Skip to main content

Promotion Steps Reference

This reference document describes the promotion steps that are built directly into Kargo. Steps are presented roughly in the order in which they might appear in a typical promotion process. Similarly, configuration options for each step are laid out in order of their applicability to typical use cases.

git-clone​

git-clone is often the first step in a promotion process. It creates a bare clone of a remote Git repository, then checks out one or more branches, tags, or commits to working trees at specified paths. Checking out different revisions to different paths is useful for the common scenarios of combining content from multiple sources or rendering Stage-specific manifests to a Stage-specific branch.

note

It is a noteworthy limitation of Git that one branch cannot be checked out in multiple working trees.

git-clone Configuration​

NameTypeRequiredDescription
repoURLstringYThe URL of a remote Git repository to clone.
insecureSkipTLSVerifybooleanNWhether to bypass TLS certificate verification when cloning (and for all subsequent operations involving this clone). Setting this to true is highly discouraged in production.
checkout[]objectYThe commits, branches, or tags to check out from the repository and the paths where they should be checked out. At least one must be specified.
checkout[].branchstringNA branch to check out. Mutually exclusive with tag and fromFreight=true. If none of these is specified, the default branch will be checked out.
checkout[].createbooleanNIn the event branch does not already exist on the remote, whether a new, empty, orphaned branch should be created. Default is false, but should commonly be set to true for Stage-specific branches, which may not exist yet at the time of a Stage's first promotion.
checkout[].tagstringNA tag to check out. Mutually exclusive with branch and fromFreight=true. If none of these is specified, the default branch will be checked out.
checkout[].fromFreightbooleanNWhether a commit to check out should be obtained from the Freight being promoted. A value of true is mutually exclusive with branch and tag. If none of these is specified, the default branch will be checked out. Default is false, but is often set to true.
checkout[].fromOriginobjectNSee specifying origins.
checkout[].pathstringYThe path for a working tree that will be created from the checked out revision. This path is relative to the temporary workspace that Kargo provisions for use by the promotion process.

git-clone Examples​

The most common usage of this step is to check out a commit specified by the Freight being promoted as well as a Stage-specific branch. Subsequent steps are likely to perform actions that revise the contents of the Stage-specific branch using the commit from the Freight as input.

steps:
- uses: git-clone
  config:
    repoURL: https://github.com/example/repo.git
    checkout:
    - fromFreight: true
      path: ./src
    - branch: stage/test
      create: true
      path: ./out
# Prepare the contents of ./out ...
# Commit, push, etc...

git-clear​

git-clear deletes the the entire contents of a specified Git working tree (except for the .git file). It is equivalent to executing git add . && git rm -rf --ignore-unmatch .. This step is useful for the common scenario where the entire content of a Stage-specific branch is to be replaced with content from another branch or with content rendered using some configuration management tool.

git-clear Configuration​

NameTypeRequiredDescription
pathstringYPath to a Git working tree whose entire contents are to be deleted.

git-clear Example​

steps:
- uses: git-clone
  config:
    repoURL: https://github.com/example/repo.git
    checkout:
    - branch: stage/test
      create: true
      path: ./out
- uses: git-clear
  config:
    path: ./out
# Prepare the contents of ./out ...
# Commit, push, etc...

copy​

copy copies files or the contents of entire directories from one specified location to another.

copy Configuration​

NameTypeRequiredDescription
inPathstringYPath to the file or directory to be copied. This path is relative to the temporary workspace that Kargo provisions for use by the promotion process.
outPathstringYPath to the destination. This path is relative to the temporary workspace that Kargo provisions for use by the promotion process.

copy Example​

The most common (though still advanced) usage of this step is to combine content from two working trees to use as input to a subsequent step, such as one that renders Stage-specific manifests.

Consider a Stage that requests Freight from two Warehouses, where one provides Kustomize "base" configuration, while the other provides a Stage-specific Kustomize overlay. Rendering the manifests intended for such a Stage will require combining the base and overlay configurations:

steps:
- uses: git-clone
  config:
    repoURL: https://github.com/example/repo.git
    checkout:
    - fromFreight: true
      fromOrigin:
        kind: Warehouse
        name: base
      path: ./src
    - fromFreight: true
      fromOrigin:
        kind: Warehouse
        name: test-overlay
      path: ./overlay
    - branch: stage/test
      create: true
      path: ./out
- uses: git-clear
  config:
    path: ./out
- uses: copy
  config:
    inPath: ./overlay/stages/test/kustomization.yaml
    outPath: ./src/stages/test/kustomization.yaml
# Render manifests to ./out, commit, push, etc...

kustomize-set-image​

kustomize-set-image updates the kustomization.yaml file in a specified directory to reflect a different revision of a container image. It is equivalent to executing kustomize edit set image. This step is commonly followed by a kustomize-build step.

kustomize-set-image Configuration​

NameTypeRequiredDescription
pathstringYPath to a directory containing a kustomization.yaml file. This path is relative to the temporary workspace that Kargo provisions for use by the promotion process.
images[]objectYThe details of changes to be applied to the kustomization.yaml file. At least one must be specified.
images[].imagestringYName/URL of the image being updated. The Freight being promoted presumably contains a reference to a revision of this image.
images[].fromOriginobjectNSee specifying origins.
images[].newNamestringNA substitution for the name/URL of the image being updated. This is useful when different Stages have access to different container image repositories (assuming those different repositories contain equivalent images that are tagged identically). This may be a frequent consideration for users of Amazon's Elastic Container Registry.
images[].useDigestbooleanNWhether to update the kustomization.yaml file using the container image's digest instead of its tag.

kustomize-set-image Examples​

steps:
- uses: git-clone
  config:
    repoURL: https://github.com/example/repo.git
    checkout:
    - fromFreight: true
      fromOrigin:
        kind: Warehouse
        name: base
      path: ./src
    - branch: stage/test
      create: true
      path: ./out
- uses: git-clear
  config:
    path: ./out
- uses: kustomize-set-image
  config:
    path: ./src/base
    images:
    - image: my/image
# Render manifests to ./out, commit, push, etc...

kustomize-set-image Output​

NameTypeDescription
commitMessagestringA description of the change(s) applied by this step. Typically, a subsequent git-commit step will reference this output and aggregate this commit message fragment with other like it to build a comprehensive commit message that describes all changes.

kustomize-build​

kustomize-build renders manifests from a specified directory containing a kustomization.yaml file to a specified file or to many files in a specified directory. This step is useful for the common scenario of rendering Stage-specific manifests to a Stage-specific branch. This step is commonly preceded by a git-clear step and followed by git-commit and git-push steps.

kustomize-build Configuration​

NameTypeRequiredDescription
pathstringYPath to a directory containing a kustomization.yaml file. This path is relative to the temporary workspace that Kargo provisions for use by the promotion process.
outPathstringYPath to the file or directory where rendered manifests are to be written. If the path ends with .yaml or .yml it is presumed to indicate a file and is otherwise presumed to indicate a directory. This path is relative to the temporary workspace that Kargo provisions for use by the promotion process.
plugin.helm.apiVersions[]stringNOptionally specifies a list of supported API versions to be used when rendering manifests using Kustomize's Helm chart plugin. This is useful for charts that may contain logic specific to different Kubernetes API versions.
plugin.helm.kubeVersionstringNOptionally specifies a Kubernetes version to be assumed when rendering manifests using Kustomize's Helm chart plugin. This is useful for charts that may contain logic specific to different Kubernetes versions.

kustomize-build Examples​

steps:
- uses: git-clone
  config:
    repoURL: https://github.com/example/repo.git
    checkout:
    - fromFreight: true
      path: ./src
    - branch: stage/test
      create: true
      path: ./out
- uses: git-clear
  config:
    path: ./out
- uses: kustomize-build
  config:
    path: ./src/stages/test
    outPath: ./out/manifests.yaml
# Commit, push, etc...

helm-update-image​

helm-update-image updates the values of specified keys in a specified Helm values file (e.g. values.yaml) to reflect a new version of a container image. This step is useful for the common scenario of updating such a values.yaml file with new version information which is referenced by the Freight being promoted. This step is commonly followed by a helm-template step.

helm-update-image Configuration​

NameTypeRequiredDescription
pathstringYPath to Helm values file (e.g. values.yaml). This path is relative to the temporary workspace that Kargo provisions for use by the promotion process.
images[]objectYThe details of changes to be applied to the values file. At least one must be specified.
images[].imagestringYName/URL of the image being updated. The Freight being promoted presumably contains a reference to a revision of this image.
images[].fromOriginobjectNSee specifying origins
images[].keystringYThe key to update within the values file. See Helm documentation on the format and limitations of the notation used in this field.
images[].valuestringYSpecifies how the value of key is to be updated. Possible values for this field are limited to:
  • ImageAndTag: Replaces the value of key with a string in form <image url>:<tag>
  • Tag: Replaces the value of key with the image's tag
  • ImageAndDigest: Replaces the value of key with a string in form <image url>@<digest>
  • Digest: Replaces the value of key with the image's digest

helm-update-image Example​

steps:
- uses: git-clone
  config:
    repoURL: https://github.com/example/repo.git
    checkout:
    - fromFreight: true
      path: ./src
    - branch: stage/test
      create: true
      path: ./out
- uses: git-clear
  config:
    path: ./out
- uses: helm-update-image
  config:
    path: ./src/charts/my-chart/values.yaml
    images:
    - image: my/image
      key: image.tag
      value: Tag
# Render manifests to ./out, commit, push, etc...

helm-update-image Output​

NameTypeDescription
commitMessagestringA description of the change(s) applied by this step. Typically, a subsequent git-commit step will reference this output and aggregate this commit message fragment with other like it to build a comprehensive commit message that describes all changes.

helm-update-chart​

helm-update-chart performs specified updates on the dependencies section of a specified Helm chart's Chart.yaml file. This step is useful for the common scenario of updating a chart's dependencies to reflect new versions of charts referenced by the Freight being promoted. This step is commonly followed by a helm-template step.

helm-update-chart Configuration​

NameTypeRequiredDescription
pathstringYPath to a Helm chart (i.e. to a directory containing a Chart.yaml file). This path is relative to the temporary workspace that Kargo provisions for use by the promotion process.
charts[]stringYThe details of dependency (subschart) updates to be applied to the chart's Chart.yaml file.
charts[].repositorystringYThe URL of the Helm chart repository in the dependencies entry whose version field is to be updated. Must exactly match the repository field of that entry.
charts[].namestringYThe name of the chart in in the dependencies entry whose version field is to be updated. Must exactly match the name field of that entry.
charts[].fromOriginobjectNSee specifying origins

helm-update-chart Examples​

Given a Chart.yaml file such as the following:

apiVersion: v2
name: example
type: application
version: 0.1.0
appVersion: 0.1.0
dependencies:
- repository: https://example-chart-repo
  name: some-chart
  version: 1.2.3

The dependencies can be updated to reflect the version of some-chart referenced by the Freight being promoted like so:

steps:
- uses: git-clone
  config:
    repoURL: https://github.com/example/repo.git
    checkout:
    - fromFreight: true
      path: ./src
    - branch: stage/test
      create: true
      path: ./out
- uses: git-clear
  config:
    path: ./out
- uses: helm-update-chart
  config:
    path: ./src/charts/my-chart
    charts:
    - repository: https://example-chart-repo
      name: some-chart
# Render manifests to ./out, commit, push, etc...

helm-update-chart Output​

NameTypeDescription
commitMessagestringA description of the change(s) applied by this step. Typically, a subsequent git-commit step will reference this output and aggregate this commit message fragment with other like it to build a comprehensive commit message that describes all changes.

helm-template​

helm-template renders a specified Helm chart to a specified directory or to many files in a specified directory. This step is useful for the common scenario of rendering Stage-specific manifests to a Stage-specific branch. This step is commonly preceded by a git-clear step and followed by git-commit and git-push steps.

helm-template Configuration​

NameTypeRequiredDescription
pathstringYPath to a Helm chart (i.e. to a directory containing a Chart.yaml file). This path is relative to the temporary workspace that Kargo provisions for use by the promotion process.
outPathstringYPath to the file or directory where rendered manifests are to be written. If the path ends with .yaml or .yml it is presumed to indicate a file and is otherwise presumed to indicate a directory.
releaseNamestringNOptional release name to use when rendering the manifests. This is commonly omitted.
namespacestringNOptional namespace to use when rendering the manifests. This is commonly omitted. GitOps agents such as Argo CD will generally ensure the installation of manifests into the namespace specified by their own configuration.
valuesFiles[]stringNHelm values files (apart from the chart's default values.yaml) to be used when rendering the manifests.
includeCRDsbooleanNWhether to include CRDs in the rendered manifests. This is false by default.
kubeVersionstringNOptionally specifies a Kubernetes version to be assumed when rendering manifests. This is useful for charts that may contain logic specific to different Kubernetes versions.
apiVersions[]stringNAllows a manual set of supported API versions to be specified.

helm-template Examples​

steps:
- uses: git-clone
  config:
    repoURL: https://github.com/example/repo.git
    checkout:
    - fromFreight: true
      path: ./src
    - branch: stage/test
      create: true
      path: ./out
- uses: git-clear
  config:
    path: ./out
- uses: helm-template
  config:
    path: ./src/charts/my-chart
    valuesFiles:
    - ./src/charts/my-chart/test-values.yaml
    outPath: ./out/manifests.yaml
# Commit, push, etc...

git-commit​

git-commit commits all changes in a working tree to its checked out branch. This step is often used after previous steps have put the working tree into the desired state and is commonly followed by a git-push step.

git-commit Configuration​

NameTypeRequiredDescription
pathstringYPath to a Git working tree containing changes to be committed. This path is relative to the temporary workspace that Kargo provisions for use by the promotion process.
messagestringNThe commit message. Mutually exclusive with messageFromSteps.
messageFromSteps[]stringNReferences the commitMessage output of previous steps. When one or more are specified, the commit message will be constructed by concatenating the messages from individual steps. Mutually exclusive with message.
author[]objectNOptionally provider authorship information for the commit.
author.namestringNThe committer's name.
author.emailstringNThe committer's email address.

git-commit Example​

steps:
- uses: git-clone
  config:
    repoURL: https://github.com/example/repo.git
    checkout:
    - fromFreight: true
      path: ./src
    - branch: stage/test
      create: true
      path: ./out
- uses: git-clear
  config:
    path: ./out
- uses: kustomize-set-image
  as: update-image
  config:
    images:
    - image: my/image
- uses: kustomize-build
  config:
    path: ./src/stages/test
    outPath: ./out
- uses: git-commit
  config:
    path: ./out
    messageFromSteps:
    - update-image
# Push, etc...

git-commit Output​

NameTypeDescription
commitstringThe ID (SHA) of the commit created by this step. If the step short-circuited and did not create a new commit because there were no differences from the current head of the branch, this value will be the ID of the existing commit at the head of the branch instead. Typically, a subsequent argocd-update step will reference this output to learn the ID of the commit that an applicable Argo CD ApplicationSource should be observably synced to under healthy conditions.

git-push​

git-push pushes the committed changes in a specified working tree to a specified branch in the remote repository. This step typically follows a git-commit step and is often followed by a git-open-pr step.

git-push Configuration​

NameTypeRequiredDescription
pathstringYPath to a Git working tree containing committed changes.
targetBranchstringNThe branch to push to in the remote repository. Mutually exclusive with generateTargetBranch=true. If neither of these is provided, the target branch will be the same as the branch currently checked out in the working tree.
generateTargetBranchbooleanNWhether to push to a remote branch named like kargo/<project>/<stage>/promotion. If such a branch does not already exist, it will be created. A value of 'true' is mutually exclusive with targetBranch. If neither of these is provided, the target branch will be the currently checked out branch. This option is useful when a subsequent promotion step will open a pull request against a Stage-specific branch. In such a case, the generated target branch pushed to by the git-push step can later be utilized as the source branch of the pull request.

git-push Examples​

steps:
# Clone, prepare the contents of ./out, etc...
- uses: git-commit
  config:
    path: ./out
    message: rendered updated manifests
- uses: git-push
  config:
    path: ./out

git-push Output​

NameTypeDescription
branchstringThe name of the remote branch pushed to by this step. This is especially useful when the generateTargetBranch=true option has been used, in which case a subsequent git-open-pr will typically reference this output to learn what branch to use as the head branch of a new pull request.
commitstringThe ID (SHA) of the commit pushed by this step.

git-open-pr​

git-open-pr opens a pull request in a specified remote repository using specified source and target branches. This step is often used after a git-push and is commonly followed by a git-wait-for-pr step.

At present, this feature only supports GitHub pull requests and GitLab merge requests.

git-open-pr Configuration​

NameTypeRequiredDescription
repoURLstringYThe URL of a remote Git repository.
providerstringNThe name of the Git provider to use. Currently only github and gitlab are supported. Kargo will try to infer the provider if it is not explicitly specified.
insecureSkipTLSVerifybooleanNIndicates whether to bypass TLS certificate verification when interfacing with the Git provider. Setting this to true is highly discouraged in production.
sourceBranchstringNSpecifies the source branch for the pull request. Mutually exclusive with sourceBranchFromStep.
sourceBranchFromStepstringNIndicates the source branch should be determined by the branch key in the output of a previous promotion step with the specified alias. Mutually exclusive with sourceBranch.
targetBranchstringNThe branch to which the changes should be merged.
createTargetBranchbooleanNIndicates whether a new, empty orphaned branch should be created and pushed to the remote if the target branch does not already exist there. Default is false.

git-open-pr Example​

steps:
# Clone, prepare the contents of ./out, commit, etc...
- uses: git-push
  as: push
  config:
    path: ./out
    generateTargetBranch: true
- uses: git-open-pr
  as: open-pr
  config:
    repoURL: https://github.com/example/repo.git
    createTargetBranch: true
    sourceBranchFromStep: push
    targetBranch: stage/prod
# Wait for the PR to be merged or closed...

git-open-pr Output​

NameTypeDescription
prNumbernumberThe numeric identifier of the pull request opened by this step. Typically, a subsequent git-wait-for-pr step will reference this output to learn what pull request to monitor.

git-wait-for-pr​

git-wait-for-pr waits for a specified open pull request to be merged or closed. This step commonly follows a git-open-pr step and is commonly followed by an argocd-update step.

git-wait-for-pr Configuration​

NameTypeRequiredDescription
repoURLstringYThe URL of a remote Git repository.
providerstringNThe name of the Git provider to use. Currently only github and gitlab are supported. Kargo will try to infer the provider if it is not explicitly specified.
insecureSkipTLSVerifybooleanNIndicates whether to bypass TLS certificate verification when interfacing with the Git provider. Setting this to true is highly discouraged in production.
prNumberstringNThe number of the pull request to wait for. Mutually exclusive with prNumberFromStep.
prNumberFromStepstringNReferences the prNumber output from a previous step. Mutually exclusive with prNumber.

git-wait-for-pr Output​

NameTypeDescription
commitstringThe ID (SHA) of the new commit at the head of the target branch after merge. Typically, a subsequent argocd-update step will reference this output to learn the ID of the commit that an applicable Argo CD ApplicationSource should be observably synced to under healthy conditions.

git-wait-for-pr Example​

steps:
# Clone, prepare the contents of ./out, commit, etc...
- uses: git-push
  as: push
  config:
    path: ./out
    generateTargetBranch: true
- uses: git-open-pr
  as: open-pr
  config:
    repoURL: https://github.com/example/repo.git
    createTargetBranch: true
    sourceBranchFromStep: push
    targetBranch: stage/prod
- uses: git-wait-for-pr
  as: wait-for-pr
  config:
    repoURL: https://github.com/example/repo.git
    prNumberFromStep: open-pr

argocd-update​

argocd-update updates one or more Argo CD Application resources in various ways. Among other scenarios, this step is useful for the common one of forcing an Argo CD Application to sync after previous steps have updated a remote branch referenced by the Application. This step is commonly the last step in a promotion process.

note

For an Argo CD Application resource to be managed by a Kargo Stage, the Application must have an annotation of the following form:

kargo.akuity.io/authorized-stage: "<project-name>:<stage-name>"

Such an annotation offers proof that a user who is themselves authorized to update the Application in question has consented to a specific Stage updating the Application as well.

The following example shows how to configure an Argo CD Application manifest to authorize the test Stage of the kargo-demo Project:

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: kargo-demo-test
  namespace: argocd
  annotations:
    kargo.akuity.io/authorized-stage: kargo-demo:test
spec:
  # Application specifications go here

argocd-update Configuration​

NameTypeRequiredDescription
apps[]objectYDescribes Argo CD Application resources to update and how to update them. At least one must be specified.
apps[].namestringYThe name of the Argo CD Application.
apps[].namespacestringNThe namespace of the Argo CD Application resource to be updated. If left unspecified, the namespace will be the Kargo controller's configured default -- typically argocd.
apps[].sources[]objectNDescribes Argo CD ApplicationSources to update and how to update them.
apps[].sources[].repoURLstringYThe value of the target ApplicationSource's own repoURL field. This must match exactly.
apps[].sources[].chartstringNApplicable only when the target ApplicationSource references a Helm chart repository, the value of the target ApplicationSource's own chart field. This must match exactly.
apps[].sources[].desiredCommitFromStepstringNApplicable only when repoURL references a Git repository, this field references the commit output from a previous step and uses it as the desired revision for the source. If this is left undefined, the desired revision will be determined by Freight (if possible). Note that the source's targetRevision will not be updated to this commit unless updateTargetRevision=true is set. The utility of this field is to ensure that health checks on Argo CD ApplicationSources can account for scenarios where the desired revision differs from what may be found in Freight, likely due to the use of rendered branches and/or PR-based promotion workflows.
apps[].sources[].updateTargetRevisionbooleanYIndicates whether the target ApplicationSource should be updated such that its targetRevision field points at the most recently Git commit (if repoURL references a Git repository) or chart version (if repoURL references a chart repository).
apps[].sources[].kustomizeobjectNDescribes updates to an Argo CD ApplicationSource's Kustomize-specific properties.
apps[].sources[].kustomize.images[]objectYDescribes how to update an Argo CD ApplicationSource's Kustomize-specific properties to reference specific versions of container images.
apps[].sources[].kustomize.images[].repoURLstringYURL of the image being updated. The Freight being promoted must contain a reference to a revision of this image.
apps[].sources[].kustomize.images[].newNamestringNA substitution for the name/URL of the image being updated. This is useful when different Stages have access to different container image repositories (assuming those different repositories contain equivalent images that are tagged identically). This may be a frequent consideration for users of Amazon's Elastic Container Registry.
apps[].sources[].kustomize.images[].useDigestbooleanNWhether to use the container image's digest instead of its tag.
apps[].sources[].kustomize.images[].fromOriginobjectNSee specifying origins. If not specified, may inherit a value from apps[].sources[].kustomize.fromOrigin.
apps[].sources[].kustomize.fromOriginobjectNSee specifying origins. If not specified, may inherit a value from apps[].sources[].fromOrigin.
apps[].sources[].helmobjectNDescribes updates to an Argo CD ApplicationSource's Helm parameters.
apps[].sources[].helm.images[]objectYDescribes how to update an Argo CD ApplicationSource's Helm parameters to reference specific versions of container images.
apps[].sources[].helm.images[].repoURLstringYURL of the image being updated. The Freight being promoted must contain a reference to a revision of this image.
apps[].sources[].helm.images[].keystringYThe key to update within the target ApplicationSource's helm.parameters map. See Helm documentation on the format and limitations of the notation used in this field.
apps[].sources[].helm.images[].valuestringYSpecifies how the value of key is to be updated. Possible values for this field are limited to:
  • ImageAndTag: Replaces the value of key with a string in form <image url>:<tag>
  • Tag: Replaces the value of key with the image's tag
  • ImageAndDigest: Replaces the value of key with a string in form <image url>@<digest>
  • Digest: Replaces the value of key with the image's digest
apps[].sources[].helm.images[].fromOriginobjectNSee specifying origins. If not specified, may inherit a value from apps[].sources[].helm.fromOrigin
apps[].sources[].helm.fromOriginobjectNSee [specifying origins].(#specifying-origins). If not specified, may inherit a value from apps[].sources[].
apps[].sources[].fromOriginobjectNSee specifying origins. If not specified, may inherit a value from apps[].fromOrigin.
apps[].fromOriginobjectNSee specifying origins. If not specified, may inherit a value from fromOrigin.
fromOriginobjectNSee specifying origins

argocd-update Examples​

steps:
# Clone, render manifests, commit, push, etc...
- uses: git-commit
  as: commit
  config:
    path: ./out
    messageFromSteps:
    - update-image
- uses: git-push
  config:
    path: ./out
- uses: argocd-update
  config:
    apps:
    - name: my-app
      sources:
      - repoURL: https://github.com/example/repo.git
        desiredCommitFromStep: commit

argocd-update Health Checks​

The argocd-update step is unique among all other built-in promotion steps in that, on successful completion, it will register health checks to be performed upon the target Stage on an ongoing basis. This health check configuration is opaque to the rest of Kargo and is understood only by health check functionality built into the step. This permits Kargo to factor the health and sync state of Argo CD Application resources into the overall health of a Stage without requiring Kargo to understand Application health directly.

info

Although the argocd-update step is the only promotion step to currently utilize this health check framework, we anticipate that future built-in and third-party promotion steps will take advantage of it as well.

Specifying Origins​

Many promotion steps, or parts of those steps, will (whether optionally or unconditionally) attempt to learn the desired revision(s) of some artifact(s) by consulting the revisions of those artifact(s) references by the Freight being promoted.

By way of example, this kustomize-set-image step will consult the Freight being promoted to learn the desired revision of the my/image container image:

- uses: kustomize-set-image
  config:
    path: ./src/base
    images:
    - image: my/image

In some advanced uses cases, Stages may request Freight from multiple origins (Warehouses). In such scenarios, it is possible (although somewhat rare) that the multiple Freight being promoted may collectively reference multiple distinct revisions of the same artifact. In such as case, it can become ambiguous which revision of an artifact referenced by a promotion step should be used.

To permit disambiguation in cases such as those described above, all promotion steps that have the potential to reference Freight from multiple origins support a fromOrigin option that can be used to clarify which piece of Freight's reference to the artifact should be used by identifying the origin (Warehouse) from which the Freight should have originated.

The best way to illustrate this involves a complex example wherein a Stage requests Freight from two Warehouses. Both Warehouses subscribe to the same Git repository, with one watching for changes to a Kustomize "base" configuration and the other watching for changes to a Stage-specific Kustomize overlay. Rendering the manifests intended for such a Stage will require combining the base and overlay configurations with the help of a copy step. For this case, a git-clone step may be configured similarly to the following:

steps:
- uses: git-clone
  config:
    repoURL: https://github.com/example/repo.git
    checkout:
    - fromFreight: true
      fromOrigin:
        kind: Warehouse
        name: base
      path: ./src
    - fromFreight: true
      fromOrigin:
        kind: Warehouse
        name: test-overlay
      path: ./overlay
    - branch: stage/test
      create: true
      path: ./out
- uses: git-clear
  config:
    path: ./out
- uses: copy
  config:
    inPath: ./overlay/stages/test/kustomization.yaml
    outPath: ./src/stages/test/kustomization.yaml
- uses: kustomize-build
  config:
    path: ./src/stages/test
    outPath: ./out
# Commit, push, etc...

Note that when checking out specific revisions of the https://github.com/example/repo.git repository to different working trees, the git-clone step has twice utilized fromOrigin to clarify which of the Freight being promoted should be used to determine the revision to check out.

info

fromOrigin never needs to be specified in the majority of use cases wherein there is no inherent ambiguity. Kargo will automatically select the correct revision of an artifact when there is only one possibility. When Kargo detects that there may be multiple possibilities, it will fail and raise an error indicating that the user must disambiguate by specifying fromOrigin in applicable steps.