test: sanity tests for primary and replica

* new --replica option to `postgrest-with-postgresql-*`
* new command `postgrest-test-replica`
* new sanity tests on test_replica.py
* add postgrest-test-replica to postgrest-check and postgrest-coverage

nix/tools/devTools.nix

@@ -77,6 +77,7 @@ let
         ${tests}/bin/postgrest-test-doctests
         ${tests}/bin/postgrest-test-io
         ${tests}/bin/postgrest-test-big-schema
+        ${tests}/bin/postgrest-test-replica
         ${style}/bin/postgrest-lint
         ${style}/bin/postgrest-style-check
       '';

nix/tools/tests.nix

@@ -84,7 +84,7 @@ let
       ''
         ${cabal-install}/bin/cabal v2-build ${devCabalOptions}
         ${cabal-install}/bin/cabal v2-exec -- ${withTools.withPg} -f test/io/fixtures.sql \
-          ${ioTestPython}/bin/pytest --ignore=test/io/test_big_schema.py -v test/io "''${_arg_leftovers[@]}"
+          ${ioTestPython}/bin/pytest --ignore=test/io/test_big_schema.py --ignore=test/io/test_replica.py -v test/io "''${_arg_leftovers[@]}"
       '';
 
   testBigSchema =
@@ -102,6 +102,21 @@ let
           ${ioTestPython}/bin/pytest -v test/io/test_big_schema.py "''${_arg_leftovers[@]}"
       '';
 
+  testReplica =
+    checkedShellScript
+      {
+        name = "postgrest-test-replica";
+        docs = "Run a pytest-based IO test on a replica. Add -k to run tests that match a given expression.";
+        args = [ "ARG_LEFTOVERS([pytest arguments])" ];
+        workingDir = "/";
+        withEnv = postgrest.env;
+      }
+      ''
+        ${cabal-install}/bin/cabal v2-build ${devCabalOptions}
+        ${cabal-install}/bin/cabal v2-exec -- ${withTools.withPg} --replica -f test/io/replica.sql \
+          ${ioTestPython}/bin/pytest -v test/io/test_replica.py "''${_arg_leftovers[@]}"
+      '';
+
   dumpSchema =
     checkedShellScript
       {
@@ -150,12 +165,16 @@ let
           # collect all tests
           HPCTIXFILE="$tmpdir"/io.tix \
             ${withTools.withPg} -f test/io/fixtures.sql \
-            ${cabal-install}/bin/cabal v2-exec ${devCabalOptions} -- ${ioTestPython}/bin/pytest --ignore=test/io/test_big_schema.py -v test/io
+            ${cabal-install}/bin/cabal v2-exec ${devCabalOptions} -- ${ioTestPython}/bin/pytest --ignore=test/io/test_big_schema.py --ignore=test/io/test_replica.py -v test/io
 
           HPCTIXFILE="$tmpdir"/big_schema.tix \
             ${withTools.withPg} -f test/io/big_schema.sql \
             ${cabal-install}/bin/cabal v2-exec ${devCabalOptions} -- ${ioTestPython}/bin/pytest -v test/io/test_big_schema.py
 
+          HPCTIXFILE="$tmpdir"/replica.tix \
+            ${withTools.withPg} --replica -f test/io/replica.sql \
+            ${cabal-install}/bin/cabal v2-exec ${devCabalOptions} -- ${ioTestPython}/bin/pytest -v test/io/test_replica.py
+
           HPCTIXFILE="$tmpdir"/spec.tix \
             ${withTools.withPg} -f test/spec/fixtures/load.sql \
             ${cabal-install}/bin/cabal v2-run ${devCabalOptions} test:spec
@@ -164,7 +183,7 @@ let
 
           # collect all the tix files
           ${ghc}/bin/hpc sum  --union --exclude=Paths_postgrest --output="$tmpdir"/tests.tix \
-            "$tmpdir"/io*.tix "$tmpdir"/big_schema*.tix "$tmpdir"/spec.tix
+            "$tmpdir"/io*.tix "$tmpdir"/big_schema*.tix "$tmpdir"/replica*.tix "$tmpdir"/spec.tix
 
           # prepare the overlay
           ${ghc}/bin/hpc overlay --output="$tmpdir"/overlay.tix test/coverage.overlay
@@ -220,6 +239,7 @@ buildToolbox
       testSpecIdempotence
       testIO
       testBigSchema
+      testReplica
       dumpSchema
       coverage
       coverageDraftOverlay;

nix/tools/withTools.nix

@@ -28,6 +28,7 @@ let
             "ARG_USE_ENV([PGRST_DB_SCHEMAS], [test], [Schema to expose])"
             "ARG_USE_ENV([PGTZ], [utc], [Timezone to use])"
             "ARG_USE_ENV([PGOPTIONS], [-c search_path=public,test], [PG options to use])"
+            "ARG_OPTIONAL_BOOLEAN([replica],, [Enable a replica for the database])"
           ];
         positionalCompletion = "_command";
         workingDir = "/";
@@ -61,6 +62,7 @@ let
           HBA_FILE="$tmpdir/pg_hba.conf"
           echo "local $PGDATABASE some_protected_user password" > "$HBA_FILE"
           echo "local $PGDATABASE all trust" >> "$HBA_FILE"
+          echo "local replication all trust" >> "$HBA_FILE"
 
           log "Initializing database cluster..."
           # We try to make the database cluster as independent as possible from the host
@@ -74,19 +76,50 @@ let
           pg_ctl -l "$tmpdir/db.log" -w start -o "-F -c listen_addresses=\"\" -c hba_file=$HBA_FILE -k $PGHOST -c log_statement=\"all\" " \
             >> "$setuplog"
 
-          # shellcheck disable=SC2317
-          stop () {
-            log "Stopping the database cluster..."
-            pg_ctl stop -m i >> "$setuplog"
-            rm -rf "$tmpdir/db"
-          }
-          trap stop EXIT
-
           log "Creating a minimally privileged $PGUSER connection role..."
           createuser "$PGUSER" -U postgres --host="$tmpdir/socket" --no-createdb --no-inherit --no-superuser --no-createrole --no-replication --login
 
-          >&2 echo "${commandName}: You can connect with: psql 'postgres:///$PGDATABASE?host=$tmpdir/socket' -U postgres"
+          >&2 echo "${commandName}: You can connect with: psql 'postgres:///$PGDATABASE?host=$PGHOST' -U postgres"
           >&2 echo "${commandName}: You can tail the logs with: tail -f $tmpdir/db.log"
+
+          if test "$_arg_replica" = "on"; then
+            replica_slot="replica_$RANDOM"
+            replica_dir="$tmpdir/$replica_slot"
+            replica_host="$tmpdir/socket_$replica_slot"
+
+            mkdir -p "$replica_host"
+
+            replica_dblog="$tmpdir/db_$replica_slot.log"
+
+            log "Running pg_basebackup for $replica_slot"
+
+            pg_basebackup -v -h "$PGHOST" -U postgres --wal-method=stream --create-slot --slot="$replica_slot" --write-recovery-conf -D "$replica_dir" \
+              >> "$setuplog" 2>&1
+
+            log "Starting replica on $replica_host"
+
+            pg_ctl -D "$replica_dir" -l "$replica_dblog" -w start -o "-F -c listen_addresses=\"\" -c hba_file=$HBA_FILE -k $replica_host -c log_statement=\"all\" " \
+              >> "$setuplog"
+
+            >&2 echo "${commandName}: Replica enabled. You can connect to it with: psql 'postgres:///$PGDATABASE?host=$replica_host' -U postgres"
+            >&2 echo "${commandName}: You can tail the replica logs with: tail -f $replica_dblog"
+
+            export PGREPLICAHOST="$replica_host"
+            export PGREPLICASLOT="$replica_slot"
+          fi
+
+          # shellcheck disable=SC2317
+          stop () {
+            log "Stopping the database cluster..."
+            pg_ctl stop --mode=immediate >> "$setuplog"
+            rm -rf "$tmpdir/db"
+            if test "$_arg_replica" = "on"; then
+              log "Stopping the replica cluster..."
+              pg_ctl -D "$replica_dir" stop --mode=immediate >> "$setuplog"
+              rm -rf "$replica_dir"
+            fi
+          }
+          trap stop EXIT
         fi
 
         if test "$_arg_fixtures"; then

test/io/config.py

@@ -45,6 +45,27 @@ def defaultenv(baseenv):
     }
 
 
+@pytest.fixture
+def replicaenv(defaultenv):
+    "Default environment for a PostgREST replica."
+    conf = {
+        "PGRST_DB_ANON_ROLE": "postgrest_test_anonymous",
+        "PGRST_DB_SCHEMAS": "replica",
+    }
+    return {
+        "primary": {
+            **defaultenv,
+            **conf,
+        },
+        "replica": {
+            **defaultenv,
+            **conf,
+            "PGHOST": os.environ["PGREPLICAHOST"],
+            "PGREPLICASLOT": os.environ["PGREPLICASLOT"],
+        },
+    }
+
+
 @pytest.fixture
 def slow_schema_cache_env(defaultenv):
     "Slow schema cache load environment PostgREST."

test/io/replica.sql

@@ -0,0 +1,21 @@
+create schema replica;
+
+create or replace function replica.is_replica() returns bool as $$
+  select pg_is_in_recovery();
+$$ language sql;
+
+create or replace function replica.get_replica_slot() returns name as $$
+  select slot_name from pg_replication_slots limit 1;
+$$ language sql;
+
+create table replica.items as select x as id from generate_series(1, 10) x;
+
+DROP ROLE IF EXISTS postgrest_test_anonymous;
+CREATE ROLE postgrest_test_anonymous;
+
+GRANT postgrest_test_anonymous TO :PGUSER;
+
+GRANT USAGE ON SCHEMA replica TO postgrest_test_anonymous;
+
+GRANT ALL PRIVILEGES ON ALL TABLES IN SCHEMA replica
+TO postgrest_test_anonymous;

test/io/test_replica.py

@@ -0,0 +1,28 @@
+"IO tests for PostgREST started on replicas"
+
+import pytest
+
+from config import *
+from util import *
+from postgrest import *
+
+
+def test_sanity_replica(replicaenv):
+    "Test that primary and replica are working as intended"
+
+    with run(env=replicaenv["primary"]) as postgrest:
+        response = postgrest.session.get("/rpc/is_replica")
+        assert response.text == "false"
+
+        response = postgrest.session.get("/rpc/get_replica_slot")
+        assert response.text == '"' + replicaenv["replica"]["PGREPLICASLOT"] + '"'
+
+        response = postgrest.session.get("/items?select=count")
+        assert response.text == '[{"count":10}]'
+
+    with run(env=replicaenv["replica"]) as postgrest:
+        response = postgrest.session.get("/rpc/is_replica")
+        assert response.text == "true"
+
+        response = postgrest.session.get("/items?select=count")
+        assert response.text == '[{"count":10}]'