Deploy docker containers using GitOps approach

If you were searching for the tool like ArgoCD to implement GitOps pattern for Docker containers - you are on the right place.

Simplecontainer enables the GitOps approach to deploying containers on single or cluster of docker daemon hosts with simplecontainer enabled nodes.

This allows to pull the latest changes on the definitions from the git repository instead of pushing the changes to the node via CLI.

To checkout gitops deployment - first, you need to have simplecontainer running and CLI configured already. If you didn't do that you need to do that first.

simplecontainer

Simplecontainer manager a.k.a smr. Standalone and cluster mode, GitOps, Secrets, Reconciliation, and YAML definitions for Docker.

Afterward, clone the examples repository and list the definitions inside the directories.

git clone https://github.com/simplecontainer/examples

GitOps manual sync for simplecontainer

An example definition of the GitOps object is given below.

kind: gitops
meta:
  group: examples
  name: plain-manual
spec:
  repoURL: "https://github.com/simplecontainer/examples"
  revision: "main"
  directoryPath: "/tests/minimal"

Applying this object: examples/tests/gitops-apps/gitops-manual.yaml simplecontainer willl create an GitOps object on the node and will reconcile all definitions specified under the directoryPath on the revision of the git repository.

smrctl apply examples/tests/gitops-apps/definitions/gitops-plain.yaml
object proposed for apply: gitops

smrctl ps gitops
RESOURCE                      REVISION  SYNCED        AUTO SYNC  STATUS  
──────────────────────────────────────────────────────────────────────────
gitops/examples/plain-manual  main      Never synced  false      drifted 

A GitOps object can do auto sync and manual sync. Since the sync is manual in this case we need to trigger the sync manually via CLI.

smrctl gitops sync gitops/examples/plain-manual
smrctl ps
NODE                    RESOURCE                              PORTS  IMAGE STATE  ENGINE STATE      SMR STATE     
───────────────────────────────────────────────────────────────────────────────────────────────────────────────────
smr-development-node-1  containers/example/example-busybox-1  -      pulled       running (docker)  running (14s)

sc ps gitops
RESOURCE                      REVISION  SYNCED   AUTO SYNC  STATUS 
────────────────────────────────────────────────────────────────────
gitops/examples/plain-manual  main      64f879e  false      insync

sc gitops repositories
RESOURCE                      REPOSITORY                                   COMMIT   REVISION 
──────────────────────────────────────────────────────────────────────────────────────────────
gitops/examples/plain-manual  https://github.com/simplecontainer/examples  64f879e  main

sc gitops definitions gitops/examples/plain-manual 
RESOURCE                      DEFINITIONS                 DRIFTED  LAST SYNC 
──────────────────────────────────────────────────────────────────────────────
gitops/examples/plain-manual  containers/example/busybox  InSync   1m15s

Simplecontainer will pick up definitions from the definition.yaml and will reconcile the state - create containers on the node.

GitOps auto sync for simplecontainer

kind: gitops
meta:
  group: examples
  name: plain-auto
spec:
  repoURL: "https://github.com/simplecontainer/examples"
  revision: "main"
  automaticSync: true
  directoryPath: "/tests/minimal"

After applying this object it will auto-sync changes.

GitOps App of apps pattern for simplecontainer

kind: gitops
meta:
  group: examples
  name: app-of-apps
spec:
  repoURL: "https://github.com/simplecontainer/examples"
  revision: "main"
  directoryPath: "tests/gitops-apps"

Using this pattern we can create one GitOps object that will automate creation and syncing of new GitOps objects.

smrctl apply examples/tests/gitops-app-of-apps.yaml
object proposed for apply: gitops

smrctl ps gitops
RESOURCE                             REVISION  SYNCED        AUTO SYNC  STATUS              
─────────────────────────────────────────────────────────────────────────────────────────────
gitops/examples/app-of-apps          main      64f879e       true       insync              
gitops/examples/plain-auto           main      64f879e       true       insync              
gitops/examples/plain-manual-spread  main      Never synced  false      definitions_invalid 
gitops/examples/plain-manual         main      Never synced  false      drifted
 
smrctl ps
NODE                    RESOURCE                              PORTS  IMAGE STATE  ENGINE STATE      SMR STATE     
───────────────────────────────────────────────────────────────────────────────────────────────────────────────────
smr-development-node-1  containers/example/example-busybox-1  -      pulled       running (docker)  running (41s) 

As you can see, after syncing app-of-apps GitOps object will generate the rest of the GitOps objects from /tests/gitops/apps the directory.

Using the dashboard we can investigate in real time what is happening to the GitOps objects and what they hold inside. For this example in particular, the output would be similar to the one in the video below.