A charm’s resources can be inspected using the
charmcraft tool. The following examples will work on the assumption of the following resource definition:
# ... resources: someresource: type: file filename: superdb.bin description: the DB with needed info # ...
Once the resource has been defined, you can build the charm as normal, then upload it to Charmhub:
# Build the charm $ charmcraft pack Created 'my-super-charm.charm'. # Upload the charm to Charmhub $ charmcraft upload my-super-charm.charm Revision 13 of 'my-super-charm' created # Query Charmhub about the charm's resources $ charmcraft resources my-super-charm Name Type Revision Optional someresource file 13 True
Now we’ve confirmed that the resource is associated with the charm, we can upload the resource to Charmhub.
Uploading file resources
# Upload the resource $ charmcraft upload-resource my-super-charm someresource --filepath=/tmp/superdb.bin Revision 1 created of resource 'someresource' for charm 'my-super-charm' # Update the resource to a new revision $ charmcraft upload-resource my-super-charm someresource --filepath=/tmp/superdb.bin Revision 2 created of resource 'someresource' for charm 'my-super-charm' # Verify the revisions of the charm resource $ charmcraft resource-revisions my-super-charm someresource Revision Created at Size 2 2021-03-05 192.3K 1 2021-03-05 204.9K
Uploading oci-image resources
oci-image resources is similar to uploading
file resources, but with a few different parameters to the command.
For example, if an
oci-image is defined in
metadata.yaml like so:
# ... resources: redis-image: type: oci-image description: OCI image for Redis # ...
It can be uploaded like so:
# charmcraft upload-resource --image <image digest> <charm name> <resource name> $ charmcraft upload-resource my-super-charm redis-image --image=sha256:64aa8983ec5cea7bc143af18829836914fa405184d56dcbdfd9df672ade85249 Revision 1 created of resource 'redis-image' for charm 'my-super-charm'
--image must indicate an OCI image’s digest, being it in the short or long form (e.g.:
Charmcraft will first check if that specific image is available in Canonical’s Registry, and just use it if that’s the case. If not, it will try to get it from the developer’s local OCI repository (needs
dockerd to be installed and running), push it to the Canonical’s Registry, and then use it.
When using the “short form” of the digest, the image needs to be present locally so its proper ID (the “long form”) can be retrieved.
The following is an example of
charmcraft using an image already present in Canonical’s Registry:
$ charmcraft upload-resource my-super-charm redis-image --image=sha256:c8f0dbc0d5a5e3aef7281a4d3941e97f204390b2cba9de6c117341361cbe84e4 Using the OCI image from Canonical's registry Revision 7 created of resource 'redis-image' for charm 'my-super-charm'
The following is the case of
charmcraft needing to push the image first:
$ charmcraft upload-resource my-super-charm redis-image --image=sha256:70aa8983ec5cea7bc143af188b4bdc424fa405184d56dcbdfd9df672ade85249 Remote image not found, uploading from local registry Image uploaded, new remote digest: sha256:29b027d656acae6e50693a2ec063d40c7de59a2f7b4c0d62c765d2f1cbde616c Revision 5 created of resource 'redis-image' for charm 'my-super-charm'
One detail to take into consideration: when
charmcraft pushes the local image to Canonical’s registry, the remote manifest ends up slightly different to the local one. This is deterministic, so future operations will continue to use the same manifest, but it does take some work each time to compute the target manifest.
Attach a resource to a release
Any uploaded revision of your charm’s resources can be associated with the charm at release time. This way, you can decide which revision of the resource will work with each revision of your charm.
$ charmcraft release my-super-charm --revision=13 --channel=stable --resource=someresource:2 Revision 13 of charm 'my-super-charm' released to stable (attaching resources: 'someresource' r2)
We can inspect the charm, and any associated resources at any time with
$ charmcraft status my-super-charm $ charmcraft status my-super-charm Track Channel Version Revision Resources latest stable 7.4a 13 someresource (r1) candidate ↑ ↑ ↑ beta 7.4a 10 edge 7.4a 14 someresource (r3)
Last updated 21 days ago.