There are two ways to configure Flipt: using a configuration file or through environment variables.

Configuration File

The default way that Flipt is configured is with the use of a configuration file default.yml.

This file is read when Flipt starts up and configures several important properties for the server.

You can edit any of these properties to your liking, and on restart Flipt will pick up the new changes.

These defaults are commented out in default.yml to give you an idea of what they are. To change them you'll first need to uncomment them.

These properties are as follows:


log.levelLevel at which messages are logged (trace, debug, info, warn, error, fatal, panic)info
log.fileFile to log to instead of STDOUTv0.10.0
ui.enabledEnable UI and API docstrue
cors.enabledEnable CORS supportfalsev0.7.0
cors.allowed_originsSets Access-Control-Allow-Origin header on server“*” (all domains)v0.7.0
tracing.jaeger.enabledEnable tracing support with Jaegerfalsev0.17.0
tracing.jaeger.hostThe UDP host destination to report spanslocalhostv0.17.0
tracing.jaeger.portThe UDP port destination to report spans6831v0.17.0
meta.check_for_updatesEnable check for newer versions of Flipt on startuptruev0.17.0


server.protocolhttp or httpshttpv0.8.0
server.hostThe host address on which to serve the Flipt application0.0.0.0
server.http_portThe HTTP port on which to serve the Flipt REST API and UI8080
server.https_portThe HTTPS port on which to serve the Flipt REST API and UI443v0.8.0
server.grpc_portThe port on which to serve the Flipt GRPC server9000
server.cert_filePath to the certificate file (if protocol is set to https)v0.8.0
server.cert_keyPath to the certificate key file (if protocol is set to https)v0.8.0


cache.memory.enabledEnable in-memory cachingfalse
cache.memory.expirationDuration at which cache items are considered expired-1 (none)v0.12.0
cache.memory.eviction_intervalInterval at which expired items are evicted from the cache10m (10 minutes)v0.12.0


db.urlURL to access Flipt databasefile:/var/opt/flipt/flipt.db
db.protocolProtocol (Sqlite, MySQL, Postgres) for Flipt database (URL takes precedence)v0.18.0
db.hostHost to access Flipt database (URL takes precedence)v0.18.0
db.portPort to access Flipt database (URL takes precedence)v0.18.0
db.nameName of Flipt database (URL takes precedence)v0.18.0
db.userUser to access Flipt database (URL takes precedence)v0.18.0
db.passwordPassword to access Flipt database (URL takes precedence)v0.18.0
db.max_idle_connThe maximum number of connections in the idle connection pool2v0.17.0
db.max_open_connThe maximum number of open connections to the databaseunlimitedv0.17.0
db.conn_max_lifetimeSets the maximum amount of time in which a connection can be reusedunlimitedv0.17.0
db.migrations.pathWhere the Flipt database migration files are kept/etc/flipt/config/migrations

Environment Variables

All options in the configuration file can be overridden using environment variables using the syntax:

Using environment variables to override defaults is especially helpful when running with Docker as described in the Installation documentation.

Everything should be upper case, . should be replaced by _. For example, given these configuration settings:

  grpc_port: 9000

  url: file:/var/opt/flipt/flipt.db

You can override them using:

export FLIPT_DB_URL="postgres://postgres@localhost:5432/flipt?sslmode=disable"


Flipt supports SQLite, Postgres and MySQL databases as of v0.16.0.

SQLite is enabled by default for simplicity, however you should use Postgres or MySQL if you intend to run multiple copies of Flipt in a high availability configuration.

The database connection can be configured as follows:


  # file: informs flipt to use SQLite
  url: file:/var/opt/flipt/flipt.db


  url: postgres://postgres@localhost:5432/flipt?sslmode=disable
The Postgres database must exist and be up and running before Flipt will be able to connect to it.


  url: mysql://mysql@localhost:3306/flipt
The MySQL database must exist and be up and running before Flipt will be able to connect to it.


From time to time the Flipt database must be updated with new schema. To accomplish this, Flipt includes a migrate command that will run any pending database migrations for you.

If Flipt is started and there are pending migrations, you will see the following error in the console:

migrations pending, please backup your database and run `flipt migrate`

If it is your first run of Flipt, all migrations will automatically be run before starting the Flipt server.

You should backup your database before running flipt migrate to ensure that no data is lost if an error occurs during migration.

If running Flipt via Docker, you can run the migrations in a separate container before starting Flipt by running:

docker run -it markphelps/flipt:latest /bin/sh -c './flipt migrate'


Flipt supports importing and exporting your feature flag data since v0.13.0.


To import previously exported Flipt data, use the flipt import command. You can import either from a file or from STDIN.

To import from STDIN, Flipt requires the --stdin flag:

cat flipt.yaml | flipt import --stdin

If not importing using --stdin, Flipt requires the file to be imported as an argument:

flipt import flipt.yaml

This command supports the --drop flag that will drop all of the data in your Flipt database tables before importing. This is to ensure that no data collisions occur during the import.

Be careful when using the --drop flag as it will immediately drop all of your data and there is no undo. It is recommend to first backup you database before running this command just to be safe.


To export Flipt data, use the flipt export command.

By default, export will output to STDOUT:

$ flipt export

- key: new-contact-page
  name: New Contact Page
  description: Show users our Beta contact page
  enabled: true
  - key: blue
    name: Blue
  - key: green
    name: Green

You can also export to a file using the -o filename or --output filename flags:

flipt export -o flipt.yaml


Flipt supports an in-memory cache to enable faster reads and evaluations. Enabling in-memory cache has been shown to speed up read performance by several orders of magnitude.

Enabling in-memory caching when running more that one instance of Flipt is not advised as it may lead to unpredictable results.

Caching works as follows:

  • All reads go through the cache
  • All writes flush the entire cache to ensure the cache is kept up to date
  • A cache miss will fetch the item from the database and add the item to the cache for the next read
  • A cache hit will simply return the item from the cache, not interacting with the database

To enable caching set the following in your config:

    enabled: true


You can also configure an optional duration at which items in the cache are marked as expired.

For example, if you set the cache expiration to 5m, items that have been in the cache for longer than 5 minutes will be marked as expired, meaning the next read for that item will hit the database.

Setting an eviction interval will automatically remove expired items from your cache at a defined period.

The combination of cache expiration and eviction can help lessen the amount of memory your cache uses, as infrequently accessed items will be removed over time.

To tune the expiration and eviction interval of the cache set the following in your config:

    enabled: true
    expiration: 5m # items older than 5 minutes will be marked as expired
    eviction_interval: 2m # expired items will be evicted from the cache every 2 minutes


Flipt exposes Prometheus metrics at the /metrics HTTP endpoint. To see which metrics are currently supported, point your browser to FLIPT_HOST/metrics (ex: localhost:8080/metrics).

You should see a bunch of metrics being recorded such as:

flipt_cache_hit_total{cache="memory",type="flag"} 1
flipt_cache_miss_total{cache="memory",type="flag"} 1
go_gc_duration_seconds{quantile="0"} 8.641e-06
go_gc_duration_seconds{quantile="0.25"} 2.499e-05
go_gc_duration_seconds{quantile="0.5"} 3.5359e-05
go_gc_duration_seconds{quantile="0.75"} 6.6594e-05
go_gc_duration_seconds{quantile="1"} 0.00026651
go_gc_duration_seconds_sum 0.000402094
go_gc_duration_seconds_count 5

There is an example provided in the GitHub repository showing how to setup Flipt with Prometheus.


Flipt supports distributed tracing via the OpenTracing protocol and Jaeger library. Enable tracing via the configuration values described above and point Flipt to your Jaeger host to record spans.

There is an example provided in the GitHub repository showing how to setup Flipt with Jaeger.


There is currently no built in authentication, authorization or encryption as Flipt was designed to work inside your trusted architecture and not be exposed publicly. If you wish to expose the Flipt dashboard and REST API publicly using HTTP Basic Authentication, you can do so by using a reverse proxy.

There is an example provided in the GitHub repository showing how this can work.