feat: Add generic database connection mechanism

crates/stackable-operator/src/builder/pod/container.rs

@@ -1,4 +1,4 @@
-use std::fmt;
+use std::{borrow::Borrow, fmt};
 
 use indexmap::IndexMap;
 use k8s_openapi::api::core::v1::{
@@ -175,8 +175,14 @@ impl ContainerBuilder {
         self
     }
 
-    pub fn add_env_vars(&mut self, env_vars: Vec<EnvVar>) -> &mut Self {
-        self.env.get_or_insert_with(Vec::new).extend(env_vars);
+    pub fn add_env_vars<I>(&mut self, env_vars: I) -> &mut Self
+    where
+        I: IntoIterator,
+        I::Item: std::borrow::Borrow<EnvVar>,
+    {
+        self.env
+            .get_or_insert_with(Vec::new)
+            .extend(env_vars.into_iter().map(|e| e.borrow().clone()));
         self
     }
 

crates/stackable-operator/src/builder/pod/env.rs

@@ -0,0 +1,20 @@
+use k8s_openapi::api::core::v1::{EnvVar, EnvVarSource, SecretKeySelector};
+
+pub fn env_var_from_secret(
+    env_var_name: impl Into<String>,
+    secret_name: impl Into<String>,
+    secret_key: impl Into<String>,
+) -> EnvVar {
+    EnvVar {
+        name: env_var_name.into(),
+        value_from: Some(EnvVarSource {
+            secret_key_ref: Some(SecretKeySelector {
+                name: secret_name.into(),
+                key: secret_key.into(),
+                ..Default::default()
+            }),
+            ..Default::default()
+        }),
+        ..Default::default()
+    }
+}

crates/stackable-operator/src/builder/pod/mod.rs

@@ -29,6 +29,7 @@ use crate::{
 };
 
 pub mod container;
+pub mod env;
 pub mod probe;
 pub mod resources;
 pub mod security;

crates/stackable-operator/src/crd/git_sync/v1alpha1_impl.rs

@@ -197,7 +197,7 @@ impl GitSyncResources {
                 one_time,
                 container_log_config,
             )])
-            .add_env_vars(env_vars.into())
+            .add_env_vars(env_vars)
             .add_volume_mounts(volume_mounts.to_vec())
             .context(AddVolumeMountSnafu)?
             .resources(

crates/stackable-operator/src/crd/git_sync/v1alpha2_impl.rs

@@ -241,7 +241,7 @@ impl GitSyncResources {
                 one_time,
                 container_log_config,
             )])
-            .add_env_vars(env_vars.into())
+            .add_env_vars(env_vars)
             .add_volume_mounts(volume_mounts.to_vec())
             .context(AddVolumeMountSnafu)?
             .resources(

crates/stackable-operator/src/databases/databases/derby.rs

@@ -0,0 +1,47 @@
+use schemars::JsonSchema;
+use serde::{Deserialize, Serialize};
+use snafu::{ResultExt, Snafu};
+
+use crate::databases::{
+    TemplatingMechanism,
+    drivers::jdbc::{JDBCDatabaseConnection, JDBCDatabaseConnectionDetails},
+};
+
+#[derive(Debug, Snafu)]
+pub enum Error {
+    #[snafu(display("failed to parse connection URL"))]
+    ParseConnectionUrl { source: url::ParseError },
+}
+
+/// TODO docs
+#[derive(Clone, Debug, Deserialize, JsonSchema, PartialEq, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct DerbyConnection {
+    /// TODO docs, especially on default
+    pub location: Option<String>,
+}
+
+impl JDBCDatabaseConnection for DerbyConnection {
+    fn jdbc_connection_details_with_templating(
+        &self,
+        unique_database_name: &str,
+        _templating_mechanism: &TemplatingMechanism,
+    ) -> Result<JDBCDatabaseConnectionDetails, crate::databases::Error> {
+        let location = self
+            .location
+            .clone()
+            .unwrap_or_else(|| format!("/tmp/derby/{unique_database_name}/derby.db"));
+        let connection_uri = format!("jdbc:derby:{location};create=true",);
+        let connection_uri = connection_uri.parse().context(ParseConnectionUrlSnafu)?;
+
+        Ok(JDBCDatabaseConnectionDetails {
+            // Sadly the Derby driver class name is a bit complicated, e.g. for HMS up to 4.1.x we used
+            // "org.apache.derby.jdbc.EmbeddedDriver",
+            // for HMS 4.2.x we used "org.apache.derby.iapi.jdbc.AutoloadedDriver".
+            driver: "org.apache.derby.jdbc.EmbeddedDriver".to_owned(),
+            connection_uri,
+            username_env: None,
+            password_env: None,
+        })
+    }
+}

crates/stackable-operator/src/databases/databases/mod.rs

@@ -0,0 +1,4 @@
+pub mod derby;
+pub mod mysql;
+pub mod postgresql;
+pub mod redis;

crates/stackable-operator/src/databases/databases/mysql.rs

@@ -0,0 +1,79 @@
+use std::collections::BTreeMap;
+
+use schemars::JsonSchema;
+use serde::{Deserialize, Serialize};
+use snafu::{ResultExt, Snafu};
+
+use crate::{
+    commons::networking::HostName,
+    databases::{
+        TemplatingMechanism,
+        drivers::jdbc::{JDBCDatabaseConnection, JDBCDatabaseConnectionDetails},
+        helpers::{connection_parameters_as_url_query_parameters, username_and_password_envs},
+    },
+};
+
+#[derive(Debug, Snafu)]
+pub enum Error {
+    #[snafu(display("failed to parse connection URL"))]
+    ParseConnectionUrl { source: url::ParseError },
+}
+
+/// TODO docs
+#[derive(Clone, Debug, Deserialize, JsonSchema, PartialEq, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct MysqlConnection {
+    /// TODO docs
+    pub host: HostName,
+
+    /// TODO docs
+    #[serde(default = "MysqlConnection::default_port")]
+    pub port: u16,
+
+    /// TODO docs
+    pub database: String,
+
+    /// TODO docs
+    pub credentials_secret: String,
+
+    /// TODO docs
+    #[serde(default)]
+    pub parameters: BTreeMap<String, String>,
+}
+
+impl MysqlConnection {
+    fn default_port() -> u16 {
+        3306
+    }
+}
+
+impl JDBCDatabaseConnection for MysqlConnection {
+    fn jdbc_connection_details_with_templating(
+        &self,
+        unique_database_name: &str,
+        _templating_mechanism: &TemplatingMechanism,
+    ) -> Result<JDBCDatabaseConnectionDetails, crate::databases::Error> {
+        let Self {
+            host,
+            port,
+            database,
+            credentials_secret,
+            parameters,
+        } = self;
+        let (username_env, password_env) =
+            username_and_password_envs(unique_database_name, credentials_secret);
+
+        let connection_uri = format!(
+            "jdbc:mysql://{host}:{port}/{database}{parameters}",
+            parameters = connection_parameters_as_url_query_parameters(parameters)
+        );
+        let connection_uri = connection_uri.parse().context(ParseConnectionUrlSnafu)?;
+
+        Ok(JDBCDatabaseConnectionDetails {
+            driver: "com.mysql.jdbc.Driver".to_owned(),
+            connection_uri,
+            username_env: Some(username_env),
+            password_env: Some(password_env),
+        })
+    }
+}