fix: Force kaniko to run on GitHub action's environment

When skipping the push on unchanged digests, it's not enough to push the current tag,
which is probably semver, we also need to push the latest, so we can later check if
the latest digest equals the currently built image

.dockerignore

@@ -1,3 +1,3 @@
 *
 !entrypoint.sh
-
+.env*

Dockerfile

@@ -1,6 +1,20 @@
+FROM alpine as certs
+
+RUN apk --update add ca-certificates
+
 FROM gcr.io/kaniko-project/executor:debug
 
+SHELL ["/busybox/sh", "-c"]
+
+RUN wget -O /kaniko/jq \
+    https://github.com/stedolan/jq/releases/download/jq-1.6/jq-linux64 && \
+    chmod +x /kaniko/jq && \
+    wget -O /kaniko/reg \
+    https://github.com/genuinetools/reg/releases/download/v0.16.1/reg-linux-386 && \
+    chmod +x /kaniko/reg
+
 COPY entrypoint.sh /
+COPY --from=certs /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/ca-certificates.crt
 
 ENTRYPOINT ["/entrypoint.sh"]
 

Makefile

@@ -0,0 +1,24 @@
+build:
+	docker build -t aevea/kaniko .
+
+run: build
+	docker run \
+		-v $(shell pwd):/tmp \
+		-e GITHUB_REPOSITORY \
+		-e GITHUB_REF \
+		-e GITHUB_ACTOR \
+		-e GITHUB_TOKEN \
+		-e GITHUB_WORKSPACE="/tmp" \
+		-e INPUT_IMAGE \
+		-e INPUT_CACHE \
+		-e INPUT_CACHE_TTL \
+		-e INPUT_CACHE_REGISTRY \
+		-e INPUT_STRIP_TAG_PREFIX \
+		-e INPUT_SKIP_UNCHANGED_DIGEST \
+	aevea/kaniko
+
+shell: build
+	docker run \
+		-ti \
+		--entrypoint sh \
+	aevea/kaniko

README.md

@@ -40,7 +40,7 @@ the most used values. So, technically there is a single required argument
 ## 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    |                 |
@@ -52,6 +52,10 @@ the most used values. So, technically there is a single required argument
 | 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    |                 |
+| skip_unchanged_digest | Avoids pushing the image if the build generated the same digest | false    |                 |
+| path                  | Path to the build context. Defaults to `.`                      | false    | .               |
+| tag_with_latest       | Tags the built image with additional latest tag                 | false    |                 |
+| target                | Sets the target stage to build                                  | false    |                 |
 
 **Here is where it gets specific, as the optional arguments become required depending on the registry targeted**
 

action.yml

@@ -5,6 +5,10 @@ branding:
   icon: anchor
   color: orange
 inputs:
+  path:
+    description: Path to the build context
+    required: false
+    default: "."
   registry:
     description: "Docker registry where the image will be pushed"
     required: false
@@ -41,6 +45,15 @@ inputs:
   extra_args:
     description: "Additional arguments to be passed to the kaniko executor"
     required: false
+  skip_unchanged_digest:
+    description: "Avoids pushing the image if the build generated the same digest"
+    required: false
+  tag_with_latest:
+    description: "Tags the built image with additional latest tag"
+    required: false
+  target:
+    description: Sets the target stage to build
+    required: false
 runs:
   using: "docker"
   image: "Dockerfile"

entrypoint.sh

@@ -9,24 +9,33 @@ export TAG=${TAG:-"latest"}
 export TAG=${TAG#$INPUT_STRIP_TAG_PREFIX}
 export USERNAME=${INPUT_USERNAME:-$GITHUB_ACTOR}
 export PASSWORD=${INPUT_PASSWORD:-$GITHUB_TOKEN}
+export REPOSITORY=$IMAGE
+export IMAGE_LATEST=${INPUT_TAG_WITH_LATEST:+"$IMAGE:latest"}
 export IMAGE=$IMAGE:$TAG
+export CONTEXT_PATH=${INPUT_PATH}
 
-function sanitize() {
+function ensure() {
     if [ -z "${1}" ]; then
-        echo >&2 "Unable to find the ${2}. Did you set with.${2}?"
+        echo >&2 "Unable to find the ${2} variable. Did you set with.${2}?"
         exit 1
     fi
 }
 
-sanitize "${REGISTRY}" "registry"
+ensure "${REGISTRY}" "registry"
-sanitize "${USERNAME}" "username"
+ensure "${USERNAME}" "username"
-sanitize "${PASSWORD}" "password"
+ensure "${PASSWORD}" "password"
-sanitize "${IMAGE}" "image"
+ensure "${IMAGE}" "image"
-sanitize "${TAG}" "tag"
+ensure "${TAG}" "tag"
+ensure "${CONTEXT_PATH}" "path"
 
 if [ "$REGISTRY" == "docker.pkg.github.com" ]; then
     IMAGE_NAMESPACE="$(echo $GITHUB_REPOSITORY | tr '[:upper:]' '[:lower:]')"
     export IMAGE="$IMAGE_NAMESPACE/$IMAGE"
+    export REPOSITORY="$IMAGE_NAMESPACE/$REPOSITORY"
+
+    if [ ! -z $IMAGE_LATEST ]; then
+        export IMAGE_LATEST="$IMAGE_NAMESPACE/$IMAGE_LATEST"
+    fi
 
     if [ ! -z $INPUT_CACHE_REGISTRY ]; then
         export INPUT_CACHE_REGISTRY="$REGISTRY/$IMAGE_NAMESPACE/$INPUT_CACHE_REGISTRY"
@@ -37,18 +46,30 @@ if [ "$REGISTRY" == "docker.io" ]; then
     export REGISTRY="index.${REGISTRY}/v1/"
 else
     export IMAGE="$REGISTRY/$IMAGE"
+
+    if [ ! -z $IMAGE_LATEST ]; then
+        export IMAGE_LATEST="$REGISTRY/$IMAGE_LATEST"
+    fi
 fi
 
 export CACHE=${INPUT_CACHE:+"--cache=true"}
 export CACHE=$CACHE${INPUT_CACHE_TTL:+" --cache-ttl=$INPUT_CACHE_TTL"}
 export CACHE=$CACHE${INPUT_CACHE_REGISTRY:+" --cache-repo=$INPUT_CACHE_REGISTRY"}
 export CACHE=$CACHE${INPUT_CACHE_DIRECTORY:+" --cache-dir=$INPUT_CACHE_DIRECTORY"}
-export CONTEXT="--context $GITHUB_WORKSPACE"
+export CONTEXT="--context $GITHUB_WORKSPACE/$CONTEXT_PATH"
-export DOCKERFILE="--dockerfile ${INPUT_BUILD_FILE:-Dockerfile}"
+export DOCKERFILE="--dockerfile $CONTEXT_PATH/${INPUT_BUILD_FILE:-Dockerfile}"
-export DESTINATION="--destination $IMAGE"
+export TARGET=${INPUT_TARGET:+"--target=$INPUT_TARGET"}
 
-export ARGS="$CACHE $CONTEXT $DOCKERFILE $DESTINATION $INPUT_EXTRA_ARGS"
+if [ ! -z $INPUT_SKIP_UNCHANGED_DIGEST ]; then
-echo $ARGS
+    export DESTINATION="--no-push --digest-file digest"
+else
+    export DESTINATION="--destination $IMAGE"
+    if [ ! -z $IMAGE_LATEST ]; then
+        export DESTINATION="$DESTINATION --destination $IMAGE_LATEST"  
+    fi
+fi
+
+export ARGS="$CACHE $CONTEXT $DOCKERFILE $TARGET $DESTINATION $INPUT_EXTRA_ARGS"
 
 cat <<EOF >/kaniko/.docker/config.json
 {
@@ -61,4 +82,35 @@ cat <<EOF >/kaniko/.docker/config.json
 }
 EOF
 
-/kaniko/executor $ARGS
+# https://github.com/GoogleContainerTools/kaniko/issues/1349
+/kaniko/executor --reproducible --force $ARGS
+
+if [ ! -z $INPUT_SKIP_UNCHANGED_DIGEST ]; then
+    export DIGEST=$(cat digest)
+
+    if [ "$REGISTRY" == "docker.pkg.github.com" ]; then
+        wget -q -O manifest --header "Authorization: Basic $(echo -n $USERNAME:$PASSWORD | base64)" https://docker.pkg.github.com/v2/$REPOSITORY/manifests/latest || true
+        export REMOTE="sha256:$(cat manifest | sha256sum | awk '{ print $1 }')"
+    else
+        export REMOTE=$(reg digest -u $USERNAME -p $PASSWORD $REGISTRY/$REPOSITORY | tail -1)
+    fi
+
+    if [ "$DIGEST" == "$REMOTE" ]; then
+        echo "Digest hasn't changed, skipping, $DIGEST"
+        echo "Done 🎉️"
+        exit 0
+    fi
+
+    export DESTINATION="--destination $IMAGE"
+    if [ ! -z $IMAGE_LATEST ]; then
+        export DESTINATION="$DESTINATION --destination $IMAGE_LATEST"  
+    fi
+    
+    export ARGS="$CACHE $CONTEXT $DOCKERFILE $TARGET $DESTINATION $INPUT_EXTRA_ARGS"
+
+    echo "Pushing image..."
+
+    /kaniko/executor --reproducible $ARGS >/dev/null 2>&1
+
+    echo "Done 🎉️"
+fi