Home Gradle Plugin to Drive Two Ollama Pro Instances in Parallel

Table des matières

Introduction
Why Gradle for infra?
The complete build.gradle.kts
Anatomy of Key Tasks
Complete Workflow — From Zero to Two Sessions
Why not make it a real Gradle plugin?
Lessons Learned
Conclusion
Resources

reading time : 18 minutes

Why type docker commands by hand when you can encapsulate everything in Gradle tasks? Here’s how I industrialized my dual-Ollama Pro config with zero external shell script. Start, stop, identity, sign-in, pull — everything goes through`./gradlew`.

Introduction

In the previous article, I showed how to make two Ollama Pro accounts coexist on the same machine by isolating the second instance in a Docker container. The setup works, but everyday management quickly becomes painful: remembering the container name, running the right commands.docker exec, check which port is active…

You know that moment when you have 14 terminals open, and you’re typing`docker exec ollama-instance-b ollama list`for the fourth time, and you tell yourself 'there must be a cleaner way' ?

This is Gradle.

Not just for building code. Gradle like a conductor of local infrastructure. Tasks that provision, verify, test, and clean. All versioned in a`build.gradle.kts`who lives next to the`docker-compose.yml`.

@startuml
!theme plain

skinparam handwritten false
skinparam shadowing false
skinparam BoxPadding 8
skinparam DefaultFontSize 11
skinparam ArrowThickness 1.5

left to right direction

actor "Developer" as Dev

package "build.gradle.kts" as GradleFile {

  usecase "startOllamaB" as Start
  usecase "stopOllamaB" as Stop
  usecase "checkIdentity" as Check
  usecase "signInB" as SignIn
  usecase "pullModelB" as Pull
  usecase "testOllamaB" as Test
  usecase "statusOllamaAll" as Status
  usecase "cleanOllamaB" as Clean
}

package "Docker Daemon" as DockerDaemon {

  node "ollama-instance-b" as ContainerB {
    component ":11435" as Port
    database "~/ollama-b-data" as Volume
  }
}

package "Ollama Native" as Native {
  component ":11434" as NatPort
}

Dev --> Start
Dev --> SignIn
Dev --> Pull
Dev --> Test
Dev --> Status
Dev --> Check
Dev --> Stop
Dev --> Clean

Start ..> ContainerB : docker run -d
Stop ..> ContainerB : docker stop
Check ..> Volume : cat id_ed25519.pub
SignIn ..> ContainerB : ollama signin
Pull ..> ContainerB : ollama pull
Test ..> ContainerB : curl /v1/chat/completions
Status ..> ContainerB : docker ps
Status ..> Native : curl :11434
Clean ..> ContainerB : docker rm -f

note bottom of GradleFile
  Zéro script bash externe.
  Tout est dans le build.gradle.kts,
  versionné avec le projet.
end note

@enduml

Why Gradle for infra?

The question is legitimate. Gradle is a build tool. Normally, it compiles, it tests, it packages. It doesn’t launch Docker containers.

But Gradle is also a dependency graph engine — and that’s where it gets interesting for our case.

We want:

Let the container be started before a sign-in
That the identity be verified before a model pull
That an API test fails silently if the container is down

From the pure dependency graph. Gradle is tailored for that. The Kotlin DSL makes writing tasks fluid, and the`doLast`allows executing system commands as if it were application code.

And above all: no bashrc to maintain, no scripts lying around in`~/bin`, no Makefile next to the docker-compose. Everything lives in a single file, in the same place as the project code.

The complete build.gradle.kts

Here is the file I ended up writing. It does everything, from volume provisioning to the verification curl, going through the interactive sign-in.

import java.io.ByteArrayOutputStream

plugins {
    base
}

// -------------------------------------------------------------------------
// Configuration
// -------------------------------------------------------------------------
val instanceName   = "ollama-instance-b"
val instancePort   = 11435
val instanceImage  = "ollama/ollama:0.20.2"
val dataDir        = file("${System.getProperty("user.home")}/ollama-b-data")
val nativePort     = 11434

// Modèles à gérer — cloud Pro + un modèle local gratuit pour les tests
val proModels      = listOf("deepseek-v4-pro:cloud", "gemma4:31b-cloud")
val freeModels     = listOf("qwen3:0.6b")

// -------------------------------------------------------------------------
// Tâche préparatoire — création du volume si absent
// -------------------------------------------------------------------------
val prepareVolume by tasks.registering {
    group       = "ollama"
    description = "Crée le répertoire de volume pour l'instance B si absent"
    doLast {
        if (!dataDir.exists()) {
            dataDir.mkdirs()
            println("Volume créé : ${dataDir.absolutePath}")
        } else {
            println("Volume existant : ${dataDir.absolutePath}")
        }
    }
}

// -------------------------------------------------------------------------
// Démarrage du conteneur Docker
// -------------------------------------------------------------------------
val startOllamaB by tasks.registering(Exec::class) {
    group       = "ollama"
    description = "Lance le conteneur Docker pour l'instance Ollama B"
    dependsOn(prepareVolume)

    commandLine(
        "docker", "run", "-d",
        "--name", instanceName,
        "-p", "$instancePort:11434",
        "-v", "${dataDir.absolutePath}:/root/.ollama",
        "-e", "OLLAMA_HOST=0.0.0.0",
        "--restart", "always",
        instanceImage
    )
    isIgnoreExitValue = true

    doLast {
        val alreadyRunning = executionResult.get().exitValue != 0
        if (alreadyRunning) {
            logger.lifecycle("Le conteneur '$instanceName' existe déjà — tentative de démarrage")
        } else {
            logger.lifecycle("Conteneur '$instanceName' lancé")
        }
    }
}

// -------------------------------------------------------------------------
// Arrêt du conteneur
// -------------------------------------------------------------------------
val stopOllamaB by tasks.registering(Exec::class) {
    group       = "ollama"
    description = "Arrête le conteneur Docker de l'instance B"

    commandLine("docker", "stop", instanceName)
    isIgnoreExitValue = true

    doLast {
        logger.lifecycle("Conteneur '$instanceName' arrêté")
    }
}

// -------------------------------------------------------------------------
// Affichage de la clé publique (Device Key)
// -------------------------------------------------------------------------
val checkIdentity by tasks.registering(Exec::class) {
    group       = "ollama"
    description = "Affiche la clé publique SSH de l'instance B"
    dependsOn(startOllamaB)

    commandLine("docker", "exec", instanceName, "cat", "/root/.ollama/id_ed25519.pub")
    standardOutput = ByteArrayOutputStream()

    doLast {
        val pubKey = standardOutput.toString().trim()
        println("=".repeat(60))
        println("Device Key (Instance B)")
        println("=".repeat(60))
        println(pubKey)
        println("=".repeat(60))
        println("→ Enregistre cette clé sur https://ollama.com/settings/keys")
        println("→ Puis exécute : ./gradlew signInB")
        println("=".repeat(60))
    }
}

// -------------------------------------------------------------------------
// Sign-in interactif (Ouvrira le navigateur)
// -------------------------------------------------------------------------
val signInB by tasks.registering(Exec::class) {
    group       = "ollama"
    description = "Lance l'authentification interactive Ollama pour le compte B"
    dependsOn(startOllamaB)

    standardInput  = System.`in`
    standardOutput = System.out
    errorOutput    = System.err

    commandLine("docker", "exec", "-it", instanceName, "ollama", "signin")

    doFirst {
        logger.lifecycle("Authentification pour le Compte Pro B...")
        logger.lifecycle("Ouvre ton navigateur et connecte-toi avec l'email du compte B")
    }
}

// -------------------------------------------------------------------------
// Pull d'un modèle (paramétrable via propriété Gradle)
// -------------------------------------------------------------------------
val pullModelB by tasks.registering(Exec::class) {
    group       = "ollama"
    description = "Pull un modèle sur l'instance B. Usage : ./gradlew pullModelB -Pmodel=nom:tag"
    dependsOn(startOllamaB)

    val modelName = project.findProperty("model") as? String ?: "qwen3:0.6b"

    commandLine("docker", "exec", instanceName, "ollama", "pull", modelName)

    doFirst {
        logger.lifecycle("Pull du modèle '$modelName' sur l'instance B...")
    }

    doLast {
        logger.lifecycle("Modèle '$modelName' pullé avec succès")
    }
}

// -------------------------------------------------------------------------
// Pull de tous les modèles Pro (batch)
// -------------------------------------------------------------------------
val pullAllProModels by tasks.registering {
    group       = "ollama"
    description = "Pull tous les modèles cloud Pro sur l'instance B"
    dependsOn(startOllamaB)

    doLast {
        proModels.forEach { model ->
            logger.lifecycle("→ Pull $model...")
            val process = ProcessBuilder("docker", "exec", instanceName, "ollama", "pull", model)
                .inheritIO()
                .start()
            process.waitFor()
        }
        logger.lifecycle("Tous les modèles Pro pullés")
    }
}

// -------------------------------------------------------------------------
// Pull de tous les modèles gratuits (batch / première install)
// -------------------------------------------------------------------------
val pullAllFreeModels by tasks.registering {
    group       = "ollama"
    description = "Pull tous les modèles locaux gratuits sur l'instance B"
    dependsOn(startOllamaB)

    doLast {
        freeModels.forEach { model ->
            logger.lifecycle("→ Pull $model...")
            val process = ProcessBuilder("docker", "exec", instanceName, "ollama", "pull", model)
                .inheritIO()
                .start()
            process.waitFor()
        }
        logger.lifecycle("Tous les modèles gratuits pullés")
    }
}

// -------------------------------------------------------------------------
// Liste des modèles disponibles sur l'instance B
// -------------------------------------------------------------------------
val listModelsB by tasks.registering(Exec::class) {
    group       = "ollama"
    description = "Liste les modèles disponibles sur l'instance B"
    dependsOn(startOllamaB)

    commandLine("docker", "exec", instanceName, "ollama", "list")
}

// -------------------------------------------------------------------------
// Health check — test API sur les deux instances
// -------------------------------------------------------------------------
val testOllamaB by tasks.registering {
    group       = "ollama"
    description = "Teste la connectivité API de l'instance B avec un simple chat"
    dependsOn(startOllamaB)

    doLast {
        val model = project.findProperty("model") as? String ?: "qwen3:0.6b"
        logger.lifecycle("Test de l'instance B avec le modèle '$model'...")

        val payload = """
            {
              "model": "$model",
              "messages": [{"role": "user", "content": "Réponds uniquement par OK"}],
              "max_tokens": 5
            }
        """.trimIndent()

        val process = ProcessBuilder(
            "curl", "-s", "http://localhost:$instancePort/v1/chat/completions",
            "-H", "Content-Type: application/json",
            "-d", payload
        ).start()

        val response = process.inputStream.bufferedReader().readText()
        process.waitFor()

        if (response.contains("\"id\":\"chatcmpl") || response.contains("\"choices\"")) {
            println("✓ Instance B OK — port $instancePort répond")
            println("  Response: ${response.take(120)}...")
        } else {
            println("✗ Instance B INACTIVE — vérifie le conteneur avec './gradlew statusOllamaAll'")
            println("  Raw: $response")
        }
    }
}

// -------------------------------------------------------------------------
// Health check sur les deux instances simultanément
// -------------------------------------------------------------------------
val statusOllamaAll by tasks.registering {
    group       = "ollama"
    description = "Vérifie le statut des deux instances Ollama (native + Docker)"

    doLast {
        // Instance native
        runCatching {
            val process = ProcessBuilder(
                "curl", "-s", "-o", "/dev/null", "-w", "%{http_code}",
                "http://localhost:$nativePort/api/tags"
            ).start()
            val code = process.inputStream.bufferedReader().readText().trim()
            process.waitFor()
            println(if (code == "200") "✓ Instance Native   — port $nativePort OK (HTTP $code)"
                    else "✗ Instance Native — port $nativePort (HTTP $code)")
        }.getOrElse {
            println("✗ Instance Native — injoignable sur le port $nativePort")
        }

        // Instance Docker
        runCatching {
            val process = ProcessBuilder(
                "curl", "-s", "-o", "/dev/null", "-w", "%{http_code}",
                "http://localhost:$instancePort/api/tags"
            ).start()
            val code = process.inputStream.bufferedReader().readText().trim()
            process.waitFor()
            println(if (code == "200") "✓ Instance Docker B — port $instancePort OK (HTTP $code)"
                    else "✗ Instance Docker B — port $instancePort (HTTP $code)")
        }.getOrElse {
            println("✗ Instance Docker B — injoignable sur le port $instancePort")
        }

        // Info conteneur
        runCatching {
            val process = ProcessBuilder("docker", "ps", "--filter", "name=$instanceName",
                "--format", "table {{.Names}}\\t{{.Status}}\\t{{.Ports}}").start()
            val status = process.inputStream.bufferedReader().readText()
            process.waitFor()
            println()
            println("Conteneur Docker :")
            println(status)
        }
    }
}

// -------------------------------------------------------------------------
// Nettoyage complet
// -------------------------------------------------------------------------
val cleanOllamaB by tasks.registering(Exec::class) {
    group       = "ollama"
    description = "Arrête et supprime le conteneur Docker de l'instance B"
    dependsOn(stopOllamaB)

    commandLine("docker", "rm", instanceName)
    isIgnoreExitValue = true

    doLast {
        logger.lifecycle("Conteneur '$instanceName' supprimé")
        logger.lifecycle("Le volume ${dataDir.absolutePath} est conservé (identité persistante)")
    }
}

// -------------------------------------------------------------------------
// Affichage des instructions
// -------------------------------------------------------------------------
val helpOllama by tasks.registering {
    group       = "ollama"
    description = "Affiche l'aide des tâches Ollama disponibles"

    doLast {
        println("""
        ╔══════════════════════════════════════════════════════════════╗
        ║         Tâches Gradle — Pilotage Dual Ollama Pro            ║
        ╠══════════════════════════════════════════════════════════════╣
        ║  ./gradlew startOllamaB      Démarrer l'instance Docker B   ║
        ║  ./gradlew stopOllamaB       Arrêter l'instance Docker B    ║
        ║  ./gradlew checkIdentity     Afficher la clé SSH publique   ║
        ║  ./gradlew signInB           Sign-in interactif compte B    ║
        ║  ./gradlew pullModelB        Pull un modèle (-Pmodel=...)   ║
        ║  ./gradlew pullAllProModels  Pull tous les modèles Pro      ║
        ║  ./gradlew pullAllFreeModels Pull tous les modèles gratuits ║
        ║  ./gradlew listModelsB       Lister les modèles instance B  ║
        ║  ./gradlew testOllamaB       Test API avec un chat simple   ║
        ║  ./gradlew statusOllamaAll   Santé des 2 instances          ║
        ║  ./gradlew cleanOllamaB      Supprimer le conteneur         ║
        ║  ./gradlew helpOllama        Cette aide                     ║
        ╚══════════════════════════════════════════════════════════════╝
        """.trimIndent())
    }
}

Here it is. Twelve tasks, a single entry point, and zero friction.

Anatomy of Key Tasks

startOllamaB` — The Launcher

Nothing complicated: a`docker run -d`with the right parameters. The trick is in`isIgnoreExitValue = true`.

isIgnoreExitValue = true

If the container already exists, the command`docker run`fails (exit code ≠ 0). Without this property, Gradle would stop the entire build with an error. Here, the failure is silent — and the`doLast`detects if it was an "already existing" or a real error.

Le `doLast`It is crucial: it runs after executing the command, which allows inspection.`executionResult.get().exitValue`and log an appropriate message.

signInB` — The Interactive

This is the only task that requires human interaction. Gradle transmits`System.in`to the process so that the prompt`ollama signin`can be displayed normally :

standardInput  = System.`in`
standardOutput = System.out
errorOutput    = System.err

Without that, the sign-in would block because stdin would be closed and you would never see the prompt.

pullModelB` — The Configurable

A generic task that accepts a parameter via`-P`:

./gradlew pullModelB -Pmodel=deepseek-v4-pro:cloud
./gradlew pullModelB                           # fallback : qwen3:0.6b

Fallback is important:`project.findProperty("model") as? String ?: "qwen3:0.6b"`ensures that the task doesn’t blow up if we forget the parameter

statusOllamaAll` — The diagnostic

Two`curl`health on the ports`11434` et 11435, with a fallback in`runCatching`To avoid crashing if one of the instances is down. The output is structured:

✓ Instance Native   — port 11434 OK (HTTP 200)
✓ Instance Docker B — port 11435 OK (HTTP 200)

Conteneur Docker :
NAMES               STATUS         PORTS
ollama-instance-b   Up 3 hours     0.0.0.0:11435->11434/tcp

A glance, and you know exactly what’s working and what’s wrong.

cleanOllamaB` — The Cleaning that Preserves Identity

commandLine("docker", "rm", instanceName)
isIgnoreExitValue = true

The container is removed, but the volume`~/ollama-b-data`ispreserved. The SSH identity survives cleanup. At the next`startOllamaB`, the same keys will be reused — no need to redo the sign-in nor to re-register the Device Key.

cleanOllamaB`do not touch the volume. If you want to delete identity B (and start over from scratch), you need to delete~/ollama-b-data`manually. It’s voluntary — a`clean`should not destroy credentials

Complete Workflow — From Zero to Two Sessions

Here is the ideal sequence for someone who joins the project and wants to set everything up without opening any documentation:

# 1. Premier contact — que faire ?
$ ./gradlew helpOllama

# 2. On démarre l'instance B
$ ./gradlew startOllamaB

# 3. On récupère la Device Key et on l'enregistre sur ollama.com
$ ./gradlew checkIdentity
# → copier-coller de la clé sur https://ollama.com/settings/keys

# 4. Authentification interactive
$ ./gradlew signInB

# 5. Pull d'un petit modèle gratuit pour tester la plomberie
$ ./gradlew pullModelB

# 6. Test API
$ ./gradlew testOllamaB

# 7. Si tout est vert, pull des modèles Pro
$ ./gradlew pullAllProModels

# 8. Vérification finale des deux instances
$ ./gradlew statusOllamaAll

Less than two minutes, everything is provisioned. No README to read, no environment variables to set. The task`helpOllama`serves as integrated documentation.

@startuml
!theme plain
skinparam DefaultFontSize 11

actor Développeur as Dev
participant "Gradle\n(build.gradle.kts)" as Gradle
participant "Docker\nDaemon" as Docker
participant "Ollama\nInstance B" as OllamaB
participant "Ollama\nCloud" as Cloud

== Provisionnement ==
Dev -> Gradle : helpOllama
Gradle --> Dev : Aide et instructions

Dev -> Gradle : startOllamaB
Gradle -> Docker : docker run -d ollama/ollama:0.20.2
Docker -> OllamaB : Génération clés SSH (id_ed25519)
Docker --> Gradle : conteneur lancé
Gradle --> Dev : OK

Dev -> Gradle : checkIdentity
Gradle -> Docker : cat id_ed25519.pub
Gradle --> Dev : Clé publique SSH

Dev -> Cloud : Enregistrement clé SSH\n(sur ollama.com/settings/keys)

== Authentification ==
Dev -> Gradle : signInB
Gradle -> Docker : ollama signin (interactif)
Dev <-> Cloud : Login navigateur (compte B)
Docker -> Cloud : Échange token ⇔ Device Key
Gradle --> Dev : Authentifié

== Vérification ==
Dev -> Gradle : pullModelB
Gradle -> Docker : ollama pull qwen3:0.6b
Gradle --> Dev : Modèle pullé

Dev -> Gradle : testOllamaB
Gradle -> Docker : curl /v1/chat/completions
Gradle --> Dev : ✓ Instance B OK

== Production ==
Dev -> Gradle : pullAllProModels
Gradle -> Docker : ollama pull deepseek-v4-pro:cloud
Gradle -> Docker : ollama pull gemma4:31b-cloud
Gradle --> Dev : Modèles Pro pullés

Dev -> Gradle : statusOllamaAll
Gradle --> Dev : ✓ Native ✓ Docker B
@enduml

Why not make it a real Gradle plugin?

Legitimate question. Extract this`build.gradle.kts`Having a standalone Gradle plugin would have advantages: reuse between projects, declarative configuration, DSL extension.

But for now, it doesn’t make sense. This build has no complex business logic — it’s just a wrapper around Docker and curl commands. Adding a full Gradle plugin layer (with extension, unit tests, publication) would be overkill for 12 utility tasks.

Le `build.gradle.kts`It lives in the project that needs it. It is trivial to copy elsewhere. If one day I have three projects that depend on it, I will turn it into a plugin. For now, KISS.

The day you have three`build.gradle.kts`Identical in three projects, it’s the signal that we need to extract a plugin. Before that, duplication is less costly than abstraction. Developer wisdom.

Lessons Learned

Gradle is not just a build tool— The dependency graph engine makes it a formidable infrastructure orchestrator.doLast, isIgnoreExitValue, dependsOn: these three primitives are enough to drive a Docker container with the same reliability as a CI pipeline.
isIgnoreExitValue` is your friend— In an ideal world,docker run`on an already existing container would return a warning instead of an error exit code. In the real world, you put`isIgnoreExitValue = true`and you manage the diagnostic in`doLast.
Configurable tasks kill ambiguity — Un pullModelB`generic with-Pmodel=…`replaces N specialized tasks. A single task, a single doc, a single behavior.
runCatching` for the health checks— When you test N endpoints, the crash of the first should not prevent testing the others.runCatching+`getOrElse`per endpoint, and the diagnosis remains complete even in case of partial failure.
The task helpOllama as executable documentation — Un `println()`A well‑formatted one replaces a three‑paragraph README. It’s self‑documenting, always up to date, and accessible without leaving the terminal.

Conclusion

We went from typing Docker commands manually to a complete, versioned, reusable Gradle workflow. Twelve tasks cover the entire lifecycle: provisioning, identity, sign‑in, pull, testing, diagnostics, cleanup.

The docker-compose + build.gradle.kts + opencode.json combo forms a clean trinity: Docker for isolation, Gradle for orchestration, OpenCode for consumption. Each layer has its responsibility, and none overstep onto another.

Next step? Automate the lifecycle in CI so that Ollama instances are available in ephemeral dev environments. But that’s another article.

Resources

Article published on 2026-05-08

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