feat: Support configuring Parseable via TOML config file

Signed-off-by: “niladrix719” <niladrix719@gmail.com>

Author: niladrix719

Cargo.lock

@@ -62,6 +62,7 @@ erased-serde = "=0.3.16"
 serde = { version = "1.0", features = ["rc", "derive"] }
 serde_json = "1.0"
 serde_repr = "0.1.17"
+toml = "0.9.8"
 
 # Async and Runtime
 async-trait = "0.1"

Cargo.toml

@@ -85,6 +85,26 @@ curl --location --request POST 'http://localhost:8000/api/v1/ingest' \
 
 Access the UI at [http://localhost:8000 ↗︎](http://localhost:8000). You can login to the dashboard default credentials `admin`, `admin`.
 
+### Configure with TOML
+
+We can keep Parseable configuration in a TOML file instead of managing dozens of environment variables. When a file named `parseable.toml` is present in the working directory, Parseable automatically loads it; you can also point to a different file via `parseable --config-file /path/to/config.toml` (or by setting `P_CONFIG_FILE`).
+
+Example:
+
+```toml
+# parseable.toml
+storage = "s3-store"
+
+[env]
+P_S3_URL = "https://s3.amazonaws.com"
+P_S3_REGION = "us-east-1"
+P_S3_BUCKET = "my-observability-bucket"
+P_USERNAME = "admin"
+P_PASSWORD = "super-secret"
+```
+
+Values from the TOML file are written to the corresponding `P_*` environment variables unless they are already set in the shell. Command-line flags still take precedence over everything else, so you can override individual fields without editing the file.
+
 ## Getting started :bulb:
 
 For quickstart, refer the [quickstart section ↗︎](#quickstart-zap).

README.md

@@ -66,6 +66,16 @@ Join the community at https://logg.ing/community.
     subcommand_required = true,
 )]
 pub struct Cli {
+    #[arg(
+        long = "config-file",
+        short = 'c',
+        env = "P_CONFIG_FILE",
+        value_name = "path",
+        global = true,
+        value_parser = validation::file_path,
+        help = "Path to a TOML file containing Parseable environment defaults"
+    )]
+    pub config_file: Option<PathBuf>,
     #[command(subcommand)]
     pub storage: StorageOptions,
 }