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Version: 0.8

Git Repository Contents

Fleet will create bundles from a git repository. This happens either explicitly by specifying paths, or when a fleet.yaml is found.

Each bundle is created from paths in a GitRepo and modified further by reading the discovered fleet.yaml file. Bundle lifecycles are tracked between releases by the helm releaseName field added to each bundle. If the releaseName is not specified within fleet.yaml it is generated from GitRepo.name + path. Long names are truncated and a -<hash> prefix is added.

The git repository has no explicitly required structure. It is important to realize the scanned resources will be saved as a resource in Kubernetes so you want to make sure the directories you are scanning in git do not contain arbitrarily large resources. Right now there is a limitation that the resources deployed must gzip to less than 1MB.

How repos are scanned

Multiple paths can be defined for a GitRepo and each path is scanned independently. Internally each scanned path will become a bundle that Fleet will manage, deploy, and monitor independently.

The following files are looked for to determine the how the resources will be deployed.

FileLocationMeaning
Chart.yaml:/ relative to path or custom path from fleet.yamlThe resources will be deployed as a Helm chart. Refer to the fleet.yaml for more options.
kustomization.yaml:/ relative to path or custom path from fleet.yamlThe resources will be deployed using Kustomize. Refer to the fleet.yaml for more options.
fleet.yamlAny subpathIf any fleet.yaml is found a new bundle will be defined. This allows mixing charts, kustomize, and raw YAML in the same repo
*.yaml Any subpathIf a Chart.yaml or kustomization.yaml is not found then any .yaml or .yml file will be assumed to be a Kubernetes resource and will be deployed.
overlays/{name}/ relative to pathWhen deploying using raw YAML (not Kustomize or Helm) overlays is a special directory for customizations.

Excluding files and directories from bundles

Fleet supports file and directory exclusion by means of .fleetignore files, in a similar fashion to how .gitignore files behave in git repositories:

  • Glob syntax is used to match files or directories, using Golang's filepath.Match
  • Empty lines are skipped, and can therefore be used to improve readability
  • Characters like white spaces and # can be escaped with a backslash
  • Trailing spaces are ignored, unless escaped
  • Comments, ie lines starting with unescaped #, are skipped
  • A given line can match a file or a directory, even if no separator is provided: eg. subdir/* and subdir are both valid .fleetignore lines, and subdir matches both files and directories called subdir
  • A match may be found for a file or directory at any level below the directory where a .fleetignore lives, ie foo.yaml will match ./foo.yaml as well as ./path/to/foo.yaml
  • Multiple .fleetignore files are supported. For instance, in the following directory structure, only root/something.yaml, bar/something2.yaml and foo/something.yaml will end up in a bundle:
root/
├── .fleetignore # contains `ignore-always.yaml'
├── something.yaml
├── bar
│   ├── .fleetignore # contains `something.yaml`
│   ├── ignore-always.yaml
│   ├── something2.yaml
│   └── something.yaml
└── foo
   ├── ignore-always.yaml
   └── something.yaml

This currently comes with a few limitations, the following not being supported:

  • Double asterisks (**)
  • Explicit inclusions with !

fleet.yaml

The fleet.yaml is an optional file that can be included in the git repository to change the behavior of how the resources are deployed and customized. The fleet.yaml is always at the root relative to the path of the GitRepo and if a subdirectory is found with a fleet.yaml a new bundle is defined that will then be configured differently from the parent bundle.

caution

Helm chart dependencies: It is up to the user to fulfill the dependency list for the Helm charts. As such, you must manually run helm dependencies update $chart OR run helm dependencies build $chart prior to install. See the Fleet docs in Rancher for more information.

The available fields are documented in the fleet.yaml reference

For a private Helm repo, users can reference a secret from the git repo resource. See Using Private Helm Repositories for more information.

Using Helm Values

How changes are applied to values.yaml:

  • Note that the most recently applied changes to the values.yaml will override any previously existing values.

  • When changes are applied to the values.yaml from multiple sources at the same time, the values will update in the following order: helm.values -> helm.valuesFiles -> helm.valuesFrom. That means valuesFrom will take precedence over both, valuesFiles and values.

Using ValuesFrom

These examples showcase the style and format for using valuesFrom. ConfigMaps and Secrets should be created in downstream clusters.

Example ConfigMap:

apiVersion: v1
kind: ConfigMap
metadata:
name: configmap-values
namespace: default
data:
values.yaml: |-
replication: true
replicas: 2
serviceType: NodePort

Example Secret:

apiVersion: v1
kind: Secret
metadata:
name: secret-values
namespace: default
stringData:
values.yaml: |-
replication: true
replicas: 3
serviceType: NodePort

A secret like that, can be created from a YAML file secretdata.yaml by running the following kubectl command: kubectl create secret generic secret-values --from-file=values.yaml=secretdata.yaml

The resources can then be referenced from a fleet.yaml:

helm:
chart: simple-chart
valuesFrom:
- secretKeyRef:
name: secret-values
namespace: default
key: values.yaml
- configMapKeyRef:
name: configmap-values
namespace: default
key: values.yaml
values:
replicas: "4"

Per Cluster Customization

The GitRepo defines which clusters a git repository should be deployed to and the fleet.yaml in the repository determines how the resources are customized per target.

All clusters and cluster groups in the same namespace as the GitRepo will be evaluated against all targets of that GitRepo. The targets list is evaluated one by one and if there is a match the resource will be deployed to the cluster. If no match is made against the target list on the GitRepo then the resources will not be deployed to that cluster. Once a target cluster is matched the fleet.yaml from the git repository is then consulted for customizations. The targetCustomizations in the fleet.yaml will be evaluated one by one and the first match will define how the resource is to be configured. If no match is made the resources will be deployed with no additional customizations.

There are three approaches to matching clusters for both GitRepo targets and fleet.yaml targetCustomizations. One can use cluster selectors, cluster group selectors, or an explicit cluster group name. All criteria is additive so the final match is evaluated as "clusterSelector && clusterGroupSelector && clusterGroup". If any of the three have the default value it is dropped from the criteria. The default value is either null or "". It is important to realize that the value {} for a selector means "match everything."

targetCustomizations:
- name: all
# Match everything
clusterSelector: {}
- name: none
# Selector ignored
clusterSelector: null

When matching a cluster by name, make sure to use the name of the clusters.fleet.cattle.io resource. The Rancher UI also has a provisioning and a management cluster resource. Since the management cluster resource is not namespaced, its name is different and contains a random suffix.

targetCustomizations:
- name: prod
clusterName: fleetname

See Mapping to Downstream Clusters for more information and a list of supported customizations.

Raw YAML Resource Customization

When using Kustomize or Helm the kustomization.yaml or the helm.values will control how the resource are customized per target cluster. If you are using raw YAML then the following simple mechanism is built-in and can be used. The overlays/ folder in the git repo is treated specially as folder containing folders that can be selected to overlay on top per target cluster. The resource overlay content uses a file name based approach. This is different from kustomize which uses a resource based approach. In kustomize the resource Group, Kind, Version, Name, and Namespace identify resources and are then merged or patched. For Fleet the overlay resources will override or patch content with a matching file name.

# Base files
deployment.yaml
svc.yaml

# Overlay files

# The following file will be added
overlays/custom/configmap.yaml
# The following file will replace svc.yaml
overlays/custom/svc.yaml
# The following file will patch deployment.yaml
overlays/custom/deployment_patch.yaml

A file named foo will replace a file called foo from the base resources or a previous overlay. In order to patch the contents of a file the convention of adding _patch. (notice the trailing period) to the filename is used. The string _patch. will be replaced with . from the file name and that will be used as the target. For example deployment_patch.yaml will target deployment.yaml. The patch will be applied using JSON Merge, Strategic Merge Patch, or JSON Patch. Which strategy is used is based on the file content. Even though JSON strategies are used, the files can be written using YAML syntax.

Cluster and Bundle State

See Cluster and Bundle state.