Use the local solver service#

This tutorial introduces the two local integrations added for repeated conda work. You will start the broker-managed HTTP service, call its public API, and delegate one conda dry-run to the internal Presto solver backend.

Verify service discovery#

Use the latest-release installation from Quick start, then list the discovered services from that activated environment:

conda broker list

The output should include conda-presto.server. The service is manual and does not start with ordinary conda presto commands.

Start the service#

Start it and wait for its persistent worker to load configured indexes:

conda broker start conda-presto.server
conda broker wait conda-presto.server --timeout 180
conda broker endpoint conda-presto.server

The endpoint command prints a broker-assigned loopback URL. Keep that URL for the next step.

Call the public HTTP API#

Replace PORT with the reported port:

curl -sS http://127.0.0.1:PORT/resolve \
  --json '{
    "specs": ["python=3.13"],
    "channels": ["conda-forge"],
    "platforms": ["linux-64"]
  }' | jq '.[0] | {platform, error}'

The broker service exposes the same public HTTP API as conda presto --serve. Its persistent worker keeps Python, conda, repodata, and solver indexes loaded between requests.

Delegate a conda dry-run#

The internal solver backend discovers this same service through conda-broker:

conda create --dry-run --solver=presto \
  -n presto-demo \
  -c conda-forge \
  python=3.13

The service computes the final package state. The calling conda process still computes the local transaction. Without --dry-run, package downloads and prefix changes would also remain in the calling process.

Run the same dry-run again before changing the prefix. Its complete serialized solver state may reuse the private final-state cache. There is currently no client header or command output that proves a cache hit, so timing alone is not a reliable cache diagnostic.

Inspect and stop the service#

Check status and recent logs:

conda broker status conda-presto.server
conda broker logs conda-presto.server --lines 50

Stop the service when finished:

conda broker stop conda-presto.server

What you learned#

  • The broker service is opt-in and loopback-only.

  • Public HTTP solves and internal conda final-state solves share one service.

  • The solver receives the caller’s effective installed state and virtual packages, while the prefix transaction stays local.

  • Docker does not expose the internal solver route or run scheduled solver-cache refresh.

For operational commands, see Run a broker-managed local service and Use the Presto solver backend. Exact contracts are in Broker service reference and Presto solver backend.

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