add github workflow, improve readme

Author: gardenerik

.github/workflows/build.yml

@@ -0,0 +1,40 @@
+on:
+  push:
+    tags:
+      - "*"
+
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}
+
+jobs:
+  build-and-push-image:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+
+      - name: Log in to the Container registry
+        uses: docker/login-action@65b78e6e13532edd9afa3aa52ac7964289d1a9c1
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract metadata (tags, labels) for Docker
+        id: meta
+        uses: docker/metadata-action@9ec57ed1fcdbf14dcef7dfbe97b2010124a938b7
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+
+      - name: Build and push Docker image
+        uses: docker/build-push-action@f2a1d5e99d037542a71f64918e516c093c6f3fc4
+        with:
+          context: .
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}

README.md

@@ -9,6 +9,8 @@
 WebTeX Render is a simple program used to generate static images from LaTeX equations. It was designed to be used as
 an alternative to <https://latex.codecogs.com/>. It also allows you to use arbitrary LaTeX packages in your images.
 
+We also provide a simple web API to generate images on demand.
+
 ## Usage
 
 ```shell
@@ -30,6 +32,19 @@ img.math.inline {
 }
 ```
 
+## Using the web API
+
+The `webtex_web` requires a configuration file to define "renderers".
+
+```yaml
+- name: render_name
+  key: secret
+  template: template.tex
+```
+
+The TeX image can be then generated at URL `http://...:8080/render/render_name/?eq=EQUATION&sig=SIGNATURE`.
+`EQUATION` should be a base64 encoded TeX. `SIGNATURE` should be a HMAC-SHA-256 of the `EQUATION` using the key from config.
+
 ## Minimal template
 
 ```tex
@@ -50,4 +65,19 @@ the document to make sure that all output files are at least `1em` high.
 
 ```shell
 go build -o wr ./webtex_render
+go build -o wr_web ./webtex_web
 ```
+
+## Docker image
+
+We also provide a Docker image. The image contains both `wr` and `wr_web` binaries, but is set up to start the web
+API by default.
+
+```shell
+docker run --rm \
+  -v ./config.yml:/app/config.yml:ro \
+  -v ./template.tex:/app/template.tex:ro \
+  -p 8080:8080 \
+  ghcr.io/naboj-org/webtex_render
+```
+