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Postgres

Since v0.20.0

Introduction

The Testcontainers module for Postgres.

Adding this module to your project dependencies

Please run the following command to add the Postgres module to your Go dependencies:

go get github.com/testcontainers/testcontainers-go/modules/postgres

Usage example

ctx := context.Background()

dbName := "users"
dbUser := "user"
dbPassword := "password"

postgresContainer, err := postgres.Run(ctx,
    "postgres:16-alpine",
    postgres.WithInitScripts(filepath.Join("testdata", "init-user-db.sh")),
    postgres.WithConfigFile(filepath.Join("testdata", "my-postgres.conf")),
    postgres.WithDatabase(dbName),
    postgres.WithUsername(dbUser),
    postgres.WithPassword(dbPassword),
    postgres.BasicWaitStrategies(),
)
defer func() {
    if err := testcontainers.TerminateContainer(postgresContainer); err != nil {
        log.Printf("failed to terminate container: %s", err)
    }
}()
if err != nil {
    log.Printf("failed to start container: %s", err)
    return
}

Module Reference

Run function

Info

The RunContainer(ctx, opts...) function is deprecated and will be removed in the next major release of Testcontainers for Go.

The Postgres module exposes one entrypoint function to create the Postgres container, and this function receives three parameters:

func Run(ctx context.Context, img string, opts ...testcontainers.ContainerCustomizer) (*PostgresContainer, error)
  • context.Context, the Go context.
  • string, the Docker image to use.
  • testcontainers.ContainerCustomizer, a variadic argument for passing options.

Image

Use the second argument in the Run function to set a valid Docker image. In example: Run(context.Background(), "postgres:16-alpine").

Container Options

When starting the Postgres container, you can pass options in a variadic way to configure it.

Tip

You can find all the available configuration and environment variables for the Postgres Docker image on Docker Hub.

Initial Database

If you need to set a different database, and its credentials, you can use the WithDatabase(db string), WithUsername(user string) and WithPassword(pwd string) options.

WithInitScripts

If you would like to do additional initialization in the Postgres container, add one or more *.sql, *.sql.gz, or *.sh scripts to the container request with the WithInitScripts function. Those files will be copied after the container is created but before it's started under /docker-entrypoint-initdb.d. According to Postgres Docker image, it will run any *.sql files, run any executable *.sh scripts, and source any non-executable *.sh scripts found in that directory to do further initialization before starting the service.

An example of a *.sh script that creates a user and database is shown below:

#!/bin/bash
set -e

psql -v ON_ERROR_STOP=1 --username "$POSTGRES_USER" --dbname "$POSTGRES_DB" <<-EOSQL
    CREATE USER docker;
    CREATE DATABASE docker;
    GRANT ALL PRIVILEGES ON DATABASE docker TO docker;
    CREATE TABLE IF NOT EXISTS testdb (id int, name varchar(255));
    INSERT INTO testdb (id, name) VALUES (1, 'test')
EOSQL

Ordered Init Scripts

If you would like to run the init scripts in a specific order, you can use the WithOrderedInitScripts function, which copies the given scripts in the order they are provided to the container, prefixed with the order number so that Postgres executes them in the correct order.

// Executes first the init-user-db shell-script, then the do-insert-user SQL script
// Using WithInitScripts, this would not work.
// This is because aaaa-insert-user would get executed first, but requires init-user-db to be executed before.
postgres.WithOrderedInitScripts(
    filepath.Join("testdata", "init-user-db.sh"),
    filepath.Join("testdata", "aaaa-insert-user.sql"),
),

WithConfigFile

In the case you have a custom config file for Postgres, it's possible to copy that file into the container before it's started, using the WithConfigFile(cfgPath string) function.

This function can be used WithSSLSettings but requires your configuration correctly sets the SSL properties. See the below section for more information.

Tip

For information on what is available to configure, see the PostgreSQL docs for the specific version of PostgreSQL that you are running.

SSL Configuration

If you would like to use SSL with the container you can use the WithSSLSettings. This function accepts a SSLSettings which has the required secret material, namely the ca-certificate, server certificate and key. The container will copy this material to /tmp/testcontainers-go/postgres/ca_cert.pem, /tmp/testcontainers-go/postgres/server.cert and /tmp/testcontainers-go/postgres/server.key

This function requires a custom postgres configuration file that enables SSL and correctly sets the paths on the key material.

If you use this function by itself or in conjunction with WithConfigFile your custom conf must set the required ssl fields. The configuration must correctly align the key material provided via SSLSettings with the server configuration, namely the paths. Your configuration will need to contain the following:

ssl = on
ssl_ca_file = '/tmp/testcontainers-go/postgres/ca_cert.pem'
ssl_cert_file = '/tmp/testcontainers-go/postgres/server.cert'
ssl_key_file = '/tmp/testcontainers-go/postgres/server.key'

Warning

This function assumes the postgres user in the container is postgres

There is no current support for mutual authentication.

The SSLSettings function will modify the container entrypoint. This is done so that key material copied over to the container is chowned by postgres. All other container arguments will be passed through to the original container entrypoint.

Snapshot/Restore with custom driver

You can tell the module to use the database driver you have imported in your test package by setting postgres.WithSQLDriver("name") to your driver name.

The following options are exposed by the testcontainers package.

Basic Options

Lifecycle Options

Files & Mounts Options

Build Options

Logging Options

Image Options

Networking Options

Advanced Options

Experimental Options

Container Methods

ConnectionString

This method returns the connection string to connect to the Postgres container, using the default 5432 port. It's possible to pass extra parameters to the connection string, e.g. sslmode=disable or application_name=myapp, in a variadic way.

// explicitly set sslmode=disable because the container is not configured to use TLS
connStr, err := ctr.ConnectionString(ctx, "sslmode=disable", "application_name=test")

Postgres variants

It's possible to use the Postgres container with PGVector, Timescale or Postgis, to name a few. You simply need to update the image name and the wait strategy.

image: "pgvector/pgvector:pg16",

image: "timescale/timescaledb:2.1.0-pg11",

image: "postgis/postgis:12-3.0",

Examples

Wait Strategies

The postgres module works best with these wait strategies. No default is supplied, so you need to set it explicitly.

return testcontainers.WithAdditionalWaitStrategy(
    // First, we wait for the container to log readiness twice.
    // This is because it will restart itself after the first startup.
    wait.ForLog("database system is ready to accept connections").WithOccurrence(2),
    // Then, we wait for docker to actually serve the port on localhost.
    // For non-linux OSes like Mac and Windows, Docker or Rancher Desktop will have to start a separate proxy.
    // Without this, the tests will be flaky on those OSes!
    wait.ForListeningPort("5432/tcp"),
)

Using Snapshots

This example shows the usage of the postgres module's Snapshot feature to give each test a clean database without having to recreate the database container on every test or run heavy scripts to clean your database. This makes the individual tests very modular, since they always run on a brand-new database.

Tip

You should never pass the "postgres" system database as the container database name if you want to use snapshots. The Snapshot logic requires dropping the connected database and using the system database to run commands, which will not work if the database for the container is set to "postgres".

ctx := context.Background()

// 1. Start the postgres ctr and run any migrations on it
ctr, err := postgres.Run(
    ctx,
    "postgres:16-alpine",
    postgres.WithDatabase(dbname),
    postgres.WithUsername(user),
    postgres.WithPassword(password),
    postgres.BasicWaitStrategies(),
    postgres.WithSQLDriver("pgx"),
)
testcontainers.CleanupContainer(t, ctr)
require.NoError(t, err)

// Run any migrations on the database
_, _, err = ctr.Exec(ctx, []string{"psql", "-U", user, "-d", dbname, "-c", "CREATE TABLE users (id SERIAL, name TEXT NOT NULL, age INT NOT NULL)"})
require.NoError(t, err)

// 2. Create a snapshot of the database to restore later
// tt.options comes the test case, it can be specified as e.g. `postgres.WithSnapshotName("custom-snapshot")` or omitted, to use default name
err = ctr.Snapshot(ctx, tt.options...)
require.NoError(t, err)

dbURL, err := ctr.ConnectionString(ctx)
require.NoError(t, err)

t.Run("Test inserting a user", func(t *testing.T) {
    t.Cleanup(func() {
        // 3. In each test, reset the DB to its snapshot state.
        err = ctr.Restore(ctx)
        require.NoError(t, err)
    })

    conn, err := pgx.Connect(context.Background(), dbURL)
    require.NoError(t, err)
    defer conn.Close(context.Background())

    _, err = conn.Exec(ctx, "INSERT INTO users(name, age) VALUES ($1, $2)", "test", 42)
    require.NoError(t, err)

    var name string
    var age int64
    err = conn.QueryRow(context.Background(), "SELECT name, age FROM users LIMIT 1").Scan(&name, &age)
    require.NoError(t, err)

    require.Equal(t, "test", name)
    require.EqualValues(t, 42, age)
})

// 4. Run as many tests as you need, they will each get a clean database
t.Run("Test querying empty DB", func(t *testing.T) {
    t.Cleanup(func() {
        err = ctr.Restore(ctx)
        require.NoError(t, err)
    })

    conn, err := pgx.Connect(context.Background(), dbURL)
    require.NoError(t, err)
    defer conn.Close(context.Background())

    var name string
    var age int64
    err = conn.QueryRow(context.Background(), "SELECT name, age FROM users LIMIT 1").Scan(&name, &age)
    require.ErrorIs(t, err, pgx.ErrNoRows)
})

Snapshot/Restore with custom driver

The snapshot/restore feature tries to use the postgres driver with go's included sql.DB package to perform database operations. If the postgres driver is not installed, it will fall back to using docker exec, which works, but is slower.

You can tell the module to use the database driver you have imported in your test package by setting postgres.WithSQLDriver("name") to your driver name.

For example, if you use pgx, see the example below.

package my_test

import (
    "testing"

    _ "github.com/jackc/pgx/v5/stdlib"

    "github.com/testcontainers/testcontainers-go/modules/postgres"
)

The above code snippet is importing the pgx driver and the Testcontainers for Go Postgres module.

ctx := context.Background()

// 1. Start the postgres ctr and run any migrations on it
ctr, err := postgres.Run(
    ctx,
    "postgres:16-alpine",
    postgres.WithDatabase(dbname),
    postgres.WithUsername(user),
    postgres.WithPassword(password),
    postgres.BasicWaitStrategies(),
    postgres.WithSQLDriver("pgx"),
)
testcontainers.CleanupContainer(t, ctr)
require.NoError(t, err)

// Run any migrations on the database
_, _, err = ctr.Exec(ctx, []string{"psql", "-U", user, "-d", dbname, "-c", "CREATE TABLE users (id SERIAL, name TEXT NOT NULL, age INT NOT NULL)"})
require.NoError(t, err)

// 2. Create a snapshot of the database to restore later
// tt.options comes the test case, it can be specified as e.g. `postgres.WithSnapshotName("custom-snapshot")` or omitted, to use default name
err = ctr.Snapshot(ctx, tt.options...)
require.NoError(t, err)

dbURL, err := ctr.ConnectionString(ctx)
require.NoError(t, err)

t.Run("Test inserting a user", func(t *testing.T) {
    t.Cleanup(func() {
        // 3. In each test, reset the DB to its snapshot state.
        err = ctr.Restore(ctx)
        require.NoError(t, err)
    })

    conn, err := pgx.Connect(context.Background(), dbURL)
    require.NoError(t, err)
    defer conn.Close(context.Background())

    _, err = conn.Exec(ctx, "INSERT INTO users(name, age) VALUES ($1, $2)", "test", 42)
    require.NoError(t, err)

    var name string
    var age int64
    err = conn.QueryRow(context.Background(), "SELECT name, age FROM users LIMIT 1").Scan(&name, &age)
    require.NoError(t, err)

    require.Equal(t, "test", name)
    require.EqualValues(t, 42, age)
})

// 4. Run as many tests as you need, they will each get a clean database
t.Run("Test querying empty DB", func(t *testing.T) {
    t.Cleanup(func() {
        err = ctr.Restore(ctx)
        require.NoError(t, err)
    })

    conn, err := pgx.Connect(context.Background(), dbURL)
    require.NoError(t, err)
    defer conn.Close(context.Background())

    var name string
    var age int64
    err = conn.QueryRow(context.Background(), "SELECT name, age FROM users LIMIT 1").Scan(&name, &age)
    require.ErrorIs(t, err, pgx.ErrNoRows)
})