My way of using Signal-CLI-Rest-API to send Editable Messages in Home Assistant
There are multiple ways to send a Signal message in home assistant.
This post describes my way of sending Editable Signal messages using the signal-cli-rest-api.
I choose to use the REST integration to build a script that is able to send messages while can also edit sent messages.
The default way using notify does not allow you to edit messages, so this is a workaround to send messages that are updatable.
Prerequisites
A running signal-cli-rest-api instance. (preferably secured with a reverse proxy and authentication).
Changes in configuration.yaml
rest_command:
signal_cli:
url: "http://:signal-rest-api/v2/send"
method: "POST"
payload: "{{payload}}"
username: "hass"
password: ""
content_type: "application/json"
Notice: The
usernameandpasswordare optional, but I choose to protect the signal-cli-rest-api with a reverse proxy and basic authentication.
Script
Create a new script in your home assistant.
alias: Signal Message
description: Send a message using the Signal CLI Rest API
fields:
number:
name: Number
description: Phone Number to send message from
required: true
example: "+01123456789"
selector:
text: {}
recipients:
name: Recipients
description: |
List of recipients to add
Need to be in the form of
+01123456789
group.123456789
required: true
selector:
text:
multiple: true
message:
name: Message (Optional)
description: Message to send
required: false
example: Hello World
selector:
text:
multiline: true
attachments:
name: Attachments (Optional)
description: |
Attachments to add
Need to be in the form of
<BASE64 ENCODED DATA>
data:<MIME-TYPE>;base64<comma><BASE64 ENCODED DATA>
data:<MIME-TYPE>;filename=<FILENAME>;base64<comma><BASE64 ENCODED DATA>
required: false
selector:
text:
multiple: true
load_edit_timestamp_helper:
name: Load Edit Timestamp from Helper (Optional)
description: >-
Load the Edit Timestamp value from the specified helper (This can be used
to edit a previously sent message)
required: false
selector:
entity:
filter:
domain: input_text
save_edit_timestamp_helper:
name: Save Timestamp to Helper (Optional)
description: Set this helper to the Timestamp of the sent message
required: false
selector:
entity:
filter:
domain: input_text
sequence:
- variables:
base_payload:
recipients: "{{recipients}}"
message_payload: |-
{% if message and message != "" %}
{"message": "{{message}}"}
{% else %}
{}
{% endif %}
attachments_payload: |-
{% if attachments|length > 0 %}
{"base64_attachments": {{attachments}}}
{% else %}
{}
{% endif %}
edit_timestamp_payload: |-
{% if load_edit_timestamp_helper %}
{"edit_timestamp": {{states(load_edit_timestamp_helper) | int}}}
{% else %}
{}
{% endif %}
payload: >
{{ base_payload | combine({"number": number}) | combine(message_payload)
| combine(attachments_payload) | combine(edit_timestamp_payload) }}
- action: rest_command.signal_cli
response_variable: response
data:
payload: "{{payload | to_json}}"
- if:
- condition: template
value_template: "{{response['status'] != 201}}"
then:
- stop: Status was not 201
error: true
- if:
- condition: template
value_template: "{{ save_edit_timestamp_helper and save_edit_timestamp_helper != \"\"}}"
then:
- action: input_text.set_value
metadata: {}
target:
entity_id: "{{ save_edit_timestamp_helper }}"
data:
value: "{{response['content']['timestamp']}}"
mode: single
Usage
From an automation or script you can call the script like this:
action: script.signal_message
metadata: {}
data:
recipients:
- group....
number: "+0123456789"
message: Hello World
Editing Messages
In order to edit a message you need to use the save_edit_timestamp_helper to save the timestamp of the sent message. When you call the script again you can use the load_edit_timestamp_helper to load the timestamp of the message you want to edit.
Example Automation:
alias: Send Signal Attachment
triggers: []
conditions: []
actions:
- action: script.signal_message
metadata: {}
data:
recipients:
- group....
number: "+123456789"
message: Hello World
save_edit_timestamp_helper: input_text.signal_edit_timestamp
enabled: true
- delay: "00:00:05"
- action: script.signal_message
metadata: {}
data:
recipients:
- group....
number: "+123456789"
message: Hello Earth
load_edit_timestamp_helper: input_text.signal_edit_timestamp
enabled: true
mode: single
Attachments
A big caveat is that attachments cannot be updated!
You can add attachments to the message by using the attachments field. I wanted to send videos, so I a base64 command to the configuration.yaml:
shell_command:
base64: "base64 "
Then I used following automation:
alias: Send Signal Attachment
triggers: []
conditions: []
actions:
- action: shell_command.base64
metadata: {}
data:
args: "-i /config/www/previews/cam2.20250526-102212.mp4"
response_variable: response
- if:
- condition: template
value_template: "{{response['returncode'] != 0 }}"
then:
- stop: Return code was not 0
error: true
- action: script.signal_message
metadata: {}
data:
recipients:
- group....
number: "+123456789"
message: CAM2 Preview
attachments:
- "{{response['stdout']}}"
enabled: true
mode: single