diff --git a/action.yml b/action.yml
index 5feff10..dae6b09 100644
--- a/action.yml
+++ b/action.yml
@@ -13,6 +13,14 @@ inputs:
   cluster-name:
     description: "Name of SKE cluster."
     required: true
+  service-account-key:
+    description: "JSON representation of STACKIT service account key."
+    required: false
+    default: ""
+  service-account-key-path:
+    description: "Path to STACKIT service account key file."
+    required: false
+    default: ""
   timeout-seconds:
     description: "Time in seconds after which target state check fails."
     required: false
@@ -39,6 +47,8 @@ runs:
         INPUT_TIMEOUT_SECS: ${{ inputs.timeout-seconds }}
         INPUT_INTERVAL_SECS: ${{ inputs.interval-seconds }}
         INPUT_WAIT: ${{ inputs.wait }}
+        INPUT_SERVICE_ACCOUNT_KEY: ${{ inputs.service-account-key }}
+        INPUT_SERVICE_ACCOUNT_KEY_PATH: ${{ inputs.service-account-key-path }}
       run: |
         set -e
 
@@ -58,6 +68,11 @@ runs:
           fi
         done
 
+        if [ -z "$INPUT_SERVICE_ACCOUNT_KEY" ] && [ -z "$INPUT_SERVICE_ACCOUNT_KEY_PATH" ]; then
+          echo "::error:: You must provide either 'service-account-key' or 'service-account-key-path'."
+          exit 1
+        fi
+
         TIMEOUT_SECS="${INPUT_TIMEOUT_SECS:-900}"
         INTERVAL_SECS="${INPUT_INTERVAL_SECS:-5}"
         WAIT="${INPUT_WAIT:-true}"
@@ -91,8 +106,16 @@ runs:
 
         echo "::group::Authenticating with service account and triggering operation"
 
-        STACKIT_ACCESS_TOKEN="$(stackit auth activate-service-account --only-print-access-token)"
-        export STACKIT_ACCESS_TOKEN
+        if [ -n "$INPUT_SERVICE_ACCOUNT_KEY_PATH" ]; then
+          STACKIT_SERVICE_ACCOUNT_KEY_PATH="$INPUT_SERVICE_ACCOUNT_KEY_PATH"
+        else
+          STACKIT_SERVICE_ACCOUNT_KEY_PATH="$(mktemp)"
+
+          echo "Writing STACKIT service account key to $STACKIT_SERVICE_ACCOUNT_KEY_PATH"
+          echo "$INPUT_SERVICE_ACCOUNT_KEY" > "$STACKIT_SERVICE_ACCOUNT_KEY_PATH"
+        fi
+
+        export STACKIT_SERVICE_ACCOUNT_KEY_PATH
 
         STACKIT_PROJECT_ID="$INPUT_PROJECT_ID"
         export STACKIT_PROJECT_ID