Advanced usage

Environment variables

Several environment variables can be passed to Gokapi. They can be used to modify settings that are not present during setup or to pass cloud storage credentials without saving them to the filesystem.

Passing environment variables to Gokapi

Docker

Pass the variable with the -e argument. Example for setting the port in use to 12345 and the chunk size to 60MB:

docker run -it -e GOKAPI_PORT=12345 -e GOKAPI_CHUNK_SIZE_MB=60 f0rc3/gokapi:latest

Native Deployment

Linux / Unix

For Linux / Unix environments, execute the binary in this format:

GOKAPI_PORT=12345 GOKAPI_CHUNK_SIZE_MB=60 [...] ./Gokapi

Windows

For Windows environments, you need to run set first, e.g.:

set GOKAPI_PORT=12345
set GOKAPI_CHUNK_SIZE_MB=60
[...]
Gokapi.exe

Available environment variables

Name	Action	Persistent [*]	Default
GOKAPI_CHUNK_SIZE_MB	Sets the size of chunks that are uploaded in MB	Yes	45
GOKAPI_CONFIG_DIR	Sets the directory for the config file	No	config
GOKAPI_CONFIG_FILE	Sets the name of the config file	No	config.json
GOKAPI_DATA_DIR	Sets the directory for the data	Yes	data
GOKAPI_DISABLE_CORS_CHECK	Disables the CORS check on startup and during setup, if set to true	No	false
GOKAPI_DISABLE_DOCKER_TRUSTED_PROXY	Disables automatically adding Docker subnet to trusted proxies, if set to true	No	false
GOKAPI_ENABLE_HOTLINK_VIDEOS	Allow hotlinking of videos. Note: Due to buffering, playing a video might count as multiple downloads. It is only recommended to use video hotlinking for uploads with unlimited downloads enabled	No	false
GOKAPI_GUEST_UPLOAD_BY_DEFAULT	Allows all users by default to create file requests, if set to true	No	false
GOKAPI_LENGTH_HOTLINK_ID	Sets the length of the hotlink IDs. Value must be 8 or greater	No	40
GOKAPI_LENGTH_ID	Sets the length of the download IDs. Value must be 5 or greater	No	15
GOKAPI_LOG_STDOUT	Also outputs all log file entries to the console output, if set to true	No	false
GOKAPI_MAX_FILESIZE	Sets the maximum allowed file size in MB Default 102400 = 100GB	Yes	102400
GOKAPI_MAX_FILES_GUESTUPLOAD	Sets the maximum number of files that can be uploaded per file requests created by non-admin users Set to 0 to allow unlimited file count for all users	No	100
GOKAPI_MAX_MEMORY_UPLOAD	Sets the amount of RAM in MB that can be allocated for an upload chunk or file Any chunk or file with a size greater than that will be written to a temporary file	Yes	50
GOKAPI_MAX_PARALLEL_UPLOADS	Set the number of chunks that are uploaded in parallel for a single file	Yes	3
GOKAPI_MAX_SIZE_GUESTUPLOAD	Sets the maximum file size for file requests created by non-admin users Set to 0 to allow files with a size of up to a value set with GOKAPI_MAX_FILESIZE for all users Default 10240 = 10GB	No	10240
GOKAPI_MIN_FREE_SPACE	Sets the minium free space on the disk in MB for accepting an upload	No	400
GOKAPI_MIN_LENGTH_PASSWORD	Sets the minium password length. Value must be 6 or greater	No	8
GOKAPI_PORT	Sets the webserver port	Yes	53842
GOKAPI_TRUSTED_PROXIES	Sets a list of trusted proxies. If set, the webserver will trust the IP addresses sent by these proxies with the X-Forwarded-For and X-REAL-IP header List is comma separated; entries can be fixed IPs (“10.0.0.1, 10.0.0.2”) and subnets (“10.0.0.0/24”)	No	127.0.0.1
GOKAPI_USE_CLOUDFLARE	Set this to true if you are using Cloudflare	No	false
TMPDIR	Sets the path which contains temporary files	No	Non-Docker: Default OS path Docker: [DATA_DIR]
DOCKER_NONROOT	DEPRECATED. Docker only: Runs the binary in the container as a non-root user, if set to “true”	No	false

[*]

Variables that are persistent must be submitted during the first start when Gokapi creates a new config file. They can be omitted afterwards. Non-persistent variables need to be set on every start.

All values that are described in Cloudstorage can be passed as environment variables as well. No values are persistent; therefore, they need to be set on every start.

Name	Action	Example
GOKAPI_AWS_BUCKET	Sets the bucket name	gokapi
GOKAPI_AWS_REGION	Sets the region name	eu-central-000
GOKAPI_AWS_KEY	Sets the API key	123456789
GOKAPI_AWS_KEY_SECRET	Sets the API key secret	abcdefg123
GOKAPI_AWS_ENDPOINT	Sets the endpoint	eu-central-000.provider.com

Databases

By default, Gokapi uses an SQLite database for data storage, which should suffice for most use cases. Additionally, Redis is available as an experimental option.

Migrating to a different database

To switch to a different database, Gokapi provides a migration tool. By running:

gokapi migrate-database --source [old Database URL] --destination [new Database URL]

all existing data, except for user sessions, will be transferred to the new database. After the migration, you will need to rerun the setup and specify the new database location. For details on the correct database URL format, refer to the section Database URL format.

For Docker users, the command is:

docker run --rm -v gokapi-data:/app/data f0rc3/gokapi:latest /app/run.sh migrate-database --source [old Database URL] --destination [new Database URL]

Database URL format

Database URLs must start with either sqlite:// or redis://.

For SQLite, the path to the database follows the prefix. No additional options are allowed.

For Redis, the URL can include authentication credentials (username and password), an optional prefix for keys, and parameter to use SSL.

Redis URL Format

A Redis URL has the following structure:

redis://[username:password@]host[:port][?options]

• username: (optional) The username for authentication.

• password: (optional) The password for authentication.

• host: (required) The address of the Redis server.

• port: (optional) The port of the Redis server (default is 6379).

• options: (optional) Additional options such as SSL (ssl=true) and key prefix (prefix=).

Examples

Migrating SQLite (/app/data/gokapi.sqlite) to Redis (127.0.0.1:6379):

gokapi migrate-database --source sqlite:///app/data/gokapi.sqlite --destination redis://127.0.0.1:6379

Migrating SQLite (/app/data/gokapi.sqlite) to SQLite (./data/gokapi.sqlite):

gokapi migrate-database --source sqlite:///app/data/gokapi.sqlite --destination sqlite://./data/gokapi.sqlite

Migrating Redis (127.0.0.1:6379, User: test, Password: 1234, Prefix: gokapi_, using SSL) to SQLite (./data/gokapi.sqlite):

gokapi migrate-database --source "redis://test:1234@127.0.0.1:6379?prefix=gokapi_&ssl=true" --destination sqlite://./data/gokapi.sqlite

CLI Tool

The Gokapi CLI tool enables seamless file uploads and downloads directly from the command line.

Installation

Official binaries for Linux, Windows, and macOS are available on the GitHub releases page.

To build the tool from source:

1. Download the repository.

2. Run make build-cli from the root directory.

Note

Gokapi v2.1.0 or newer is required for CLI functionality. For file downloads, version v2.2.0 or newer is required.

Authentication

To begin, authenticate your session using the following command:

gokapi-cli login

You will be prompted to provide your server URL, an API key with upload permissions, and your end-to-end encryption key (if applicable).

• Storage: By default, credentials are saved in plain text to gokapi-cli.json. You may specify a custom path using the -c parameter.

• Logout: To logout, run gokapi-cli logout or manually delete the configuration file.

Warning

The configuration file stores login credentials in plain text. Ensure the file is stored in a secure environment.

Docker Usage

While the native binary is recommended for the best experience, the CLI can be run via Docker. By default, the configuration is stored at /app/config/config.json.

To persist your login session, mount a volume as shown below:

docker run -it --rm -v gokapi-cli-config:/app/config docker.io/f0rc3/gokapi-cli:latest login

Uploading Files

To upload a file, use the upload command with the -f flag:

gokapi-cli upload -f /path/to/file

By default, files are encrypted (if enabled) and have no expiration date. The following parameters are available to customize the upload:

Parameter	Description
--file, -f [path]	(Required) Path to the file to be uploaded.
--expiry-days, -e [int]	Sets the file expiration in days.
--expiry-downloads, -d [int]	Limits the number of allowed downloads.
--password, -p [string]	Protects the download with a password.
--name, -n [string]	Assigns a custom filename on the server.
--disable-e2e, -x	Disables end-to-end encryption for this upload.
--json, -j	Returns output in JSON format (unless failed).
--configuration, -c [path]	Uses a specific configuration file.

Example: Upload a file that expires in 10 days, has no download limit, and is protected by the password “abcd”:

gokapi-cli upload -f /tmp/example --expiry-days 10 --password abcd

Warning

To avoid race conditions, do not initiate multiple simultaneous uploads if end-to-end encryption is enabled.

Docker

As a Docker container cannot access your host files without a volume, you will need to mount the folder that contains your file to upload and then specify the internal file path with -f. If no -f parameter is supplied and only a single file exists in the container folder /upload/, this file will be uploaded.

Example: Uploading the file /tmp/example. It will expire after 5 downloads, has no time expiry and has no password.

docker run --rm -v gokapi-cli-config:/app/config -v /tmp/:/upload/ docker.io/f0rc3/gokapi-cli:latest upload -f /upload/example --expiry-downloads 5

Example: Uploading the file /tmp/single/example. There is no other file in the folder /tmp/single/.

docker run --rm -v gokapi-cli-config:/app/config -v /tmp/single/:/upload/ docker.io/f0rc3/gokapi-cli:latest upload

Example: Uploading the file /tmp/multiple/example. There are other files in the folder /tmp/multiple/.

docker run --rm -v gokapi-cli-config:/app/config -v /tmp/multiple/example:/upload/example docker.io/f0rc3/gokapi-cli:latest upload

Uploading a directory

By running gokapi-cli upload-dir -D /path/to/directory/, gokapi-cli compresses the given folder as a zip file and then uploads it. By default the foldername is used for the name of the zip file. Also the file is encrypted (if enabled) and stored without any expiration.

In addition to all the options seen in chapter Uploading Files, the following optional options are also available:

Parameter	Effect
--tmpfolder, -t	Sets the path for temporary files.

Example: Uploading the folder /tmp/example/. It will expire in 10 days, has unlimited downloads and requires the password abcd:

gokapi-cli upload-dir -D /tmp/example --expiry-days 10 --password abcd

Warning

If you are using end-to-end encryption, do not upload other encrypted files simultaneously to avoid race conditions.

Docker

As a Docker container cannot access your host files without a volume, you will need to mount the folder that contains your file to upload and then specify the internal path with -D. If no -D parameter is supplied, the folder /upload/ will be uploaded (if it contains any files).

Example: Uploading the folder /tmp/example/. It will expire after 5 downloads, has no time expiry and has no password.

docker run --rm -v gokapi-cli-config:/app/config -v /tmp/example/:/upload/example docker.io/f0rc3/gokapi-cli:latest upload-dir -D /upload/example/ --expiry-downloads 5

Example: Uploading the folder /tmp/another/example and setting the filename to example.zip

docker run --rm -v gokapi-cli-config:/app/config -v /tmp/another/example:/upload/ docker.io/f0rc3/gokapi-cli:latest upload-dir -n "example.zip"

Downloading Files

To retrieve a file from the server, use the download command followed by the file ID. Files downloaded with the CLI tool do not increase the download count.

gokapi-cli download -i [FILE_ID]

Available parameters for downloads:

Parameter	Description
--id, -i [id]	(Required) The unique ID of the file.
--output, -o [string]	Renames the file upon download.
--output-path, -k [path]	Target directory (defaults to current folder).
--remove, -r	Deletes the file from the server after download.

Example: Download the file with ID Eukohc6r to the /home/user/downloads folder and delete it from the server after a successful transfer:

gokapi-cli download -i Eukohc6r --output-path /home/user/downloads --remove

API

Gokapi offers an API that can be reached at http(s)://your.gokapi.url/api/. You can find the current documentation with an overview of all API functions and examples at http(s)://your.gokapi.url/apidocumentation/.

Interacting with the API

All API calls will need an API key as authentication. An API key can be generated in the web UI in the menu “API”. The API key needs to be passed as a header.

Example: Getting a list of all stored files with curl

curl -X GET "https://your.gokapi.url/api/files/list" -H "accept: application/json" -H "apikey: secret"

Some calls expect parameters as form/post parameter, others as headers. Please refer to the current API documentation.

Example: Uploading a file

curl -X POST "https://your.gokapi.url/api/files/add" -H "accept: application/json" -H "apikey: secret" -H "Content-Type: multipart/form-data" -F "allowedDownloads=1" -F "expiryDays=5" -F "password=" -F "file=@yourfile.dat"

Example: Deleting a file

curl -X DELETE "https://your.gokapi.url/api/files/delete" -H "accept: */*" -H "id: PFnh2DlQRS2PVKM" -H "apikey: secret"

Chunk Sizes / Considerations for servers with limited or high amount of RAM

By default, Gokapi uploads files in 45MB chunks stored in RAM. Up to 3 chunks are sent in parallel to enhance upload speed, requiring up to 150MB of RAM per file during upload in the standard configuration.

Servers with limited RAM

To conserve RAM, you can either

• configure Gokapi to save the chunks on disk instead of RAM, by setting the MaxMemory setting to a value lower than your chunk size

• reduce the chunk size by setting the ChunkSize to a lower value

• decrease the amount of parallel uploads by setting MaxParallelUploads to a lower value

Refer to Changing the configuration for instructions on changing these values.

Servers with high amount of RAM

If your server has a lot of available RAM, you can improve upload speed by increasing the chunk size, which reduces overhead during upload.

• Increase the chunk size by setting the ChunkSize to a larger value

• Make sure that the MaxMemory setting is a higher value than your chunk size

• Increasing the amount of parallel uploads by setting MaxParallelUploads to a higher value is possible, but not recommended if using HTTP1.1 (see warning below).

Refer to Changing the configuration for instructions on changing these values.

Note

Ensure your reverse proxy and CDN (if applicable) support the chosen chunk size. Cloudflare users on the free tier are limited to 100MB file chunks.

Warning

Most browsers do not support more than 6 open connections with HTTP1.1 (which is the default connection). There is always one connection per tab used in the background for receiving status updates, therefore increasing the MaxParallelUploads value is not recommended in that case. If you require more connections, you can consider switching to HTTP2.

Changing the configuration

If you have not completed the Gokapi setup yet, you can set all the values mentioned above using environment variables. See Passing environment variables to Gokapi for instructions. If the setup is complete, Gokapi will ignore these environment variables, and you’ll need to modify the configuration file (by default: config.json in the folder config). See the table below on how to change the values:

Configuration	Environment Variable	Configuration File Entry	Default
Chunk size for uploads	GOKAPI_CHUNK_SIZE_MB	ChunkSize	45
Maximum size for chunks or whole files to store in RAM during upload	GOKAPI_MAX_MEMORY_UPLOAD	MaxMemory	50
Parallel uploads per file	GOKAPI_MAX_PARALLEL_UPLOADS	MaxParallelUploads	3

Automatic Deployment

It is possible to deploy Gokapi without having to run the setup. You will need to complete the setup on a temporary instance first. This is to create the configuration files, which can then be used for deployment.

Configuration Files

The configuration consists of up to two files in the configuration directory (default: config). All files can be read-only, however config.json might need write access in some situations.

cloudconfig.yml

Stores the access data for cloud storage. This can be reused without modification, however all fields can also be set with environment variables. The file does not exist if no cloud storage is used and can always be read-only.

config.json

Contains the server configuration. If you want to deploy Gokapi in multiple instances for redundancy (e.g. all instances share the same data), then the configuration file can be reused without modification. Otherwise you need to modify it before deploying (see below). Can be read-only, but might need write access when upgrading Gokapi to a newer version. Needs write access when re-running setup or changing the admin password.

Modifying config.json to deploy without setup

If you want to deploy Gokapi to multiple instances that contain different data, you have to modify the config.json. Open it and change the following fields:

Field	Operation	Example
SaltAdmin	Change to empty value	“SaltAdmin”: “”,
SaltFiles	Change to empty value	“SaltFiles”: “”,
Password	Change to empty value	“Password”: “”,
Username	Change to the username of your preference, if you are using internal username/password authentication	“Username”: “admin”,

Setting an admin password

If you are using internal username/password authentication, run the binary with the parameter --deployment-password [YOUR_PASSWORD]. This sets the password and also generates a new salt for the password. This has to be done before Gokapi is run for the first time on the new instance. Alternatively you can do this on the orchestrating machine and then copy the configuration file to the new instance.

If you are using a Docker image, this has to be done by starting a container with the entrypoint /app/run.sh, for example:

docker run --rm -v gokapi-data:/app/data -v gokapi-config:/app/config  f0rc3/gokapi:latest /app/run.sh --deployment-password newPassword

Customising

If you want to change the layout (e.g. add your company logo or add/disable certain features), follow these steps:

1. Create a new folder named custom where your executable is. When using Docker, mount a new folder to /app/custom/. Any file in this directory will be publicly available in the sub-URL /custom/.

2. To have custom CSS included, create a file in the folder named custom.css. The CSS will be applied to all pages.

3. To have custom JavaScript included, create the file public.js for all public pages and/or admin.js for all admin-related pages. Please note that the admin.js will be readable to all users.

4. In order to prevent caching issues, you can version your files by creating the file version.txt with a version number.

5. To have a custom Favicon, place a 512x512 PNG image named favicon.png in the folder custom.

6. Restart the server. If the folders exist, the server will now add the local files.

Optional: If you require further changes or want to embedded the changes permanently, you can clone the source code and then modify the templates in internal/webserver/web/templates. Afterwards run make to build a new binary with these changes.