Note changes to DD_TRACE_CLI_ENABLED and resource sampling

content/en/tracing/guide/trace-php-cli-scripts.md

@@ -14,10 +14,7 @@ further_reading:
 
 A short-running script typically runs for a few seconds or minutes. The expected behavior is to receive one trace each time the script is executed.
 
-By default, tracing is disabled for PHP scripts that run from the command line. Opt in by setting `DD_TRACE_CLI_ENABLED` to `1`.
-
 ```
-$ export DD_TRACE_CLI_ENABLED=1
 # Optionally, set the agent host and port if different from localhost and 8126, respectively
 $ export DD_AGENT_HOST=agent
 $ export DD_TRACE_AGENT_PORT=8126
@@ -47,13 +44,9 @@ Once the script is run, the trace is generated and sent to the Datadog backend w
 
 A long-running script runs for hours or days. Typically, such scripts repetitively execute a specific task, for example processing new incoming messages or new lines added to a table in a database. The expected behavior is that one trace is generated for each "unit of work", for example the processing of a message.
 
-By default, tracing is disabled for PHP scripts that run from the command line. Opt in by setting `DD_TRACE_CLI_ENABLED` to `1`.
-
 ```
-$ export DD_TRACE_CLI_ENABLED=1
-# With this pair of settings, traces for each "unit of work" is sent as soon as the method execution terminates.
+# With this setting, traces for each "unit of work" are sent as soon as the method execution terminates.
 $ export DD_TRACE_GENERATE_ROOT_SPAN=0
-$ export DD_TRACE_AUTO_FLUSH_ENABLED=1
 # Optionally, set service name, env, etc...
 $ export DD_SERVICE=my_service
 # Optionally, set the agent host and port if different from localhost and 8126, respectively

content/en/tracing/trace_collection/compatibility/php.md

@@ -128,7 +128,7 @@ Datadog is continuously adding more support for in-depth tracing for PHP web-fra
 
 #### CLI library compatibility
 
-Tracing from the CLI SAPI is disabled by default. To enable tracing of PHP CLI scripts, set `DD_TRACE_CLI_ENABLED=true`.
+Tracing from the CLI SAPI is enabled by default. To selectively disable tracing of PHP CLI scripts, set `DD_TRACE_CLI_ENABLED=false`.
 
 | Module          | Versions            | Support Type               |
 |:----------------|:--------------------|:---------------------------|
@@ -171,14 +171,6 @@ To request support for additional datastores, contact our awesome [support team]
 
 To request support for additional libraries, contact our awesome [support team][3].
 
-#### Deep call stacks on PHP 5
-
-The call stack is limited on PHP 5. See the [deep call stack troubleshooting page][5] for more details.
-
-### Generators
-
-Instrumenting [generators][6] is not supported on PHP 5 and PHP 7.
-
 ### PCNTL
 
 Datadog supports tracing forked processes using [pcntl][7]. When a call to `pcntl_fork` is detected, a dedicated span is created, and the forked process is instrumented. This can be disabled with `DD_TRACE_FORKED_PROCESS`. Refer to the [library configuration page][9] for more details.
@@ -193,8 +185,6 @@ If the application invokes `pcntl_unshare(CLONE_NEWUSER);` and the tracer is ins
 [2]: https://www.datadoghq.com/support/
 [3]: /help
 [4]: https://pecl.php.net/package/mongo
-[5]: /tracing/troubleshooting/php_5_deep_call_stacks
-[6]: https://www.php.net/manual/en/language.generators.overview.php
 [7]: https://www.php.net/manual/en/book.pcntl.php
 [8]: https://man7.org/linux/man-pages/man2/unshare.2.html
 [9]: /tracing/trace_collection/library_config/php/#environment-variable-configuration

content/en/tracing/trace_collection/library_config/php.md

@@ -162,12 +162,12 @@ The Agent URL; takes precedence over `DD_AGENT_HOST` and `DD_TRACE_AGENT_PORT`.
 
 `DD_TRACE_AUTO_FLUSH_ENABLED`
 : **INI**: `datadog.trace.auto_flush_enabled`<br>
-**Default**: `0`<br>
+**Default**: `0` (`1` in CLI environment)<br>
 Automatically flush the tracer when all the spans are closed; set to `1` in conjunction with `DD_TRACE_GENERATE_ROOT_SPAN=0` to trace [long-running processes][14].
 
 `DD_TRACE_CLI_ENABLED`
 : **INI**: `datadog.trace.cli_enabled`<br>
-**Default**: `0`<br>
+**Default**: `1`<br>
 Enable tracing of PHP scripts from the CLI. See [Tracing CLI scripts][15].
 
 `DD_TRACE_DEBUG`

content/en/tracing/trace_pipeline/ingestion_mechanisms.md

@@ -196,13 +196,23 @@ Read more about sampling controls in the [Node.js tracing library documentation]
 [1]: /tracing/trace_collection/dd_libraries/nodejs
 {{% /tab %}}
 {{% tab "PHP" %}}
+**Remote configuration**
+
+<div class="alert alert-info"><strong>Resource-based sampling rules are in Preview</strong>. Starting from version <a href="https://github.com/DataDog/dd-trace-php/releases/tag/1.4.0">1.4.0</a>, for PHP applications, set by-service and by-resource sampling rates from the <a href="https://app.datadoghq.com/apm/traces/ingestion-control">Ingestion Control Page</a>. Use <a href="https://www.datadoghq.com/product-preview/resource-based-sampling-adaptive-sampling/">this form</a> to request access today.</div>
+
+Read more about how to remotely configure sampling rates by service and resource in the [Resource-based sampling guide][1].
+
+**Note**: Remotely-set configuration takes precedence over local configuration.
+
+**Local configuration**
+
 For PHP applications, set a global sampling rate for the library using the `DD_TRACE_SAMPLE_RATE` environment variable. Set by-service sampling rates with the `DD_TRACE_SAMPLING_RULES` environment variable.
 
-For example, to send 50% of the traces for the service named `my-service` and 10% for the rest of the traces:
+For example, to send 50% of the traces for the service named `my-service`, 20% of other endpoints' traces, and 10% for the rest of the traces, set:
 
 ```
 export DD_TRACE_SAMPLE_RATE=0.1
-export DD_TRACE_SAMPLING_RULES='[{"service": "my-service", "sample_rate": 0.5}]'
+export DD_TRACE_SAMPLING_RULES='[{"service": "my-service", "resource":"GET /checkout", "sample_rate": 1},{"service": "my-service", "sample_rate": 0.2}]'
 ```
 
 Read more about sampling controls in the [PHP tracing library documentation][1].