latexgrambot: inline LaTeX bot for Telegram in Go

Renders LaTeX expressions into PNG pictures, PDF documents and native
Telegram rich text messages, entirely locally with TeX Live and poppler.

- Chat mode with /image, /pdf, /rich plus per-user preamble and DPI
- Inline mode delivering picture, PDF and rich text results
- Broad default package set preloaded into a TeX format at image build
- MongoDB persistence: settings, users, groups, render statistics
- Private S3-compatible bucket with short-lived presigned URLs
- OpenTelemetry traces over OTLP
- Kubernetes manifests and Argo CD application, Docker Compose, GitHub
  Actions CI, BSD 3-Clause license

k8s/secret.example.yaml

@@ -0,0 +1,31 @@
+# Copy to a private file, fill in the values and apply it manually:
+#   kubectl apply -f latexgrambot-secrets.yaml
+#
+# Two secrets are used so the S3 credentials can be managed separately from
+# the Telegram token.
+---
+apiVersion: v1
+kind: Secret
+metadata:
+  name: latexgrambot-secrets
+  namespace: latexgrambot
+  labels:
+    app.kubernetes.io/name: latexgrambot
+type: Opaque
+stringData:
+  # The token must not be long-polled by any other process (Telegram
+  # delivers updates to a single consumer per token).
+  TELEGRAM_BOT_TOKEN: "replace-with-bot-token"
+---
+apiVersion: v1
+kind: Secret
+metadata:
+  name: latexgrambot-s3
+  namespace: latexgrambot
+  labels:
+    app.kubernetes.io/name: latexgrambot
+type: Opaque
+stringData:
+  # Credentials of an S3-compatible bucket (read/write on S3_BUCKET).
+  AWS_ACCESS_KEY_ID: "replace-with-s3-access-key"
+  AWS_SECRET_ACCESS_KEY: "replace-with-s3-secret-key"