docs: add API reference for pushgateway, textfile, and multiprocess

docs/content/exporting/pushgateway.md

@@ -85,3 +85,109 @@ g = Gauge('job_last_success_unixtime', 'Last time a batch job successfully finis
 g.set_to_current_time()
 push_to_gateway('localhost:9091', job='batchA', registry=registry, handler=my_auth_handler)
 ```
+
+## API Reference
+
+### `push_to_gateway(gateway, job, registry, grouping_key=None, timeout=30, handler=default_handler, compression=None)`
+
+Pushes metrics to the pushgateway, replacing all metrics with the same job and grouping key.
+Uses the HTTP `PUT` method.
+
+| Parameter | Type | Default | Description |
+|-----------|------|---------|-------------|
+| `gateway` | `str` | required | URL of the pushgateway. If no scheme is provided, `http://` is assumed. |
+| `job` | `str` | required | Value for the `job` label attached to all pushed metrics. |
+| `registry` | `Collector` | required | Registry whose metrics are pushed. Typically a `CollectorRegistry` instance. |
+| `grouping_key` | `Optional[Dict[str, Any]]` | `None` | Additional labels to identify the group. See the [Pushgateway documentation](https://github.com/prometheus/pushgateway/blob/master/README.md) for details. |
+| `timeout` | `Optional[float]` | `30` | Seconds before the request is aborted. Pass `None` for no timeout. |
+| `handler` | `Callable` | `default_handler` | Function that performs the HTTP request. See [Handlers](#handlers) below. |
+| `compression` | `Optional[str]` | `None` | Compress the payload before sending. Accepts `'gzip'` or `'snappy'`. Snappy requires the [`python-snappy`](https://github.com/andrix/python-snappy) package. |
+
+### `pushadd_to_gateway(gateway, job, registry, grouping_key=None, timeout=30, handler=default_handler, compression=None)`
+
+Pushes metrics to the pushgateway, replacing only metrics with the same name, job, and grouping key.
+Uses the HTTP `POST` method.
+
+| Parameter | Type | Default | Description |
+|-----------|------|---------|-------------|
+| `gateway` | `str` | required | URL of the pushgateway. |
+| `job` | `str` | required | Value for the `job` label attached to all pushed metrics. |
+| `registry` | `Optional[Collector]` | required | Registry whose metrics are pushed. Pass `None` to use the default `REGISTRY`. |
+| `grouping_key` | `Optional[Dict[str, Any]]` | `None` | Additional labels to identify the group. |
+| `timeout` | `Optional[float]` | `30` | Seconds before the request is aborted. Pass `None` for no timeout. |
+| `handler` | `Callable` | `default_handler` | Function that performs the HTTP request. |
+| `compression` | `Optional[str]` | `None` | Compress the payload. Accepts `'gzip'` or `'snappy'`. |
+
+### `delete_from_gateway(gateway, job, grouping_key=None, timeout=30, handler=default_handler)`
+
+Deletes metrics from the pushgateway for the given job and grouping key.
+Uses the HTTP `DELETE` method. Has no `registry` or `compression` parameters.
+
+| Parameter | Type | Default | Description |
+|-----------|------|---------|-------------|
+| `gateway` | `str` | required | URL of the pushgateway. |
+| `job` | `str` | required | Value for the `job` label identifying the group to delete. |
+| `grouping_key` | `Optional[Dict[str, Any]]` | `None` | Additional labels to identify the group. |
+| `timeout` | `Optional[float]` | `30` | Seconds before the request is aborted. Pass `None` for no timeout. |
+| `handler` | `Callable` | `default_handler` | Function that performs the HTTP request. |
+
+### `instance_ip_grouping_key()`
+
+Returns a grouping key dict with the `instance` label set to the IP address of the current host.
+Takes no parameters.
+
+```python
+from prometheus_client.exposition import instance_ip_grouping_key
+
+push_to_gateway('localhost:9091', job='batchA', registry=registry,
+                grouping_key=instance_ip_grouping_key())
+```
+
+## Handlers
+
+A handler is a callable with the signature:
+
+```python
+def my_handler(url, method, timeout, headers, data):
+    # url: str — full request URL
+    # method: str — HTTP method (PUT, POST, DELETE)
+    # timeout: Optional[float] — seconds before aborting, or None
+    # headers: List[Tuple[str, str]] — HTTP headers to include
+    # data: bytes — request body
+    ...
+    return callable_that_performs_the_request
+```
+
+The handler must return a no-argument callable that performs the actual HTTP request and raises
+an exception (e.g. `IOError`) on failure. Three built-in handlers are available in
+`prometheus_client.exposition`:
+
+### `default_handler`
+
+Standard HTTP/HTTPS handler. Used by default in all push functions.
+
+### `basic_auth_handler(url, method, timeout, headers, data, username=None, password=None)`
+
+Wraps `default_handler` and adds an HTTP Basic Auth header.
+
+| Extra parameter | Type | Default | Description |
+|----------------|------|---------|-------------|
+| `username` | `Optional[str]` | `None` | HTTP Basic Auth username. |
+| `password` | `Optional[str]` | `None` | HTTP Basic Auth password. |
+
+### `tls_auth_handler(url, method, timeout, headers, data, certfile, keyfile, cafile=None, protocol=ssl.PROTOCOL_TLS_CLIENT, insecure_skip_verify=False)`
+
+Performs the request over HTTPS using TLS client certificate authentication.
+
+| Extra parameter | Type | Default | Description |
+|----------------|------|---------|-------------|
+| `certfile` | `str` | required | Path to the client certificate PEM file. |
+| `keyfile` | `str` | required | Path to the client private key PEM file. |
+| `cafile` | `Optional[str]` | `None` | Path to a CA certificate file for server verification. Uses system defaults if not set. |
+| `protocol` | `int` | `ssl.PROTOCOL_TLS_CLIENT` | SSL/TLS protocol version. |
+| `insecure_skip_verify` | `bool` | `False` | Skip server certificate verification. Use only in controlled environments. |
+
+### `passthrough_redirect_handler`
+
+Like `default_handler` but automatically follows redirects for all HTTP methods, including `PUT`
+and `POST`. Use only when you control or trust the source of redirect responses.

docs/content/exporting/textfile.md

@@ -20,4 +20,24 @@ write_to_textfile('/configured/textfile/path/raid.prom', registry)
 ```
 
 A separate registry is used, as the default registry may contain other metrics
-such as those from the Process Collector.
+such as those from the Process Collector.
+
+## API Reference
+
+### `write_to_textfile(path, registry, escaping='allow-utf-8', tmpdir=None)`
+
+Writes metrics from the registry to a file in Prometheus text format.
+
+The file is written atomically: metrics are first written to a temporary file in the same
+directory as `path` (or in `tmpdir` if provided), then renamed into place. This prevents the
+Node exporter from reading a partially written file.
+
+| Parameter | Type | Default | Description |
+|-----------|------|---------|-------------|
+| `path` | `str` | required | Destination file path. Must end in `.prom` for the Node exporter textfile collector to process it. |
+| `registry` | `Collector` | required | Registry whose metrics are written. |
+| `escaping` | `str` | `'allow-utf-8'` | Escaping scheme for metric and label names. Accepted values: `'allow-utf-8'`, `'underscores'`, `'dots'`, `'values'`. |
+| `tmpdir` | `Optional[str]` | `None` | Directory for the temporary file used during the atomic write. Defaults to the same directory as `path`. If provided, must be on the same filesystem as `path`. |
+
+Returns `None`. Raises an exception if the file cannot be written; the temporary file is cleaned
+up automatically on failure.

docs/content/multiprocess/_index.md

@@ -96,3 +96,53 @@ from prometheus_client import Gauge
 # Example gauge
 IN_PROGRESS = Gauge("inprogress_requests", "help", multiprocess_mode='livesum')
 ```
+
+## API Reference
+
+### `MultiProcessCollector(registry, path=None)`
+
+Collector that aggregates metrics written by all processes in the multiprocess directory.
+
+| Parameter | Type | Default | Description |
+|-----------|------|---------|-------------|
+| `registry` | `CollectorRegistry` | required | Registry to register with. Pass a registry created inside the request context to avoid duplicate metrics. |
+| `path` | `Optional[str]` | `None` | Path to the directory containing the per-process metric files. Defaults to the `PROMETHEUS_MULTIPROC_DIR` environment variable. |
+
+Raises `ValueError` if `path` is not set or does not point to an existing directory.
+
+```python
+from prometheus_client import multiprocess, CollectorRegistry
+
+def app(environ, start_response):
+    registry = CollectorRegistry(support_collectors_without_names=True)
+    multiprocess.MultiProcessCollector(registry)
+    ...
+```
+
+To use a custom path instead of the environment variable:
+
+```python
+collector = multiprocess.MultiProcessCollector(registry, path='/var/run/prom')
+```
+
+### `mark_process_dead(pid, path=None)`
+
+Removes the per-process metric files for a dead process. Call this from your process manager
+when a worker exits to prevent stale `live*` gauge values from accumulating.
+
+| Parameter | Type | Default | Description |
+|-----------|------|---------|-------------|
+| `pid` | `int` | required | PID of the process that has exited. |
+| `path` | `Optional[str]` | `None` | Path to the multiprocess directory. Defaults to the `PROMETHEUS_MULTIPROC_DIR` environment variable. |
+
+Returns `None`. Only removes files for `live*` gauge modes (e.g. `livesum`, `liveall`); files
+for non-live modes are left in place so their last values remain visible until the directory is
+wiped on restart.
+
+```python
+# Gunicorn config
+from prometheus_client import multiprocess
+
+def child_exit(server, worker):
+    multiprocess.mark_process_dead(worker.pid)
+```