One search backend to talk to: its :endpoint, :auth, the :httpc profile to send through, and how to cast the responses it returns.

The name follows elastic/cli's notion of a context — a named cluster you address by name instead of repeating its coordinates at every call site.

Build one inline with new/1, or configure named ones at compile time:

config :dowser_client,
  contexts: [
    default: [endpoint: "http://localhost:9200", auth: {:basic, "user", "changeme"}],
    logs: [endpoint: "https://logs.internal:9200", profile: :logs]
  ]

Fields

• :endpoint — the backend's base URL (required).

• :auth — credentials, applied as an authorization request header:

  {:basic, "dXNlcjpwYXNz"}          # Basic <value>, already encoded
  {:basic, "user", "changeme"}      # Basic <base64("user:changeme")>
  {:api_key, "VnVhQ2ZHY0..."}       # ApiKey <value>
  {:api_key, "id", "api_key"}       # ApiKey <base64("id:api_key")>
  {:bearer, "token"}                # Bearer <token>
  {:header, "x-custom-auth", "..."} # any header you like

• :profile — the :httpc profile requests go through, giving this backend its own connection pool and session settings. Defaults to :dowser_client; see Dowser.Client.HTTP.Profile.

• :profile_opts — that profile's :httpc.set_options/2 settings (max_sessions, max_keep_alive_length, keep_alive_timeout, pipeline_timeout, cookies, ...). Applied once, when the profile starts.

• :http_opts — per-request transport options: :headers, :connect_timeout, :timeout, :ssl, ...; see Dowser.Client.HTTP.

• :keys — :strings (default), :atoms, :atoms! or a function; how a decoded response body's keys are cast.

• :decoder — a module exporting decode/2, a (body, opts -> term) function, or either paired with the options it needs ({MyDecoder, mapping: mapping}), owning the decoded response body: the backend package's own casting, whatever its envelope looks like. With neither :keys nor :decoder set, a response stays the plain, string-keyed term Dowser.Client.JSON produced. See Dowser.Client.Decoder.

• :encoder — a module exporting encode/2, a (source, opts -> term) function, or either paired with the options it needs ({MyEncoder, index: "articles"}), casting a document source in a request body. It only runs when a request's :encode says where that source is; a query is never touched. See Dowser.Client.Encoder.

resolve/1 — used by Dowser.Client.request/4 on opts[:context] — turns any of the following into a %Context{}:

• nil — resolves the :default entry from config :dowser_client, contexts: [...]. There is no built-in fallback; a :default entry must be configured, or every call site must pass :context explicitly.
• an atom — looks up that name in the same contexts list/map.
• a map or keyword list — builds an ad-hoc context inline via new/1.
• a %Context{} — returned as-is.

Every field but :endpoint defaults to nil/[] on the struct itself; when unset, Dowser.Client.Request resolves it at request time from config :dowser_client, <the same key>, falling back to the :dowser_client profile, string keys and no decoder — so they can be changed at runtime (e.g. in config/runtime.exs), not just at compile time.