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//! Runs Postgres instances.
//!
//! `pgdb` supports configuring and starting a Postgres database instance through a builder pattern,
//! with shutdown and cleanup on `Drop`.
//!
//! # Example
//!
//! ```
//! let user = "dev";
//! let pw = "devpw";
//! let db = "dev";
//!
//! // Run a postgres instance on port `15432`.
//! let pg = pgdb::Postgres::build()
//! .start()
//! .expect("could not build postgres database");
//!
//! // We can now create a regular user and a database.
//! pg.as_superuser()
//! .create_user(user, pw)
//! .expect("could not create normal user");
//!
//! pg.as_superuser()
//! .create_database(db, user)
//! .expect("could not create normal user's db");
//!
//! // Now we can run DDL commands, e.g. creating a table.
//! let client = pg.as_user(user, pw);
//! client
//! .run_sql(db, "CREATE TABLE foo (id INT PRIMARY KEY);")
//! .expect("could not run table creation command");
//! ```
use std::{
collections::BTreeSet,
fs, io, net, path, process,
sync::Mutex,
thread,
time::{Duration, Instant},
};
use process_guard::ProcessGuard;
use rand::{rngs::OsRng, Rng};
use thiserror::Error;
/// A counter for how many instances were spawned.
///
/// Use to assign unique port numbers.
static USED_PORTS: Mutex<BTreeSet<u16>> = Mutex::new(BTreeSet::new());
/// A wrapped postgres instance.
///
/// Contains a handle to a running Postgres process. Once dropped, the instance will be shut down
/// and the temporary directory containing all of its data removed.
#[derive(Debug)]
pub struct Postgres {
/// Host address of the instance.
host: String,
/// Port the instance is running on.
port: u16,
/// Instance of the postgres process.
#[allow(dead_code)] // Only used for its `Drop` implementation.
instance: ProcessGuard,
/// Path to the `psql` binary.
psql_binary: path::PathBuf,
/// Superuser name.
superuser: String,
/// Superuser's password.
superuser_pw: String,
/// Directory holding all the temporary data.
#[allow(dead_code)] // Only used for its `Drop` implementation.
tmp_dir: tempfile::TempDir,
}
/// A virtual client for a running postgres.
///
/// Contains credentials and enough information to connect to its parent instance.
#[derive(Debug)]
pub struct PostgresClient<'a> {
instance: &'a Postgres,
/// Superuser name.
username: String,
/// Superuser password.
password: String,
}
/// Builder for a postgres instance.
///
/// Usually constructed via [`Postgres::build`].
#[derive(Debug, Default)]
pub struct PostgresBuilder {
/// Data directory.
data_dir: Option<path::PathBuf>,
/// Listening port.
port: u16,
/// Bind host.
host: String,
/// Name of the super user.
superuser: String,
/// Password for the super user.
superuser_pw: String,
/// Path to `postgres` binary.
postgres_binary: Option<path::PathBuf>,
/// Path to `initdb` binary.
initdb_binary: Option<path::PathBuf>,
/// Path to `psql` binary.
psql_binary: Option<path::PathBuf>,
/// How long to wait between startup probe attempts.
probe_delay: Duration,
/// Time until giving up waiting for startup.
startup_timeout: Duration,
/// Whether to reuse an already used port.
reuse_port: bool,
}
/// A Postgres server error.
#[derive(Error, Debug)]
pub enum Error {
#[error("could not find `postgres` binary")]
FindPostgres(which::Error),
/// Failed to find the `initdb` binary.
#[error("could not find `initdb` binary")]
FindInitdb(which::Error),
/// Failed to find the `postgres` binary.
#[error("could not find `psql` binary")]
FindPsql(which::Error),
/// Could not create the temporary directory.
#[error("could not create temporary directory for database")]
CreateDatabaseDir(io::Error),
/// Could not write the temporary password to a file.
#[error("error writing temporary password")]
WriteTemporaryPw(io::Error),
/// Starting `initdb` failed.
#[error("failed to run `initdb`")]
RunInitDb(io::Error),
/// Running `initdb` was not successful.
#[error("`initdb` exited with status {}", 0)]
InitDbFailed(process::ExitStatus),
/// Postgres could not be launched.
#[error("failed to launch `postgres`")]
LaunchPostgres(io::Error),
/// Postgres was launched but failed to bring up a TCP-connection accepting socket in time.
#[error("timeout probing tcp socket")]
StartupTimeout,
/// `psql` could not be launched.
#[error("failed to run `psql`")]
RunPsql(io::Error),
/// Running `psql` returned an error.
#[error("`psql` exited with status {}", 0)]
PsqlFailed(process::ExitStatus),
}
impl Postgres {
/// Creates a new Postgres database builder.
#[inline]
pub fn build() -> PostgresBuilder {
PostgresBuilder {
data_dir: None,
port: 15432,
host: "127.0.0.1".to_string(),
superuser: "postgres".to_string(),
superuser_pw: generate_random_string(),
postgres_binary: None,
initdb_binary: None,
psql_binary: None,
probe_delay: Duration::from_millis(100),
startup_timeout: Duration::from_secs(10),
reuse_port: false,
}
}
/// Returns a postgres client with superuser credentials.
#[inline]
pub fn as_superuser(&self) -> PostgresClient<'_> {
self.as_user(&self.superuser, &self.superuser_pw)
}
/// Returns a postgres client that uses the given credentials.
#[inline]
pub fn as_user(&self, username: &str, password: &str) -> PostgresClient<'_> {
PostgresClient {
instance: self,
username: username.to_string(),
password: password.to_string(),
}
}
/// Returns the hostname the Postgres database can be connected to at.
#[inline]
pub fn host(&self) -> &str {
self.host.as_str()
}
/// Returns the port the Postgres database is bound to.
#[inline]
pub fn port(&self) -> u16 {
self.port
}
}
impl<'a> PostgresClient<'a> {
/// Runs a `psql` command against the database.
///
/// Creates a command that runs `psql -h (host) -p (port) -U (username) -d (database)` with
/// `PGPASSWORD` set.
pub fn psql(&self, database: &str) -> process::Command {
let mut cmd = process::Command::new(&self.instance.psql_binary);
cmd.arg("-h")
.arg(&self.instance.host)
.arg("-p")
.arg(self.instance.port.to_string())
.arg("-U")
.arg(&self.username)
.arg("-d")
.arg(database)
.env("PGPASSWORD", &self.password);
cmd
}
/// Runs the given SQL commands from an input file via `psql`.
pub fn load_sql<P: AsRef<path::Path>>(&self, database: &str, filename: P) -> Result<(), Error> {
let status = self
.psql(database)
.arg("-f")
.arg(filename.as_ref())
.status()
.map_err(Error::RunPsql)?;
if !status.success() {
return Err(Error::PsqlFailed(status));
}
Ok(())
}
/// Runs the given SQL command through `psql`.
pub fn run_sql(&self, database: &str, sql: &str) -> Result<(), Error> {
let status = self
.psql(database)
.arg("-c")
.arg(sql)
.status()
.map_err(Error::RunPsql)?;
if !status.success() {
return Err(Error::PsqlFailed(status));
}
Ok(())
}
/// Creates a new database with the given owner.
///
/// This typically requires superuser credentials, see [`Postgres::as_superuser`].
#[inline]
pub fn create_database(&self, database: &str, owner: &str) -> Result<(), Error> {
self.run_sql(
"postgres",
&format!(
"CREATE DATABASE {} OWNER {};",
escape_ident(database),
escape_ident(owner)
),
)
}
/// Creates a new user on the system that is allowed to login.
///
/// This typically requires superuser credentials, see [`Postgres::as_superuser`].
#[inline]
pub fn create_user(&self, username: &str, password: &str) -> Result<(), Error> {
self.run_sql(
"postgres",
&format!(
"CREATE ROLE {} LOGIN ENCRYPTED PASSWORD {};",
escape_ident(username),
escape_string(password)
),
)
}
/// Returns the `Postgres` instance associated with this client.
#[inline]
pub fn instance(&self) -> &Postgres {
self.instance
}
/// Returns the username used by this client.
pub fn username(&self) -> &str {
self.username.as_str()
}
/// Returns a libpq-style connection URI.
pub fn uri(&self, database: &str) -> String {
format!(
"postgres://{}:{}@{}:{}/{}",
self.username,
self.password,
self.instance.host(),
self.instance.port(),
database
)
}
/// Returns the password used by this client.
#[inline]
pub fn password(&self) -> &str {
self.password.as_str()
}
}
impl PostgresBuilder {
/// Sets the postgres data directory.
///
/// If not set, a temporary directory will be used.
#[inline]
pub fn data_dir<T: Into<path::PathBuf>>(&mut self, data_dir: T) -> &mut Self {
self.data_dir = Some(data_dir.into());
self
}
/// Sets the location of the `initdb` binary.
#[inline]
pub fn initdb_binary<T: Into<path::PathBuf>>(&mut self, initdb_binary: T) -> &mut Self {
self.initdb_binary = Some(initdb_binary.into());
self
}
/// Sets the bind address.
#[inline]
pub fn host(&mut self, host: String) -> &mut Self {
self.host = host;
self
}
/// Sets listening port.
///
/// Note that by default, ports will not be reused, every subsequently created database in the
/// same process will attempt to use a different port number. If this behavior is not desired,
/// call `reuse_port()`.
#[inline]
pub fn port(&mut self, port: u16) -> &mut Self {
self.port = port;
self
}
/// Sets the location of the `postgres` binary.
#[inline]
pub fn postgres_binary<T: Into<path::PathBuf>>(&mut self, postgres_binary: T) -> &mut Self {
self.postgres_binary = Some(postgres_binary.into());
self
}
/// Sets the startup probe delay.
///
/// Between two startup probes, waits this long.
#[inline]
pub fn probe_delay(&mut self, probe_delay: Duration) -> &mut Self {
self.probe_delay = probe_delay;
self
}
/// Sets the location of the `psql` binary.
#[inline]
pub fn psql_binary<T: Into<path::PathBuf>>(&mut self, psql_binary: T) -> &mut Self {
self.psql_binary = Some(psql_binary.into());
self
}
/// Reuse port when spawning multiple databases.
///
/// By default, the builder checks if any given port has been previously used, and if so, tries
/// to find the next available adjacent port instead.
#[inline]
pub fn reuse_port(&mut self) -> &mut Self {
self.reuse_port = true;
self
}
/// Sets the maximum time to probe for startup.
#[inline]
pub fn startup_timeout(&mut self, startup_timeout: Duration) -> &mut Self {
self.startup_timeout = startup_timeout;
self
}
/// Sets the password for the superuser.
#[inline]
pub fn superuser_pw<T: Into<String>>(&mut self, superuser_pw: T) -> &mut Self {
self.superuser_pw = superuser_pw.into();
self
}
/// Starts the Postgres server.
///
/// Postgres will start using a newly created temporary directory as its data dir. The function
/// will only return once a TCP connection to postgres has been made successfully.
pub fn start(&self) -> Result<Postgres, Error> {
const PRIVILEDGED_PORT_RANGE: u16 = 1024;
// If not set, we will use the default port of 15432.
let mut port = self.port;
// Take note of whether the user has set a priviledged port.
if !self.reuse_port {
let priviledged = port < PRIVILEDGED_PORT_RANGE;
let mut guard = USED_PORTS.lock().expect("lock poisoned");
while !guard.insert(port) {
port = port.wrapping_add(1);
// If we overflowed, do not bind to zero, but try next port instead. Skip if in
// priviledged range and not priviledged.
if port == 0 {
port += if priviledged {
1
} else {
PRIVILEDGED_PORT_RANGE
};
}
}
}
let postgres_binary = self
.postgres_binary
.clone()
.map(Ok)
.unwrap_or_else(|| which::which("postgres").map_err(Error::FindPostgres))?;
let initdb_binary = self
.initdb_binary
.clone()
.map(Ok)
.unwrap_or_else(|| which::which("initdb").map_err(Error::FindInitdb))?;
let psql_binary = self
.psql_binary
.clone()
.map(Ok)
.unwrap_or_else(|| which::which("psql").map_err(Error::FindPsql))?;
let tmp_dir = tempfile::tempdir().map_err(Error::CreateDatabaseDir)?;
let data_dir = self
.data_dir
.clone()
.unwrap_or_else(|| tmp_dir.path().join("db"));
let superuser_pw_file = tmp_dir.path().join("superuser-pw");
fs::write(&superuser_pw_file, self.superuser_pw.as_bytes())
.map_err(Error::WriteTemporaryPw)?;
let initdb_status = process::Command::new(initdb_binary)
.args(&[
// No default locale (== 'C').
"--no-locale",
// Require a password for all users.
"--auth=md5",
// Set default encoding to UTF8.
"--encoding=UTF8",
// Do not sync data, which is fine for tests.
"--nosync",
// Path to data directory.
"--pgdata",
])
.arg(&data_dir)
.arg("--pwfile")
.arg(&superuser_pw_file)
.arg("--username")
.arg(&self.superuser)
.status()
.map_err(Error::RunInitDb)?;
if !initdb_status.success() {
return Err(Error::InitDbFailed(initdb_status));
}
// Start the database.
let mut postgres_command = process::Command::new(postgres_binary);
postgres_command
.arg("-D")
.arg(&data_dir)
.arg("-c")
.arg(format!("port={}", port))
.arg("-k")
.arg(tmp_dir.path());
let instance = ProcessGuard::spawn_graceful(&mut postgres_command, Duration::from_secs(5))
.map_err(Error::LaunchPostgres)?;
// Wait for the server to come up.
let socket_addr = format!("{}:{}", self.host, port);
let started = Instant::now();
loop {
match net::TcpStream::connect(socket_addr.as_str()) {
Ok(_) => break,
Err(_) => {
let now = Instant::now();
if now.duration_since(started) >= self.startup_timeout {
return Err(Error::StartupTimeout);
}
thread::sleep(self.probe_delay);
}
}
}
Ok(Postgres {
host: self.host.clone(),
port,
instance,
psql_binary,
superuser: self.superuser.clone(),
superuser_pw: self.superuser_pw.clone(),
tmp_dir,
})
}
}
/// Generates a random hex string string 32 characters long.
fn generate_random_string() -> String {
let raw: [u8; 16] = OsRng.gen();
format!("{:x}", hex_fmt::HexFmt(&raw))
}
/// Escapes an identifier by wrapping in quote char. Any quote character inside the unescaped string
/// will be doubled.
fn quote(quote_char: char, unescaped: &str) -> String {
let mut result = String::new();
result.push(quote_char);
for c in unescaped.chars() {
if c == quote_char {
result.push(quote_char);
result.push(quote_char);
} else {
result.push(c);
}
}
result.push(quote_char);
result
}
/// Escapes an identifier.
fn escape_ident(unescaped: &str) -> String {
quote('"', unescaped)
}
/// Escapes a string.
fn escape_string(unescaped: &str) -> String {
quote('\'', unescaped)
}
#[cfg(test)]
mod tests {
use super::Postgres;
#[test]
fn can_change_superuser_pw() {
let pg = Postgres::build()
.superuser_pw("helloworld")
.start()
.expect("could not build postgres database");
let su = pg.as_superuser();
su.create_user("foo", "bar")
.expect("could not create normal user");
// Command executed successfully, check we used the right password.
assert_eq!(su.password, "helloworld");
}
#[test]
fn instances_use_different_port_by_default() {
let a = Postgres::build()
.start()
.expect("could not build postgres database");
let b = Postgres::build()
.start()
.expect("could not build postgres database");
let c = Postgres::build()
.start()
.expect("could not build postgres database");
// Note: We could test for sequentiality, but that would be racy if other tests are running
// at the same time.
assert_ne!(a.port(), b.port());
assert_ne!(a.port(), c.port());
assert_ne!(b.port(), c.port());
}
}