""
+
+          # (ec2) Security group IDs. Omit or use {} to use the
+          # default security group.
           SecurityGroupIDs:
             "SAMPLE": {}
+
+          # (ec2) One or more subnet IDs. Omit or leave empty to let
+          # AWS choose a default subnet from your default VPC. If
+          # multiple subnets are configured here (enclosed in brackets
+          # like [subnet-abc123, subnet-def456]) the cloud dispatcher
+          # will detect subnet-related errors and retry using a
+          # different subnet. Most sites specify one subnet.
           SubnetID: ""
-          Region: ""
+
           EBSVolumeType: gp2
           AdminUsername: debian
           # (ec2) name of the IAMInstanceProfile for instances started by