add some env vars for default configuration

docs/configure.md

@@ -399,11 +399,28 @@ As we love {{twelvefactorapp}} plenty of default behavior of `stlog` can be conf
     - environment variables
     - explicit configuration in the code (always wins)
 
+### `STLOG_LEVEL`
+
+This variable can tune the default "log level". Use `CRITICAL`, `FATAL`, `ERROR`, `WARN`, `WARNING`, `INFO`, `DEBUG` or `NOTSET` as value.
+
+### `STLOG_DESTINATION`
+
+This variable can tune the default destination. Use `stdout` or `stderr` as value. Default to `stderr`.
+
+### `STLOG_OUTPUT`
+
+This variable can set the default output and format. You can use:
+
+- `console`: the output will be sent to `stdout` or `stderr` (depending on `STLOG_DESTINATION` value) with a "human formatter" and will be use a `rich` (colors...) output depending in `STLOG_USE_RICH` value. By default, `rich` output will be automatically used if the terminal support it and if the `rich` library is installed.
+- `json`: the output will be sent to `stdout` or `stderr` (depending on `STLOG_DESTINATION` value) with a generic "JSON formatter" in a compact mode (without indentation) 
+- `json-human`: the output will be sent to `stdout` or `stderr` (depending on `STLOG_DESTINATION` value) with a generic "JSON formatter" in an indented way
+- `json-gcp`: the output will be sent to `stdout` or `stderr` (depending on `STLOG_DESTINATION` value) with a GCP "JSON formatter" (to be automatically decoded and displayed in GCP logging products)
+
 ### `STLOG_USE_RICH`
 
 This variable can tune the behavior of {{apilink("output.make_stream_or_rich_stream_output")}} function:
 
-- if empty or set to `NONE`  or `AUTO` => nothing (the function makes automatically a `StreamOuput` or a `RichStreamOutput`, see above for details)
+- if empty or set to `NONE`  or `AUTO` => nothing (the function makes automatically a `StreamOuput` or a `RichStreamOutput` depending on the terminal support and if the `rich` library is installed)
 - if set to `1`, `TRUE`, `YES` => the function will always return a `RichStreamOutput` (even the log stream is redirected to a file!)
 - else (`0`, `FALSE`, `NO`...) => the function will always return a standard `StreamOutput` (with colors and fancy things)
 
@@ -433,13 +450,23 @@ This variable can change the default value of `read_extra_kwargs_from_standard_l
 
 These variables can be used to inject a global context. See [usage documentation](../usage) for details.
 
+### `STLOG_DEFAULT_IGNORE_COMPOUND_TYPES`
+
+- if set to `1`, `TRUE`, `YES`: compound types (dict, list...) are silently ignored in `LogFmtKVFormatter` (used by default by "human" outputs)
+- else (`0`, `FALSE`, `NO`...): compound type will be displayed
+
+The default is to ignore.
+
+!!! note "What about JSON outputs?"
+
+    This variable has no effect on JSON outputs.
+
 ### `STLOG_UNIT_TESTS_MODE`
 
 !!! warning "Private feature!"
 
     This is a private feature (DON'T USE IT) to get always the same output (fixed date, fixed process number...)
 
-### FIXME (document)
+### `STLOG_PROGRAM_NAME`
 
-- STLOG_IGNORE_COMPOUND_TYPES
-- STLOG_PROGRAM_NAME
+Default program name when getting a logger without name. If not set, we will try to guess.

stlog/formatter.py

@@ -47,6 +47,24 @@
     }}
 }}
 """
+DEFAULT_STLOG_GCP_JSON_FORMAT = """
+{{
+    "timestamp": {asctime},
+    "logger": {name},
+    "severity": {levelname},
+    "message": {message},
+    "source": {{
+        "path": {pathname},
+        "lineno": {lineno},
+        "module": {module},
+        "funcName": {funcName},
+        "process": {process},
+        "processName": {processName},
+        "thread": {thread},
+        "threadName": {threadName}
+    }}
+}}
+"""
 DEFAULT_STLOG_DATE_FORMAT = "%Y-%m-%dT%H:%M:%SZ"
 
 

stlog/setup.py

@@ -10,15 +10,48 @@
 
 from stlog.adapter import getLogger
 from stlog.base import GLOBAL_LOGGING_CONFIG, check_env_false
-from stlog.output import Output, make_stream_or_rich_stream_output
+from stlog.formatter import DEFAULT_STLOG_GCP_JSON_FORMAT, JsonFormatter
+from stlog.output import Output, StreamOutput, make_stream_or_rich_stream_output
 
 DEFAULT_LEVEL: str = os.environ.get("STLOG_LEVEL", "INFO")
 DEFAULT_CAPTURE_WARNINGS: bool = check_env_false("STLOG_CAPTURE_WARNINGS", True)
 DEFAULT_PROGRAM_NAME: str | None = os.environ.get("STLOG_PROGRAM_NAME", None)
+DEFAULT_DESTINATION: str = os.environ.get("STLOG_DESTINATION", "stderr").lower()
+DEFAULT_OUTPUT: str = os.environ.get("STLOG_OUTPUT", "console").lower()
+
+
+def _make_default_stream() -> typing.TextIO:
+    if DEFAULT_DESTINATION == "stderr":
+        return sys.stderr
+    elif DEFAULT_DESTINATION == "stdout":
+        return sys.stdout
+    raise Exception(
+        f"bad value:{DEFAULT_DESTINATION} for STLOG_DESTINATION env var => must be 'stderr' or 'stdout'"
+    )
 
 
 def _make_default_outputs() -> list[Output]:
-    return [make_stream_or_rich_stream_output(stream=sys.stderr)]
+    if DEFAULT_OUTPUT == "console":
+        return [make_stream_or_rich_stream_output(stream=_make_default_stream())]
+    elif DEFAULT_OUTPUT == "json":
+        return [StreamOutput(stream=_make_default_stream(), formatter=JsonFormatter())]
+    elif DEFAULT_OUTPUT == "json-human":
+        return [
+            StreamOutput(
+                stream=_make_default_stream(), formatter=JsonFormatter(indent=4)
+            )
+        ]
+    elif DEFAULT_OUTPUT == "json-gcp":
+        return [
+            StreamOutput(
+                stream=_make_default_stream(),
+                formatter=JsonFormatter(fmt=DEFAULT_STLOG_GCP_JSON_FORMAT),
+            )
+        ]
+    else:
+        raise Exception(
+            f"bad value:{DEFAULT_OUTPUT} for STLOG_OUTPUT env var => must be 'console', 'json', 'json-human' or 'json-gcp'"
+        )
 
 
 def _logging_excepthook(