Multi-Check YAML Configuration

Wait4it supports defining one or more checks using a YAML file (via --config / W4IT_CONFIG) or inline YAML content (via the W4IT_CONFIG_YAML environment variable).

A single check can also be expressed in YAML (see example below). When a configuration source is provided, all other check-specific flags and their environment variable equivalents are ignored.

Basic Usage

Using a YAML file

wait4it --config checks.yaml
# or
W4IT_CONFIG=checks.yaml wait4it

Using inline YAML

W4IT_CONFIG_YAML='version: "1"
checks:
  - type: tcp
    host: 127.0.0.1
    port: 8080' wait4it

Using Docker

docker run -v $(pwd)/checks.yaml:/config.yaml ph4r5h4d/wait4it --config /config.yaml

Single Check via YAML

You can use the same YAML format for a single check:

version: "1"
checks:
  - type: tcp
    host: 127.0.0.1
    port: 8080
    timeout: 10

wait4it --config single-check.yaml

This is useful if you want a consistent configuration format even when only one service is involved.

YAML Schema

version: "1"              # Recommended. Only "1" is currently supported.
timeout: 30               # Global default timeout (seconds). Default: 30
fail_fast: true           # Stop on first required failure. Default: true

checks:                   # Required. At least one check.
  - name: "string"        # Optional. Used in log messages.
    type: "string"        # Required. One of the supported check types (tcp, mysql, redis, etc.).
    host: "string"        # Required for most types.
    port: 0               # Required for most types.
    username: "string"
    password: "string"
    password_file: "string"
    database: "string"

    optional: false       # If true, failure is non-fatal (warning + continue). Default: false
    timeout: 0            # Per-check timeout override (seconds).

    # Database-specific
    ssl_mode: "disable"
    operation_mode: "standalone"

    # HTTP-specific
    http_status_code: 200
    http_text: "string"
    http_follow_redirect: true

    # Kafka-specific
    kafka_connection_type: "tcp"
    kafka_connect_to_leader_via_non_leader: false

    # DNS-specific
    dns_type: "A"
    dns_expect: "string"
    dns_server: "string"

    # InfluxDB-specific
    influx_token: "string"
    influx_org: "string"
    influx_bucket: "string"

See the individual service documentation pages for the exact meaning and validation rules of each field.

Execution Behavior

Checks run sequentially (not concurrently) in the order defined.
Each check uses its own timeout (per-check > global > 30s default).
Required checks (optional: false or omitted): Failure causes non-zero exit.
Optional checks (optional: true): Failure prints a warning and continues. Overall exit is 0 if all required checks succeed.
fail_fast: true (default): Stop on the first required failure.
fail_fast: false: Attempt all checks; report the first required failure.

Output Examples

All required succeed:

Waiting for primary-db (mysql)...
Wait4it...
Waiting for cache (redis, optional)...
Wait4it.
Success!

Optional fails:

Waiting for primary-db (mysql)...
Wait4it...
Waiting for cache (redis, optional)...
Wait4it.
Warning: optional check "cache" (redis) failed: check failed: context deadline exceeded
Success with 1 optional warning(s)!

Examples

1. Single Check (TCP)

version: "1"
checks:
  - type: tcp
    host: 127.0.0.1
    port: 8080
    timeout: 10

2. Multiple Checks with One Optional

version: "1"
timeout: 30
fail_fast: true

checks:
  - name: "primary-db"
    type: mysql
    host: db
    port: 3306
    username: root
    password: secret
    database: app
    optional: false

  - name: "cache"
    type: redis
    host: redis
    port: 6379
    optional: true

3. Using fail_fast: false

version: "1"
fail_fast: false

checks:
  - name: "must-start-first"
    type: tcp
    host: 10.0.0.5
    port: 5432
    timeout: 60

  - name: "optional-later"
    type: http
    host: http://10.0.0.10/health
    http_status_code: 200
    optional: true
    timeout: 15

4. Mixed Services with Password File

version: "1"
timeout: 45

checks:
  - name: "postgres"
    type: postgres
    host: postgres
    port: 5432
    username: appuser
    password_file: /secrets/db-password
    database: myapp
    ssl_mode: require

  - name: "elasticsearch"
    type: elasticsearch
    host: es
    port: 9200
    optional: true

5. Inline via Environment Variable (Single or Multi)

W4IT_CONFIG_YAML='version: "1"
checks:
  - type: kafka
    host: kafka
    port: 9092
    timeout: 20' wait4it

6. Per-Check Timeouts + Optional

version: "1"
timeout: 30

checks:
  - type: mysql
    host: primary-db
    port: 3306
    username: root
    password: secret
    timeout: 120          # slow startup DB gets more time

  - type: redis
    host: redis
    port: 6379
    optional: true
    timeout: 5

Global CLI / Env Options (still apply)

--no-banner / W4IT_NO_BANNER
The --config flag and W4IT_CONFIG / W4IT_CONFIG_YAML vars.

Notes

password_file is supported per-check and validated early (similar to single-check mode).
When using a config, single-check flags like -type, -h, etc. are ignored.
Unknown check types or validation errors in specs produce clear errors.
YAML comments and standard features are supported.

Exit Codes

Code	Meaning
0	All required checks succeeded (optional failures produce warnings only).
Non-zero	At least one required check failed (or config parse error).

See individual service pages for service-specific details. The multi-check feature reuses the same per-service check implementations.