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Looker Startup Options

There are a number of Looker startup settings that can optionally be configured. If you do not need to change these options you may start Looker without them.

To see the options available, run the Looker startup script with --help.

Startup Option List

  -p, --port=<i>                                           Port to run on (default: 9999)
  --core-port=<i>                                          Port to run core on (default: 19999)
  --daemonize, --no-daemonize                              Run as daemon (default: true)
  --ssl, --no-ssl                                          Use SSL (default: true)
  --ssl-provided-externally                                DEPRECATED, use --ssl-provided-externally-by instead
  --ssl-provided-externally-by=<s>                         Provides the host:port for an external SSL provider as accessible from the server running Looker. When not specified, the Looker app server provides SSL.
  --ssl-keystore=<s>                                       Path to keystore file for SSL
  --ssl-keystore-pass-file=<s>                             Path to file containing ssl-keystore password
  --ssl-keystore-pass=<s>                                  Password for ssl-keystore file
  -h, --hosted                                             Hosted by Looker
  --prefer-ipv4                                            Prefer IPv4
  --log-level=<s>                                          Log level (default: info)
  --log-format=<s>                                         Log format, one of [text, json] (default: text)
  --log-to-file, --no-log-to-file                          Send log output to looker log file (default: true)
  -r, --root                                               Allow running as root
  --marketplace=<s>                                        Running in a Looker marketplace instance
  --disable-db-log                                         Disable logging of internal DB queries
  --core-on-loopback                                       Expose Core API on loopback interface
  --self-signup                                            Allow anyone to create an account for themselves
  --lock-out-lookers                                       No longer supported
  --scheduler-start-delay=<i>                              Delay task runner startup (seconds) (default: 60)
  --force-error-emails                                     Force Looker to report errors via email
  --error-emails-to=<s>                                    Error emails to <email address>
  --report-backend-errors, --no-report-backend-errors      Report errors from the backend (default: true)
  --report-frontend-errors, --no-report-frontend-errors    Report errors from the frontend (default: true)
  --scheduler-threads=<i>                                  Number of simultaneous scheduled tasks (default: 3)
  --alerts-scheduler-threads=<i>                           Number of simultaneous scheduled alerts (default: 3)
  --unlimited-scheduler-threads=<i>                        Number of simultaneous unlimited scheduled tasks (default: 3)
  --default-mailer-port=<i>                                Port over which to send mail when using default mailer (default: 587)
  --super-max-query-limit                                  Restricted Usage. Elevates the number of max query results
  --max-unstreamed-limit=<i>                               Elevates the number of rows allowed for download without streaming (default: 100000)
  --concurrent-render-jobs=<i>                             Number of simultaneous phantomjs or Chromium rendering processes (default: 2)
  --force-enable-pendo                                     Enable pendo guides on whitelabel instances or in embed contexts
  --git-performance-logging                                Enable logging of jgit performance
  --ssl-cert=<s>                                           Deprecated. Use --ssl-keystore instead
  --ssl-key=<s>                                            Deprecated. Use --ssl-keystore instead
  --ssl-ca-cert=<s>                                        Deprecated. Use --ssl-keystore instead
  --clustered                                              Whether this server is part of a cluster
  -H, --hostname=<s>                                       Hostname for node-to-node communication
  -n, --node-to-node-port=<i>                              Port for node-to-node communication (default: 1551)
  -d, --internal-db-creds=<s>                              Path to yaml file with db credentials
  --shared-storage-dir=<s>                                 Path to network file system shared storage
  --experimental-routes=<s>                                Comma separated list of allowed experimental routes that generate routes with the suffix of -next
  --experimental-features=<s>                              Comma separated list of allowed experimental features
  --snowplow-host=<s>                                      Extra snowplow collector
  --staging                                                Run server as staging
  --staging-override-email=<s>                             Send emails on a staging instance to this address instead of their normal destination
  --async-results-cache-time=<i>                           Length of time to keep async results cached (default: 300)
  --max-async-threads=<i>                                  Maximum number of async query threads (default: 200)
  --dashboard-query-throttle=<i>                           Deprecated. Use --per-user-query-limit instead
  --per-user-query-limit=<i>                               Limits number of concurrent queries per user (default: 15)
  --per-user-query-timeout=<i>                             Length of per-user timeout to wait for connection (default: 600)
  --scheduler-query-limit=<i>                              Limits number of concurrent scheduled queries (default: 10)
  --scheduler-query-timeout=<i>                            Length of scheduler timeout to wait for connection (default: 1200)
  --max-pdt-regen-threads=<i>                              Maximum number of PDT regenerator threads (default: 25)
  --force-cdn                                              force enable CDN
  --force-no-cdn                                           force disable CDN
  --cdn-hosts=<s>                                          comma separated hostnames for cdn pool (default: static-a.lookercdn.com,static-b.lookercdn.com)
  --use-custom-jdbc-config                                 Whether to use custom jdbc driver config
  --force-gcm-encryption                                   Force GCM encryption (works only for new installs)
  --cipher-key-file=<s>                                    Path to file containing cipher key (legacy encryption only)
  --new-cipher-key-file=<s>                                Path to file containing new cipher key (legacy encryption only)
  --force-cipher-key                                       Disregard safeguards for the cipher key settings (legacy encryption only)
  --loose-cipher-key-file                                  Don't require 0600 permissions for cipher key file (legacy encryption only)
  --in-memory-cache-size=<i>                               Size (in MB) of in memory cache (default: 50)
  --on-disk-cache-size=<i>                                 Size (in MB) of disk cache (default: 2000)
  --force-mismatched-internal-db                           Allow use of out-of-sync Looker Internal DB
  -q, --queue-broker-port=<i>                              Port for queue broker (default: 61616)
  --use-maestro                                            Use Maestro for job orchestration
  --user-db-credentials                                    Restricted Usage. Connections can use per-user credentials
  --public-embed-auth-param-file=<s>                       Authentication param file for public auth
  --worker-service-host=<s>                                (Looker internal use only)
  --worker-service-port=<i>                                (Looker internal use only)
  --worker-admin-port=<i>                                  (Looker internal use only)
  --worker-eval                                            (Looker internal use only)
  --dogstatsd-host-ip=<s>                                  Datadog statsd server host ip
  --dogstatsd-host-port=<i>                                Datadog server host port
  --k8s-deployment-api-s3bucket-url=<s>                    url where this Looker process can write S3 bucket credentials to be persisted as k8s secrets
  --google-analytics-tracker-id=<s>                        Tracking ID to use for sending pageviews to additional Google Analytics trackers
  --cloud-trace-json-file=<s>                              JSON file containing the service account credentials to upload trace data to Google Cloud Trace
  --cloud-trace-sample-rate=<f>                            The rate (0-1) with which to sample traces. Defaults to 1% (default: 0.01)
  -v, --version                                            Print version and exit
  -e, --help                                               Show this message

Additional Startup Option Details

-r, --root

Looker does not require root privileges for normal operation. For security purposes, we recommend you run Looker in a non-root account. Use the option to run as root only when required, for example if requested by a Looker analyst for troubleshooting purposes.


This option will prevent your staging instance from sending out scheduled reports. However, the staging instance will still continue to run scheduled tasks and will send out error emails to scheduled plan owners if the scheduled task has any issues.


This option provides the host:port to be used as an external SSL provider that is accessible from the server running Looker.

Here is an example for an SSL proxy in front of a Looker cluster:


Here is an example of an SSL provider on the same host as your Looker instance:


A null value indicates that the Looker app server provides SSL. If your Looker instance is running on a server with restricted access to the public internet, you will need to specify an IP address on your internal network that is reachable by the server for your Looker instance.

Credentials File Format

If you have changed the application database to MySQL, you’ll need a credentials file named looker-db.yml that includes these settings:

dialect: mysql
database: YOUR_DBNAME

If your MySQL database requires an SSL connection, the looker-db.yml file also requires the following:

ssl: true

Making Startup Options Permanent

The preferred method for making startup configuration settings permanent is to create a file named lookerstart.cfg in the Looker application directory. This file will be executed by the Looker startup script that was provided with your looker.jar. The lookerstart.cfg file is the recommended place to set environment variables for JAVAARGS and LOOKERARGS because they will not be overwritten when new versions of the Looker startup script are installed.

Here is an example lookerstart.cfg, which disables Looker’s SSL and sets it to run on port 8080:

LOOKERARGS="--no-ssl --port 8080"

Looker will need to be restarted after making changes to lookerstart.cfg.

Next Step

After you have configured Looker startup options you’re ready to configure your SSL certificate for proper HTTPS.