Merge pull request #435 from databasus/develop

FEATURE (agent): Add postgres verification and e2e tests for agent
2026-04-06 00:32:03 +02:00 · 2026-03-14 12:43:51 +03:00
parent 1b011bdcd4 0ffc7c8c96
commit d98acfc4af
24 changed files with 965 additions and 47 deletions
--- a/.github/workflows/ci-release.yml
+++ b/.github/workflows/ci-release.yml
@@ -164,6 +164,25 @@ jobs:
          cd agent
          go test -count=1 -failfast ./internal/...

+  e2e-agent:
+    runs-on: self-hosted
+    needs: [lint-agent]
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v4
+
+      - name: Run e2e tests
+        run: |
+          cd agent
+          make e2e
+
+      - name: Cleanup
+        if: always()
+        run: |
+          cd agent/e2e
+          docker compose down -v --rmi local || true
+          rm -rf artifacts || true
+
  test-backend:
    runs-on: self-hosted
    needs: [lint-backend]
@@ -497,7 +516,7 @@ jobs:
    runs-on: self-hosted
    container:
      image: node:20
-    needs: [test-backend, test-frontend, test-agent]
+    needs: [test-backend, test-frontend, test-agent, e2e-agent]
    if: ${{ github.ref == 'refs/heads/main' && !contains(github.event.head_commit.message, '[skip-release]') }}
    outputs:
      should_release: ${{ steps.version_bump.outputs.should_release }}
@@ -590,7 +609,7 @@ jobs:

  build-only:
    runs-on: self-hosted
-    needs: [test-backend, test-frontend, test-agent]
+    needs: [test-backend, test-frontend, test-agent, e2e-agent]
    if: ${{ github.ref == 'refs/heads/main' && contains(github.event.head_commit.message, '[skip-release]') }}
    steps:
      - name: Clean workspace
--- a/agent/Makefile
+++ b/agent/Makefile
@@ -1,3 +1,5 @@
+.PHONY: run build test lint e2e e2e-clean
+
 # Usage: make run ARGS="start --pg-host localhost"
 run:
 	go run cmd/main.go $(ARGS)
@@ -10,3 +12,15 @@ test:

 lint:
 	golangci-lint fmt ./cmd/... ./internal/... && golangci-lint run ./cmd/... ./internal/...
+
+e2e:
+	cd e2e && docker compose build
+	cd e2e && docker compose run --rm e2e-agent-builder
+	cd e2e && docker compose up -d e2e-postgres e2e-mock-server
+	cd e2e && docker compose run --rm e2e-agent-runner
+	cd e2e && docker compose run --rm e2e-agent-docker
+	cd e2e && docker compose down -v
+
+e2e-clean:
+	cd e2e && docker compose down -v --rmi local
+	rm -rf e2e/artifacts
--- a/agent/cmd/main.go
+++ b/agent/cmd/main.go
@@ -3,6 +3,7 @@ package main
 import (
 	"flag"
 	"fmt"
+	"log/slog"
 	"os"
 	"path/filepath"
 	"strings"
@@ -116,12 +117,7 @@ func printUsage() {
 	fmt.Fprintln(os.Stderr, "  version  Print agent version")
 }

-func runUpdateCheck(host string, isSkipUpdate, isDev bool, log interface {
-	Info(string, ...any)
-	Warn(string, ...any)
-	Error(string, ...any)
-},
-) {
+func runUpdateCheck(host string, isSkipUpdate, isDev bool, log *slog.Logger) {
 	if isSkipUpdate {
 		return
 	}
--- a/agent/e2e/.gitignore
+++ b/agent/e2e/.gitignore
@@ -0,0 +1 @@
+artifacts/
--- a/agent/e2e/Dockerfile.agent-builder
+++ b/agent/e2e/Dockerfile.agent-builder
@@ -0,0 +1,13 @@
+# Builds agent binaries with different versions so
+# we can test upgrade behavior (v1 -> v2)
+FROM golang:1.26.1-alpine AS build
+WORKDIR /src
+COPY go.mod go.sum ./
+RUN go mod download
+COPY . .
+RUN CGO_ENABLED=0 go build -ldflags "-X main.Version=v1.0.0" -o /out/agent-v1 ./cmd/main.go
+RUN CGO_ENABLED=0 go build -ldflags "-X main.Version=v2.0.0" -o /out/agent-v2 ./cmd/main.go
+
+FROM alpine:3.21
+COPY --from=build /out/ /out/
+CMD ["cp", "-v", "/out/agent-v1", "/out/agent-v2", "/artifacts/"]
--- a/agent/e2e/Dockerfile.agent-docker
+++ b/agent/e2e/Dockerfile.agent-docker
@@ -0,0 +1,8 @@
+# Runs pg_basebackup-via-docker-exec test (test 5) which tests
+# that the agent can connect to Postgres inside Docker container
+FROM docker:27-cli
+
+RUN apk add --no-cache bash curl
+
+WORKDIR /tmp
+ENTRYPOINT []
--- a/agent/e2e/Dockerfile.agent-runner
+++ b/agent/e2e/Dockerfile.agent-runner
@@ -0,0 +1,14 @@
+# Runs upgrade and host-mode pg_basebackup tests (tests 1-4). Needs
+# Postgres client tools to be installed inside the system
+FROM debian:bookworm-slim
+
+RUN apt-get update && \
+    apt-get install -y --no-install-recommends \
+      ca-certificates curl gnupg2 postgresql-common && \
+    /usr/share/postgresql-common/pgdg/apt.postgresql.org.sh -y && \
+    apt-get install -y --no-install-recommends \
+      postgresql-client-17 && \
+    rm -rf /var/lib/apt/lists/*
+
+WORKDIR /tmp
+ENTRYPOINT []
--- a/agent/e2e/Dockerfile.mock-server
+++ b/agent/e2e/Dockerfile.mock-server
@@ -0,0 +1,10 @@
+# Mock databasus API server for version checks and binary downloads. Just
+# serves static responses and files from the `artifacts` directory.
+FROM golang:1.26.1-alpine AS build
+WORKDIR /app
+COPY mock-server/main.go .
+RUN CGO_ENABLED=0 go build -o mock-server main.go
+
+FROM alpine:3.21
+COPY --from=build /app/mock-server /usr/local/bin/mock-server
+ENTRYPOINT ["mock-server"]
--- a/agent/e2e/mock-server/main.go
+++ b/agent/e2e/mock-server/main.go
@@ -0,0 +1,84 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"log"
+	"net/http"
+	"sync"
+)
+
+type server struct {
+	mu         sync.RWMutex
+	version    string
+	binaryPath string
+}
+
+func main() {
+	version := "v2.0.0"
+	binaryPath := "/artifacts/agent-v2"
+	port := "4050"
+
+	s := &server{version: version, binaryPath: binaryPath}
+
+	http.HandleFunc("/api/v1/system/version", s.handleVersion)
+	http.HandleFunc("/api/v1/system/agent", s.handleAgentDownload)
+	http.HandleFunc("/mock/set-version", s.handleSetVersion)
+	http.HandleFunc("/health", s.handleHealth)
+
+	addr := ":" + port
+	log.Printf("Mock server starting on %s (version=%s, binary=%s)", addr, version, binaryPath)
+
+	if err := http.ListenAndServe(addr, nil); err != nil {
+		log.Fatalf("Server failed: %v", err)
+	}
+}
+
+func (s *server) handleVersion(w http.ResponseWriter, r *http.Request) {
+	s.mu.RLock()
+	v := s.version
+	s.mu.RUnlock()
+
+	log.Printf("GET /api/v1/system/version -> %s", v)
+
+	w.Header().Set("Content-Type", "application/json")
+	_ = json.NewEncoder(w).Encode(map[string]string{"version": v})
+}
+
+func (s *server) handleAgentDownload(w http.ResponseWriter, r *http.Request) {
+	s.mu.RLock()
+	path := s.binaryPath
+	s.mu.RUnlock()
+
+	log.Printf("GET /api/v1/system/agent (arch=%s) -> serving %s", r.URL.Query().Get("arch"), path)
+
+	http.ServeFile(w, r, path)
+}
+
+func (s *server) handleSetVersion(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		http.Error(w, "POST only", http.StatusMethodNotAllowed)
+		return
+	}
+
+	var body struct {
+		Version string `json:"version"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+
+	s.mu.Lock()
+	s.version = body.Version
+	s.mu.Unlock()
+
+	log.Printf("POST /mock/set-version -> %s", body.Version)
+
+	fmt.Fprintf(w, "version set to %s", body.Version)
+}
+
+func (s *server) handleHealth(w http.ResponseWriter, _ *http.Request) {
+	w.WriteHeader(http.StatusOK)
+	_, _ = w.Write([]byte("ok"))
+}
--- a/agent/e2e/scripts/run-all.sh
+++ b/agent/e2e/scripts/run-all.sh
@@ -0,0 +1,48 @@
+#!/bin/bash
+set -euo pipefail
+
+MODE="${1:-host}"
+SCRIPT_DIR="$(dirname "$0")"
+PASSED=0
+FAILED=0
+
+run_test() {
+  local name="$1"
+  local script="$2"
+
+  echo ""
+  echo "========================================"
+  echo "  $name"
+  echo "========================================"
+
+  if bash "$script"; then
+    echo "  PASSED: $name"
+    PASSED=$((PASSED + 1))
+  else
+    echo "  FAILED: $name"
+    FAILED=$((FAILED + 1))
+  fi
+}
+
+if [ "$MODE" = "host" ]; then
+  run_test "Test 1: Upgrade success (v1 -> v2)" "$SCRIPT_DIR/test-upgrade-success.sh"
+  run_test "Test 2: Upgrade skip (version matches)" "$SCRIPT_DIR/test-upgrade-skip.sh"
+  run_test "Test 3: pg_basebackup in PATH" "$SCRIPT_DIR/test-pg-host-path.sh"
+  run_test "Test 4: pg_basebackup via bindir" "$SCRIPT_DIR/test-pg-host-bindir.sh"
+
+elif [ "$MODE" = "docker" ]; then
+  run_test "Test 5: pg_basebackup via docker exec" "$SCRIPT_DIR/test-pg-docker-exec.sh"
+
+else
+  echo "Unknown mode: $MODE (expected 'host' or 'docker')"
+  exit 1
+fi
+
+echo ""
+echo "========================================"
+echo "  Results: $PASSED passed, $FAILED failed"
+echo "========================================"
+
+if [ "$FAILED" -gt 0 ]; then
+  exit 1
+fi
--- a/agent/e2e/scripts/test-pg-docker-exec.sh
+++ b/agent/e2e/scripts/test-pg-docker-exec.sh
@@ -0,0 +1,51 @@
+#!/bin/bash
+set -euo pipefail
+
+ARTIFACTS="/opt/agent/artifacts"
+AGENT="/tmp/test-agent"
+PG_CONTAINER="e2e-agent-postgres"
+
+# Copy agent binary
+cp "$ARTIFACTS/agent-v1" "$AGENT"
+chmod +x "$AGENT"
+
+# Verify docker CLI works and PG container is accessible
+if ! docker exec "$PG_CONTAINER" pg_basebackup --version > /dev/null 2>&1; then
+  echo "FAIL: Cannot reach pg_basebackup inside container $PG_CONTAINER (test setup issue)"
+  exit 1
+fi
+
+# Run start with --skip-update and pg-type=docker
+echo "Running agent start (pg_basebackup via docker exec)..."
+OUTPUT=$("$AGENT" start \
+  --skip-update \
+  --databasus-host http://e2e-mock-server:4050 \
+  --db-id test-db-id \
+  --token test-token \
+  --pg-host e2e-postgres \
+  --pg-port 5432 \
+  --pg-user testuser \
+  --pg-password testpassword \
+  --wal-dir /tmp/wal \
+  --pg-type docker \
+  --pg-docker-container-name "$PG_CONTAINER" 2>&1)
+
+EXIT_CODE=$?
+echo "$OUTPUT"
+
+if [ "$EXIT_CODE" -ne 0 ]; then
+  echo "FAIL: Agent exited with code $EXIT_CODE"
+  exit 1
+fi
+
+if ! echo "$OUTPUT" | grep -q "pg_basebackup verified (docker)"; then
+  echo "FAIL: Expected output to contain 'pg_basebackup verified (docker)'"
+  exit 1
+fi
+
+if ! echo "$OUTPUT" | grep -q "PostgreSQL connection verified"; then
+  echo "FAIL: Expected output to contain 'PostgreSQL connection verified'"
+  exit 1
+fi
+
+echo "pg_basebackup found via docker exec and DB connection verified"
--- a/agent/e2e/scripts/test-pg-host-bindir.sh
+++ b/agent/e2e/scripts/test-pg-host-bindir.sh
@@ -0,0 +1,57 @@
+#!/bin/bash
+set -euo pipefail
+
+ARTIFACTS="/opt/agent/artifacts"
+AGENT="/tmp/test-agent"
+CUSTOM_BIN_DIR="/opt/pg/bin"
+
+# Copy agent binary
+cp "$ARTIFACTS/agent-v1" "$AGENT"
+chmod +x "$AGENT"
+
+# Move pg_basebackup out of PATH into custom directory
+mkdir -p "$CUSTOM_BIN_DIR"
+cp "$(which pg_basebackup)" "$CUSTOM_BIN_DIR/pg_basebackup"
+
+# Hide the system one by prepending an empty dir to PATH
+export PATH="/opt/empty-path:$PATH"
+mkdir -p /opt/empty-path
+
+# Verify pg_basebackup is NOT directly callable from default location
+# (we copied it, but the original is still there in debian — so we test
+# that the agent uses the custom dir, not PATH, by checking the output)
+
+# Run start with --skip-update and custom bin dir
+echo "Running agent start (pg_basebackup via --pg-host-bin-dir)..."
+OUTPUT=$("$AGENT" start \
+  --skip-update \
+  --databasus-host http://e2e-mock-server:4050 \
+  --db-id test-db-id \
+  --token test-token \
+  --pg-host e2e-postgres \
+  --pg-port 5432 \
+  --pg-user testuser \
+  --pg-password testpassword \
+  --wal-dir /tmp/wal \
+  --pg-type host \
+  --pg-host-bin-dir "$CUSTOM_BIN_DIR" 2>&1)
+
+EXIT_CODE=$?
+echo "$OUTPUT"
+
+if [ "$EXIT_CODE" -ne 0 ]; then
+  echo "FAIL: Agent exited with code $EXIT_CODE"
+  exit 1
+fi
+
+if ! echo "$OUTPUT" | grep -q "pg_basebackup verified"; then
+  echo "FAIL: Expected output to contain 'pg_basebackup verified'"
+  exit 1
+fi
+
+if ! echo "$OUTPUT" | grep -q "PostgreSQL connection verified"; then
+  echo "FAIL: Expected output to contain 'PostgreSQL connection verified'"
+  exit 1
+fi
+
+echo "pg_basebackup found via custom bin dir and DB connection verified"
--- a/agent/e2e/scripts/test-pg-host-path.sh
+++ b/agent/e2e/scripts/test-pg-host-path.sh
@@ -0,0 +1,49 @@
+#!/bin/bash
+set -euo pipefail
+
+ARTIFACTS="/opt/agent/artifacts"
+AGENT="/tmp/test-agent"
+
+# Copy agent binary
+cp "$ARTIFACTS/agent-v1" "$AGENT"
+chmod +x "$AGENT"
+
+# Verify pg_basebackup is in PATH
+if ! which pg_basebackup > /dev/null 2>&1; then
+  echo "FAIL: pg_basebackup not found in PATH (test setup issue)"
+  exit 1
+fi
+
+# Run start with --skip-update and pg-type=host
+echo "Running agent start (pg_basebackup in PATH)..."
+OUTPUT=$("$AGENT" start \
+  --skip-update \
+  --databasus-host http://e2e-mock-server:4050 \
+  --db-id test-db-id \
+  --token test-token \
+  --pg-host e2e-postgres \
+  --pg-port 5432 \
+  --pg-user testuser \
+  --pg-password testpassword \
+  --wal-dir /tmp/wal \
+  --pg-type host 2>&1)
+
+EXIT_CODE=$?
+echo "$OUTPUT"
+
+if [ "$EXIT_CODE" -ne 0 ]; then
+  echo "FAIL: Agent exited with code $EXIT_CODE"
+  exit 1
+fi
+
+if ! echo "$OUTPUT" | grep -q "pg_basebackup verified"; then
+  echo "FAIL: Expected output to contain 'pg_basebackup verified'"
+  exit 1
+fi
+
+if ! echo "$OUTPUT" | grep -q "PostgreSQL connection verified"; then
+  echo "FAIL: Expected output to contain 'PostgreSQL connection verified'"
+  exit 1
+fi
+
+echo "pg_basebackup found in PATH and DB connection verified"
--- a/agent/e2e/scripts/test-upgrade-skip.sh
+++ b/agent/e2e/scripts/test-upgrade-skip.sh
@@ -0,0 +1,51 @@
+#!/bin/bash
+set -euo pipefail
+
+ARTIFACTS="/opt/agent/artifacts"
+AGENT="/tmp/test-agent"
+
+# Set mock server to return v1.0.0 (same as agent)
+curl -sf -X POST http://e2e-mock-server:4050/mock/set-version \
+  -H "Content-Type: application/json" \
+  -d '{"version":"v1.0.0"}'
+
+# Copy v1 binary to writable location
+cp "$ARTIFACTS/agent-v1" "$AGENT"
+chmod +x "$AGENT"
+
+# Verify initial version
+VERSION=$("$AGENT" version)
+if [ "$VERSION" != "v1.0.0" ]; then
+  echo "FAIL: Expected initial version v1.0.0, got $VERSION"
+  exit 1
+fi
+
+# Run start — agent should see version matches and skip upgrade
+echo "Running agent start (expecting upgrade skip)..."
+OUTPUT=$("$AGENT" start \
+  --databasus-host http://e2e-mock-server:4050 \
+  --db-id test-db-id \
+  --token test-token \
+  --pg-host e2e-postgres \
+  --pg-port 5432 \
+  --pg-user testuser \
+  --pg-password testpassword \
+  --wal-dir /tmp/wal \
+  --pg-type host 2>&1) || true
+
+echo "$OUTPUT"
+
+# Verify output contains "up to date"
+if ! echo "$OUTPUT" | grep -qi "up to date"; then
+  echo "FAIL: Expected output to contain 'up to date'"
+  exit 1
+fi
+
+# Verify binary is still v1
+VERSION=$("$AGENT" version)
+if [ "$VERSION" != "v1.0.0" ]; then
+  echo "FAIL: Expected version v1.0.0 (unchanged), got $VERSION"
+  exit 1
+fi
+
+echo "Upgrade correctly skipped, version still $VERSION"
--- a/agent/e2e/scripts/test-upgrade-success.sh
+++ b/agent/e2e/scripts/test-upgrade-success.sh
@@ -0,0 +1,52 @@
+#!/bin/bash
+set -euo pipefail
+
+ARTIFACTS="/opt/agent/artifacts"
+AGENT="/tmp/test-agent"
+
+# Ensure mock server returns v2.0.0
+curl -sf -X POST http://e2e-mock-server:4050/mock/set-version \
+  -H "Content-Type: application/json" \
+  -d '{"version":"v2.0.0"}'
+
+# Copy v1 binary to writable location
+cp "$ARTIFACTS/agent-v1" "$AGENT"
+chmod +x "$AGENT"
+
+# Verify initial version
+VERSION=$("$AGENT" version)
+if [ "$VERSION" != "v1.0.0" ]; then
+  echo "FAIL: Expected initial version v1.0.0, got $VERSION"
+  exit 1
+fi
+echo "Initial version: $VERSION"
+
+# Run start — agent will:
+# 1. Fetch version from mock (v2.0.0 != v1.0.0)
+# 2. Download v2 binary from mock
+# 3. Replace itself on disk
+# 4. Re-exec with same args
+# 5. Re-exec'd v2 fetches version (v2.0.0 == v2.0.0) → skips update
+# 6. Proceeds to start → verifies pg_basebackup + DB → exits 0 (stub)
+echo "Running agent start (expecting upgrade v1 -> v2)..."
+OUTPUT=$("$AGENT" start \
+  --databasus-host http://e2e-mock-server:4050 \
+  --db-id test-db-id \
+  --token test-token \
+  --pg-host e2e-postgres \
+  --pg-port 5432 \
+  --pg-user testuser \
+  --pg-password testpassword \
+  --wal-dir /tmp/wal \
+  --pg-type host 2>&1) || true
+
+echo "$OUTPUT"
+
+# Verify binary on disk is now v2
+VERSION=$("$AGENT" version)
+if [ "$VERSION" != "v2.0.0" ]; then
+  echo "FAIL: Expected upgraded version v2.0.0, got $VERSION"
+  exit 1
+fi
+
+echo "Binary upgraded successfully to $VERSION"
--- a/agent/go.mod
+++ b/agent/go.mod
@@ -2,10 +2,18 @@ module databasus-agent

 go 1.26.1

-require github.com/stretchr/testify v1.11.1
+require (
+	github.com/jackc/pgx/v5 v5.8.0
+	github.com/stretchr/testify v1.11.1
+)

 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/jackc/pgpassfile v1.0.0 // indirect
+	github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 // indirect
+	github.com/kr/text v0.2.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/rogpeppe/go-internal v1.14.1 // indirect
+	golang.org/x/text v0.29.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
--- a/agent/go.sum
+++ b/agent/go.sum
@@ -1,10 +1,35 @@
+github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/jackc/pgpassfile v1.0.0 h1:/6Hmqy13Ss2zCq62VdNG8tM1wchn8zjSGOBJ6icpsIM=
+github.com/jackc/pgpassfile v1.0.0/go.mod h1:CEx0iS5ambNFdcRtxPj5JhEz+xB6uRky5eyVu/W2HEg=
+github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 h1:iCEnooe7UlwOQYpKFhBabPMi4aNAfoODPEFNiAnClxo=
+github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761/go.mod h1:5TJZWKEWniPve33vlWYSoGYefn3gLQRzjfDlhSJ9ZKM=
+github.com/jackc/pgx/v5 v5.8.0 h1:TYPDoleBBme0xGSAX3/+NujXXtpZn9HBONkQC7IEZSo=
+github.com/jackc/pgx/v5 v5.8.0/go.mod h1:QVeDInX2m9VyzvNeiCJVjCkNFqzsNb43204HshNSZKw=
+github.com/jackc/puddle/v2 v2.2.2 h1:PR8nw+E/1w0GLuRFSmiioY6UooMp6KJv0/61nB7icHo=
+github.com/jackc/puddle/v2 v2.2.2/go.mod h1:vriiEXHvEE654aYKXXjOvZM39qJ0q+azkZFrfEOc3H4=
+github.com/kr/pretty v0.3.0 h1:WgNl7dwNpEZ6jJ9k1snq4pZsg7DOEN8hP9Xw0Tsjwk0=
+github.com/kr/pretty v0.3.0/go.mod h1:640gp4NfQd8pI5XOwp5fnNeVWj67G7CFk/SaSQn7NBk=
+github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
+github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/rogpeppe/go-internal v1.14.1 h1:UQB4HGPB6osV0SQTLymcB4TgvyWu6ZyliaW0tI/otEQ=
+github.com/rogpeppe/go-internal v1.14.1/go.mod h1:MaRKkUm5W0goXpeCfT7UZI6fk/L7L7so1lCWt35ZSgc=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
 github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+golang.org/x/sync v0.17.0 h1:l60nONMj9l5drqw6jlhIELNv9I0A4OFgRsG9k2oT9Ug=
+golang.org/x/sync v0.17.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
+golang.org/x/text v0.29.0 h1:1neNs90w9YzJ9BocxfsQNHKuAT4pkghyXc4nhZ6sJvk=
+golang.org/x/text v0.29.0/go.mod h1:7MhJOA9CD2qZyOKYazxdYMF85OwPdEr9jTtBpO7ydH4=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
--- a/agent/internal/config/config.go
+++ b/agent/internal/config/config.go
@@ -3,6 +3,7 @@ package config
 import (
 	"encoding/json"
 	"flag"
+	"fmt"
 	"os"

 	"databasus-agent/internal/logger"
@@ -13,9 +14,18 @@ var log = logger.GetLogger()
 const configFileName = "databasus.json"

 type Config struct {
-	DatabasusHost string `json:"databasusHost"`
-	DbID          string `json:"dbId"`
-	Token         string `json:"token"`
+	DatabasusHost          string `json:"databasusHost"`
+	DbID                   string `json:"dbId"`
+	Token                  string `json:"token"`
+	PgHost                 string `json:"pgHost"`
+	PgPort                 int    `json:"pgPort"`
+	PgUser                 string `json:"pgUser"`
+	PgPassword             string `json:"pgPassword"`
+	PgType                 string `json:"pgType"`
+	PgHostBinDir           string `json:"pgHostBinDir"`
+	PgDockerContainerName  string `json:"pgDockerContainerName"`
+	WalDir                 string `json:"walDir"`
+	IsDeleteWalAfterUpload *bool  `json:"deleteWalAfterUpload"`

 	flags parsedFlags
 }
@@ -24,15 +34,24 @@ type Config struct {
 // and overrides JSON values with any explicitly provided CLI flags.
 func (c *Config) LoadFromJSONAndArgs(fs *flag.FlagSet, args []string) {
 	c.loadFromJSON()
+	c.applyDefaults()
 	c.initSources()

-	c.flags.host = fs.String(
+	c.flags.databasusHost = fs.String(
 		"databasus-host",
 		"",
 		"Databasus server URL (e.g. http://your-server:4005)",
 	)
 	c.flags.dbID = fs.String("db-id", "", "Database ID")
 	c.flags.token = fs.String("token", "", "Agent token")
+	c.flags.pgHost = fs.String("pg-host", "", "PostgreSQL host")
+	c.flags.pgPort = fs.Int("pg-port", 0, "PostgreSQL port")
+	c.flags.pgUser = fs.String("pg-user", "", "PostgreSQL user")
+	c.flags.pgPassword = fs.String("pg-password", "", "PostgreSQL password")
+	c.flags.pgType = fs.String("pg-type", "", "PostgreSQL type: host or docker")
+	c.flags.pgHostBinDir = fs.String("pg-host-bin-dir", "", "Path to PG bin directory (host mode)")
+	c.flags.pgDockerContainerName = fs.String("pg-docker-container-name", "", "Docker container name (docker mode)")
+	c.flags.walDir = fs.String("wal-dir", "", "Path to WAL queue directory")

 	if err := fs.Parse(args); err != nil {
 		os.Exit(1)
@@ -76,11 +95,35 @@ func (c *Config) loadFromJSON() {
 	log.Info("Configuration loaded from " + configFileName)
 }

+func (c *Config) applyDefaults() {
+	if c.PgPort == 0 {
+		c.PgPort = 5432
+	}
+
+	if c.PgType == "" {
+		c.PgType = "host"
+	}
+
+	if c.IsDeleteWalAfterUpload == nil {
+		v := true
+		c.IsDeleteWalAfterUpload = &v
+	}
+}
+
 func (c *Config) initSources() {
 	c.flags.sources = map[string]string{
-		"databasus-host": "not configured",
-		"db-id":          "not configured",
-		"token":          "not configured",
+		"databasus-host":           "not configured",
+		"db-id":                    "not configured",
+		"token":                    "not configured",
+		"pg-host":                  "not configured",
+		"pg-port":                  "not configured",
+		"pg-user":                  "not configured",
+		"pg-password":              "not configured",
+		"pg-type":                  "not configured",
+		"pg-host-bin-dir":          "not configured",
+		"pg-docker-container-name": "not configured",
+		"wal-dir":                  "not configured",
+		"delete-wal-after-upload":  "not configured",
 	}

 	if c.DatabasusHost != "" {
@@ -94,11 +137,44 @@ func (c *Config) initSources() {
 	if c.Token != "" {
 		c.flags.sources["token"] = configFileName
 	}
+
+	if c.PgHost != "" {
+		c.flags.sources["pg-host"] = configFileName
+	}
+
+	// PgPort always has a value after applyDefaults
+	c.flags.sources["pg-port"] = configFileName
+
+	if c.PgUser != "" {
+		c.flags.sources["pg-user"] = configFileName
+	}
+
+	if c.PgPassword != "" {
+		c.flags.sources["pg-password"] = configFileName
+	}
+
+	// PgType always has a value after applyDefaults
+	c.flags.sources["pg-type"] = configFileName
+
+	if c.PgHostBinDir != "" {
+		c.flags.sources["pg-host-bin-dir"] = configFileName
+	}
+
+	if c.PgDockerContainerName != "" {
+		c.flags.sources["pg-docker-container-name"] = configFileName
+	}
+
+	if c.WalDir != "" {
+		c.flags.sources["wal-dir"] = configFileName
+	}
+
+	// IsDeleteWalAfterUpload always has a value after applyDefaults
+	c.flags.sources["delete-wal-after-upload"] = configFileName
 }

 func (c *Config) applyFlags() {
-	if c.flags.host != nil && *c.flags.host != "" {
-		c.DatabasusHost = *c.flags.host
+	if c.flags.databasusHost != nil && *c.flags.databasusHost != "" {
+		c.DatabasusHost = *c.flags.databasusHost
 		c.flags.sources["databasus-host"] = "command line args"
 	}

@@ -111,18 +187,73 @@ func (c *Config) applyFlags() {
 		c.Token = *c.flags.token
 		c.flags.sources["token"] = "command line args"
 	}
+
+	if c.flags.pgHost != nil && *c.flags.pgHost != "" {
+		c.PgHost = *c.flags.pgHost
+		c.flags.sources["pg-host"] = "command line args"
+	}
+
+	if c.flags.pgPort != nil && *c.flags.pgPort != 0 {
+		c.PgPort = *c.flags.pgPort
+		c.flags.sources["pg-port"] = "command line args"
+	}
+
+	if c.flags.pgUser != nil && *c.flags.pgUser != "" {
+		c.PgUser = *c.flags.pgUser
+		c.flags.sources["pg-user"] = "command line args"
+	}
+
+	if c.flags.pgPassword != nil && *c.flags.pgPassword != "" {
+		c.PgPassword = *c.flags.pgPassword
+		c.flags.sources["pg-password"] = "command line args"
+	}
+
+	if c.flags.pgType != nil && *c.flags.pgType != "" {
+		c.PgType = *c.flags.pgType
+		c.flags.sources["pg-type"] = "command line args"
+	}
+
+	if c.flags.pgHostBinDir != nil && *c.flags.pgHostBinDir != "" {
+		c.PgHostBinDir = *c.flags.pgHostBinDir
+		c.flags.sources["pg-host-bin-dir"] = "command line args"
+	}
+
+	if c.flags.pgDockerContainerName != nil && *c.flags.pgDockerContainerName != "" {
+		c.PgDockerContainerName = *c.flags.pgDockerContainerName
+		c.flags.sources["pg-docker-container-name"] = "command line args"
+	}
+
+	if c.flags.walDir != nil && *c.flags.walDir != "" {
+		c.WalDir = *c.flags.walDir
+		c.flags.sources["wal-dir"] = "command line args"
+	}
 }

 func (c *Config) logConfigSources() {
-	log.Info(
-		"databasus-host",
-		"value",
-		c.DatabasusHost,
-		"source",
-		c.flags.sources["databasus-host"],
-	)
+	log.Info("databasus-host", "value", c.DatabasusHost, "source", c.flags.sources["databasus-host"])
 	log.Info("db-id", "value", c.DbID, "source", c.flags.sources["db-id"])
 	log.Info("token", "value", maskSensitive(c.Token), "source", c.flags.sources["token"])
+	log.Info("pg-host", "value", c.PgHost, "source", c.flags.sources["pg-host"])
+	log.Info("pg-port", "value", c.PgPort, "source", c.flags.sources["pg-port"])
+	log.Info("pg-user", "value", c.PgUser, "source", c.flags.sources["pg-user"])
+	log.Info("pg-password", "value", maskSensitive(c.PgPassword), "source", c.flags.sources["pg-password"])
+	log.Info("pg-type", "value", c.PgType, "source", c.flags.sources["pg-type"])
+	log.Info("pg-host-bin-dir", "value", c.PgHostBinDir, "source", c.flags.sources["pg-host-bin-dir"])
+	log.Info(
+		"pg-docker-container-name",
+		"value",
+		c.PgDockerContainerName,
+		"source",
+		c.flags.sources["pg-docker-container-name"],
+	)
+	log.Info("wal-dir", "value", c.WalDir, "source", c.flags.sources["wal-dir"])
+	log.Info(
+		"delete-wal-after-upload",
+		"value",
+		fmt.Sprintf("%v", *c.IsDeleteWalAfterUpload),
+		"source",
+		c.flags.sources["delete-wal-after-upload"],
+	)
 }

 func maskSensitive(value string) string {
--- a/agent/internal/config/config_test.go
+++ b/agent/internal/config/config_test.go
@@ -86,10 +86,12 @@ func Test_LoadFromJSONAndArgs_PartialArgsOverrideJSON(t *testing.T) {
 func Test_SaveToJSON_ConfigSavedCorrectly(t *testing.T) {
 	setupTempDir(t)

+	deleteWal := true
 	cfg := &Config{
-		DatabasusHost: "http://save-host:4005",
-		DbID:          "save-db-id",
-		Token:         "save-token",
+		DatabasusHost:          "http://save-host:4005",
+		DbID:                   "save-db-id",
+		Token:                  "save-token",
+		IsDeleteWalAfterUpload: &deleteWal,
 	}

 	err := cfg.SaveToJSON()
@@ -126,6 +128,143 @@ func Test_SaveToJSON_AfterArgsOverrideJSON_SavedFileContainsMergedValues(t *test
 	assert.Equal(t, "json-token", saved.Token)
 }

+func Test_LoadFromJSONAndArgs_PgFieldsLoadedFromJSON(t *testing.T) {
+	dir := setupTempDir(t)
+	deleteWal := false
+	writeConfigJSON(t, dir, Config{
+		DatabasusHost:          "http://json-host:4005",
+		DbID:                   "json-db-id",
+		Token:                  "json-token",
+		PgHost:                 "pg-json-host",
+		PgPort:                 5433,
+		PgUser:                 "pg-json-user",
+		PgPassword:             "pg-json-pass",
+		PgType:                 "docker",
+		PgHostBinDir:           "/usr/bin",
+		PgDockerContainerName:  "pg-container",
+		WalDir:                 "/opt/wal",
+		IsDeleteWalAfterUpload: &deleteWal,
+	})
+
+	cfg := &Config{}
+	fs := flag.NewFlagSet("test", flag.ContinueOnError)
+	cfg.LoadFromJSONAndArgs(fs, []string{})
+
+	assert.Equal(t, "pg-json-host", cfg.PgHost)
+	assert.Equal(t, 5433, cfg.PgPort)
+	assert.Equal(t, "pg-json-user", cfg.PgUser)
+	assert.Equal(t, "pg-json-pass", cfg.PgPassword)
+	assert.Equal(t, "docker", cfg.PgType)
+	assert.Equal(t, "/usr/bin", cfg.PgHostBinDir)
+	assert.Equal(t, "pg-container", cfg.PgDockerContainerName)
+	assert.Equal(t, "/opt/wal", cfg.WalDir)
+	assert.Equal(t, false, *cfg.IsDeleteWalAfterUpload)
+}
+
+func Test_LoadFromJSONAndArgs_PgFieldsLoadedFromArgs(t *testing.T) {
+	setupTempDir(t)
+
+	cfg := &Config{}
+	fs := flag.NewFlagSet("test", flag.ContinueOnError)
+	cfg.LoadFromJSONAndArgs(fs, []string{
+		"--pg-host", "arg-pg-host",
+		"--pg-port", "5433",
+		"--pg-user", "arg-pg-user",
+		"--pg-password", "arg-pg-pass",
+		"--pg-type", "docker",
+		"--pg-host-bin-dir", "/custom/bin",
+		"--pg-docker-container-name", "my-pg",
+		"--wal-dir", "/var/wal",
+	})
+
+	assert.Equal(t, "arg-pg-host", cfg.PgHost)
+	assert.Equal(t, 5433, cfg.PgPort)
+	assert.Equal(t, "arg-pg-user", cfg.PgUser)
+	assert.Equal(t, "arg-pg-pass", cfg.PgPassword)
+	assert.Equal(t, "docker", cfg.PgType)
+	assert.Equal(t, "/custom/bin", cfg.PgHostBinDir)
+	assert.Equal(t, "my-pg", cfg.PgDockerContainerName)
+	assert.Equal(t, "/var/wal", cfg.WalDir)
+}
+
+func Test_LoadFromJSONAndArgs_PgArgsOverrideJSON(t *testing.T) {
+	dir := setupTempDir(t)
+	writeConfigJSON(t, dir, Config{
+		PgHost: "json-host",
+		PgPort: 5432,
+		PgUser: "json-user",
+		PgType: "host",
+		WalDir: "/json/wal",
+	})
+
+	cfg := &Config{}
+	fs := flag.NewFlagSet("test", flag.ContinueOnError)
+	cfg.LoadFromJSONAndArgs(fs, []string{
+		"--pg-host", "arg-host",
+		"--pg-port", "5433",
+		"--pg-user", "arg-user",
+		"--pg-type", "docker",
+		"--pg-docker-container-name", "my-container",
+		"--wal-dir", "/arg/wal",
+	})
+
+	assert.Equal(t, "arg-host", cfg.PgHost)
+	assert.Equal(t, 5433, cfg.PgPort)
+	assert.Equal(t, "arg-user", cfg.PgUser)
+	assert.Equal(t, "docker", cfg.PgType)
+	assert.Equal(t, "my-container", cfg.PgDockerContainerName)
+	assert.Equal(t, "/arg/wal", cfg.WalDir)
+}
+
+func Test_LoadFromJSONAndArgs_DefaultsApplied_WhenNoJSONAndNoArgs(t *testing.T) {
+	setupTempDir(t)
+
+	cfg := &Config{}
+	fs := flag.NewFlagSet("test", flag.ContinueOnError)
+	cfg.LoadFromJSONAndArgs(fs, []string{})
+
+	assert.Equal(t, 5432, cfg.PgPort)
+	assert.Equal(t, "host", cfg.PgType)
+	require.NotNil(t, cfg.IsDeleteWalAfterUpload)
+	assert.Equal(t, true, *cfg.IsDeleteWalAfterUpload)
+}
+
+func Test_SaveToJSON_PgFieldsSavedCorrectly(t *testing.T) {
+	setupTempDir(t)
+
+	deleteWal := false
+	cfg := &Config{
+		DatabasusHost:          "http://host:4005",
+		DbID:                   "db-id",
+		Token:                  "token",
+		PgHost:                 "pg-host",
+		PgPort:                 5433,
+		PgUser:                 "pg-user",
+		PgPassword:             "pg-pass",
+		PgType:                 "docker",
+		PgHostBinDir:           "/usr/bin",
+		PgDockerContainerName:  "pg-container",
+		WalDir:                 "/opt/wal",
+		IsDeleteWalAfterUpload: &deleteWal,
+	}
+
+	err := cfg.SaveToJSON()
+	require.NoError(t, err)
+
+	saved := readConfigJSON(t)
+
+	assert.Equal(t, "pg-host", saved.PgHost)
+	assert.Equal(t, 5433, saved.PgPort)
+	assert.Equal(t, "pg-user", saved.PgUser)
+	assert.Equal(t, "pg-pass", saved.PgPassword)
+	assert.Equal(t, "docker", saved.PgType)
+	assert.Equal(t, "/usr/bin", saved.PgHostBinDir)
+	assert.Equal(t, "pg-container", saved.PgDockerContainerName)
+	assert.Equal(t, "/opt/wal", saved.WalDir)
+	require.NotNil(t, saved.IsDeleteWalAfterUpload)
+	assert.Equal(t, false, *saved.IsDeleteWalAfterUpload)
+}
+
 func setupTempDir(t *testing.T) string {
 	t.Helper()

--- a/agent/internal/config/dto.go
+++ b/agent/internal/config/dto.go
@@ -1,9 +1,17 @@
 package config

 type parsedFlags struct {
-	host  *string
-	dbID  *string
-	token *string
+	databasusHost         *string
+	dbID                  *string
+	token                 *string
+	pgHost                *string
+	pgPort                *int
+	pgUser                *string
+	pgPassword            *string
+	pgType                *string
+	pgHostBinDir          *string
+	pgDockerContainerName *string
+	walDir                *string

 	sources map[string]string
 }
--- a/agent/internal/features/start/start.go
+++ b/agent/internal/features/start/start.go
@@ -1,17 +1,38 @@
 package start

 import (
+	"context"
 	"errors"
+	"fmt"
 	"log/slog"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/jackc/pgx/v5"

 	"databasus-agent/internal/config"
 )

+const (
+	pgBasebackupVerifyTimeout = 10 * time.Second
+	dbVerifyTimeout           = 10 * time.Second
+)
+
 func Run(cfg *config.Config, log *slog.Logger) error {
 	if err := validateConfig(cfg); err != nil {
 		return err
 	}

+	if err := verifyPgBasebackup(cfg, log); err != nil {
+		return err
+	}
+
+	if err := verifyDatabase(cfg, log); err != nil {
+		return err
+	}
+
 	log.Info("start: stub — not yet implemented",
 		"dbId", cfg.DbID,
 		"hasToken", cfg.Token != "",
@@ -33,5 +54,126 @@ func validateConfig(cfg *config.Config) error {
 		return errors.New("argument token is required")
 	}

+	if cfg.PgHost == "" {
+		return errors.New("argument pg-host is required")
+	}
+
+	if cfg.PgPort <= 0 {
+		return errors.New("argument pg-port must be a positive number")
+	}
+
+	if cfg.PgUser == "" {
+		return errors.New("argument pg-user is required")
+	}
+
+	if cfg.PgType != "host" && cfg.PgType != "docker" {
+		return fmt.Errorf("argument pg-type must be 'host' or 'docker', got '%s'", cfg.PgType)
+	}
+
+	if cfg.WalDir == "" {
+		return errors.New("argument wal-dir is required")
+	}
+
+	if cfg.PgType == "docker" && cfg.PgDockerContainerName == "" {
+		return errors.New("argument pg-docker-container-name is required when pg-type is 'docker'")
+	}
+
+	return nil
+}
+
+func verifyPgBasebackup(cfg *config.Config, log *slog.Logger) error {
+	switch cfg.PgType {
+	case "host":
+		return verifyPgBasebackupHost(cfg, log)
+	case "docker":
+		return verifyPgBasebackupDocker(cfg, log)
+	default:
+		return fmt.Errorf("unexpected pg-type: %s", cfg.PgType)
+	}
+}
+
+func verifyPgBasebackupHost(cfg *config.Config, log *slog.Logger) error {
+	binary := "pg_basebackup"
+	if cfg.PgHostBinDir != "" {
+		binary = filepath.Join(cfg.PgHostBinDir, "pg_basebackup")
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), pgBasebackupVerifyTimeout)
+	defer cancel()
+
+	output, err := exec.CommandContext(ctx, binary, "--version").CombinedOutput()
+	if err != nil {
+		if cfg.PgHostBinDir != "" {
+			return fmt.Errorf(
+				"pg_basebackup not found at '%s': %w. Verify pg-host-bin-dir is correct",
+				binary, err,
+			)
+		}
+
+		return fmt.Errorf(
+			"pg_basebackup not found in PATH: %w. Install PostgreSQL client tools or set pg-host-bin-dir",
+			err,
+		)
+	}
+
+	log.Info("pg_basebackup verified", "version", strings.TrimSpace(string(output)))
+
+	return nil
+}
+
+func verifyPgBasebackupDocker(cfg *config.Config, log *slog.Logger) error {
+	ctx, cancel := context.WithTimeout(context.Background(), pgBasebackupVerifyTimeout)
+	defer cancel()
+
+	output, err := exec.CommandContext(ctx,
+		"docker", "exec", cfg.PgDockerContainerName,
+		"pg_basebackup", "--version",
+	).CombinedOutput()
+	if err != nil {
+		return fmt.Errorf(
+			"pg_basebackup not available in container '%s': %w. "+
+				"Check that the container is running and pg_basebackup is installed inside it",
+			cfg.PgDockerContainerName, err,
+		)
+	}
+
+	log.Info("pg_basebackup verified (docker)",
+		"container", cfg.PgDockerContainerName,
+		"version", strings.TrimSpace(string(output)),
+	)
+
+	return nil
+}
+
+func verifyDatabase(cfg *config.Config, log *slog.Logger) error {
+	connStr := fmt.Sprintf(
+		"host=%s port=%d user=%s password=%s dbname=postgres sslmode=disable",
+		cfg.PgHost, cfg.PgPort, cfg.PgUser, cfg.PgPassword,
+	)
+
+	ctx, cancel := context.WithTimeout(context.Background(), dbVerifyTimeout)
+	defer cancel()
+
+	conn, err := pgx.Connect(ctx, connStr)
+	if err != nil {
+		return fmt.Errorf(
+			"failed to connect to PostgreSQL at %s:%d as user '%s': %w",
+			cfg.PgHost, cfg.PgPort, cfg.PgUser, err,
+		)
+	}
+	defer func() { _ = conn.Close(ctx) }()
+
+	if err := conn.Ping(ctx); err != nil {
+		return fmt.Errorf("PostgreSQL ping failed at %s:%d: %w",
+			cfg.PgHost, cfg.PgPort, err,
+		)
+	}
+
+	log.Info("PostgreSQL connection verified",
+		"host", cfg.PgHost,
+		"port", cfg.PgPort,
+		"user", cfg.PgUser,
+	)
+
 	return nil
 }
--- a/agent/internal/features/upgrade/dto.go
+++ b/agent/internal/features/upgrade/dto.go
@@ -0,0 +1,5 @@
+package upgrade
+
+type versionResponse struct {
+	Version string `json:"version"`
+}
--- a/agent/internal/features/upgrade/upgrader.go
+++ b/agent/internal/features/upgrade/upgrader.go
@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"log/slog"
 	"net/http"
 	"os"
 	"os/exec"
@@ -14,17 +15,7 @@ import (
 	"time"
 )

-type Logger interface {
-	Info(msg string, args ...any)
-	Warn(msg string, args ...any)
-	Error(msg string, args ...any)
-}
-
-type versionResponse struct {
-	Version string `json:"version"`
-}
-
-func CheckAndUpdate(databasusHost, currentVersion string, isDev bool, log Logger) error {
+func CheckAndUpdate(databasusHost, currentVersion string, isDev bool, log *slog.Logger) error {
 	if isDev {
 		log.Info("Skipping update check (development mode)")
 		return nil
@@ -32,7 +23,11 @@ func CheckAndUpdate(databasusHost, currentVersion string, isDev bool, log Logger

 	serverVersion, err := fetchServerVersion(databasusHost, log)
 	if err != nil {
-		return nil
+		return fmt.Errorf(
+			"unable to check version, please verify Databasus server is available at %s: %w",
+			databasusHost,
+			err,
+		)
 	}

 	if serverVersion == currentVersion {
@@ -74,7 +69,7 @@ func CheckAndUpdate(databasusHost, currentVersion string, isDev bool, log Logger
 	return syscall.Exec(selfPath, os.Args, os.Environ())
 }

-func fetchServerVersion(host string, log Logger) (string, error) {
+func fetchServerVersion(host string, log *slog.Logger) (string, error) {
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 	defer cancel()

--- a/agent/internal/logger/logger.go
+++ b/agent/internal/logger/logger.go
@@ -32,8 +32,6 @@ func Init(isDebug bool) {
 				return a
 			},
 		}))
-
-		loggerInstance.Info("Text structured logger initialized")
 	})
 }