Your first config file

File-based routing alone can’t vary a response by header, method, or body content — for that, apimock needs a config file.

Generate one

apimock --init

Interactive by default — it prompts for the port, IP, fallback directory, and whether to scaffold a rule-set file, a middleware file, and a TLS section, then writes apimock.toml accordingly (plus whichever of apimock-rule-set.toml / apimock-middleware.rhai you opted into). Passing --yes skips the prompts and writes the defaults directly — see the CLI reference for both.

Run it, and the startup log names every config file it loaded:

apimock
# @ rule_set #1 (./apimock-rule-set.toml)
# Listening on http://127.0.0.1:3001 ...

TOML, briefly

apimock.toml and rule-set files are ordinary TOML. A few things worth knowing if you haven’t used it before:

• [table] starts a section; everything until the next [...] header belongs to it.
• Nested tables can be written with dotted headers: [rules.when.request.headers] is shorthand for a headers table inside a when table inside a request table inside rules.
• [[rules]] (double brackets) is an array of tables — each [[rules]] block starts a new entry in a list, which is why a rule set can have several [[rules]] sections.
• Keys with characters TOML treats specially (like the . in a dotted body path) need quoting: "customer.tier" = { ... }, not customer.tier = { ... }.

The full TOML specification is at toml.io if you want more than this project needs day to day.

Where files live, relative to what

If you move apimock.toml and its rule-set files into a subdirectory and point apimock at it explicitly:

apimock -c tests/apimock.toml

paths inside that config — service.rule_sets, service.fallback_respond_dir — resolve relative to apimock.toml’s own location, not the directory you ran apimock from. (TLS certificate paths are the one exception — see Serve over HTTPS.)

Next: Your first rule.