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Version: 0.5


Acorn image

When you install acorn, it will launch several workloads in your cluster, including an api-server and controller. By default, these workloads will use the image. You can customize this image by setting the --image option. This is useful if you are installing acorn in an environment where you are required to pull images from a private registry.

TLS via Let's Encrypt

When you launch an acorn and it has published ports, acorn will generate a unique URL for accessing it, like so:

$ acorn run -P

$ acorn ps
black-sea 1 1 6s ago => webapp:80 OK

By default, endpoints are http. To have acorn automatically generate a Let's Encrypt certificate and secure your endpoints, you can enable acorn's Let's Encrypt integration like this:

acorn install --lets-encrypt enabled

If you add this flag, you'll be prompted during install to agree to Let's Encrypt's Terms of Service and supply an email. You can supply these as flags too:

acorn install --lets-encrypt enabled --lets-encrypt-tos-agree=true --lets-encrypt-email <your email>

Let's Encrypt integration is only useful if you are running a non-local Kubernetes cluster. If you are running acorn on a local cluster such as Docker Desktop, Rancher Desktop, or minikube, enabling Let's Encrypt will have no effect. We don't issue certificates for the domains that are used in this scenario.

Endpoint domain names

Acorn provides several installation options for controlling the domain name used to generate endpoints. These are outlined in detail on our networking page.

Custom CA bundle

Acorn allows a user to provide a custom certificate authority (CA) bundle so that users can add their own private CA that acorn will trust. The most common use case is for acorn to trust an internal image registry that is signed by a private CA.

To do so, you will need to go through the following steps:

  1. Provide your CA certificate chain in the following secret.
kubectl -n acorn-image-system create secret generic cabundle --from-file=ca-certificates.crt=/path/to/your/ca-certificates.crt

kubectl -n acorn-system create secret generic cabundle --from-file=ca-certificates.crt=/path/to/your/ca-certificates.crt

You must provide the full CA certificate chain as it will override existing CA certificates in acorn control plane.

  1. Install acorn with the following option
acorn install --use-custom-ca-bundle

Ingress class name

Acorn requires an ingress controller to function properly. If your cluster has more than one ingress controller or if it has one but it isn't set as the default, you can explicitly set the ingress class using --ingress-class-name.


There are two install flags for interacting memory: --workload-memory-default and --workload-memory-maximum. Their values can both be viewed by running acorn info.

Check out the memory reference documentation for more information.


This flag is responsible for setting the memory amount that will get defaulted to should no other value be found.

acorn install --workload-memory-default 512Mi

Running the above will set all Acorns on the cluster (current and future) to use 512Mi as their default memory.


This flag sets a maximum that when exceeded prevents the offending Acorn from being installed.

acorn install --workload-memory-maximum 1Gi

This will set it so all Acorns on this cluster will be unable to install should they exceed 1Gi of memory.

Ignoring user-defined labels and annotations

There are situations where you may not want a user to be able to label or annotate the objects created by Acorn in the workload cluster. For such circumstances, the installation flag --ignore-user-labels-and-annotations exists. If this flag is passed to acorn install, then, except for the metadata scope, labels and annotations defined by users in their Acorns will be ignored when creating objects. No error nor warning will be produced.

If this is too restrictive, and you would like to allow certain user-defined labels and annotations to propagate to the Kubernetes objects then you can use the --allow-user-label and allow-user-annotation installation flags. These flags take a comma-delimited list of label/annotation keys that are allowed to propagate. You can also specify the flags multiple times and the values will be concatenated to create the final list. If the --ignore-user-labels-and-annotations is not supplied or is false, then these flags have no effect.

Note that in order to allow propagation of user-defined labels and annotations on an Acorn installation that previous disallowed it, one must pass --ignore-user-labels-and-annotations=false to acorn install.

Changing install options

If you want to change your installation options after the initial installation, just rerun acorn install with the new options. This will update the existing install dynamically.