Update dockerimage.yml

.github/main.workflow

@@ -0,0 +1,31 @@
+workflow "Build and Publish" {
+  on = "push"
+  resolves = ["Master", "Docker Push"]
+}
+
+# Filter for master branch
+action "Master" {
+  uses = "actions/bin/filter@master"
+  args = "branch master"
+}
+
+action "Docker Build" {
+  uses = "actions/docker/cli@fe7ed3ce992160973df86480b83a2f8ed581cd50"
+  needs = ["Master"]
+  args = "build -t pihole-exporter ."
+}
+
+action "Docker Registry" {
+  uses = "actions/docker/login@fe7ed3ce992160973df86480b83a2f8ed581cd50"
+  env = {
+    DOCKER_REGISTRY_URL = "docker.pkg.github.com"
+  }
+  secrets = ["DOCKER_PASSWORD", "DOCKER_USERNAME"]
+  needs = ["Docker Build"]
+}
+
+action "Docker Push" {
+  uses = "actions/docker/cli@fe7ed3ce992160973df86480b83a2f8ed581cd50"
+  args = "push pihole-exporter"
+  needs = ["Docker Registry"]
+}