Update README file to also include instructions about Docker image usage.

Author: ericof

README.md

@@ -5,68 +5,46 @@
 </p>
 
 <h1 align="center">
-  Docker Stack Deploy Action
+  Docker Stack Deploy Tool
 </h1>
 
+<div align="center">
+
 [![GitHub Actions Marketplace](https://img.shields.io/badge/action-marketplace-blue.svg?logo=github&color=orange)](https://github.com/marketplace/actions/docker-stack-deploy-action)
 [![Release version badge](https://img.shields.io/github/v/release/kitconcept/docker-stack-deploy)](https://github.com/kitconcept/docker-stack-deploy/release)
+
 ![GitHub Repo stars](https://img.shields.io/github/stars/kitconcept/docker-stack-deploy?style=flat-square)
 [![license badge](https://img.shields.io/github/license/kitconcept/docker-stack-deploy)](./LICENSE)
 
-GitHub Action and Docker image used to deploy a Docker stack on a Docker Swarm.
-
-## Inputs
-
-## `registry`
-
-When using private images, specify which registry to login to. If no value is provided, we fallback to Docker Hub.
-
-To use GitHub Container registry, set the value to **ghcr.io**.
-
-## `username`
-
-When using private images, specify username to be used to log in.
-
-## `password`
-
-When using private images, specify password to be used to log in.
-
-## `remote_host`
-
-**Required** Hostname or address of the machine running the Docker Swarm manager node.
-
-## `remote_port`
-
-SSH port to connect on the the machine running the Docker Swarm manager node.
-
-**Default value**: 22
-
-## `remote_user`
-
-**Required** User with SSH and Docker privileges on the machine running the Docker Swarm manager node.
-
-## `remote_private_key`
-
-**Required** Private key used for ssh authentication.
+</div>
 
-## `deploy_timeout`
-
-Seconds, to wait until the deploy finishes.
+GitHub Action and Docker image used to deploy a Docker stack on a Docker Swarm.
 
-**Default value**: 300
 
-## `stack_file`
+## Configuration options
 
-**Required** Path to the stack file used in the deploy.
+| GitHub Action Input | Environment Variable | Summary | Required | Default Value |
+| --- | --- | --- | --- | --- |
+| `registry` | `REGISTRY` | Specify which container registry to login to. | |
+| `username` | `USERNAME` | Container registry username. | | |
+| `password` | `PASSWORD` | Container registry password. | | |
+| `remote_host` | `REMOTE_HOST` | Hostname or address of the machine running the Docker Swarm manager node | ✅ | |
+| `remote_port` | `REMOTE_PORT` | SSH port to connect on the the machine running the Docker Swarm manager node. | | **22** |
+| `remote_user` | `REMOTE_USER` | User with SSH and Docker privileges on the machine running the Docker Swarm manager node. | ✅ | |
+| `remote_private_key` | `REMOTE_PRIVATE_KEY` | Private key used for ssh authentication. | ✅ | |
+| `deploy_timeout` | `DEPLOY_TIMEOUT` | Seconds, to wait until the deploy finishes | | **600** |
+| `stack_file` | `STACK_FILE` | Path to the stack file used in the deploy. | ✅ | |
+| `stack_name` | `STACK_NAME` | Name of the stack to be deployed. | ✅ | |
+| `debug` | `DEBUG` | Verbose logging | | **0** |
 
-## `stack_name`
 
-**Required** Name of the stack to be deployed.
+## Using the GitHub Action
 
+Add, or edit an existing, `yaml` file inside `.github/actions` and use the configuration options listed above.
 
-## Examples
+### Examples
 
-### Deploying public images
+#### Deploying public images
 
 
 ```yaml
@@ -86,7 +64,7 @@ jobs:
         uses: actions/checkout@v2
 
       - name: Deploy
-        uses: kitconcept/[email protected].0
+        uses: kitconcept/[email protected].1
         with:
           remote_host: ${{ secrets.REMOTE_HOST }}
           remote_user: ${{ secrets.REMOTE_USER }}
@@ -95,7 +73,7 @@ jobs:
           stack_name: "plone-staging"
 ```
 
-### Deploying private images from GitHub Container Registry
+#### Deploying private images from GitHub Container Registry
 
 First, follow the steps to [create a Personal Access Token](https://docs.github.com/en/packages/working-with-a-github-packages-registry/working-with-the-container-registry#authenticating-to-the-container-registry).
 
@@ -116,7 +94,7 @@ jobs:
         uses: actions/checkout@v2
 
       - name: Deploy
-        uses: kitconcept/[email protected].0
+        uses: kitconcept/[email protected].1
         with:
           registry: "ghcr.io"
           username: ${{ secrets.GHCR_USERNAME }}
@@ -128,6 +106,85 @@ jobs:
           stack_name: "plone-live"
 ```
 
+## Using the Docker Image
+
+It is possible to directly use the `ghcr.io/kitconcept/docker-stack-deploy` Docker image, passing the configuration options as environment variables.
+
+### Examples
+
+#### Local machine
+
+Considering you have a local file named `.env_deploy` with content:
+
+```
+REGISTRY=hub.docker.com
+USERNAME=foo_usr
+PASSWORD=averylargepasswordortoken
+REMOTE_HOST=192.168.17.2
+REMOTE_PORT=22
+REMOTE_USER=user
+STACK_FILE=path/to/stack.yml
+STACK_NAME=mystack
+DEBUG=1
+```
+
+Run the following command:
+```shell
+docker run --rm
+  -v "$(pwd)":/github/workspace
+  -v /var/run/docker.sock:/var/run/docker.sock
+  --env-file=.env_deploy
+  -e REMOTE_PRIVATE_KEY="$(cat ~/.ssh/id_rsa)"
+  ghcr.io/kitconcept/docker-stack-deploy:latest
+```
+
+#### GitLab CI
+
+On your GitLab project, go to  `Settings -> CI/CD` and add the environment variables under **Variables**.
+
+Then edit your `.gitlab-cy.yml` to include the `deploy` step:
+
+```yaml
+image: busybox:latest
+
+services:
+  - docker:20.10.16-dind
+
+before_script:
+  - docker info
+
+deploy:
+  stage: deploy
+  varibles:
+    REGISTRY: ${REGISTRY}
+    USERNAME: ${REGISTRY_USER}
+    PASSWORD: ${REGISTRY_PASSWORD}
+    REMOTE_HOST: ${DEPLOY_HOST}
+    REMOTE_PORT: 22
+    REMOTE_USER: ${DEPLOY_USER}
+    REMOTE_PRIVATE_KEY: "${DEPLOY_KEY}"
+    STACK_FILE: stacks/app.yml
+    STACK_NAME: app
+    DEPLOY_IMAGE: ghcr.io/kitconcept/docker-stack-deploy:latest
+  script:
+    - docker pull ${DEPLOY_IMAGE}
+    - docker run --rm
+       -v "$(pwd)":/github/workspace
+       -v /var/run/docker.sock:/var/run/docker.sock
+       -e REGISTRY=${REGISTRY}
+       -e USERNAME=${USERNAME}
+       -e PASSWORD=${PASSWORD}
+       -e REMOTE_HOST=${REMOTE_HOST}
+       -e REMOTE_PORT=${REMOTE_PORT}
+       -e REMOTE_USER=${REMOTE_USER}
+       -e REMOTE_PRIVATE_KEY="${REMOTE_PRIVATE_KEY}"
+       -e STACK_FILE=${STACK_FILE}
+       -e STACK_NAME=${STACK_NAME}
+       -e DEBUG=1
+       ${DEPLOY_IMAGE}
+
+```
+
 ## Contribute
 
 - [Issue Tracker](https://github.com/kitconcept/docker-stack-deploy/issues)