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DEBUGGING.md

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Debugging Issues

This document provides information on the best approaches to debug DM issues on a running system.

Checking deployment-manager status

The following command will display the deployment-manager status:

kubectl -n deployment get datanetworks,hostprofiles,hosts,platformnetworks,systems

Of primary interest is the INSYNC column, which shows whether the deployment-manager has been able to synchronize the deployment configuration with the system, and the RECONCILED column, which shows that the synchronization completed once:

controller-0:~$ kubectl -n deployment get datanetworks,hostprofiles,hosts,platformnetworks,systems
NAME                                               TYPE   INSYNC   RECONCILED
datanetwork.starlingx.windriver.com/group0-data0   vlan   true     true

NAME                                                       BASE
hostprofile.starlingx.windriver.com/compute-0-profile
hostprofile.starlingx.windriver.com/compute-1-profile
hostprofile.starlingx.windriver.com/controller-0-profile
hostprofile.starlingx.windriver.com/storage-0-profile

NAME                                        ADMINISTRATIVE   OPERATIONAL   AVAILABILITY   PROFILE                INSYNC   RECONCILED
host.starlingx.windriver.com/compute-0      unlocked         enabled       available      compute-0-profile      true     true
host.starlingx.windriver.com/compute-1      unlocked         enabled       available      compute-1-profile      true     true
host.starlingx.windriver.com/compute-2      unlocked         enabled       available      compute-1-profile      true     true
host.starlingx.windriver.com/controller-0   unlocked         enabled       available      controller-0-profile   true     true
host.starlingx.windriver.com/controller-1   unlocked         enabled       available      controller-0-profile   true     true
host.starlingx.windriver.com/storage-0      unlocked         enabled       available      storage-0-profile      true     true
host.starlingx.windriver.com/storage-1      unlocked         enabled       available      storage-0-profile      true     true

NAME                                                    MODE     TYPE       VERSION   INSYNC   RECONCILED
system.starlingx.windriver.com/sample-system   duplex   standard   20.06     true     true

Looking at logs of the currently running Pod

The logs from the currently running Pod can be queried using the following command. The "-f" argument follows the log stream much like the Linux "tail" command.

kubectl -n platform-deployment-manager logs platform-deployment-manager-0 manager -f

Looking at logs of the previously running Pod

If the Pod crashes, is deleted, or restarts the logs from the previous instantiation of the Pod are kept and can be accessed with the "-p" argument.
But, if the Pod restarts multiple time the logs from the preceding instantiations are lost unless the platform is configured with a more advance data collection mechanism.

kubectl -n platform-deployment-manager logs platform-deployment-manager-0 manager -p

Viewing event history

Recorded events can show actions taken by deployment-manager and system events.

kubectl -n deployment get events --sort-by='.metadata.creationTimestamp'

Increasing the log level

The DM log level can be increased by specifying the desired log level with the  "--v" parameter when running the "manager" binary.  The manager Container can be modified to change the "manager" launch arguments with a custom log level.  The "Args:" section would look like the following if the log level was changed from the default (0) to a new value (2).

Args:
/manager
--metrics-addr=127.0.0.1:8080
--alsologtostderr=true
--v=2

Alternatively, if the log level needs to be set to a non-default value before the first instantiation, it can be set as a Helm chart override.  The following sample Helm override file demonstrates how to set the log level to 2 in addition to other attributes that may already be present in the file.  The Helm chart override method can also be used to update an already running system to increase or decrease the log level.

manager:
  logLevel: 2
  image:
    repository: wind-river/cloud-platform-deployment-manager
    tag: latest
    pullPolicy: IfNotPresent

To re-apply a new set of overrides to an existing installation the Helm upgrade command can simply be re-executed.

helm upgrade --install deployment-manager --values deployment-manager-overrides.yaml wind-river-cloud-platform-deployment-manager-2.0.9.tgz

Enabling version API interaction logs

If the problem being debugged involves looking at details of exact REST API interactions with the StarlingX System API then more verbose logging can be enabled. To enable verbose API logging you must set the OS_DEBUG attribute in the system-endpoint Secret resource which defines the System API endpoint through which the DM will interact with the system being configured. For example, to enable more detailed logs the system-endpoint Secret would look similar to the following.

apiVersion: v1
data:
  OS_PASSWORD: TGk2OW51eCo=
  OS_USERNAME: YWRtaW4=
kind: Secret
metadata:
  name: system-endpoint
  namespace: deployment
stringData:
  OS_AUTH_URL: http://192.168.204.102:5000/v3
  OS_INTERFACE: internal
  OS_PROJECT_DOMAIN_NAME: Default
  OS_PROJECT_NAME: admin
  OS_REGION_NAME: RegionOne
  OS_DEBUG: True
type: Opaque

Note: The OS_DEBUG value is parsed using standard Go libraries therefore the value used must be understood as a boolean by strconv.ParseBool which at the time of writing is "1", "t", "T", "true", "TRUE", and "True".

Disabling individual sub-reconcilers

For debugging and isolation purposes each of the reconcilers implemented in the DM is sub-divided into smaller "sub-reconciler" entities that can be selectively enabled/disabled for debugging purposes.  This functionality does not provide much usefulness for customer deployments but has been useful on occasion to isolate problematic parts of the system so that the DM does not try to reconcile its data. 

The DM consumes a ConfigMap at runtime which can contain individual boolean values that control the state of each reconciler.  Any changes to the ConfigMap are immediately read into the DM's internal configuration and go into effect the next time the DM queries its internal state.   The set of supported values can be found in the pkg/config/config.go file within the DM repo.  The following Helm chart override file provides an example of how to set ConfigMap values as an override to disable the Host Memory sub-reconciler.

manager:
  image:
    repository: wind-river/cloud-platform-deployment-manager
    tag: latest
    pullPolicy: IfNotPresent
  configmap:
    reconcilers:
      host:
        memory:
          enabled: false

Attaching a remote debugger

The GoLang ecosystem supports remote debugging.  The best resource available for remote debugging at the moment is the Delve debugger.   https://github.com/go-delve/delve.   

Like programs written in C, debugging a Go program requires compilation with special flags.  The DM is deployed as a Docker image; therefore, a new image needs to be built which contains a debug-enabled binary. A debug image can be built by setting the DEBUG=yes environment variable when invoking make.  

For example, the following command will build a debug version of the DM image and will tag it "debug" rather than "latest".

DEBUG=yes make docker-build

Attaching a remote debugger to the running Pod from outside of the Cluster requires exposing a TCP port on the Container. It may also require other networking or firewall changes depending on the policies in place in your environment. The DM Helm chart is structured to make exposing this port and configuring the environment for debugging possible through a simple Helm chart override. The following Helm chart override file provides an example of how to configure debugging.

manager:
  logLevel: 2
  debugger:
    enabled: true
    wait: false
    port: 30000
  image:
    repository: wind-river/cloud-platform-deployment-manager
    tag: debug
    pullPolicy: Always

The manager.debugger.enabled value controls whether a debug port is exposed to make the Pod accessible from outside of the Cluster.

The manager.debugger.wait value controls whether the "manager" binary is forced to stop and wait for a debugger to attach before running. This is handy if debugging an issue on initial startup and there is not sufficient time to manually attach a debugger before the problem occurs. This option is not recommended until it is necessary to debug a startup issue - because it causes webhooks to fail if a configuration change is requested before the debugger can be attached. This value defaults to false therefore it does not need to be specified unless it is being set explicitly.

The manager.debugger.port value controls which port is exposed for accessibility from outside of the cluster. This value defaults to 30000 and does not need to be specified unless different from the default value.

Suspending the Deployment Manager

In some scenarios, it may be necessary to stop the DM from processing changes altogether in order to debug an issue or to correct a problem with the underlying system API state. You can adjust the replica count of the DM statefulset to 0 to force its termination. Reversing the change by setting the replica count back to the normal value of 1 should relaunch the DM.

kubectl scale --replicas=0 -n platform-deployment-manager statefulset platform-deployment-manager

Restarting the Deployment Manager

As a last resort, if the DM does not appear to be making progress or you wish to force the DM to re-evaluate the state of all hosts you can elect to restart the DM Pod.

kubectl -n platform-deployment-manager delete pods platform-deployment-manager-0

Deleting the Deployment Manager

For testing purposes, it is sometimes necessary to remove all resources related to the Deployment Manager. If the DM was installed using the recommended Helm chart install method then it can be removed using a similar operation.

helm delete --purge deployment-manager