Allow timescale_prometheus_extra installation without superuser

We expect most of our users to run the connector without superuser, as
is best practice. This commit enables the installation of the
timescale_prometheus_extra extension without using superuser, via the
pgextwhlist extension. To enable this, we add an additional catalog
table to the public schema, including information about the connector's
installation, most importantly the schemas it's storing things in. We
then use this in the extension to setup the search_path for extension
creation. We need to do this since we do not want to hardcode the
schemas we use, but we cannot easily reset the search path to the one
set by the connector, due to the way pgextwlist runs the
extension-creation scripts.

This commit also makes our test code run as non-SUPERUSER wherever
possible.

extension/003-enable-pgextwlist.sh

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+set -ex
+
+sed -i -e "s/#shared_preload_libraries/shared_preload_libraries/" \
+    /var/lib/postgresql/data/postgresql.conf \
+
+sed -i \
+    -e "s/shared_preload_libraries = '/shared_preload_libraries = 'pgextwlist,/" \
+    /var/lib/postgresql/data/postgresql.conf
+
+echo "extwlist.extensions = 'timescale_prometheus_extra,timescaledb'" >> \
+    /var/lib/postgresql/data/postgresql.conf

extension/Dockerfile

@@ -4,10 +4,6 @@ FROM timescale/timescaledb:${TIMESCALEDB_VERSION}-${PG_VERSION_TAG}
 
 MAINTAINER Timescale https://www.timescale.com
 
-COPY timescale_prometheus_extra.control Makefile /build/timescale-prometheus/
-COPY src/*.c src/*.h /build/timescale-prometheus/src/
-COPY sql/timescale-prometheus.sql /build/timescale-prometheus/sql/
-
 RUN set -ex \
     && apk add --no-cache --virtual .build-deps \
                 coreutils \
@@ -16,10 +12,26 @@ RUN set -ex \
                 libc-dev \
                 make \
                 util-linux-dev \
-		clang \
-		llvm \
-    \
+                clang \
+		        llvm \
+                git
+RUN set -ex \
+    && git clone  --branch v1.9 --depth 1 \
+         https://github.com/dimitri/pgextwlist.git /pgextwlist \
+    && cd /pgextwlist \
+    && make \
+    && make install \
+    && cp /pgextwlist/pgextwlist.so `pg_config --pkglibdir`/plugins \
+    && rm -rf /pgextwlist
+
+COPY timescale_prometheus_extra.control Makefile /build/timescale-prometheus/
+COPY src/*.c src/*.h /build/timescale-prometheus/src/
+COPY sql/timescale-prometheus.sql /build/timescale-prometheus/sql/
+
+RUN set -ex \
     && make -C /build/timescale-prometheus install \
     \
     && apk del .build-deps \
     && rm -rf /build
+
+COPY 003-enable-pgextwlist.sh /docker-entrypoint-initdb.d/

extension/sql/timescale-prometheus.sql

@@ -1,26 +1,53 @@
 
 DO $$
     DECLARE
-        version INT;
-        dirty BOOLEAN;
+        current_version INT;
+        is_dirty BOOLEAN;
+        original_message TEXT;
     BEGIN
         BEGIN
             SELECT version, dirty
-            INTO STRICT version, dirty
-            FROM public.prom_schema_migrations;
+              INTO STRICT current_version, is_dirty
+              FROM public.prom_schema_migrations;
         EXCEPTION WHEN OTHERS THEN
-            RAISE EXCEPTION 'could not determine the version of the timescale-prometheus connector that was installed'
+            GET STACKED DIAGNOSTICS original_message = MESSAGE_TEXT;
+            RAISE EXCEPTION 'could not determine the version of the timescale-prometheus connector that was installed due to: %', original_message
             USING HINT='This extension should not be created manually. It will be created by the timescale-prometheus connector and requires the connector to be installed first.';
             RETURN;
+        END;
 
-        IF version < 1 OR DIRTY THEN
+        IF current_version < 1 OR is_dirty THEN
             RAISE EXCEPTION 'the requisite version of the timescale-prometheus connector has not been installed'
             USING HINT='This extension should not be created manually. It will be created by the timescale-prometheus connector and requires the connector to be installed first.';
         END IF;
     END
 $$;
 
-SET LOCAL search_path TO DEFAULT;
+-- Set the search path to one that will find all the definitions provided by the
+-- connector. Since the connector can change the schemas it stores things
+-- in we cannot just hardcode the searchpath, instead we switch the search path
+-- based on the schemas declared by the connector.
+DO $$
+    DECLARE
+        ext_schema TEXT;
+        prom_schema TEXT;
+        metric_schema TEXT;
+        catalog_schema TEXT;
+        new_path TEXT;
+    BEGIN
+        SELECT value FROM public.prom_installation_info
+         WHERE key = 'extension schema'
+          INTO ext_schema;
+        SELECT value FROM public.prom_installation_info
+         WHERE key = 'prometheus API schema'
+          INTO prom_schema;
+        SELECT value FROM public.prom_installation_info
+         WHERE key = 'catalog schema'
+          INTO catalog_schema;
+        new_path := format('public,%s,%s,%s', ext_schema, prom_schema, catalog_schema);
+        PERFORM set_config('search_path', new_path, false);
+    END
+$$;
 
 DO $$
     BEGIN
@@ -56,48 +83,48 @@ GRANT EXECUTE ON FUNCTION @extschema@.label_unnest(anyarray) TO prom_reader;
 
 ---------------------  comparison functions ---------------------
 
-CREATE OR REPLACE FUNCTION @extschema@.label_find_key_equal(label_key label_key, pattern pattern)
+CREATE OR REPLACE FUNCTION @extschema@.label_find_key_equal(key label_key, pat pattern)
 RETURNS matcher_positive
 AS $func$
     SELECT COALESCE(array_agg(l.id), array[]::int[])::matcher_positive
-    FROM _prom_catalog.label l
-    WHERE l.key = label_key and l.value = pattern
+    FROM label l
+    WHERE l.key = key and l.value = pat
 $func$
 LANGUAGE SQL STABLE PARALLEL SAFE
-SUPPORT const_support;
+SUPPORT @extschema@.const_support;
 GRANT EXECUTE ON FUNCTION @extschema@.label_find_key_equal(label_key, pattern) TO prom_reader;
 
-CREATE OR REPLACE FUNCTION @extschema@.label_find_key_not_equal(key label_key, pattern pattern)
+CREATE OR REPLACE FUNCTION @extschema@.label_find_key_not_equal(key label_key, pat pattern)
 RETURNS matcher_negative
 AS $func$
     SELECT COALESCE(array_agg(l.id), array[]::int[])::matcher_negative
-    FROM _prom_catalog.label l
-    WHERE l.key = key and l.value = pattern
+    FROM label l
+    WHERE l.key = key and l.value = pat
 $func$
 LANGUAGE SQL STABLE PARALLEL SAFE
-SUPPORT const_support;
+SUPPORT @extschema@.const_support;
 GRANT EXECUTE ON FUNCTION @extschema@.label_find_key_not_equal(label_key, pattern) TO prom_reader;
 
-CREATE OR REPLACE FUNCTION @extschema@.label_find_key_regex(key label_key, pattern pattern)
+CREATE OR REPLACE FUNCTION @extschema@.label_find_key_regex(key label_key, pat pattern)
 RETURNS matcher_positive
 AS $func$
     SELECT COALESCE(array_agg(l.id), array[]::int[])::matcher_positive
-    FROM _prom_catalog.label l
-    WHERE l.key = key and l.value ~ pattern
+    FROM label l
+    WHERE l.key = key and l.value ~ pat
 $func$
 LANGUAGE SQL STABLE PARALLEL SAFE
-SUPPORT const_support;
+SUPPORT @extschema@.const_support;
 GRANT EXECUTE ON FUNCTION @extschema@.label_find_key_regex(label_key, pattern) TO prom_reader;
 
-CREATE OR REPLACE FUNCTION @extschema@.label_find_key_not_regex(key label_key, pattern pattern)
+CREATE OR REPLACE FUNCTION @extschema@.label_find_key_not_regex(key label_key, pat pattern)
 RETURNS matcher_negative
 AS $func$
     SELECT COALESCE(array_agg(l.id), array[]::int[])::matcher_negative
-    FROM _prom_catalog.label l
-    WHERE l.key = key and l.value ~ pattern
+    FROM label l
+    WHERE l.key = key and l.value ~ pat
 $func$
 LANGUAGE SQL STABLE PARALLEL SAFE
-SUPPORT const_support;
+SUPPORT @extschema@.const_support;
 GRANT EXECUTE ON FUNCTION @extschema@.label_find_key_not_regex(label_key, pattern) TO prom_reader;
 
 CREATE OPERATOR @extschema@.== (

pkg/internal/testhelpers/containers.go

@@ -10,20 +10,27 @@ import (
 	"io/ioutil"
 	"runtime"
 
+	"os"
+	"path/filepath"
+	"testing"
+
 	"github.com/docker/go-connections/nat"
 	"github.com/jackc/pgx/v4"
 	"github.com/jackc/pgx/v4/pgxpool"
 	_ "github.com/jackc/pgx/v4/stdlib"
 	"github.com/testcontainers/testcontainers-go"
 	"github.com/testcontainers/testcontainers-go/wait"
-	"os"
-	"path/filepath"
-	"testing"
 )
 
 const (
 	defaultDB       = "postgres"
-	connectTemplate = "postgres://postgres:password@%s:%d/%s"
+	connectTemplate = "postgres://%s:password@%s:%d/%s"
+
+	postgresUser = "postgres"
+	promUser     = "prom"
+
+	Superuser   = true
+	NoSuperuser = false
 )
 
 var (
@@ -34,25 +41,31 @@ var (
 	pgPort nat.Port = "5432/tcp"
 )
 
-func pgConnectURL(dbName string) string {
-	return fmt.Sprintf(connectTemplate, pgHost, pgPort.Int(), dbName)
+type SuperuserStatus = bool
+
+func pgConnectURL(dbName string, superuser SuperuserStatus) string {
+	user := postgresUser
+	if !superuser {
+		user = promUser
+	}
+	return fmt.Sprintf(connectTemplate, user, pgHost, pgPort.Int(), dbName)
 }
 
 // WithDB establishes a database for testing and calls the callback
-func WithDB(t testing.TB, DBName string, f func(db *pgxpool.Pool, t testing.TB, connectString string)) {
-	db, err := dbSetup(DBName)
+func WithDB(t testing.TB, DBName string, superuser SuperuserStatus, f func(db *pgxpool.Pool, t testing.TB, connectString string)) {
+	db, err := dbSetup(DBName, superuser)
 	if err != nil {
 		t.Fatal(err)
 		return
 	}
 	defer func() {
 		db.Close()
 	}()
-	f(db, t, pgConnectURL(DBName))
+	f(db, t, pgConnectURL(DBName, superuser))
 }
 
 func GetReadOnlyConnection(t testing.TB, DBName string) *pgxpool.Pool {
-	dbPool, err := pgxpool.Connect(context.Background(), pgConnectURL(DBName))
+	dbPool, err := pgxpool.Connect(context.Background(), pgConnectURL(DBName, NoSuperuser))
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -65,8 +78,8 @@ func GetReadOnlyConnection(t testing.TB, DBName string) *pgxpool.Pool {
 	return dbPool
 }
 
-func dbSetup(DBName string) (*pgxpool.Pool, error) {
-	db, err := pgx.Connect(context.Background(), pgConnectURL(defaultDB))
+func dbSetup(DBName string, superuser SuperuserStatus) (*pgxpool.Pool, error) {
+	db, err := pgx.Connect(context.Background(), pgConnectURL(defaultDB, Superuser))
 	if err != nil {
 		return nil, err
 	}
@@ -76,7 +89,7 @@ func dbSetup(DBName string) (*pgxpool.Pool, error) {
 		return nil, err
 	}
 
-	_, err = db.Exec(context.Background(), fmt.Sprintf("CREATE DATABASE %s", DBName))
+	_, err = db.Exec(context.Background(), fmt.Sprintf("CREATE DATABASE %s OWNER %s", DBName, promUser))
 	if err != nil {
 		return nil, err
 	}
@@ -86,7 +99,7 @@ func dbSetup(DBName string) (*pgxpool.Pool, error) {
 		return nil, err
 	}
 
-	dbPool, err := pgxpool.Connect(context.Background(), pgConnectURL(DBName))
+	dbPool, err := pgxpool.Connect(context.Background(), pgConnectURL(DBName, superuser))
 	if err != nil {
 		return nil, err
 	}
@@ -138,6 +151,21 @@ func StartPGContainer(ctx context.Context, withExtension bool, testDataDir strin
 		return nil, err
 	}
 
+	db, err := pgx.Connect(context.Background(), pgConnectURL(defaultDB, Superuser))
+	if err != nil {
+		return nil, err
+	}
+
+	_, err = db.Exec(context.Background(), fmt.Sprintf("CREATE USER %s WITH NOSUPERUSER CREATEROLE PASSWORD 'password'", promUser))
+	if err != nil {
+		return nil, err
+	}
+
+	err = db.Close(context.Background())
+	if err != nil {
+		return nil, err
+	}
+
 	return container, nil
 }
 

pkg/internal/testhelpers/containers_test.go

@@ -27,7 +27,7 @@ func TestPGConnection(t *testing.T) {
 	if testing.Short() {
 		t.Skip("skipping integration test")
 	}
-	db, err := pgx.Connect(context.Background(), pgConnectURL(defaultDB))
+	db, err := pgx.Connect(context.Background(), pgConnectURL(defaultDB, Superuser))
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -46,7 +46,7 @@ func TestWithDB(t *testing.T) {
 	if testing.Short() {
 		t.Skip("skipping integration test")
 	}
-	WithDB(t, *database, func(db *pgxpool.Pool, t testing.TB, connectURL string) {
+	WithDB(t, *database, Superuser, func(db *pgxpool.Pool, t testing.TB, connectURL string) {
 		var res int
 		err := db.QueryRow(context.Background(), "SELECT 1").Scan(&res)
 		if err != nil {

pkg/pgmodel/migrate.go

@@ -21,8 +21,8 @@ import (
 )
 
 const (
-	extensionInstall = `CREATE EXTENSION "timescale_prometheus_extra" SCHEMA %s;
-`
+	timescaleInstall = "CREATE EXTENSION IF NOT EXISTS timescaledb WITH SCHEMA public;"
+	extensionInstall = "CREATE EXTENSION timescale_prometheus_extra WITH SCHEMA %s;"
 )
 
 type mySrc struct {
@@ -73,9 +73,14 @@ func (t *mySrc) ReadDown(version uint) (r io.ReadCloser, identifier string, err
 func Migrate(db *sql.DB) error {
 	// The migration table will be put in the public schema not in any of our schema because we never want to drop it and
 	// our scripts and our last down script drops our shemas
-	driver, err := postgres.WithInstance(db, &postgres.Config{MigrationsTable: fmt.Sprintf("%s_schema_migrations", promSchema)})
+	driver, err := postgres.WithInstance(db, &postgres.Config{MigrationsTable: "prom_schema_migrations"})
 	if err != nil {
-		return err
+		return fmt.Errorf("cannot create driver due to %w", err)
+	}
+
+	_, err = db.Exec(timescaleInstall)
+	if err != nil {
+		return fmt.Errorf("timescaledb failed to install due to %w", err)
 	}
 
 	src, err := httpfs.New(migrations.SqlFiles, "/")