feat(kustomize): add TBC envsubst support for Kustomize based deployment

README.md

@@ -145,7 +145,7 @@ The Kubernetes template supports three techniques to deploy your code:
 
 1. script-based deployment,
 2. template-based deployment using raw Kubernetes manifests (with [variables substitution](#variables-substitution-mechanism)),
-3. template-based deployment using [Kustomization files](https://kubectl.docs.kubernetes.io/references/kustomize/kustomization/).
+3. template-based deployment using [Kustomization files](https://kubectl.docs.kubernetes.io/references/kustomize/kustomization/) (with [variables substitution](#variables-substitution-mechanism)).
 
 #### 1: script-based deployment
 
@@ -182,15 +182,12 @@ in your project structure, and let the template [`kubectl apply`](https://kubern
 The template processes the following steps:
 
 1. _optionally_ executes the `k8s-pre-apply.sh` script in your project to perform specific environment pre-initialization (for e.g. create required services),
-2. looks for your Kustomization file, performs variables substitution and [`kubectl apply`](https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands#apply) it,
+2. looks for your Kustomization file, performs [variables substitution](#variables-substitution-mechanism), generates the manifests with [`kubectl kustomize`](https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands#kustomize) and [`kubectl apply`](https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands#apply) it,
     1. looks for an environment-specific [overlay](https://kubectl.docs.kubernetes.io/references/kustomize/glossary/#overlay) file `./$environment_type/kustomization.yaml` (e.g. `./staging/kustomization.yaml ` for staging environment),
     2. fallbacks to default `kustomization.yaml`.
 3. _optionally_ executes the `k8s-post-apply.sh` script in your project to perform specific environment post-initialization stuff,
 
 :warning: `k8s-pre-apply.sh` or `k8s-post-apply.sh` needs to be executable, you can add flag execution with:  `git update-index --chmod=+x k8s-pre-apply.sh`
-
-Variables substitution is performed by the deprecated feature from Kustomize based on `configMapGenerator`, using a non-valuated variable from a config map.
-
 #### Readiness script
 
 After deployment (either script-based or template-based), the GitLab CI template _optionally_ executes the `k8s-readiness-check.sh` hook script to wait & check for the application to be ready (if not found, the template assumes the application was successfully started).
@@ -228,7 +225,7 @@ In this mode, you mainly let Kubernetes delete all objects from your Kubernetes
 The template processes the following steps:
 
 1. _optionally_ executes the `k8s-pre-cleanup.sh` script in your project to perform specific environment pre-cleanup stuff,
-2. looks for your Kubernetes deployment file, performs [variables substitution](#using-variables) and [`kubectl delete`](https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands#apply) it,
+2. looks for your Kubernetes deployment file, performs [variables substitution](#variables-substitution-mechanism) and [`kubectl delete`](https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands#apply) it,
     1. look for a specific `deployment-$environment_type.yml` in your project (e.g. `deployment-staging.yml` for staging environment),
     2. fallbacks to default `deployment.yml`.
 3. _optionally_ executes the `k8s-post-cleanup.sh` script in your project to perform specific environment post-cleanup (for e.g. delete bound services).

templates/gitlab-ci-k8s.yml

@@ -593,10 +593,16 @@ stages:
       fi
       deploymentdir=$(dirname "$kustofile")
 
+      # variables substitution
+      tbc_envsubst "$kustofile" > generated-kustomization.yml
+      # overwrite kustomization file with substitued variables
+      mv generated-kustomization.yml "$kustofile"
+
       # apply/delete deployment descriptor
       log_info "--- \\e[32mkustomize\\e[0m"
       # shellcheck disable=SC2086
-      kubectl kustomize "$deploymentdir" ${K8S_KUSTOMIZE_ARGS}  > ./generated-deployment.yml
+      kubectl kustomize "$deploymentdir" ${K8S_KUSTOMIZE_ARGS}  > generated-deployment.yml
+
       log_info "--- \\e[32mkubectl $action\\e[0m"
       kubectl ${TRACE+-v=5} "$action" -f ./generated-deployment.yml
     else
@@ -785,7 +791,7 @@ stages:
         log_info "--- \\e[32mpre-cleanup hook\\e[0m (\\e[33;1m${prescript}\\e[0m) not found: skip"
       fi
 
-      # has to be valuated for envsubst
+      # has to be valuated for tbc_envsubst
       export hostname=hostname
 
       do_kubectl delete
@@ -813,8 +819,18 @@ stages:
       fi
       deploymentdir=$(dirname "$kustofile")
 
+      # variables substitution
+      tbc_envsubst "$kustofile" > generated-kustomization.yml
+      # overwrite kustomization file with substitued variables
+      mv generated-kustomization.yml "$kustofile"
+
+      # apply/delete deployment descriptor
+      log_info "--- \\e[32mkustomize\\e[0m"
       # shellcheck disable=SC2086
-      kustomize build ${K8S_KUSTOMIZE_ARGS} "${deploymentdir}" | /usr/bin/kube-score score $K8S_SCORE_EXTRA_OPTS -
+      kustomize build ${K8S_KUSTOMIZE_ARGS} "$deploymentdir" > generated-deployment.yml
+
+      # shellcheck disable=SC2086
+      /usr/bin/kube-score score $K8S_SCORE_EXTRA_OPTS generated-deployment.yml
     else
       # find deployment file
       deploymentfile=$(ls -1 "$K8S_SCRIPTS_DIR/deployment-${environment_type}.yml" 2>/dev/null || ls -1 "$K8S_SCRIPTS_DIR/deployment.yml" 2>/dev/null || echo "")