feat: add PostgreSQL backend support

Dispatch the model layer between sqlx-mysql and sqlx-postgres based on
the connection URL scheme, and split schema DDL into per-backend files
(mysql_schema.rs / postgres_schema.rs). Config gains a `[database]`
section with a `backend = "mysql" | "postgres"` selector for the split
-field path; `[mysql]` is still accepted as a compatibility fallback.

Rename the preferred environment variable from MYSQL_CONNECTION_URL to
DATABASE_URL across the Fly.io workflow and docker-compose, while still
accepting the legacy name at the config layer so existing deployments
keep working.

Signed-off-by: JmPotato <github@ipotato.me>

Author: JmPotato

.github/workflows/fly-deploy.yml

@@ -21,10 +21,10 @@ jobs:
           curl -L https://fly.io/install.sh | sh
           echo "$HOME/.fly/bin" >> "$GITHUB_PATH"
       - name: Set secrets
-        run: fly secrets set --stage MYSQL_CONNECTION_URL="${MYSQL_CONNECTION_URL}" UMAMI_ID="${UMAMI_ID}"
+        run: fly secrets set --stage DATABASE_URL="${DATABASE_URL}" UMAMI_ID="${UMAMI_ID}"
         env:
           FLY_API_TOKEN: ${{ secrets.FLY_API_TOKEN }}
-          MYSQL_CONNECTION_URL: ${{ secrets.MYSQL_CONNECTION_URL }}
+          DATABASE_URL: ${{ secrets.DATABASE_URL }}
           UMAMI_ID: ${{ secrets.UMAMI_ID }}
       - name: Deploy
         run: fly deploy --remote-only

.gitignore

@@ -21,4 +21,5 @@ target/
 #.idea/
 
 # Others
-.DS_Store
+.DS_Store
+.env*

Cargo.toml

@@ -18,6 +18,7 @@ serde = { version = "1.0.210", features = ["derive"] }
 sqlx = { version = "0.8.2", features = [
     "runtime-tokio",
     "mysql",
+    "postgres",
     "chrono",
     "tls-rustls",
 ] }

README.md

@@ -19,29 +19,49 @@ rsomhaP is still a simple ready-to-use blog engine inheriting a lot from its pre
 But also introduces some new features:
 
 - More secure admin authentication.
-- Use any MySQL-compatible database to store your blog data.
+- Use either MySQL or PostgreSQL to store your blog data.
 - Easy to deploy with a single command or a simple [Dockerfile](https://github.com/JmPotato/rsomhaP/blob/main/Dockerfile).
 
 ## Deployment
 
 Edit your [`config.toml`](https://github.com/JmPotato/rsomhaP/blob/main/config.toml) to your liking, then run:
 
+When you use the split fields under `[database]`, set `backend = "mysql"` or `backend = "postgres"`.
+If you provide `connection_url` in the config or `DATABASE_URL` in the environment, that full URL wins and its scheme still selects the driver:
+
+- `mysql://...` for MySQL
+- `postgres://...` / `postgresql://...` for PostgreSQL
+
+Upgrade note:
+
+- `DATABASE_URL` is the preferred environment variable.
+- Legacy `MYSQL_CONNECTION_URL` is still accepted as a compatibility fallback.
+- Legacy `[mysql]` config still parses, but `[database]` is the preferred section name going forward.
+- The default sample config binds to `0.0.0.0` so Docker and public deployments work out of the box. If you want local-only access, change `[deploy].host` to `127.0.0.1`.
+
 ```sh
 cargo run --release
 ```
 
-Or build a Docker image and run it:
+Or build a Docker image and run it. The container still needs a reachable
+database; the simplest path is to pass `DATABASE_URL` explicitly:
 
 ```sh
 docker build -t rsomhap .
-docker run -p 5299:5299 rsomhap
+docker run -p 5299:5299 \
+  -e DATABASE_URL='postgres://user:pass@host:5432/dbname' \
+  rsomhap
 ```
 
-Access the admin page at "http://{your-deployment-url}/admin" to manage your blog. The initial password is the same as the username configured in [`config.toml`](https://github.com/JmPotato/rsomhaP/blob/62dd746dfd6f7413d161a1fde79b82a0589b241b/config.toml#L14), **which you should change after the first login as soon as possible.**.
+If you prefer the split fields in `config.toml`, make sure the container can
+actually reach that host. The default `127.0.0.1:4000` example works for a
+local host process, but inside Docker `127.0.0.1` means the container itself.
+
+Access the admin page at "http://{your-deployment-url}/admin" to manage your blog. The initial password is the same as the username configured in [`config.toml`](./config.toml), **which you should change after the first login as soon as possible.**.
 
 Technically, you can deploy rsomhaP with modern SaaS infrastructures entirely free from scratch. For example:
 
-- Use [TiDB Serverless](https://www.pingcap.com/tidb-serverless) as the MySQL-compatible database.
+- Use [TiDB Serverless](https://www.pingcap.com/tidb-serverless) for a MySQL deployment, or any managed PostgreSQL service for a Postgres deployment.
 - Use [fly.io](https://fly.io) as the hosting service.
 - Use [Cloudflare R2](https://www.cloudflare.com/developer-platform/r2) as the image hosting service.
 - Use [WebP Cloud Services](https://webp.se) as the image proxy service.

config.toml

@@ -24,9 +24,21 @@ article_per_page = 15
 # - `Solarized (dark)` and `Solarized (light)`
 code_syntax_highlight_theme = "base16-eighties.dark"
 
-[mysql]
-# If `connection_url` is set, other connection-related configs will be ignored.
+[database]
+# Which backend to use when building a connection URL from the split fields
+# below. Accepted values: `mysql`, `postgres`.
+backend = "mysql"
+#
+# If `connection_url` is set, it is used as-is and its own scheme still
+# selects the actual driver:
+#   - mysql://user:pass@host:port/db
+#   - postgres://user:pass@host:port/db  (or postgresql://)
+# Examples:
 # connection_url = "mysql://root:password@127.0.0.1:4000/rsomhaP"
+# connection_url = "postgres://postgres:password@127.0.0.1:5432/rsomhaP"
+#
+# If you use the split fields below instead of `connection_url`, `backend`
+# controls whether `mysql://` or `postgres://` is generated.
 username = "root"
 password = "password"
 host = "127.0.0.1"

docker-compose.yml

@@ -7,7 +7,7 @@ services:
     ports:
       - "5299:5299"
     environment:
-      - MYSQL_CONNECTION_URL
+      - DATABASE_URL
       - UMAMI_ID
     healthcheck:
       test: ["CMD-SHELL", "curl -sf http://localhost:5299/ping || exit 1"]

src/app.rs

@@ -29,7 +29,7 @@ use crate::{
         handler_edit_page_get, handler_edit_post, handler_feed, handler_home, handler_login_get,
         handler_login_post, handler_logout, handler_page, handler_ping, handler_tag, handler_tags,
     },
-    models::{create_tables_within_transaction, Article, Page, User},
+    models::{init_schema, Article, DbPool, Page, User},
 };
 
 const TEMPLATES_DIR: &str = "templates";
@@ -42,7 +42,7 @@ const CONFIG_FILE_PATH: &str = "config.toml";
 pub struct AppState {
     pub config: Config,
     pub env: Environment<'static>,
-    pub db: sqlx::MySqlPool,
+    pub db: DbPool,
     // Cache the feed content to reduce the database query.
     pub feed_cache: Arc<RwLock<(DateTime<Utc>, Option<String>)>>,
     // Cache the page titles to avoid querying the database on every template render.
@@ -55,11 +55,12 @@ impl AppState {
         let config = Config::new(CONFIG_FILE_PATH)?;
 
         info!("connecting to the database");
-        // connect to the database.
-        let db = sqlx::MySqlPool::connect(&config.mysql_connection_url()?).await?;
+        // connect to the database. The URL scheme selects the backend
+        // (`mysql://` or `postgres://`).
+        let db = DbPool::connect(&config.database_url()?).await?;
         info!("initializing the database");
         // create the tables if they don't exist.
-        create_tables_within_transaction(&db).await?;
+        init_schema(&db).await?;
         // init the admin user.
         let admin_username = config.admin_username();
         User::insert(