Set up PostgreSQL in the AppHost

This article is the reference for the Aspire PostgreSQL Hosting integration. It enumerates the AppHost APIs — with examples for both AppHost.cs and apphost.mts — that you use to model PostgreSQL server and database resources in your AppHost project.

If you’re new to the PostgreSQL integration, start with the Get started with PostgreSQL integrations guide. For how consuming apps read the connection information this page exposes, see Connect to PostgreSQL. For the PostgreSQL Entity Framework Core (EF Core) client integration, see Get started with the PostgreSQL Entity Framework Core integrations.

Installation

To start building an Aspire app that uses PostgreSQL, install the 📦 Aspire.Hosting.PostgreSQL NuGet package:

TypeScript

Terminal

aspire add postgres

Learn more about aspire add in the command reference.

This updates your aspire.config.json with the PostgreSQL hosting integration package:

aspire.config.json

{
  "packages": {
    "Aspire.Hosting.PostgreSQL": "13.5.3"
  }
}

C#

Terminal

aspire add postgres

Learn more about aspire add in the command reference.

Or, choose a manual installation approach:

AppHost.cs

#:package Aspire.Hosting.PostgreSQL@*

AppHost.csproj

<PackageReference Include="Aspire.Hosting.PostgreSQL" Version="*" />

Add PostgreSQL server resource

Once you’ve installed the hosting integration in your AppHost project, you can add a PostgreSQL server resource and then add a database resource as shown in the following examples:

TypeScript

apphost.mts

import { createBuilder } from './.aspire/modules/aspire.mjs';

const builder = await createBuilder();

const postgres = await builder.addPostgres("postgres");
const postgresdb = await postgres.addDatabase("postgresdb");

await builder.addNodeApp("api", "./api", "index.js")
    .withReference(postgresdb);

// After adding all resources, run the app...

C#

AppHost.cs

var builder = DistributedApplication.CreateBuilder(args);

var postgres = builder.AddPostgres("postgres");
var postgresdb = postgres.AddDatabase("postgresdb");

var exampleProject = builder.AddProject<Projects.ExampleProject>("apiservice")
    .WithReference(postgresdb);

// After adding all resources, run the app...

1. When Aspire adds a container image to the app host, as shown in the preceding example with the docker.io/library/postgres image, it creates a new PostgreSQL server instance on your local machine. A reference to the postgresdb database resource is then used to add a dependency to the consuming project.

2. When adding a database resource to the app model, the database is created if it doesn’t already exist. The creation of the database relies on the AppHost eventing APIs, specifically ResourceReadyEvent. In other words, when the postgres resource is ready, the event is raised and the database resource is created.

3. The PostgreSQL server resource includes default credentials with a username of "postgres" and a randomly generated password using the CreateDefaultPasswordParameter method.

4. The AppHost reference call configures a connection in the consuming project named after the referenced database resource, such as postgresdb in the preceding example.

Note

When you reference a PostgreSQL resource from the AppHost, Aspire makes several properties available to the consuming project, such as connection URIs, hostnames, and port numbers. For a complete list of these properties and per-language connection examples, see Connect to PostgreSQL.

• PostgreSQL container imageDocker Hub

  docker.io/library/postgres:18.3

  Added by AddPostgres()addPostgres().

  Source

Tags reflect the latest defaults on the microsoft/aspire main branch, and may be newer than the version pinned by the package you install.

Add PostgreSQL resource with database scripts

By default, when you add a PostgresDatabaseResource, it relies on the following script to create the database:

Default database creation script

CREATE DATABASE "<QUOTED_DATABASE_NAME>"

To alter the default script, configure the database resource with a custom creation script:

TypeScript

apphost.mts

import { createBuilder } from './.aspire/modules/aspire.mjs';

const builder = await createBuilder();

const postgres = await builder.addPostgres("postgres");

const databaseName = "app_db";
const creationScript = `
-- Create the database
CREATE DATABASE ${databaseName};
`;

const db = await postgres.addDatabase(databaseName);
await db.withCreationScript(creationScript);

await builder.addNodeApp("api", "./api", "index.js")
    .withReference(db)
    .waitFor(db);

// After adding all resources, run the app...

C#

AppHost.cs

var builder = DistributedApplication.CreateBuilder(args);

var postgres = builder.AddPostgres("postgres");

var databaseName = "app_db";
var creationScript = $$"""
    -- Create the database
    CREATE DATABASE {{databaseName}};

    """;

var db = postgres.AddDatabase(databaseName)
    .WithCreationScript(creationScript);

builder.AddProject<Projects.ExampleProject>()
    .WithReference(db)
    .WaitFor(db);

// After adding all resources, run the app...

The preceding example creates a database named app_db. The script is run when the database resource is created. The script is passed as a string to the database resource’s creation-script API and then run in the context of the PostgreSQL resource.

Note

The connect to a database command (\c) isn’t supported when using the creation script.

Add PostgreSQL pgAdmin resource

Add the dpage/pgadmin4 container to the PostgreSQL resource to get a web-based admin dashboard, as shown in the following examples:

TypeScript

apphost.mts

import { createBuilder } from './.aspire/modules/aspire.mjs';

const builder = await createBuilder();

const postgres = await builder.addPostgres("postgres");
await postgres.withPgAdmin();

const postgresdb = await postgres.addDatabase("postgresdb");

await builder.addNodeApp("api", "./api", "index.js")
    .withReference(postgresdb);

// After adding all resources, run the app...

C#

AppHost.cs

var builder = DistributedApplication.CreateBuilder(args);

var postgres = builder.AddPostgres("postgres")
    .WithPgAdmin();

var postgresdb = postgres.AddDatabase("postgresdb");

var exampleProject = builder.AddProject<Projects.ExampleProject>()
    .WithReference(postgresdb);

// After adding all resources, run the app...

The preceding code adds a container based on the docker.io/dpage/pgadmin4 image. The container is used to manage the PostgreSQL server and database resources and serves a web-based admin dashboard for PostgreSQL databases.

• pgAdmin container imageCompanion · PostgreSQLDocker Hub

  docker.io/dpage/pgadmin4:9.15.0

  Added by WithPgAdmin()withPgAdmin().

  Source

Tags reflect the latest defaults on the microsoft/aspire main branch, and may be newer than the version pinned by the package you install.

Configure the pgAdmin host port

To configure the host port for the pgAdmin container, configure the pgAdmin resource inside the callback as shown in the following examples:

TypeScript

apphost.mts

import { createBuilder } from './.aspire/modules/aspire.mjs';

const builder = await createBuilder();

const postgres = await builder.addPostgres("postgres");
await postgres.withPgAdmin({
    configureContainer: async pgAdmin => {
        await pgAdmin.withHostPort(5050);
    }
});

const postgresdb = await postgres.addDatabase("postgresdb");

await builder.addNodeApp("api", "./api", "index.js")
    .withReference(postgresdb);

// After adding all resources, run the app...

C#

AppHost.cs

var builder = DistributedApplication.CreateBuilder(args);

var postgres = builder.AddPostgres("postgres")
    .WithPgAdmin(pgAdmin => pgAdmin.WithHostPort(5050));

var postgresdb = postgres.AddDatabase("postgresdb");

var exampleProject = builder.AddProject<Projects.ExampleProject>()
    .WithReference(postgresdb);

// After adding all resources, run the app...

The preceding code adds and configures the host port for the pgAdmin container. The host port is otherwise randomly assigned.

Add PostgreSQL pgWeb resource

Add the sosedoff/pgweb container to the PostgreSQL resource to get a web-based admin dashboard, as shown in the following examples:

TypeScript

apphost.mts

import { createBuilder } from './.aspire/modules/aspire.mjs';

const builder = await createBuilder();

const postgres = await builder.addPostgres("postgres");
await postgres.withPgWeb();

const postgresdb = await postgres.addDatabase("postgresdb");

await builder.addNodeApp("api", "./api", "index.js")
    .withReference(postgresdb);

// After adding all resources, run the app...

C#

AppHost.cs

var builder = DistributedApplication.CreateBuilder(args);

var postgres = builder.AddPostgres("postgres")
    .WithPgWeb();

var postgresdb = postgres.AddDatabase("postgresdb");

var exampleProject = builder.AddProject<Projects.ExampleProject>()
    .WithReference(postgresdb);

// After adding all resources, run the app...

The preceding code adds a container based on the docker.io/sosedoff/pgweb image. All registered PostgresDatabaseResource instances are used to create a configuration file per instance, and each config is bound to the pgweb container bookmark directory. For more information, see PgWeb docs: Server connection bookmarks.

• pgweb container imageCompanion · PostgreSQLDocker Hub

  docker.io/sosedoff/pgweb:0.17.0

  Added by WithPgWeb()withPgWeb().

  Source

Tags reflect the latest defaults on the microsoft/aspire main branch, and may be newer than the version pinned by the package you install.

Configure the pgWeb host port

To configure the host port for the pgWeb container, configure the pgWeb resource inside the callback as shown in the following examples:

TypeScript

apphost.mts

import { createBuilder } from './.aspire/modules/aspire.mjs';

const builder = await createBuilder();

const postgres = await builder.addPostgres("postgres");
await postgres.withPgWeb({
    configureContainer: async pgWeb => {
        await pgWeb.withHostPort(5050);
    }
});

const postgresdb = await postgres.addDatabase("postgresdb");

await builder.addNodeApp("api", "./api", "index.js")
    .withReference(postgresdb);

// After adding all resources, run the app...

C#

AppHost.cs

var builder = DistributedApplication.CreateBuilder(args);

var postgres = builder.AddPostgres("postgres")
    .WithPgWeb(pgWeb => pgWeb.WithHostPort(5050));

var postgresdb = postgres.AddDatabase("postgresdb");

var exampleProject = builder.AddProject<Projects.ExampleProject>()
    .WithReference(postgresdb);

// After adding all resources, run the app...

The preceding code adds and configures the host port for the pgWeb container. The host port is otherwise randomly assigned.

Add PostgreSQL server resource with data volume

Add a data volume to the PostgreSQL server resource as shown in the following examples:

TypeScript

apphost.mts

import { createBuilder } from './.aspire/modules/aspire.mjs';

const builder = await createBuilder();

const postgres = await builder.addPostgres("postgres");
await postgres.withDataVolume({ isReadOnly: false });

const postgresdb = await postgres.addDatabase("postgresdb");

await builder.addNodeApp("api", "./api", "index.js")
    .withReference(postgresdb);

// After adding all resources, run the app...

C#

AppHost.cs

var builder = DistributedApplication.CreateBuilder(args);

var postgres = builder.AddPostgres("postgres")
    .WithDataVolume(isReadOnly: false);

var postgresdb = postgres.AddDatabase("postgresdb");

var exampleProject = builder.AddProject<Projects.ExampleProject>()
    .WithReference(postgresdb);

// After adding all resources, run the app...

The data volume is used to persist the PostgreSQL server data outside the lifecycle of its container. The container data directory depends on the PostgreSQL image version: PostgreSQL 17 and earlier use /var/lib/postgresql/data, while PostgreSQL 18 and later use /var/lib/postgresql. WithDataVolume(...) selects the correct path automatically based on the configured image tag. When a name parameter isn’t provided, the name is generated at random. For more information on data volumes and details on why they’re preferred over bind mounts, see Docker docs: Volumes.

Caution

Aspire 13.4 bumped the default PostgreSQL image to 18, which uses a different on-disk data layout than PostgreSQL 17. A data volume or data bind mount created on PostgreSQL 17 (Aspire 13.3 or earlier) is incompatible after upgrading. See PostgreSQL 18 data directory change for recovery options.

Caution

Some database integrations, including the Aspire PostgreSQL integration, can’t successfully use data volumes after deployment to Azure Container Apps (ACA). This is because ACA uses Server Message Block (SMB) to connect containers to data volumes, and some systems can’t use this connection. In the Aspire Dashboard, a database affected by this issue has a status of Activating or Activation Failed but is never listed as Running.

You can resolve the problem by using the managed service Azure Database for PostgreSQL to host the deployed database instead of a container in ACA, which is the recommended approach regardless of this issue. For that managed-service flow, see Azure Database for PostgreSQL Hosting integration.

Add PostgreSQL server resource with data bind mount

Add a data bind mount to the PostgreSQL server resource as shown in the following examples:

TypeScript

apphost.mts

import { createBuilder } from './.aspire/modules/aspire.mjs';

const builder = await createBuilder();

const postgres = await builder.addPostgres("postgres");
await postgres.withDataBindMount("/PostgreSQL/Data", { isReadOnly: false });

const postgresdb = await postgres.addDatabase("postgresdb");

await builder.addNodeApp("api", "./api", "index.js")
    .withReference(postgresdb);

// After adding all resources, run the app...

C#

AppHost.cs

var builder = DistributedApplication.CreateBuilder(args);

var postgres = builder.AddPostgres("postgres")
    .WithDataBindMount(
        source: "/PostgreSQL/Data",
        isReadOnly: false);

var postgresdb = postgres.AddDatabase("postgresdb");

var exampleProject = builder.AddProject<Projects.ExampleProject>()
    .WithReference(postgresdb);

// After adding all resources, run the app...

Note

Data bind mounts have limited functionality compared to volumes, which offer better performance, portability, and security, making them more suitable for production environments. However, bind mounts allow direct access and modification of files on the host system, ideal for development and testing where real-time changes are needed.

Data bind mounts rely on the host machine’s filesystem to persist the PostgreSQL server data across container restarts. The data bind mount is mounted at the C:\PostgreSQL\Data on Windows (or /PostgreSQL/Data on Unix) path on the host machine in the PostgreSQL server container. For more information on data bind mounts, see Docker docs: Bind mounts.

Add PostgreSQL server resource with init bind mount

Use initialization files to seed the PostgreSQL server. The C# AppHost exposes WithInitBindMount(...), while the TypeScript AppHost exposes withInitFiles(...).

TypeScript

apphost.mts

import { createBuilder } from './.aspire/modules/aspire.mjs';

const builder = await createBuilder();

const postgres = await builder.addPostgres("postgres");
await postgres.withInitFiles("./postgres-init");

const postgresdb = await postgres.addDatabase("postgresdb");

await builder.addNodeApp("api", "./api", "index.js")
    .withReference(postgresdb);

// After adding all resources, run the app...

The TypeScript AppHost doesn’t currently expose a withInitBindMount(...) API for PostgreSQL. Use withInitFiles(...) when you want to copy initialization files into the container instead.

C#

AppHost.cs

var builder = DistributedApplication.CreateBuilder(args);

var postgres = builder.AddPostgres("postgres")
    .WithInitBindMount(@"C:\PostgreSQL\Init");

var postgresdb = postgres.AddDatabase("postgresdb");

var exampleProject = builder.AddProject<Projects.ExampleProject>()
    .WithReference(postgresdb);

// After adding all resources, run the app...

The init bind mount relies on the host machine’s filesystem to initialize the PostgreSQL server database with the container’s init folder. This folder is used for initialization, running any executable shell scripts or .sql command files after the postgres-data folder is created. The init bind mount is mounted at the C:\PostgreSQL\Init on Windows (or /PostgreSQL/Init on Unix) path on the host machine in the PostgreSQL server container.

Add PostgreSQL server resource with parameters

When you want to explicitly provide the username and password used by the container image, you can provide these credentials as parameters. Consider the following alternative examples:

TypeScript

apphost.mts

import { createBuilder } from './.aspire/modules/aspire.mjs';

const builder = await createBuilder();

const userName = await builder.addParameter("username", { secret: true });
const password = await builder.addParameter("password", { secret: true });

const postgres = await builder.addPostgres("postgres", { userName, password });
const postgresdb = await postgres.addDatabase("postgresdb");

await builder.addNodeApp("api", "./api", "index.js")
    .withReference(postgresdb);

// After adding all resources, run the app...

C#

AppHost.cs

var builder = DistributedApplication.CreateBuilder(args);

var username = builder.AddParameter("username", secret: true);
var password = builder.AddParameter("password", secret: true);

var postgres = builder.AddPostgres("postgres", username, password);
var postgresdb = postgres.AddDatabase("postgresdb");

var exampleProject = builder.AddProject<Projects.ExampleProject>()
    .WithReference(postgresdb);

// After adding all resources, run the app...

Pass custom environment variables

By default, Aspire injects the PostgreSQL connection information using variable names derived from the resource name (for example, POSTGRESDB_URI, POSTGRESDB_HOST, POSTGRESDB_PORT). If your consuming app expects a different set of environment variable names, pass individual connection properties from the AppHost:

TypeScript

apphost.mts

import { createBuilder, EndpointProperty } from './.aspire/modules/aspire.mjs';

const builder = await createBuilder();

const postgres = await builder.addPostgres("postgres");
const database = await postgres.addDatabase("myDatabase");
const postgresEndpoint = await postgres.getEndpoint("tcp");
const postgresHost = await postgresEndpoint.property(EndpointProperty.Host);
const postgresPort = await postgresEndpoint.property(EndpointProperty.Port);

await builder.addNodeApp("my-app", "./app", "index.js")
    .withReference(database)
    .withEnvironment("POSTGRES_HOST", postgresHost)
    .withEnvironment("POSTGRES_PORT", postgresPort)
    .withEnvironment("POSTGRES_USER", postgres.userNameParameter)
    .withEnvironment("POSTGRES_PASSWORD", postgres.passwordParameter)
    .withEnvironment("POSTGRES_DATABASE", "myDatabase");

await builder.build().run();

C#

AppHost.cs

var builder = DistributedApplication.CreateBuilder(args);

var postgres = builder.AddPostgres("postgres");
var database = postgres.AddDatabase("myDatabase");

var app = builder.AddExecutable("my-app", "node", "app.js", ".")
    .WithReference(database)
    .WithEnvironment(context =>
    {
        context.EnvironmentVariables["POSTGRES_HOST"] = postgres.Resource.PrimaryEndpoint.Property(EndpointProperty.Host);
        context.EnvironmentVariables["POSTGRES_PORT"] = postgres.Resource.PrimaryEndpoint.Property(EndpointProperty.Port);
        context.EnvironmentVariables["POSTGRES_USER"] = postgres.Resource.UserNameParameter;
        context.EnvironmentVariables["POSTGRES_PASSWORD"] = postgres.Resource.PasswordParameter;
        context.EnvironmentVariables["POSTGRES_DATABASE"] = database.Resource.DatabaseName;
    });

builder.Build().Run();

PostgreSQL 18 data directory change

Starting with Aspire 13.4, the default PostgreSQL container image used by AddPostgres is 18.3 (previously 17.6). PostgreSQL 18 changed the on-disk data layout: the official postgres image now stores cluster files under a major-version-specific subdirectory of /var/lib/postgresql (for example, /var/lib/postgresql/18/docker), whereas PostgreSQL 17 and earlier stored data directly in /var/lib/postgresql/data. For upstream details, see docker-library/postgres#1259 and docker-library/postgres#37.

WithDataVolume(...) and WithDataBindMount(...) are version-aware: Aspire chooses the container data directory from the configured image tag at the time the method is called. PostgreSQL 17 and earlier map to /var/lib/postgresql/data; PostgreSQL 18 and later map to /var/lib/postgresql.

Because of this layout change, PostgreSQL 17 data persisted with WithDataVolume(...) or WithDataBindMount(...) (Aspire 13.3 or earlier) is incompatible with PostgreSQL 18 after upgrading to Aspire 13.4. The container fails to start with an error similar to:

Error: in 18+, these Docker images are configured to store database data in a format which is compatible with "pg_ctlcluster" ... Counter to that, there appears to be PostgreSQL data in: /var/lib/postgresql

You have two ways to recover.

Option 1: Stay on PostgreSQL 17 (recommended, no migration)

Pin the image back to a PostgreSQL 17 tag with WithImageTag(...) before calling WithDataVolume(...). Aspire then selects the legacy /var/lib/postgresql/data path and your existing volume keeps working with no migration:

TypeScript

apphost.mts

import { createBuilder } from './.aspire/modules/aspire.mjs';

const builder = await createBuilder();

const postgres = await builder.addPostgres("pgsql");
await postgres.withImageTag("17.6");
await postgres.withDataVolume();

// After adding all resources, run the app...

C#

AppHost.cs

var builder = DistributedApplication.CreateBuilder(args);

var postgres = builder.AddPostgres("pgsql")
    .WithImageTag("17.6")
    .WithDataVolume();

// After adding all resources, run the app...

Caution

Call WithImageTag(...) before WithDataVolume(...). The data directory is chosen from the configured tag at the time WithDataVolume(...) runs, so the tag must be set first.

Option 2: Upgrade the data volume to PostgreSQL 18

Follow the official PostgreSQL upgrade documentation using pg_dumpall/restore or pg_upgrade. Always back up the volume before migrating.

If the data is disposable, you can start fresh. Stop the app, remove any container still referencing the old volume (docker volume rm fails while the volume is in use), then remove the volume so Aspire creates a new PostgreSQL 18 volume on the next run:

docker volume ls
docker ps -a --filter volume=<old-volume-name>
docker rm -f <container-id>
docker volume rm <old-volume-name>

Connection properties

For the full reference of PostgreSQL connection properties — and how consuming apps in C#, TypeScript, Python, and Go read them — see Connect to PostgreSQL.

Hosting integration health checks

The PostgreSQL hosting integration automatically adds a health check for the PostgreSQL server resource. The health check verifies that the PostgreSQL server is running and that a connection can be established to it.

The hosting integration relies on the 📦 AspNetCore.HealthChecks.Npgsql NuGet package.