Use minijinja instead of handlebars

`minijinja` is explicitly built to be a light-weight templating system with minimal dependencies. Since we don't use a lot of the complexity that a full templating system like `handlebars` brings, we can reduce our number of transitive dependencies by replacing `handlebars` with `minijinja`. Note that it currently does not reduce the number of dependencies significantly, because other dependencies are still depending on these other transitive dependencies... 🙈

Author: Turbo87

Cargo.lock

@@ -58,14 +58,14 @@ flate2 = "1.0"
 futures-channel = { version = "0.3.1", default-features = false }
 futures-util = "0.3"
 git2 = "0.13.0"
-handlebars = "4.1.3"
 hex = "0.4"
 http = "0.2"
 hyper = { version = "0.14", features = ["client", "http1"] }
 indexmap = { version = "1.0.2", features = ["serde-1"] }
 jemallocator = { version = "0.3", features = ['unprefixed_malloc_on_supported_platforms', 'profiling'] }
 lettre = { version = "0.10.0-beta.3", default-features = false, features = ["file-transport", "smtp-transport", "native-tls", "hostname", "builder"] }
 license-exprs = "1.6"
+minijinja = "0.6.0"
 oauth2 = { version = "4.0.0", default-features = false, features = ["reqwest"] }
 parking_lot = "0.11"
 prometheus = { version = "0.13.0", default-features = false }

Cargo.toml

@@ -0,0 +1,9 @@
+BEGIN ISOLATION LEVEL REPEATABLE READ, READ ONLY;
+{% for table in tables %}
+{% if table.filter %}
+    \copy (SELECT {{table.columns}} FROM "{{table.name}}" WHERE {{table.filter}}) TO 'data/{{table.name}}.csv' WITH CSV HEADER
+{% else %}
+    \copy "{{table.name}}" ({{table.columns}}) TO 'data/{{table.name}}.csv' WITH CSV HEADER
+{% endif %}
+{% endfor %}
+COMMIT;

src/tasks/dump_db/dump-export.sql.hbs

@@ -0,0 +1,38 @@
+BEGIN;
+    -- Disable triggers on each table.
+{% for table in tables %}
+    ALTER TABLE "{{table.name}}" DISABLE TRIGGER ALL;
+{% endfor %}
+
+    -- Set defaults for non-nullable columns not included in the dump.
+{% for table in tables %}
+{% for cd in table.column_defaults %}
+    ALTER TABLE "{{table.name}}" ALTER COLUMN "{{cd.column}}" SET DEFAULT {{cd.value}};
+{% endfor %}
+{% endfor %}
+
+    -- Truncate all tables.
+{% for table in tables %}
+    TRUNCATE "{{table.name}}" RESTART IDENTITY CASCADE;
+{% endfor %}
+
+    -- Enable this trigger so that `crates.textsearchable_index_col` can be excluded from the export
+    ALTER TABLE "crates" ENABLE TRIGGER "trigger_crates_tsvector_update";
+
+    -- Import the CSV data.
+{% for table in tables %}
+    \copy "{{table.name}}" ({{table.columns}}) FROM 'data/{{table.name}}.csv' WITH CSV HEADER
+{% endfor %}
+
+    -- Drop the defaults again.
+{% for table in tables %}
+{% for cd in table.column_defaults %}
+    ALTER TABLE "{{table.name}}" ALTER COLUMN "{{cd.column}}" DROP DEFAULT;
+{% endfor %}
+{% endfor %}
+
+    -- Reenable triggers on each table.
+{% for table in tables %}
+    ALTER TABLE "{{table.name}}" ENABLE TRIGGER ALL;
+{% endfor %}
+COMMIT;

src/tasks/dump_db/dump-export.sql.j2

@@ -26,7 +26,7 @@ struct ColumnDefault<'a> {
 }
 
 impl TableConfig {
-    fn handlebars_context<'a>(&'a self, name: &'a str) -> Option<HandlebarsTableContext<'a>> {
+    fn template_context<'a>(&'a self, name: &'a str) -> Option<HandlebarsTableContext<'a>> {
         let columns = self
             .columns
             .iter()
@@ -58,41 +58,53 @@ impl TableConfig {
 
 /// Subset of the configuration data to be passed on to the Handlbars template.
 #[derive(Debug, Serialize)]
-struct HandlebarsContext<'a> {
+struct TemplateContext<'a> {
     tables: Vec<HandlebarsTableContext<'a>>,
 }
 
 impl VisibilityConfig {
-    fn handlebars_context(&self) -> HandlebarsContext<'_> {
+    fn template_context(&self) -> TemplateContext<'_> {
         let tables = self
             .topological_sort()
             .into_iter()
-            .filter_map(|table| self.0[table].handlebars_context(table))
+            .filter_map(|table| self.0[table].template_context(table))
             .collect();
-        HandlebarsContext { tables }
+        TemplateContext { tables }
     }
 
-    fn gen_psql_scripts<W>(&self, export_sql: W, import_sql: W) -> Result<(), PerformError>
+    fn gen_psql_scripts<W>(
+        &self,
+        mut export_writer: W,
+        mut import_writer: W,
+    ) -> Result<(), PerformError>
     where
         W: std::io::Write,
     {
-        let context = self.handlebars_context();
-        let mut handlebars = handlebars::Handlebars::new();
-        handlebars.register_escape_fn(handlebars::no_escape);
+        use minijinja::Environment;
+
+        let mut env = Environment::new();
+        env.add_template("dump-export.sql", include_str!("dump-export.sql.j2"))?;
+        env.add_template("dump-import.sql", include_str!("dump-import.sql.j2"))?;
+
+        let context = self.template_context();
+
+        debug!("Rendering dump-export.sql file…");
+        let export_sql = env
+            .get_template("dump-export.sql")
+            .unwrap()
+            .render(&context)?;
+
+        debug!("Rendering dump-import.sql file…");
+        let import_sql = env
+            .get_template("dump-import.sql")
+            .unwrap()
+            .render(&context)?;
 
         debug!("Writing dump-export.sql file…");
-        handlebars.render_template_to_write(
-            include_str!("dump-export.sql.hbs"),
-            &context,
-            export_sql,
-        )?;
+        export_writer.write_all(export_sql.as_bytes())?;
 
         debug!("Writing dump-import.sql file…");
-        handlebars.render_template_to_write(
-            include_str!("dump-import.sql.hbs"),
-            &context,
-            import_sql,
-        )?;
+        import_writer.write_all(import_sql.as_bytes())?;
 
         Ok(())
     }