fix: Ensure lowercase GitHub image namespace

README.md

@@ -34,13 +34,13 @@ This action aims to be as flexible as possible, so it tries to define the defaul
 the most used values. So, technically there is a single required argument
 
 | variable         | description                                              | required | default                     |
-|-----------------|----------------------------------------------------------|----------|-----------------------------|
+|------------------|----------------------------------------------------------|----------|-----------------------------|
 | image            | Name of the image you would like to push                 | true     |                             |
 
 ## Optional Arguments
 
 | variable         | description                                              | required | default                     |
-|-----------------|----------------------------------------------------------|----------|-----------------------------|
+|------------------|----------------------------------------------------------|----------|-----------------------------|
 | registry         | Docker registry where the image will be pushed           | false    | docker.io                   |
 | username         | Username used for authentication to the Docker registry  | false    | $GITHUB_ACTOR               |
 | password         | Password used for authentication to the Docker registry  | false    |                             |
@@ -51,6 +51,7 @@ the most used values. So, technically there is a single required argument
 | cache_directory  | Filesystem path meant to be used as cache                | false    |                             |
 | build_file       | Dockerfile filename                                      | false    | Dockerfile                  |
 | extra_args       | Additional arguments to be passed to the kaniko executor | false    |                             |
+| strip_tag_prefix | Prefix to be stripped from the tag                       | false    |                             |
 
 **Here is where it gets specific, as the optional arguments become required depending on the registry targeted**
 
@@ -154,3 +155,18 @@ If you would like to publish the image to other registries, these actions might
 
 The `tag` argument, **unless overridden**, is automatically guessed based on the branch name. If the branch is `master` then the tag will
 be `latest`, otherwise it will keep the branch name, but replacing any forward slash (/) with a hyphen (-).
+
+If the `v` prefix that it's usually added to the GitHub releases is not desired when pushed to dockerhub, the `strip_tag_prefix` allows to
+specify which part of the tag should be removed.
+
+Example:
+
+```yaml
+with:
+  registry: docker.pkg.github.com
+  password: ${{ secrets.GITHUB_TOKEN }}
+  image: kaniko
+  strip_tag_prefix: pre-
+```
+
+for the tag `pre-0.1` will push `kaniko:0.1`, as the `pre-` part will be stripped from the tag name.

action.yml

@@ -35,6 +35,9 @@ inputs:
   build_file:
     description: "Dockerfile filename"
     required: false
+  strip_tag_prefix:
+    description: "Prefix to be stripped from the tag"
+    required: false
   extra_args:
     description: "Additional arguments to be passed to the kaniko executor"
     required: false

entrypoint.sh

@@ -3,9 +3,10 @@ set -e pipefail
 
 export REGISTRY=${INPUT_REGISTRY:-"docker.io"}
 export IMAGE=${INPUT_IMAGE}
-export BRANCH=$(echo ${GITHUB_REF} | sed -e "s/refs\/heads\///g" | sed -e "s/\//-/g")
+export BRANCH=$(echo ${GITHUB_REF} | sed -E "s/refs\/(heads|tags)\///g" | sed -e "s/\//-/g")
 export TAG=${INPUT_TAG:-$([ "$BRANCH" == "master" ] && echo latest || echo $BRANCH)}
 export TAG=${TAG:-"latest"}
+export TAG=${TAG#$INPUT_STRIP_TAG_PREFIX}
 export USERNAME=${INPUT_USERNAME:-$GITHUB_ACTOR}
 export PASSWORD=${INPUT_PASSWORD:-$GITHUB_TOKEN}
 export IMAGE=$IMAGE:$TAG
@@ -24,10 +25,11 @@ sanitize "${IMAGE}" "image"
 sanitize "${TAG}" "tag"
 
 if [ "$REGISTRY" == "docker.pkg.github.com" ]; then
-    export IMAGE="$GITHUB_REPOSITORY/$IMAGE"
+    IMAGE_NAMESPACE="$(echo $GITHUB_REPOSITORY | tr '[:upper:]' '[:lower:]')"
+    export IMAGE="$IMAGE_NAMESPACE/$IMAGE"
 
     if [ ! -z $INPUT_CACHE_REGISTRY ]; then
-        export INPUT_CACHE_REGISTRY="$REGISTRY/$GITHUB_REPOSITORY/$INPUT_CACHE_REGISTRY"
+        export INPUT_CACHE_REGISTRY="$REGISTRY/$IMAGE_NAMESPACE/$INPUT_CACHE_REGISTRY"
     fi
 fi
 

renovate.json

@@ -0,0 +1,5 @@
+{
+  "extends": [
+    "config:base"
+  ]
+}