digitemp-rrdgraph is a command-line application for temperature monitoring with 1-Wire sensors. It collects measurements through digitemp, stores them in RRD files, generates graph images, and sends email notifications based on configured schedules and thresholds.

The repository is organized as a Cargo workspace with two crates:

digitemp-rrdgraph: the CLI binary crate
digitemp_rrdgraph_core: the internal library crate used by the CLI commands

Features

Read temperature data from 1-Wire sensors through digitemp
Store time-series data in RRD files
Generate graph images for hourly, daily, weekly, monthly, and yearly views
Send periodic information emails and threshold-based alert emails
Configure runtime behavior through JSON and template files

Requirements

Rust toolchain compatible with edition 2024
digitemp
RRDTool
Access to an SMTP server for email delivery

Project Layout

Cargo.toml: workspace root and CLI package definition
src/: CLI entrypoint and command modules
crates/core/: internal library crate shared by the CLI commands
crates/core/src/: shared modules for config loading, DigiTemp access, RRD operations, mail sending, and template rendering
etc/: configuration files and cron examples
templates/: Tera mail templates
db/: RRD database files
html/images/: generated graph images

Setup

Build the release binary.

cargo build --release

Choose where to place the application configuration file.

You can always override the default search order with --config /path/to/digitemp-rrdgraph.json.

Recommended locations are checked in this order:

$HOME/.config/digitemp-rrdgraph.json
/etc/digitemp-rrdgraph.json
<parent directory of the executable>/etc/digitemp-rrdgraph.json
$PWD/etc/digitemp-rrdgraph.json

For an installed layout such as /opt/digitemp-rrdgraph/bin/digitemp-rrdgraph, place the file at /opt/digitemp-rrdgraph/etc/digitemp-rrdgraph.json.

For local development from the repository root, create etc/digitemp-rrdgraph.json.

cp etc/digitemp-rrdgraph.sample.json etc/digitemp-rrdgraph.json

Create a DigiTemp configuration file.

digitemp_DS9097U -i -s /dev/ttyUSB0 -c ./etc/digitemp.conf

Edit the selected digitemp-rrdgraph.json file for your environment.

Pass --verbose if you want the CLI to print the selected configuration file path to standard error.

Configure at least these values:

digitemp and digitemp_config
database_dir, html_dir, and images_dir
templates_dir and html_template
room_name
SMTP server settings
mail recipients, subjects, and alert thresholds

room_name is required. It is used in mail templates, graph titles, and the generated top page. The update command renders html_template and writes it under html_dir using the same relative path with the .tera suffix removed. For example, index.html.tera becomes html/index.html.

SMTP settings support these combinations:

mail_smtp_security: smtp, starttls, or smtps
mail_smtp_auth: true to send SMTP AUTH credentials, false for unauthenticated servers
mail_smtp_username and mail_smtp_password: required only when mail_smtp_auth is true

Build

cargo build --release

This builds both workspace members, including the internal digitemp_rrdgraph_core crate.

The release binary is written to target/release/digitemp-rrdgraph.

To build only the CLI package explicitly:

cargo build --release -p digitemp-rrdgraph

To run tests across the workspace:

cargo test --workspace

Commands

The application provides these subcommands:

update: read sensors, update RRD files, and regenerate graph images
check-alert: evaluate current data against configured alert thresholds and send an alert email when required
send-info: send a periodic information email

Examples:

./target/release/digitemp-rrdgraph update
./target/release/digitemp-rrdgraph --verbose update
./target/release/digitemp-rrdgraph --config /opt/digitemp-rrdgraph/etc/digitemp-rrdgraph.json update
./target/release/digitemp-rrdgraph check-alert
./target/release/digitemp-rrdgraph send-info

Scheduling

Use cron or another scheduler to run the subcommands at appropriate intervals.

Run update on the data collection interval you want to keep in RRD.
Run send-info on the reporting interval you want for periodic summaries.
Run check-alert on the alert polling interval you want for threshold checks.

See etc/crontab.sample for a sample schedule.

Templates

Templates are stored in templates/ and rendered with Tera. The top page uses html_template, while the mail bodies use mail_info_template and mail_alert_template.

Development Notes

CLI subcommands live under src/commands/.
Shared application logic lives under crates/core/src/ and is exposed by the digitemp_rrdgraph_core crate.
The root crate depends on the internal core crate through a local path dependency.

License

MIT