Local development server options

The local development server (dev_appserver.py) is part of the App Engine components of the gcloud CLI. This topic provides advanced information about the dev_appserver.py usage.

We recommend that you use standard Python tools, such as virtualenv to create isolated environments and pytest to run unit tests and integration tests, rather than depending on dev_appserver, the local development server provided with the Google Cloud SDK.

See Using the Local development server for more information about local testing.

Set up the local development server tool

A sample dev_appserver.py command might look as follows:

python3 CLOUD_SDK_ROOT/bin/dev_appserver.py OPTION yaml_path FILES

Replace the following:

CLOUD_SDK_ROOT with the path to the root directory where you installed Google Cloud CLI. The default directory is ./google-cloud-sdk/.
OPTION with a flag supported by the local development server.
FILES specifies one or more app.yaml files, one per service, for the positional argument yaml_path.

For a complete list of options, run the following:

python3 CLOUD_SDK_ROOT/bin/dev_appserver.py -h

Common options

The most common options are as follows:

--admin_host=ADMIN_HOST

Host name to which the local development server's administration console should bind (default: localhost).

--admin_port=ADMIN_PORT

Port to which the local development server's administration console should bind (default: 8000).

--addn_host=ADDN_HOST

This argument allows you to allowlist additional HTTP Host header values, so that the server might be made accessible behind a proxy, without having to disable host checking (see --enable_host_checking). Additional hosts starting with *. allow all subdomains. For example, *.example.org allows host.example.org but not sub.host.example.org or example.org. Hosts starting with **. allow subdomains of any depth. For example, **.example.com allows host.example.com and sub.host.example.com, but not example.com. (default: [])

--allow_skipped_files=...

Make files specified in the app.yaml skip_files or static handles readable by the application (default: False).

-A APP_ID, --application=...

Set the application, overriding the application value from the app.yaml file (default: None).

--appidentity_email_address=...

Email address associated with a service account that has a downloadable key. May be None for no local application identity (default: None).

--appidentity_private_key_path=...

Path to private key file associated with service account (.pem format). Must be set if appidentity_email_address is set (default: None).

--api_host=API_HOST

Host name to which the API server should bind (default: localhost).

--api_port=API_PORT

Port to which the server for API calls should bind (default: 0).

--auth_domain=...

Name of the authorization domain to use (default: gmail.com).

--auto_id_policy=...

Deprecated. How the local datastore assigns automatic IDs. Options are sequential or scattered (default: scattered).

--automatic_restart=...

Restart instances automatically when files relevant to their module are changed (default: True).

--blobstore_path=...

Path to directory used to store blob contents (defaults to a subdirectory of --storage_path if not set) (default: None).

--clear_datastore=yes|no

Clears the datastore data and history files before starting the web server (default: no).

--clear_search_indexes...

Clear the search indexes (default: False).

--custom_entrypoint=...

Specify an entrypoint for custom runtime modules. This is required when such modules are present. Include {port} in the string (without quotes) to pass the port number in as an argument (default: ). For instance:

--custom_entrypoint="gunicorn -b localhost:{port}
  mymodule:application"

--datastore_consistency_policy {consistent,random,time}

The policy to apply when deciding whether a datastore write should appear in global queries (default: time).

--datastore_emulator_cmd=...

The path to a script that invokes cloud datastore emulator. If left empty, dev_appserver will try to find datastore emulator in the Google Cloud SDK (default: None).

--datastore_emulator_port=...

The port number that dev_appserver should launch Cloud Datastore emulator on (default: 0).

--datastore_path=...

The path to use for the local datastore data file. The server creates this file if it does not exist.

--default_gcs_bucket_name=...

Default Cloud Storage bucket name (default: None).

--dev_appserver_log_level {debug,info,warning,critical,error}

The log level below which logging messages generated by the development server will not be displayed on the console (this flag is more useful for diagnosing problems in dev_appserver.py rather than in application code) (default: info).

--enable_host_checking=yes|no

Determines whether to enforce HTTP Host checking for application modules, API server, and admin server. Host checking protects against DNS rebinding attacks, only disable after understanding the security implications (default: True).

--enable_console=yes|no

Enable interactive console in admin view (default: False).

--enable_sendmail=yes|no

Uses the local computer's Sendmail installation for sending email messages.

--enable_task_running=yes|no

Enables the development server to run push tasks (default: yes). If you specify no, the server will not run push tasks.

--env_var=...

User defined environment variable for the local runtime process. Each env_var is in the format of key=value, and you can define multiple environment variables. In addition to env_variables in the app.yaml, this flag allows setting extra environment variables for local processes.

For example:--env_var KEY_1=val1 --env_var KEY_2=val2

--grpc_api_port...

Port on which the gRPC API server listens (default:0).

--help

Prints a helpful message then quits.

--host=...

The host address to use for the server. You may need to set this to be able to access the development server from another computer on your network. An address of 0.0.0.0 allows both localhost access and IP or hostname access (default: localhost).

--log_level=...

The lowest logging level at which logging messages will be written to the console; messages of the specified logging level or higher will be output. Possible values are debug, info, warning, error, and critical.

--logs_path=...

By default, the logs for the local development server are stored in memory only. Specify this option when you run the local development server to store the logs into a file, which makes the logs available across server restarts. You must specify the directory path and name to a SQLite database file. A SQLite database file is created with the specified name if the file does not already exist.

For example: --logs_path=/home/logs/boglogs.db

--max_module_instances=...

The maximum number of runtime instances that can be started for a particular module. The value can be an integer, in which case all modules are limited to the number of instances or a comma-separated list of module:max_instances (default: None). For Example: default:5,backend:3

--mysql_host=MYSQL_HOST

Host name of a running MySQL server used for simulated Cloud SQL storage (default: localhost).

--mysql_port=MYSQL_PORT

Port number of a running MySQL server used for simulated Cloud SQL storage (default: 3306).

--mysql_user=MYSQL_USER

Username to use when connecting to the MySQL server specified in --mysql_host and --mysql_port or --mysql_socket (default: ).

--mysql_password=MYSQL_PASSWORD

Password to use when connecting to the MySQL server specified in --mysql_host and --mysql_port or --mysql_socket (default: ).

--mysql_socket=MYSQL_SOCKET

Path to a Unix socket file to use when connecting to a running MySQL server used for simulated Cloud SQL storage (default: None).

--port=...

The port number to use for the server. Default is 8080. If multiple servers are launched such as for services, they will be assigned subsequent ports, such as 8081, 8082.

--require_indexes=yes|no

Disables automatic generation of entries in the index.yaml file. Instead, when the application makes a query that requires that its index be defined in the file and the index definition is not found, an exception will be raised, similar to what would happen when running on App Engine (default: no).

--runtime=...

Specify the default runtimes you would like to use. For the list of supported runtimes, see the Runtime support schedule.

--running_datastore_emulator_host=...

Overrides the environment variable DATASTORE_EMULATOR_HOST, which means the hostname:port of a running Cloud Datastore emulator that dev_appserver can connect to (default: None).

--search_indexes_path=...

Path to a file used to store search indexes (defaults to a file in --storage_path if not set) (default:None).

--skip_sdk_update_check=...

Skip checking for SDK updates (if false, use .appcfg_nag to decide) (default: False).

--show_mail_body=...

Logs the contents of e-mails sent using the Mail API (default: False).

--smtp_allow_tls...

Allow TLS to be used when the SMTP server announces TLS support (ignored if --smtp_host is not set) (default: True).

--smtp_host=...

The hostname of the SMTP server to use for sending email messages.

--smtp_port=...

The port number of the SMTP server to use for sending email messages.

--smtp_user=...

The username to use with the SMTP server for sending email messages.

--smtp_password=...

The password to use with the SMTP server for sending email messages.

--storage_path=...

Path at which all local files, such as the Datastore, Blobstore, Cloud Storage files and logs, will be stored, unless overridden by --datastore_path, --blobstore_path, or --logs_path.

--support_datastore_emulator=yes|no

Use the Cloud Datastore Emulator (beta) for local datastore emulation.

--ssl_certificate_path=...

Path to SSL certificate. Must also provide --ssl_certificate_key_path if using this option (default: None).

--ssl_certificate_key_path=...

Path to corresponding SSL private key. Must also provide --ssl_certificate_path if using this option (default: None).

--threadsafe_override=...

Override the application's threadsafe configuration. The value can be a boolean, in which case all modules threadsafe setting will be overridden or a comma-separated list of module:threadsafe_override (default: None).

For example: default:False,backend:True

--use_mtime_file_watcher=...

Use mtime polling for detecting source code changes - useful if modifying code from a remote machine using a distributed file system (default: False).

--watcher_ignore_re=...

Regex string to specify files to be ignored by the filewatcher. (default: None)

Python runtime specific command options:

--python_startup_script: The script to run at the startup of new Python runtime instances (useful for tools such as debuggers) (default: None).
--python_startup_args: The arguments made available to the script specified in python_startup_script (default: None).
--python27_executable_path=...: The path to the python27 executable for python27 runtime instances (default: None).
--python_virtualenv_path: The path to the directory that is used to setup a Python 3 virtual environment for the local devappserver execution environment for Python 3 applications. If the path does not exist, the directory is created, but won't be cleaned up at the end of the devappserver execution, allowing for caching between invocations. If not defined, a temporary directory will be used and cleaned up at the end of the execution.
--runtime_python_path=...: The path to your Python binary. To run a Python app on the dev_appserver, specify this flag.