I am using a PostgreSQL TestContainer to test Liquibase schema migration in Spring Boot. I don't have any respositories. I am wondering if I can see/access the contents of the TestContainer, and test the schema migration.
Yes, you can access the Docker container spawned by Testcontainers like any other Docker container. Using the JUnit 5 extension or the JUnit 4 rule for Testcontainers will however shut down the container after your tests.
You can use the coontainer re-usability feature for Testcontainers (in alpha state since 1.12.3) for ensuring your containers are up- and running after your tests finish.
As Testcontainers will launch the container on an ephemeral port, simply execute docker ps and check to which local port the container port is mapped. E.g.:
b0df4733babb postgres:9.6.12 "docker-entrypoint.s…" 19 seconds ago Up 18 seconds 0.0.0.0:32778->5432/tcp inspiring_dewdney
You can now connect to your db on localhost:32778 with e.g. PgAdmin or the database view of IntelliJ IDEA and check your database tables.
The credentials for the access are those you specify in your test:
static PostgreSQLContainer postgreSQLContainer = (PostgreSQLContainer) new PostgreSQLContainer()
.withDatabaseName("differentDatabaseName")
.withUsername("duke")
.withPassword("s3cret")
.withReuse(true);
As a workaround you could also put in a breakpoint at the end of your test, debug the test, and quickly check your database.
UPDATE: If you want to verify the validity of your schema, you can use a Hibernate feature for this:
spring.jpa.hibernate.ddl-auto=validate
This will validate that your Java entity setup matches the underlying database schema on application startup. You can also add this to your production application.properties file as your application won't start if there is a mismatch (e.g. missing table, column).
For this to work in a test, you need to either use #DataJpaTest or use #SpringBootTest to the whole application context connect to your local container.
Find more information here.
Related
I have a Quarkus project that uses a postgresql datasource. In production, we create the necessary schemas on the db manually before.
When I run quarkusDev mode and use the devservices, I therefor would like to run an init script on the testcontainer to create the schemas before liquibase does its migrations, which otherwise will fail.
I tried this without success
quarkus.datasource.jdbc.url=jdbc:tc:postgresql:13:///quarkus?TC_INITSCRIPT=testcontainer/schema-init.sql
quarkus.datasource.jdbc.driver=org.testcontainers.jdbc.ContainerDatabaseDriver
Nothing got picked up by the postgres testcontainer.
How can I run a init script on a datasource testcontainer with quarkus?
As stated here: https://quarkus.io/guides/databases-dev-services#database-vendor-specific-configuration
specific properties supported by the Testcontainers JDBC driver such as TC_INITSCRIPT, TC_INITFUNCTION, TC_DAEMON, TC_TMPFS are not supported.
So this simply does not work
I am building a RESTful API with Phoenix and PostgreSQL and run the Phoenix app and the database in separate docker containers using docker-compose. If I attach a shell to the Phoenix container and type mix ecto.reset to reset the database, I get the following error:
** (Mix) The database for Home.Repo couldn't be dropped: ERROR 55006 (object_in_use):
database "home" is being accessed by other users
There are 10 other sessions using the database.
I already tried this:
REVOKE CONNECT ON DATABASE dbname FROM PUBLIC, username;
SELECT
pg_terminate_backend(pid)
FROM
pg_stat_activity
WHERE
pid <> pg_backend_pid()
AND datname = 'database_name';
What am I doing wrong?
You shouldn't stop only the cowboy webserver in this case, as it requires many phoenix dependencies to be up again, and most likely there will be a Supervision tree to restore the process if you find it and kill it yourself. So, as mentioned before, you should stop your whole phoenix server with Application.stop(:your_app) inside iex, and then do ecto.reset and start it again.
Although, you shouldn't need to use ecto reset within a running application, ecto.reset does the following: "ecto.drop", "ecto.create", "ecto.migrate". You should check if the drop is really necessary, as that is what's impossible to do in a running application that relies on database.
If you're resetting for testing purposes, for example, then you should also check Ecto.Sandbox, that sets up a copy database for each test:
https://hexdocs.pm/ecto/Ecto.Adapters.SQL.Sandbox.html#content
I want to run a small PostgreSQL database which runs in memory only, for each unit test I write. For instance:
#Before
void setUp() {
String port = runPostgresOnRandomPort();
connectTo("postgres://localhost:"+port+"/in_memory_db");
// ...
}
Ideally I'll have a single postgres executable checked into the version control, which the unit test will use.
Something like HSQL, but for postgres. How can I do that?
Were can I get such a Postgres version? How can I instruct it not to use the disk?
(Moving my answer from Using in-memory PostgreSQL and generalizing it):
You can't run Pg in-process, in-memory
I can't figure out how to run in-memory Postgres database for testing. Is it possible?
No, it is not possible. PostgreSQL is implemented in C and compiled to platform code. Unlike H2 or Derby you can't just load the jar and fire it up as a throwaway in-memory DB.
Its storage is filesystem based, and it doesn't have any built-in storage abstraction that would allow you to use a purely in-memory datastore. You can point it at a ramdisk, tempfs, or other ephemeral file system storage though.
Unlike SQLite, which is also written in C and compiled to platform code, PostgreSQL can't be loaded in-process either. It requires multiple processes (one per connection) because it's a multiprocessing, not a multithreading, architecture. The multiprocessing requirement means you must launch the postmaster as a standalone process.
Use throwaway containers
Since I originally wrote this the use of containers has become widespread, well understood and easy.
It should be a no-brainer to just configure a throw-away postgres instance in a Docker container for your test uses, then tear it down at the end. You can speed it up with hacks like LD_PRELOADing libeatmydata to disable that pesky "don't corrupt my data horribly on crash" feature ;).
There are a lot of wrappers to automate this for you for any test suite and language or toolchain you would like.
Alternative: preconfigure a connection
(Written before easy containerization; no longer recommended)
I suggest simply writing your tests to expect a particular hostname/username/password to work, and having the test harness CREATE DATABASE a throwaway database, then DROP DATABASE at the end of the run. Get the database connection details from a properties file, build target properties, environment variable, etc.
It's safe to use an existing PostgreSQL instance you already have databases you care about in, so long as the user you supply to your unit tests is not a superuser, only a user with CREATEDB rights. At worst you'll create performance issues in the other databases. I prefer to run a completely isolated PostgreSQL install for testing for that reason.
Instead: Launch a throwaway PostgreSQL instance for testing
Alternately, if you're really keen you could have your test harness locate the initdb and postgres binaries, run initdb to create a database, modify pg_hba.conf to trust, run postgres to start it on a random port, create a user, create a DB, and run the tests. You could even bundle the PostgreSQL binaries for multiple architectures in a jar and unpack the ones for the current architecture to a temporary directory before running the tests.
Personally I think that's a major pain that should be avoided; it's way easier to just have a test DB configured. However, it's become a little easier with the advent of include_dir support in postgresql.conf; now you can just append one line, then write a generated config file for all the rest.
Faster testing with PostgreSQL
For more information about how to safely improve the performance of PostgreSQL for testing purposes, see a detailed answer I wrote on this topic earlier: Optimise PostgreSQL for fast testing
H2's PostgreSQL dialect is not a true substitute
Some people instead use the H2 database in PostgreSQL dialect mode to run tests. I think that's almost as bad as the Rails people using SQLite for testing and PostgreSQL for production deployment.
H2 supports some PostgreSQL extensions and emulates the PostgreSQL dialect. However, it's just that - an emulation. You'll find areas where H2 accepts a query but PostgreSQL doesn't, where behaviour differs, etc. You'll also find plenty of places where PostgreSQL supports doing something that H2 just can't - like window functions, at the time of writing.
If you understand the limitations of this approach and your database access is simple, H2 might be OK. But in that case you're probably a better candidate for an ORM that abstracts the database because you're not using its interesting features anyway - and in that case, you don't have to care about database compatibility as much anymore.
Tablespaces are not the answer!
Do not use a tablespace to create an "in-memory" database. Not only is it unnecessary as it won't help performance significantly anyway, but it's also a great way to disrupt access to any other you might care about in the same PostgreSQL install. The 9.4 documentation now contains the following warning:
WARNING
Even though located outside the main PostgreSQL data directory,
tablespaces are an integral part of the database cluster and cannot be
treated as an autonomous collection of data files. They are dependent
on metadata contained in the main data directory, and therefore cannot
be attached to a different database cluster or backed up individually.
Similarly, if you lose a tablespace (file deletion, disk failure,
etc), the database cluster might become unreadable or unable to start.
Placing a tablespace on a temporary file system like a ramdisk risks
the reliability of the entire cluster.
because I noticed too many people were doing this and running into trouble.
(If you've done this you can mkdir the missing tablespace directory to get PostgreSQL to start again, then DROP the missing databases, tables etc. It's better to just not do it.)
Or you could create a TABLESPACE in a ramfs / tempfs and create all your objects there.
I recently was pointed to an article about doing exactly that on Linux. The original link is dead. But it was archived (provided by Arsinclair):
https://web.archive.org/web/20160319031016/http://magazine.redhat.com/2007/12/12/tip-from-an-rhce-memory-storage-on-postgresql/
Warning
This can endanger the integrity of your whole database cluster.
Read the added warning in the manual.
So this is only an option for expendable data.
For unit-testing it should work just fine. If you are running other databases on the same machine, be sure to use a separate database cluster (which has its own port) to be safe.
This is not possible with Postgres. It does not offer an in-process/in-memory engine like HSQLDB or MySQL.
If you want to create a self-contained environment you can put the Postgres binaries into SVN (but it's more than just a single executable).
You will need to run initdb to setup your test database before you can do anything with this. This can be done from a batch file or by using Runtime.exec(). But note that initdb is not something that is fast. You will definitely not want to run that for each test. You might get away running this before your test-suite though.
However while this can be done, I'd recommend to have a dedicated Postgres installation where you simply recreate your test database before running your tests.
You can re-create the test-database by using a template database which makes creating it quite fast (a lot faster than running initdb for each test run)
Now it is possible to run an in-memory instance of PostgreSQL in your JUnit tests via the Embedded PostgreSQL Component from OpenTable: https://github.com/opentable/otj-pg-embedded.
By adding the dependency to the otj-pg-embedded library (https://mvnrepository.com/artifact/com.opentable.components/otj-pg-embedded) you can start and stop your own instance of PostgreSQL in your #Before and #Afer hooks:
EmbeddedPostgres pg = EmbeddedPostgres.start();
They even offer a JUnit rule to automatically have JUnit starting and stopping your PostgreSQL database server for you:
#Rule
public SingleInstancePostgresRule pg = EmbeddedPostgresRules.singleInstance();
You could use TestContainers to spin up a PosgreSQL docker container for tests:
http://testcontainers.viewdocs.io/testcontainers-java/usage/database_containers/
TestContainers provide a JUnit #Rule/#ClassRule: this mode starts a database inside a container before your tests and tears it down afterwards.
Example:
public class SimplePostgreSQLTest {
#Rule
public PostgreSQLContainer postgres = new PostgreSQLContainer();
#Test
public void testSimple() throws SQLException {
HikariConfig hikariConfig = new HikariConfig();
hikariConfig.setJdbcUrl(postgres.getJdbcUrl());
hikariConfig.setUsername(postgres.getUsername());
hikariConfig.setPassword(postgres.getPassword());
HikariDataSource ds = new HikariDataSource(hikariConfig);
Statement statement = ds.getConnection().createStatement();
statement.execute("SELECT 1");
ResultSet resultSet = statement.getResultSet();
resultSet.next();
int resultSetInt = resultSet.getInt(1);
assertEquals("A basic SELECT query succeeds", 1, resultSetInt);
}
}
If you are using NodeJS, you can use pg-mem (disclaimer: I'm the author) to emulate the most common features of a postgres db.
You will have a full in-memory, isolated, platform-agnostic database replicating PG behaviour (it even runs in browsers).
I wrote an article to show how to use it for your unit tests here.
There is now an in-memory version of PostgreSQL from Russian Search company named Yandex: https://github.com/yandex-qatools/postgresql-embedded
It's based on Flapdoodle OSS's embed process.
Example of using (from github page):
// starting Postgres
final EmbeddedPostgres postgres = new EmbeddedPostgres(V9_6);
// predefined data directory
// final EmbeddedPostgres postgres = new EmbeddedPostgres(V9_6, "/path/to/predefined/data/directory");
final String url = postgres.start("localhost", 5432, "dbName", "userName", "password");
// connecting to a running Postgres and feeding up the database
final Connection conn = DriverManager.getConnection(url);
conn.createStatement().execute("CREATE TABLE films (code char(5));");
I'm using it some time. It works well.
UPDATED: this project is not being actively maintained anymore
Please be adviced that the main maintainer of this project has successfuly
migrated to the use of Test Containers project. This is the best possible
alternative nowadays.
If you can use docker you can mount postgresql data directory in memory for testing
docker run --tmpfs=/data -e PGDATA=/data postgres
You can also use PostgreSQL configuration settings (such as those detailed in the question and accepted answer here) to achieve performance without necessarily resorting to an in-memory database.
If you're using java, there is a library I've seen effectively used that provides an in memory "embedded" postgres environment used mostly for unit tests.
https://github.com/opentable/otj-pg-embedded
This might be able to solve your use case if you've come to this search result looking for the answer.
If have full control over your environment, you arguably want to run postgreSQL on zfs.
I've been having a heck of a time getting my Play! framework java app to run on Heroku, and I think I've narrowed it down to the Postgres JDBC driver not liking Heroku's DATABASE_URL parameter because it starts with postgres: and not postgresql:.
What is the proper way to configure a play! 2.0 app to connect to a heroku-provided Postgres instance?
I've tried variations on the following:
PLAY_OPTS="-Ddb.default.url=$DATABASE_URL -Ddb.default.driver=org.postgresql.Driver"
But upon startup I get a SQLException that no suitable driver can be found for $DATABASE_URL.
No need to pass them in as system properties you can pickup Heroku environment variables in your application.conf file
...
db.default.driver=org.postgresql.Driver
db.default.url=${DATABASE_URL}
Then define this in your Procfile
web: target/start -Dhttp.port=${PORT} ${JAVA_OPTS} -Dconfig.resource=application.conf
It should pick up the DATABASE_URL property for the Heroku environment. Although, I recommend creating a configuration file that is specific for the Heroku environment (i.e. heroku-prod.conf), but this is just an example.
I want to run a small PostgreSQL database which runs in memory only, for each unit test I write. For instance:
#Before
void setUp() {
String port = runPostgresOnRandomPort();
connectTo("postgres://localhost:"+port+"/in_memory_db");
// ...
}
Ideally I'll have a single postgres executable checked into the version control, which the unit test will use.
Something like HSQL, but for postgres. How can I do that?
Were can I get such a Postgres version? How can I instruct it not to use the disk?
(Moving my answer from Using in-memory PostgreSQL and generalizing it):
You can't run Pg in-process, in-memory
I can't figure out how to run in-memory Postgres database for testing. Is it possible?
No, it is not possible. PostgreSQL is implemented in C and compiled to platform code. Unlike H2 or Derby you can't just load the jar and fire it up as a throwaway in-memory DB.
Its storage is filesystem based, and it doesn't have any built-in storage abstraction that would allow you to use a purely in-memory datastore. You can point it at a ramdisk, tempfs, or other ephemeral file system storage though.
Unlike SQLite, which is also written in C and compiled to platform code, PostgreSQL can't be loaded in-process either. It requires multiple processes (one per connection) because it's a multiprocessing, not a multithreading, architecture. The multiprocessing requirement means you must launch the postmaster as a standalone process.
Use throwaway containers
Since I originally wrote this the use of containers has become widespread, well understood and easy.
It should be a no-brainer to just configure a throw-away postgres instance in a Docker container for your test uses, then tear it down at the end. You can speed it up with hacks like LD_PRELOADing libeatmydata to disable that pesky "don't corrupt my data horribly on crash" feature ;).
There are a lot of wrappers to automate this for you for any test suite and language or toolchain you would like.
Alternative: preconfigure a connection
(Written before easy containerization; no longer recommended)
I suggest simply writing your tests to expect a particular hostname/username/password to work, and having the test harness CREATE DATABASE a throwaway database, then DROP DATABASE at the end of the run. Get the database connection details from a properties file, build target properties, environment variable, etc.
It's safe to use an existing PostgreSQL instance you already have databases you care about in, so long as the user you supply to your unit tests is not a superuser, only a user with CREATEDB rights. At worst you'll create performance issues in the other databases. I prefer to run a completely isolated PostgreSQL install for testing for that reason.
Instead: Launch a throwaway PostgreSQL instance for testing
Alternately, if you're really keen you could have your test harness locate the initdb and postgres binaries, run initdb to create a database, modify pg_hba.conf to trust, run postgres to start it on a random port, create a user, create a DB, and run the tests. You could even bundle the PostgreSQL binaries for multiple architectures in a jar and unpack the ones for the current architecture to a temporary directory before running the tests.
Personally I think that's a major pain that should be avoided; it's way easier to just have a test DB configured. However, it's become a little easier with the advent of include_dir support in postgresql.conf; now you can just append one line, then write a generated config file for all the rest.
Faster testing with PostgreSQL
For more information about how to safely improve the performance of PostgreSQL for testing purposes, see a detailed answer I wrote on this topic earlier: Optimise PostgreSQL for fast testing
H2's PostgreSQL dialect is not a true substitute
Some people instead use the H2 database in PostgreSQL dialect mode to run tests. I think that's almost as bad as the Rails people using SQLite for testing and PostgreSQL for production deployment.
H2 supports some PostgreSQL extensions and emulates the PostgreSQL dialect. However, it's just that - an emulation. You'll find areas where H2 accepts a query but PostgreSQL doesn't, where behaviour differs, etc. You'll also find plenty of places where PostgreSQL supports doing something that H2 just can't - like window functions, at the time of writing.
If you understand the limitations of this approach and your database access is simple, H2 might be OK. But in that case you're probably a better candidate for an ORM that abstracts the database because you're not using its interesting features anyway - and in that case, you don't have to care about database compatibility as much anymore.
Tablespaces are not the answer!
Do not use a tablespace to create an "in-memory" database. Not only is it unnecessary as it won't help performance significantly anyway, but it's also a great way to disrupt access to any other you might care about in the same PostgreSQL install. The 9.4 documentation now contains the following warning:
WARNING
Even though located outside the main PostgreSQL data directory,
tablespaces are an integral part of the database cluster and cannot be
treated as an autonomous collection of data files. They are dependent
on metadata contained in the main data directory, and therefore cannot
be attached to a different database cluster or backed up individually.
Similarly, if you lose a tablespace (file deletion, disk failure,
etc), the database cluster might become unreadable or unable to start.
Placing a tablespace on a temporary file system like a ramdisk risks
the reliability of the entire cluster.
because I noticed too many people were doing this and running into trouble.
(If you've done this you can mkdir the missing tablespace directory to get PostgreSQL to start again, then DROP the missing databases, tables etc. It's better to just not do it.)
Or you could create a TABLESPACE in a ramfs / tempfs and create all your objects there.
I recently was pointed to an article about doing exactly that on Linux. The original link is dead. But it was archived (provided by Arsinclair):
https://web.archive.org/web/20160319031016/http://magazine.redhat.com/2007/12/12/tip-from-an-rhce-memory-storage-on-postgresql/
Warning
This can endanger the integrity of your whole database cluster.
Read the added warning in the manual.
So this is only an option for expendable data.
For unit-testing it should work just fine. If you are running other databases on the same machine, be sure to use a separate database cluster (which has its own port) to be safe.
This is not possible with Postgres. It does not offer an in-process/in-memory engine like HSQLDB or MySQL.
If you want to create a self-contained environment you can put the Postgres binaries into SVN (but it's more than just a single executable).
You will need to run initdb to setup your test database before you can do anything with this. This can be done from a batch file or by using Runtime.exec(). But note that initdb is not something that is fast. You will definitely not want to run that for each test. You might get away running this before your test-suite though.
However while this can be done, I'd recommend to have a dedicated Postgres installation where you simply recreate your test database before running your tests.
You can re-create the test-database by using a template database which makes creating it quite fast (a lot faster than running initdb for each test run)
Now it is possible to run an in-memory instance of PostgreSQL in your JUnit tests via the Embedded PostgreSQL Component from OpenTable: https://github.com/opentable/otj-pg-embedded.
By adding the dependency to the otj-pg-embedded library (https://mvnrepository.com/artifact/com.opentable.components/otj-pg-embedded) you can start and stop your own instance of PostgreSQL in your #Before and #Afer hooks:
EmbeddedPostgres pg = EmbeddedPostgres.start();
They even offer a JUnit rule to automatically have JUnit starting and stopping your PostgreSQL database server for you:
#Rule
public SingleInstancePostgresRule pg = EmbeddedPostgresRules.singleInstance();
You could use TestContainers to spin up a PosgreSQL docker container for tests:
http://testcontainers.viewdocs.io/testcontainers-java/usage/database_containers/
TestContainers provide a JUnit #Rule/#ClassRule: this mode starts a database inside a container before your tests and tears it down afterwards.
Example:
public class SimplePostgreSQLTest {
#Rule
public PostgreSQLContainer postgres = new PostgreSQLContainer();
#Test
public void testSimple() throws SQLException {
HikariConfig hikariConfig = new HikariConfig();
hikariConfig.setJdbcUrl(postgres.getJdbcUrl());
hikariConfig.setUsername(postgres.getUsername());
hikariConfig.setPassword(postgres.getPassword());
HikariDataSource ds = new HikariDataSource(hikariConfig);
Statement statement = ds.getConnection().createStatement();
statement.execute("SELECT 1");
ResultSet resultSet = statement.getResultSet();
resultSet.next();
int resultSetInt = resultSet.getInt(1);
assertEquals("A basic SELECT query succeeds", 1, resultSetInt);
}
}
If you are using NodeJS, you can use pg-mem (disclaimer: I'm the author) to emulate the most common features of a postgres db.
You will have a full in-memory, isolated, platform-agnostic database replicating PG behaviour (it even runs in browsers).
I wrote an article to show how to use it for your unit tests here.
There is now an in-memory version of PostgreSQL from Russian Search company named Yandex: https://github.com/yandex-qatools/postgresql-embedded
It's based on Flapdoodle OSS's embed process.
Example of using (from github page):
// starting Postgres
final EmbeddedPostgres postgres = new EmbeddedPostgres(V9_6);
// predefined data directory
// final EmbeddedPostgres postgres = new EmbeddedPostgres(V9_6, "/path/to/predefined/data/directory");
final String url = postgres.start("localhost", 5432, "dbName", "userName", "password");
// connecting to a running Postgres and feeding up the database
final Connection conn = DriverManager.getConnection(url);
conn.createStatement().execute("CREATE TABLE films (code char(5));");
I'm using it some time. It works well.
UPDATED: this project is not being actively maintained anymore
Please be adviced that the main maintainer of this project has successfuly
migrated to the use of Test Containers project. This is the best possible
alternative nowadays.
If you can use docker you can mount postgresql data directory in memory for testing
docker run --tmpfs=/data -e PGDATA=/data postgres
You can also use PostgreSQL configuration settings (such as those detailed in the question and accepted answer here) to achieve performance without necessarily resorting to an in-memory database.
If you're using java, there is a library I've seen effectively used that provides an in memory "embedded" postgres environment used mostly for unit tests.
https://github.com/opentable/otj-pg-embedded
This might be able to solve your use case if you've come to this search result looking for the answer.
If have full control over your environment, you arguably want to run postgreSQL on zfs.