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This project creates a small dockerized REST API aroundsignal-cli.

At the moment, the following functionality is exposed via REST:

• Register a number
• Verify the number using the code received via SMS
• Send message (+ attachments) to multiple recipients (or a group)
• Receive messages
• Link devices
• Create/List/Remove groups
• List/Serve/Delete attachments
• Update profile

andmany more

1. Create a directory for the configurationThis allows you to updatesignal-cli-rest-api by just deleting and recreating the container without the need to re-register your signal number

$ mkdir -p$HOME/.local/share/signal-api

2. Start a container

$ sudo docker run -d --name signal-api --restart=always -p 8080:8080 \      -v$HOME/.local/share/signal-api:/home/.local/share/signal-cli \      -e'MODE=native' bbernhard/signal-cli-rest-api

3. Register or Link your Signal Number

In this case we'll register our container as secondary device, assuming that you already have your primary number running / assigned to your mobile.

Therefore openhttp://localhost:8080/v1/qrcodelink?device_name=signal-api in your browser, open Signal on your mobile phone, go toSettings > Linked devices and scan the QR code using the+ button.

4. Test your new REST API

Call the REST API endpoint and send a test message: Replace+4412345 with your signal number in international number format, and+44987654 with the recipients number.

$ curl -X POST -H"Content-Type: application/json"'http://localhost:8080/v2/send' \     -d'{"message": "Test via Signal API!", "number": "+4412345", "recipients": [ "+44987654" ]}'

You should now have send a message to+44987654.

Thesignal-cli-rest-api supports three different modes of execution, which can be controlled by setting theMODE environment variable.

• normal Mode: (Default) Thesignal-cli executable is invoked for every REST API request. Being a Java application, each REST call requires a new startup of the JVM (Java Virtual Machine), increasing the latency and hence leading to the slowest mode of operation.
• native Mode: A precompiled binarysignal-cli-native (using GraalVM) is used for every REST API request. This results in a much lower latency & memory usage on each call. On thearmv7 platform this mode is not available and falls back tonormal. The native mode may also be less stable, due to the experimental state of GraalVM compiler.
• json-rpc Mode: A single, JVM-basedsignal-cli instance is spawned as daemon process. This mode is usually the fastest, but requires more memory as the JVM keeps running.

Example of runningsignal-cli-rest innative mode

$ sudo docker run -d --name signal-api --restart=always -p 9922:8080 \              -v /home/user/signal-api:/home/.local/share/signal-cli \              -e'MODE=native' bbernhard/signal-cli-rest-api

This launches an instance of the REST service accessible underhttp://localhost:9922/v2/send. To preserve the Signal number registration, i.e. for updates, the storage location for thesignal-cli configuration is mapped as Docker Volume into a local/home/user/signal-api directory.

⚠️ This setting is only needed in normal/native mode!

signal-cli, which this REST API wrapper is based on, recommends to callreceive on a regular basis. So, if you are not already calling thereceive endpoint regularly, it is recommended to set theAUTO_RECEIVE_SCHEDULE parameter in the docker-compose.yml file. TheAUTO_RECEIVE_SCHEDULE accepts cron schedule expressions and automatically calls thereceive endpoint at the given time. e.g:0 22 * * * callsreceive daily at 10pm. If you are not familiar with cron schedule expressions, you can use thiswebsite.

WARNING Callingreceive will fetch all the messages for the registered Signal number from the Signal Server! So, if you are using the REST API for receiving messages, it'snot a good idea to use theAUTO_RECEIVE_SCHEDULE parameter, as you might lose some messages that way.

Sampledocker-compose.ymlfile:

version:"3"services:signal-cli-rest-api:image:bbernhard/signal-cli-rest-api:latestenvironment:      -MODE=normal#supported modes: json-rpc, native, normal#- AUTO_RECEIVE_SCHEDULE=0 22 * * * #enable this parameter on demand (see description below)ports:      -"8080:8080"#map docker port 8080 to host port 8080.volumes:      -"./signal-cli-config:/home/.local/share/signal-cli"#map "signal-cli-config" folder on host system into docker container. the folder contains the password and cryptographic keys when a new number is registered

The Swagger API documentation can be foundhere. If you prefer a simple text file based API documentation have a lookhere.

• Running Signal Messenger REST API in Azure Web App for Containers by@stefanstranger
• Sending Signal Messages by@asad-awadia

In case you need more functionality, pleasefile a ticket orcreate a PR.

The plugin mechanism allows to register custom endpoints (with different payloads) without forking the project. Have a lookhere for details.

There are a bunch of environmental variables that can be set inside the docker container in order to change some technical details. This settings are meant for developers and advanced users. Usually you donot need to change anything here - the default values are perfectly fine!

• SIGNAL_CLI_CONFIG_DIR: Specifies the path to thesignal-cli config directory inside the docker container. Defaults to/home/.local/share/signal-cli/

• SIGNAL_CLI_UID: Specifies the uid of thesignal-api user inside the docker container. Defaults to1000

• SIGNAL_CLI_GID: Specifies the gid of thesignal-api group inside the docker container. Defaults to1000

• SWAGGER_HOST: The host that's used in the Swagger UI for the interactive examples (and useful when this runs behind a reverse proxy). Defaults to SWAGGER_IP:PORT.

• SWAGGER_IP: The IP that's used in the Swagger UI for the interactive examples. Defaults to the container ip.

• SWAGGER_USE_HTTPS_AS_PREFERRED_SCHEME: Use the HTTPS Scheme as preferred scheme in the Swagger UI.

• PORT: Defaults to port8080 unless this env var is set to tell it otherwise.

• DEFAULT_SIGNAL_TEXT_MODE: Allows to set the default text mode that should be used when sending a message (supported values:normal,styled). The setting is only used in case thetext_mode is not explicitly set in the payload of thesend method.

• LOG_LEVEL: Allows to set the log level. Supported values:debug,info,warn,error. If nothing is specified, it defaults toinfo.