Configuration

UpSlim is configured entirely through YAML files. There is no database, no web UI, and no CLI wizard.

File structure

A minimal config file looks like this:

monitors:
  - name: my-api
    type: http
    url: "https://api.example.com/health"
    conditions:
      - "[STATUS] == 200"

A full config with all sections:

defaults:
  interval: 60s
  timeout: 30s
  failure_threshold: 3
  success_threshold: 2
  send_on_resolved: true

alerting:
  - name: slack-ops
    type: slack
    token: ${SLACK_BOT_TOKEN}
    channel: "#ops-alerts"
    reminder_interval: 2h

monitors:
  - name: my-api
    type: http
    url: "https://api.example.com/health"
    conditions:
      - "[STATUS] == 200"
      - "[RESPONSE_TIME] < 500"
    alerts:
      - name: slack-ops

Environment variable substitution

Any string value can reference environment variables using ${VAR_NAME}:

alerting:
  - name: slack-ops
    type: slack
    token: ${SLACK_BOT_TOKEN}   # resolved at startup
    channel: "#ops-alerts"

If the referenced variable is not set, UpSlim will exit with a config error at startup.

defaults

Global defaults applied to every monitor unless overridden.

Field	Type	Default	Description
interval	duration	60s	How often to run the check
timeout	duration	30s	Maximum time to wait for a response
failure_threshold	integer	3	Consecutive failures before alerting
success_threshold	integer	2	Consecutive successes to mark as recovered
send_on_resolved	boolean	true	Send a recovery notification

alerting

A list of alert providers. Each provider has a name used to reference it from monitors.

See Alerting → Overview for the full provider reference.

monitors

A list of monitors. Each monitor can override any field from defaults.

See Monitors for the full monitor reference.

Duration format

Durations are strings with a unit suffix:

Suffix	Unit
ms	Milliseconds
s	Seconds
m	Minutes
h	Hours

Examples: 500ms, 30s, 5m, 2h

Loading from a directory

Pass a directory path instead of a file. UpSlim loads all *.yaml and *.yml files in lexicographic order and merges them:

• defaults — taken from the first file that defines them
• alerting — concatenated from all files
• monitors — concatenated from all files

This is useful for splitting configuration by team or service:

config/
├── 01-defaults.yaml       # global defaults + alerting
├── 02-platform.yaml       # infrastructure monitors
└── 03-apps.yaml           # application monitors

TIP

Use numeric prefixes to control merge order. 01- comes before 02-.