chore: Push on first build if skip_unchanged_digest isn't set

.dockerignore

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

Dockerfile

@@ -1,6 +1,21 @@
+FROM alpine as certs
+
+RUN apk --update add ca-certificates
+
 FROM gcr.io/kaniko-project/executor:debug
 
+SHELL ["/busybox/sh", "-c"]
+
+RUN mkdir -p /usr/local/bin && \
+    wget -O /usr/local/bin/jq \
+    https://github.com/stedolan/jq/releases/download/jq-1.6/jq-linux64 && \
+    chmod +x /usr/local/bin/jq && \
+    wget -O /usr/local/bin/reg \
+    https://github.com/genuinetools/reg/releases/download/v0.16.1/reg-linux-386 && \
+    chmod +x /usr/local/bin/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 +52,7 @@ 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    |                 |
 
 **Here is where it gets specific, as the optional arguments become required depending on the registry targeted**
 

action.yml

@@ -41,6 +41,9 @@ 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
 runs:
   using: "docker"
   image: "Dockerfile"

entrypoint.sh

@@ -11,18 +11,18 @@ export USERNAME=${INPUT_USERNAME:-$GITHUB_ACTOR}
 export PASSWORD=${INPUT_PASSWORD:-$GITHUB_TOKEN}
 export IMAGE=$IMAGE:$TAG
 
-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 "${REGISTRY}" "registry"
-sanitize "${USERNAME}" "username"
-sanitize "${PASSWORD}" "password"
-sanitize "${IMAGE}" "image"
-sanitize "${TAG}" "tag"
+ensure "${REGISTRY}" "registry"
+ensure "${USERNAME}" "username"
+ensure "${PASSWORD}" "password"
+ensure "${IMAGE}" "image"
+ensure "${TAG}" "tag"
 
 if [ "$REGISTRY" == "docker.pkg.github.com" ]; then
     IMAGE_NAMESPACE="$(echo $GITHUB_REPOSITORY | tr '[:upper:]' '[:lower:]')"
@@ -45,10 +45,14 @@ export CACHE=$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 DOCKERFILE="--dockerfile ${INPUT_BUILD_FILE:-Dockerfile}"
-export DESTINATION="--destination $IMAGE"
+
+if [ ! -z $INPUT_SKIP_UNCHANGED_DIGEST ]; then
+    export DESTINATION="--no-push --digest-file digest"
+else
+    export DESTINATION="--destination $IMAGE"
+fi
 
 export ARGS="$CACHE $CONTEXT $DOCKERFILE $DESTINATION $INPUT_EXTRA_ARGS"
-echo $ARGS
 
 cat <<EOF >/kaniko/.docker/config.json
 {
@@ -61,4 +65,24 @@ cat <<EOF >/kaniko/.docker/config.json
 }
 EOF
 
-/kaniko/executor $ARGS
+/kaniko/executor --reproducible $ARGS
+
+if [ ! -z $INPUT_SKIP_UNCHANGED_DIGEST ]; then
+    export DIGEST=$(cat digest)
+    export REMOTE=$(reg digest "$IMAGE" | tail -1)
+
+    if [ "$DIGEST" == "$REMOTE" ]; then
+        echo "Digest hasn't changed, skipping, $DIGEST"
+        echo "Done 🎉️"
+        exit 0
+    fi
+
+    export DESTINATION="--destination $IMAGE"
+    export ARGS="$CACHE $CONTEXT $DOCKERFILE $DESTINATION $INPUT_EXTRA_ARGS"
+
+    echo "Pushing image..."
+
+    /kaniko/executor --reproducible $ARGS >/dev/null 2>&1
+
+    echo "Done 🎉️"
+fi