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Chapter 6. Automating application management with the GitOps controller

GitOps with Argo CD for MicroShift is a lightweight, optional add-on controller derived from the Red Hat OpenShift GitOps Operator. GitOps for MicroShift uses the command-line interface (CLI) of Argo CD to interact with the GitOps controller that acts as the declarative GitOps engine. You can consistently configure and deploy Kubernetes-based infrastructure and applications across clusters and development lifecycles.

6.1. What you can do with the GitOps agent

By using the GitOps with Argo CD agent with MicroShift, you can utilize the following principles:

  • Implement application lifecycle management.

    • Create and manage your clusters and application configuration files using the core principles of developing and maintaining software in a Git repository.
    • You can update the single repository and GitOps automates the deployment of new applications or updates to existing ones.
    • For example, if you have 1,000 edge devices, each using MicroShift and a local GitOps agent, you can easily add or update an application on all 1,000 devices with just one change in your central Git repository.
  • The Git repository contains a declarative description of the infrastructure you need in your specified environment and contains an automated process to make your environment match the described state.
  • You can also use the Git repository as an audit trail of changes so that you can create processes based on Git flows such as review and approval for merging pull requests that implement configuration changes.

6.2. Creating GitOps applications on MicroShift

You can create a custom YAML configuration to deploy and manage applications in your MicroShift service. To install the necessary packages to run GitOps applications, follow the documentation in "Installing the GitOps Argo CD manifests from an RPM package".

Prerequisites

  • You installed the microshift-gitops packages and the Argo CD pods are running in the openshift-gitops namespace.

Procedure

  1. Create a YAML file and add your customized configurations for the application:

    Example YAML for a cert-manager application

    kind: AppProject
apiVersion: argoproj.io/v1alpha1
metadata:
  name: default
  namespace: openshift-gitops
spec:
  clusterResourceWhitelist:
  - group: '*'
    kind: '*'
  destinations:
  - namespace: '*'
    server: '*'
  sourceRepos:
  - '*'
---
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: cert-manager
  namespace: openshift-gitops
spec:
  destination:
    namespace: cert-manager
    server: https://kubernetes.default.svc
  project: default
  source:
    path: cert-manager
    repoURL: https://github.com/anandf/microshift-install
  syncPolicy:
    automated: {}
    syncOptions:
    - CreateNamespace=true
    - ServerSideApply=true

    Example YAML for a spring-petclinic application

    kind: AppProject
apiVersion: argoproj.io/v1alpha1
metadata:
  name: default
  namespace: openshift-gitops
spec:
  clusterResourceWhitelist:
  - group: '*'
    kind: '*'
  destinations:
  - namespace: '*'
    server: '*'
  sourceRepos:
  - '*'
---
kind: Application
apiVersion: argoproj.io/v1alpha1
metadata:
  name: spring-petclinic
  namespace: openshift-gitops
spec:
  destination:
    namespace: spring-petclinic
    server: https://kubernetes.default.svc
  project: default
  source:
    directory:
      recurse: true
    path: app
    repoURL: https://github.com/siamaksade/openshift-gitops-getting-started
  syncPolicy:
    automated: {}
    syncOptions:
    - CreateNamespace=true
    - ServerSideApply=true

  2. To deploy the applications defined in the YAML file, run the following command: 

    $ oc apply -f <filename>.yaml

Verification

  • To verify your application is deployed and synced, run the following command: 

    $ oc get applications -A

    It might take a few minutes for the application to show the Healthy status.

    Example output

    NAMESPACE          NAME               SYNC STATUS   HEALTH STATUS
openshift-gitops   cert-manager       Synced        Healthy
openshift-gitops   spring-petclinic   Synced        Healthy

Additional resources

6.3. Limitations of using the GitOps agent with MicroShift

GitOps with Argo CD for MicroShift has the following differences from the Red Hat OpenShift GitOps Operator:

  • The gitops-operator component is not used with MicroShift.
  • To maintain the small resource use of MicroShift, the Argo CD web console is not available. You can use the Argo CD CLI or use a pull-based approach.
  • Because MicroShift is single-node, there is no multi-cluster support. Each instance of MicroShift is paired with a local GitOps agent.
  • The oc adm must-gather command is not available in MicroShift.

6.4. Troubleshooting GitOps

If you have problems with your GitOps controller, you can use either the OpenShift CLI (oc) tool or run an sos report.

6.4.1. Debugging GitOps with oc adm inspect

You can debug GitOps by using the OpenShift CLI (oc).

Prerequisites

  • The oc command line tool is installed.

Procedure

  1. Run the oc adm inspect command when in the GitOps namespace: 

    $ oc adm inspect ns/openshift-gitops

    Example output

    Gathering data for ns/openshift-gitops...
W0501 20:34:35.978508 57625 util.go:118] the server doesn't have a resource type egressfirewalls, skipping the inspection
W0501 20:34:35.980881 57625 util.go:118] the server doesn't have a resource type egressqoses, skipping the inspection
W0501 20:34:36.040664 57625 util.go:118] the server doesn't have a resource type servicemonitors, skipping the inspection
Wrote inspect data to inspect.local.2673575938140296280.

Next steps

  • If oc adm inspect did not provide the information you need, you can run an sos report.

6.4.2. Gathering data from an sos report

Prerequisites

  • You must have the sos package installed.

Procedure

  1. Log into the failing host as a root user.

  2. Perform the debug report creation procedure by running the following command: 

    $ microshift-sos-report

    Example output

    sosreport (version 4.5.1)

This command will collect diagnostic and configuration information from
this Red Hat Enterprise Linux system and installed applications.

An archive containing the collected information will be generated in
/var/tmp/sos.o0sznf_8 and may be provided to a Red Hat support
representative.

Any information provided to Red Hat will be treated in accordance with
the published support policies at:

        Distribution Website : https://www.redhat.com/
        Commercial Support   : https://www.access.redhat.com/

The generated archive may contain data considered sensitive and its
content should be reviewed by the originating organization before being
passed to any third party.

No changes will be made to system configuration.


 Setting up archive ...
 Setting up plugins ...
 Running plugins. Please wait ...

  Starting 1/2   microshift      [Running: microshift]
  Starting 2/2   microshift_ovn  [Running: microshift microshift_ovn]
  Finishing plugins              [Running: microshift]

  Finished running plugins

Found 1 total reports to obfuscate, processing up to 4 concurrently

sosreport-microshift-rhel9-2023-03-31-axjbyxw :    Beginning obfuscation...
sosreport-microshift-rhel9-2023-03-31-axjbyxw :    Obfuscation completed

Successfully obfuscated 1 report(s)

Creating compressed archive...

A mapping of obfuscated elements is available at
	/var/tmp/sosreport-microshift-rhel9-2023-03-31-axjbyxw-private_map

Your sosreport has been generated and saved in:
	/var/tmp/sosreport-microshift-rhel9-2023-03-31-axjbyxw-obfuscated.tar.xz

 Size	444.14KiB
 Owner	root
 sha256	922e5ff2db25014585b7c6c749d2c44c8492756d619df5e9838ce863f83d4269

Please send this file to your support representative.

6.5. Additional resources

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